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Sample records for ir emission features

  1. The IR emission features - Emission from PAH molecules and amorphous carbon particles

    NASA Technical Reports Server (NTRS)

    Allamandola, L. J.; Tielens, A. G. G. M.; Barker, J. R.

    1987-01-01

    Techniques for the assessment of the importance of the various forms of PAHs, and recent infrared observations concerning the PAH problem, are considered. Spectroscopic data suggest that the observed interstellar spectrum is due to both free molecule-sized PAHs producing the narrow features, and amorphous carbon particles contributing to the broad underlying components. Explanations for the multicomponent emission spectrum are discussed. A model of the emission mechanism for the example of chrysene is presented, and an exact treatment of the IR fluorescence from highly vibrationally excited large molecules shows that species containing 20-30 carbon atoms are responsible for the narrow features, although the spectra more closely resemble those of amorphous carbon particles. It is suggested that future emphasis should be placed on the spatial characteristics of the component spectra.

  2. The ir emission features: Emission from PAH (Polycyclic Aromatic Hydrocarbons) molecules and amorphous carbon particles

    SciTech Connect

    Allamandola, L.J.; Tielens, A.G.G.M.; Barker, J.R.

    1986-01-01

    PAHs can have several forms in the interstellar medium. To assess the importance of each requires the availability of a collection of high quality, complete mid-ir interstellar emission spectra, a collection of laboratory spectra of PAH samples prepared under realistic conditions and a firm understanding of the microscopic emission mechanism. Given what we currently know about PAHs, the spectroscopic data suggests that there are at least two components which contribute to the interstellar emission spectrum: free molecule sized PAHs producing the narrow features and amorphous carbon particles (which are primarily made up of an irregular ''lattice'' of PAHs) contributing to the broad underlying components. An exact treatment of the ir fluorescence from highly vibrationally excited large molecules shows that species containing between 20 and 30 carbon atoms are responsible for the narrow features, although the spectra match more closely with the spectra of amorphous carbon particles. Since little is known about the spectroscopic properties of free PAHs and PAH clusters, much laboratory work is called for in conjunction with an observational program which focuses on the spatial characteristics of the spectra. In this way the distribution and evolution of carbon from molecule to particle can be traced. 38 refs., 9 figs.

  3. The IR emission features - Emission from PAH molecules and amorphous carbon particles

    NASA Technical Reports Server (NTRS)

    Allamandola, L. J.; Tielens, A. G. G. M.; Barker, J. R.

    1987-01-01

    Given the current understanding of polycyclic aromatic hydrocarbons (PAHs), the spectroscopic data suggest that are at least two components which contribute to the interstellar emission spectrum: (1) free molecule-sized PAHs producing the narrow features and (2) amorphous carbon particles (which are primarily composed of an irregular 'lattice' of PAHs) contributing to the broad underlying components. An exact treatment of the IR fluorescence from highly vibrationally excited large molecules demonstrates that species containing between 20 and 30 carbon atoms are responsible for the narrow features, although the spectra match more closely with the spectra of amorphous carbon particles. It is concluded that, since little is known about the spectroscopic properties of free PAHs and PAH clusters, much laboratory work is required along with an observational program focusing on the spatial characteristics of the spectra.

  4. Multicolor IR emissive pixels

    NASA Astrophysics Data System (ADS)

    Lannon, J.; Grego, S.; Solomon, S.

    2007-04-01

    We have evaluated several methods for generating multi-color emission for IR scene projector applications. The baseline requirements we employed were the ability to simulate color temperatures in the range 300-3000 K, minimum radiance levels consistent with existing IR sensor requirements, 1000 Hz frame rates and manufacturability. The analysis led us to down select two independent approaches that are capable of meeting HWIL multicolor requirements. We describe and discuss each of the approaches, their expected performance as well as their limitations.

  5. Surface temperature measurements of heterogeneous explosives by IR emission

    SciTech Connect

    Henson, B.F.; Funk, D.J.; Dickson, P.M.; Fugard, C.S.; Asay, B.W.

    1998-03-01

    The authors present measurements of the integrated IR emission (1--5 {micro}m) from both the heterogeneous explosive PBX 9501 and pure HMX at calibrated temperatures from 300 C to 2,500 C. The IR power emitted as a function of temperature is that expected of a black body, attenuated by a unique temperature independent constant which the authors report as the thermal emissivity. The authors have utilized this calibration of IR emission in measurements of the surface temperature from PBX 9501 subject to 1 GPa, two dimensional impact, and spontaneous ignition in unconfined cookoff. They demonstrate that the measurement of IR emission in this spectral region provides a temperature probe of sufficient sensitivity to resolve the thermal response from the solid explosive throughout the range of weak mechanical perturbation, prolonged heating to ignition, and combustion.

  6. Constraining Cometary Crystal Shapes from IR Spectral Features

    NASA Technical Reports Server (NTRS)

    Wooden, Diane H.; Lindsay, Sean; Harker, David E.; Kelley, Michael S. P.; Woodward, Charles E.; Murphy, James Richard

    2013-01-01

    A major challenge in deriving the silicate mineralogy of comets is ascertaining how the anisotropic nature of forsterite crystals affects the spectral features' wavelength, relative intensity, and asymmetry. Forsterite features are identified in cometary comae near 10, 11.05-11.2, 16, 19, 23.5, 27.5 and 33 microns [1-10], so accurate models for forsterite's absorption efficiency (Qabs) are a primary requirement to compute IR spectral energy distributions (SEDs, lambdaF lambda vs. lambda) and constrain the silicate mineralogy of comets. Forsterite is an anisotropic crystal, with three crystallographic axes with distinct indices of refraction for the a-, b-, and c-axis. The shape of a forsterite crystal significantly affects its spectral features [13-16]. We need models that account for crystal shape. The IR absorption efficiencies of forsterite are computed using the discrete dipole approximation (DDA) code DDSCAT [11,12]. Starting from a fiducial crystal shape of a cube, we systematically elongate/reduce one of the crystallographic axes. Also, we elongate/reduce one axis while the lengths of the other two axes are slightly asymmetric (0.8:1.2). The most significant grain shape characteristic that affects the crystalline spectral features is the relative lengths of the crystallographic axes. The second significant grain shape characteristic is breaking the symmetry of all three axes [17]. Synthetic spectral energy distributions using seven crystal shape classes [17] are fit to the observed SED of comet C/1995 O1 (Hale-Bopp). The Hale-Bopp crystalline residual better matches equant, b-platelets, c-platelets, and b-columns spectral shape classes, while a-platelets, a-columns and c-columns worsen the spectral fits. Forsterite condensation and partial evaporation experiments demonstrate that environmental temperature and grain shape are connected [18-20]. Thus, grain shape is a potential probe for protoplanetary disk temperatures where the cometary crystalline

  7. Dust processing in photodissociation regions. Mid-IR emission modelling

    NASA Astrophysics Data System (ADS)

    Compiègne, M.; Abergel, A.; Verstraete, L.; Habart, E.

    2008-12-01

    Context: Mid-infrared spectroscopy of dense illuminated ridges (or photodissociation regions, PDRs) suggests dust evolution. Such evolution must be reflected in the gas physical properties through processes like photo-electric heating or H2 formation. Aims: With Spitzer Infrared Spectrograph (IRS) and ISOCAM data, we study the mid-IR emission of closeby, well known PDRs. Focusing on the band and continuum dust emissions, we follow their relative contributions and analyze their variations in terms of abundance of dust populations. Methods: In order to disentangle dust evolution and excitation effects, we use a dust emission model that we couple to radiative transfer. Our dust model reproduces extinction and emission of the standard interstellar medium that we represent with diffuse high galactic latitude clouds called Cirrus. We take the properties of dust in Cirrus as a reference to which we compare the dust emission from more excited regions, namely the Horsehead and the reflection nebula NGC 2023 North. Results: We show that in both regions, radiative transfer effects cannot account for the observed spectral variations. We interpret these variations in term of changes of the relative abundance between polycyclic aromatic hydrocarbons (PAHs, mid-IR band carriers) and very small grains (VSGs, mid-IR continuum carriers). Conclusions: We conclude that the PAH/VSG abundance ratio is 2.4 times smaller at the peak emission of the Horsehead nebula than in the Cirrus case. For NGC 2023 North where spectral evolution is observed across the northern PDR, we conclude that this ratio is ~5 times lower in the dense, cold zones of the PDR than in its diffuse illuminated part where dust properties seem to be the same as in Cirrus. We conclude that dust in PDRs seems to evolve from “dense” to “diffuse” properties at the small spatial scale of the dense illuminated ridge.

  8. Surface Emissivity Effects on Thermodynamic Retrieval of IR Spectral Radiance

    NASA Technical Reports Server (NTRS)

    Zhou, Daniel K.; Larar, Allen M.; Smith, William L.; Liu, Xu

    2006-01-01

    The surface emissivity effect on the thermodynamic parameters (e.g., the surface skin temperature, atmospheric temperature, and moisture) retrieved from satellite infrared (IR) spectral radiance is studied. Simulation analysis demonstrates that surface emissivity plays an important role in retrieval of surface skin temperature and terrestrial boundary layer (TBL) moisture. NAST-I ultraspectral data collected during the CLAMS field campaign are used to retrieve thermodynamic properties of the atmosphere and surface. The retrievals are then validated by coincident in-situ measurements, such as sea surface temperature, radiosonde temperature and moisture profiles. Retrieved surface emissivity is also validated by that computed from the observed radiance and calculated emissions based on the retrievals of surface temperature and atmospheric profiles. In addition, retrieved surface skin temperature and emissivity are validated together by radiance comparison between the observation and retrieval-based calculation in the window region where atmospheric contribution is minimized. Both simulation and validation results have lead to the conclusion that variable surface emissivity in the inversion process is needed to obtain accurate retrievals from satellite IR spectral radiance measurements. Retrieval examples are presented to reveal that surface emissivity plays a significant role in retrieving accurate surface skin temperature and TBL thermodynamic parameters.

  9. Constraining Cometary Crystal Shapes from IR Spectral Features

    NASA Astrophysics Data System (ADS)

    Wooden, D. H.; Lindsay, S.; Harker, D. E.; Kelley, M. S.; Woodward, C. E.; Murphy, J. R.

    2013-12-01

    A major challenge in deriving the silicate mineralogy of comets is ascertaining how the anisotropic nature of forsterite crystals affects the spectral features' wavelength, relative intensity, and asymmetry. Forsterite features are identified in cometary comae near 10, 11.05-11.2, 16, 19, 23.5, 27.5 and 33 μm [1-10], so accurate models for forsterite's absorption efficiency (Qabs) are a primary requirement to compute IR spectral energy distributions (SEDs, λFλ vs. λ) and constrain the silicate mineralogy of comets. Forsterite is an anisotropic crystal, with three crystallographic axes with distinct indices of refraction for the a-, b-, and c-axis. The shape of a forsterite crystal significantly affects its spectral features [13-16]. We need models that account for crystal shape. The IR absorption efficiencies of forsterite are computed using the discrete dipole approximation (DDA) code DDSCAT [11,12]. Starting from a fiducial crystal shape of a cube, we systematically elongate/reduce one of the crystallographic axes. Also, we elongate/reduce one axis while the lengths of the other two axes are slightly asymmetric (0.8:1.2). The most significant grain shape characteristic that affects the crystalline spectral features is the relative lengths of the crystallographic axes. The second significant grain shape characteristic is breaking the symmetry of all three axes [17]. Synthetic spectral energy distributions using seven crystal shape classes [17] are fit to the observed SED of comet C/1995 O1 (Hale-Bopp). The Hale-Bopp crystalline residual better matches equant, b-platelets, c-platelets, and b-columns spectral shape classes, while a-platelets, a-columns and c-columns worsen the spectral fits. Forsterite condensation and partial evaporation experiments demonstrate that environmental temperature and grain shape are connected [18-20]. Thus, grain shape is a potential probe for protoplanetary disk temperatures where the cometary crystalline forsterite formed. The

  10. Spectroscopy of the 3 micron emission features

    NASA Technical Reports Server (NTRS)

    Geballe, T. R.; Lacy, J. H.; Persson, S. E.; Mcgregor, P. J.; Soifer, B. T.

    1985-01-01

    High-spectral-resolution observations of the 3.3 and 3.4 microns features in the three planetary nebulae NGC 7027, IC 418, and BD +30 deg 3639, in the H II region S106, and in the 'red rectangle' HD 44179 are presented. The profile of the unidentified 3.3 microns emission feature is similar in all five sources. The unidentified feature previously referred to as the 3.4 microns feature actually consists of two components, a low-level emission from 3.35 to 3.60 microns and a narrow emission peak at 3.40 microns. The strength of the latter feature relative to that of the 3.3 microns feature varies by a a factor of three from source to source. The origin and properties of these features may be explained by further development of the small-grain models of Sellgren (1984) and Leger and Puget (1984).

  11. Global Land Surface Emissivity Retrieved From Satellite Ultraspectral IR Measurements

    NASA Technical Reports Server (NTRS)

    Zhou, D. K.; Larar, A. M.; Liu, Xu; Smith, W. L.; Strow, L. L.; Yang, Ping; Schlussel, P.; Calbet, X.

    2011-01-01

    Ultraspectral resolution infrared (IR) radiances obtained from nadir observations provide information about the atmosphere, surface, aerosols, and clouds. Surface spectral emissivity (SSE) and surface skin temperature from current and future operational satellites can and will reveal critical information about the Earth s ecosystem and land-surface-type properties, which might be utilized as a means of long-term monitoring of the Earth s environment and global climate change. In this study, fast radiative transfer models applied to the atmosphere under all weather conditions are used for atmospheric profile and surface or cloud parameter retrieval from ultraspectral and/or hyperspectral spaceborne IR soundings. An inversion scheme, dealing with cloudy as well as cloud-free radiances observed with ultraspectral IR sounders, has been developed to simultaneously retrieve atmospheric thermodynamic and surface or cloud microphysical parameters. This inversion scheme has been applied to the Infrared Atmospheric Sounding Interferometer (IASI). Rapidly produced SSE is initially evaluated through quality control checks on the retrievals of other impacted surface and atmospheric parameters. Initial validation of retrieved emissivity spectra is conducted with Namib and Kalahari desert laboratory measurements. Seasonal products of global land SSE and surface skin temperature retrieved with IASI are presented to demonstrate seasonal variation of SSE.

  12. THE ROLE OF THE ACCRETION DISK, DUST, AND JETS IN THE IR EMISSION OF LOW-LUMINOSITY ACTIVE GALACTIC NUCLEI

    SciTech Connect

    Mason, R. E.; Ramos Almeida, C.; Alonso-Herrero, A.

    2013-11-10

    We use recent high-resolution infrared (IR; 1-20 μm) photometry to examine the origin of the IR emission in low-luminosity active galactic nuclei (LLAGN). The data are compared with published model fits that describe the spectral energy distribution (SED) of LLAGN in terms of an advection-dominated accretion flow, truncated thin accretion disk, and jet. The truncated disk in these models is usually not luminous enough to explain the observed IR emission, and in all cases its spectral shape is much narrower than the broad IR peaks in the data. Synchrotron radiation from the jet appears to be important in very radio-loud nuclei, but the detection of strong silicate emission features in many objects indicates that dust must also contribute. We investigate this point by fitting the IR SED of NGC 3998 using dusty torus and optically thin (τ{sub mid-IR} ∼ 1) dust shell models. While more detailed modeling is necessary, these initial results suggest that dust may account for the nuclear mid-IR emission of many LLAGN.

  13. UV extinction and IR emission in diffuse H2 regions

    NASA Technical Reports Server (NTRS)

    Aannestad, Per A.

    1994-01-01

    HII regions occupy a unique position in our understanding of the physical relationships between stars, the interstellar medium, and galactic structure. Observations show a complex interaction between a newly formed hot star and its surroundings. In particular, the ultraviolet radiation from the stars modifies the pre-existing dust, which again affects both the amount of ionizing radiation absorbed by the gas, and the infrared spectrum emitted by the heated dust. The aim of this project was to use UV and far-UV observations to gain information on the nebular dust, and to use this dust to model the far-IR emission, for a consistent picture of a few selected diffuse HII regions. Using archival data from the IUE and Voyager data banks and computed model atmospheres, we have deduced extinction curves for early-types stars. The requisite spectral resolution turned out to be a major task. We have successfully modelled these curves in terms of a multi-component, multi-size distribution of dust grains, and interpret the differences in the curves as primarily due to the presence or non-presence of intermediate size grains (0.01 to 0.04 micron). Much smaller (0.005 micron) grains must also be present. Finally, we have made calculations of the temperature fluctuations and the corresponding infra-red emission in such small grains.

  14. Robust Ground Target Detection by SAR and IR Sensor Fusion Using Adaboost-Based Feature Selection

    PubMed Central

    Kim, Sungho; Song, Woo-Jin; Kim, So-Hyun

    2016-01-01

    Long-range ground targets are difficult to detect in a noisy cluttered environment using either synthetic aperture radar (SAR) images or infrared (IR) images. SAR-based detectors can provide a high detection rate with a high false alarm rate to background scatter noise. IR-based approaches can detect hot targets but are affected strongly by the weather conditions. This paper proposes a novel target detection method by decision-level SAR and IR fusion using an Adaboost-based machine learning scheme to achieve a high detection rate and low false alarm rate. The proposed method consists of individual detection, registration, and fusion architecture. This paper presents a single framework of a SAR and IR target detection method using modified Boolean map visual theory (modBMVT) and feature-selection based fusion. Previous methods applied different algorithms to detect SAR and IR targets because of the different physical image characteristics. One method that is optimized for IR target detection produces unsuccessful results in SAR target detection. This study examined the image characteristics and proposed a unified SAR and IR target detection method by inserting a median local average filter (MLAF, pre-filter) and an asymmetric morphological closing filter (AMCF, post-filter) into the BMVT. The original BMVT was optimized to detect small infrared targets. The proposed modBMVT can remove the thermal and scatter noise by the MLAF and detect extended targets by attaching the AMCF after the BMVT. Heterogeneous SAR and IR images were registered automatically using the proposed RANdom SAmple Region Consensus (RANSARC)-based homography optimization after a brute-force correspondence search using the detected target centers and regions. The final targets were detected by feature-selection based sensor fusion using Adaboost. The proposed method showed good SAR and IR target detection performance through feature selection-based decision fusion on a synthetic database generated

  15. Robust Ground Target Detection by SAR and IR Sensor Fusion Using Adaboost-Based Feature Selection.

    PubMed

    Kim, Sungho; Song, Woo-Jin; Kim, So-Hyun

    2016-01-01

    Long-range ground targets are difficult to detect in a noisy cluttered environment using either synthetic aperture radar (SAR) images or infrared (IR) images. SAR-based detectors can provide a high detection rate with a high false alarm rate to background scatter noise. IR-based approaches can detect hot targets but are affected strongly by the weather conditions. This paper proposes a novel target detection method by decision-level SAR and IR fusion using an Adaboost-based machine learning scheme to achieve a high detection rate and low false alarm rate. The proposed method consists of individual detection, registration, and fusion architecture. This paper presents a single framework of a SAR and IR target detection method using modified Boolean map visual theory (modBMVT) and feature-selection based fusion. Previous methods applied different algorithms to detect SAR and IR targets because of the different physical image characteristics. One method that is optimized for IR target detection produces unsuccessful results in SAR target detection. This study examined the image characteristics and proposed a unified SAR and IR target detection method by inserting a median local average filter (MLAF, pre-filter) and an asymmetric morphological closing filter (AMCF, post-filter) into the BMVT. The original BMVT was optimized to detect small infrared targets. The proposed modBMVT can remove the thermal and scatter noise by the MLAF and detect extended targets by attaching the AMCF after the BMVT. Heterogeneous SAR and IR images were registered automatically using the proposed RANdom SAmple Region Consensus (RANSARC)-based homography optimization after a brute-force correspondence search using the detected target centers and regions. The final targets were detected by feature-selection based sensor fusion using Adaboost. The proposed method showed good SAR and IR target detection performance through feature selection-based decision fusion on a synthetic database generated

  16. Robust Ground Target Detection by SAR and IR Sensor Fusion Using Adaboost-Based Feature Selection.

    PubMed

    Kim, Sungho; Song, Woo-Jin; Kim, So-Hyun

    2016-07-19

    Long-range ground targets are difficult to detect in a noisy cluttered environment using either synthetic aperture radar (SAR) images or infrared (IR) images. SAR-based detectors can provide a high detection rate with a high false alarm rate to background scatter noise. IR-based approaches can detect hot targets but are affected strongly by the weather conditions. This paper proposes a novel target detection method by decision-level SAR and IR fusion using an Adaboost-based machine learning scheme to achieve a high detection rate and low false alarm rate. The proposed method consists of individual detection, registration, and fusion architecture. This paper presents a single framework of a SAR and IR target detection method using modified Boolean map visual theory (modBMVT) and feature-selection based fusion. Previous methods applied different algorithms to detect SAR and IR targets because of the different physical image characteristics. One method that is optimized for IR target detection produces unsuccessful results in SAR target detection. This study examined the image characteristics and proposed a unified SAR and IR target detection method by inserting a median local average filter (MLAF, pre-filter) and an asymmetric morphological closing filter (AMCF, post-filter) into the BMVT. The original BMVT was optimized to detect small infrared targets. The proposed modBMVT can remove the thermal and scatter noise by the MLAF and detect extended targets by attaching the AMCF after the BMVT. Heterogeneous SAR and IR images were registered automatically using the proposed RANdom SAmple Region Consensus (RANSARC)-based homography optimization after a brute-force correspondence search using the detected target centers and regions. The final targets were detected by feature-selection based sensor fusion using Adaboost. The proposed method showed good SAR and IR target detection performance through feature selection-based decision fusion on a synthetic database generated

  17. The Secret IR Lives of Cepheids: Spitzer IRS Spectroscopy of Circumstellar Envelopes, Winds and Chromospheric Emissions in Nearby Cepheids

    NASA Astrophysics Data System (ADS)

    Guinan, Edward; Engle, Scott; Evans, Nancy; Harper, Graham; Marenago, Massimo

    2007-05-01

    We are carrying out an intensive study of the physical and evolutionary properties of Classical Cepheids, known as the 'Secret Lives of Cepheids' (SLiC) program. This program covers a wide range of periods and pulsation amplitudes, and makes use of X-ray/UV/optical observations. The major science goals of our proposed Spitzer program are to investigate two recently discovered characteristics of Classical Cepheids, hitherto unknown. These are the presence of circumstellar envelopes (CSEs) around three nearby Cepheids (Polaris, delta Cep and L Car - all SLiC program stars), and the existence of O VI (1032/36A) and C III (977A) emission lines in the far-UV spectra of two program stars - Polaris and beta Dor. These lines form in the chromospheres/transition regions of the Cepheids and, in the case of beta Dor, show variations that correlate to the pulsations of the star. We propose SST/IRS high-resolution spectroscopy of these four nearby, bright Classical Cepheids, three of which have been found, from long-baseline near-IR interferometry, to have CSEs ~0.5-3.0 AU from the central star. From the proposed IRS spectra, we will determine the physical characteristics of the circumstellar material/envelopes, likely arising from mass loss or, given the young ages of Cepheids, debris disks. Also, we will use the IRS spectra to explore the presence of emission lines related to those discovered in the far-UV. Possible low density He I and H I wind lines will also be measured, if present. As in the case of the FUSE far-UV observations, SST/IRS also provides the opportunity to observe and measure these emission lines at wavelengths where the Cepheid photospheric continua are very low. In the near-UV to near-IR regions, emission lines are overwhelmed by the photospheric continua. With the modest amount of time requested (~1.86-hours), the proposed IRS observations will be crucial in understanding these newly discovered characteristics of Astronomy's most important and 'best

  18. Far-IR Absorption Features of Titan Aerosol Analogs Produced from Aromatic Precursors

    NASA Astrophysics Data System (ADS)

    Sebree, Joshua; Trainer, M. G.; Anderson, C. M.; Loeffler, M. J.

    2012-10-01

    The arrival of the Cassini spacecraft in orbit around Saturn has led to the discovery of benzene (C6H6) at ppm levels, as well as large positive ions in Titan’s atmosphere, tentatively identified as polycyclic aromatic hydrocarbons (PAHs).[1] The presence of aromatic molecules, which are photolytically active in the ultraviolet, may be an important part of the formation of aerosol particles in Titan’s haze layers, even at these low concentrations. To date, there have been no laboratory experiments in the literature exploring this area of study. The analysis of data from the Composite Infrared Spectrometer (CIRS) on-board Cassini has recently uncovered a broad emission feature centered at 140 cm-1 in the far-IR that is unique to the aerosol layers of Titan’s atmosphere.[2] Current optical constants from laboratory-generated aerosol analogs have been unable to reproduce this feature.[3,4] From the broadness of this feature, we speculate that the emission is a blended composite of low-energy vibrations of large molecules such as PAHs and their nitrogen containing counterparts, polycyclic aromatic nitrogen heterocycles (PANHs). We hypothesize that the inclusion of trace amounts of aromatic precursors will aid in the production of these large structures in the laboratory-generated aerosols. In this study, we perform UV irradiation of several aromatic precursors, both with and without nitrogen heteroatoms, to understand their influence on the observable characteristics of the aerosol. Measured optical and chemical properties will be compared to those formed from CH4/N2 mixtures [5,6] as well as to those from Cassini observations. [1] Waite, J. H., et al. (2007) Science 316 870-875. [2] Anderson, C.M, et al. (2011) Icarus 212 762-778. [3] Khare, B.N., et al. (1984) Icarus 60 127-137. [4] Imanaka, H., et al. (2012) Icarus 218 247-261. [5] Trainer, M.G., et al. (2006) PNAS 103 18035-18042. [6] Trainer, M.G., et al. (2012) Astrobiology 12 315-326.

  19. RADIO MONITORING OF THE PERIODICALLY VARIABLE IR SOURCE LRLL 54361: NO DIRECT CORRELATION BETWEEN THE RADIO AND IR EMISSIONS

    SciTech Connect

    Forbrich, Jan; Rodríguez, Luis F.; Palau, Aina; Zapata, Luis A.; Muzerolle, James; Gutermuth, Robert A.

    2015-11-20

    LRLL 54361 is an infrared source located in the star-forming region IC 348 SW. Remarkably, its infrared luminosity increases by a factor of 10 over roughly one week every 25.34 days. To understand the origin of these remarkable periodic variations, we obtained sensitive 3.3 cm JVLA radio continuum observations of LRLL 54361 and its surroundings in six different epochs: three of them during the IR-on state and three during the IR-off state. The radio source associated with LRLL 54361 remained steady and did not show a correlation with the IR variations. We suggest that the IR is tracing the results of fast (with a timescale of days) pulsed accretion from an unseen binary companion, while the radio traces an ionized outflow with an extent of ∼100 AU that smooths out the variability over a period of the order of a year. The average flux density measured in these 2014 observations, 27 ± 5 μJy, is about a factor of two less than that measured about 1.5 years before, 53 ± 11 μJy, suggesting that variability in the radio is present, but over larger timescales than in the IR. We discuss other sources in the field, in particular two infrared/X-ray stars that show rapidly varying gyrosynchrotron emission.

  20. Transmittance, Reflectance, and Emission Spectroscopy of Meteorites from the UV to the IR Spectral Range

    NASA Astrophysics Data System (ADS)

    Maturilli, A.; Helbert, J.; Koulen, J. M.; Ferrari, S.; Martellato, E.

    2016-08-01

    Transmittance, reflectance, and emissivity Spectra of six meteorites have been collected at the Planetary Spectroscopy Laboratory (PSL) of DLR in Berlin in the whole spectral range from the UV to the IR.

  1. Communication: IR spectroscopy of neutral transition metal clusters through thermionic emission.

    PubMed

    Lapoutre, Vivike J F; Haertelt, Marko; Meijer, Gerard; Fielicke, André; Bakker, Joost M

    2013-09-28

    The resonant multiple photon excitation of neutral niobium clusters using tunable infrared (IR) radiation leads to thermionic emission. By measuring the mass-resolved ionization yield as a function of IR wavenumber species selective IR spectra are obtained for Nb(n) (n = 5-20) over the 200-350 cm(-1) spectral range. The IR resonance-enhanced multiple photon ionization spectra obtained this way are in good agreement with those measured using IR photodissociation of neutral Nb(n)-Ar clusters. An investigation of the factors determining the applicability of this technique identifies the internal energy threshold towards thermionic emission in combination with a minimum required photon flux that rapidly grows as a function of excitation wavelength.

  2. Mid-IR Spectra of HED Meteorites and Synthetic Pyroxenes: Reststrahlen Features (9-12 micron)

    NASA Technical Reports Server (NTRS)

    Lim, Lucy F.; Emery, Joshua P.; Moskovitz, Nicholas A.

    2010-01-01

    In an earlier study. Hamilton (2000) mapped the behavior of the 9-12 micron reststrahlen structures with composition in a suite of primarily natural terrestrial pyroxenes. Here we examine the same set of reststrahlen features in the spectra of diogenites and eucrites and place them in the context of the terrestrial samples and of a suite of well-characterized synthetic pyroxenes. The results will be useful to the interpretation of mid-IR spectra of 4 Vesta and other basaltic asteroids.

  3. The Luminous Polycyclic Aromatic Hydrocarbon Emission Features: Applications to High Redshift Galaxies and Active Galactic Nuclei

    NASA Astrophysics Data System (ADS)

    Shipley, Heath V.

    2016-01-01

    For decades, significant work has been applied to calibrating emission from the ultra-violet, nebular emission lines, far-infrared, X-ray and radio as tracers of the star-formation rate (SFR) in distant galaxies. Understanding the exact rate of star-formation and how it evolves with time and galaxy mass has deep implications for how galaxies form. The co-evolution of star-formation and supermassive black hole (SMBH) accretion is one of the key problems in galaxy formation theory. But, many of these SFR indicators are influenced by SMBH accretion in galaxies and result in unreliable SFRs. Utilizing the luminous polycyclic aromatic hydrocarbon (PAH) emission features, I provide a new robust SFR calibration using the luminosity emitted from the PAHs at 6.2μm, 7.7μm and 11.3μm to solve this. The PAH features emit strongly in the mid-infrared (mid-IR; 5-25μm) mitigating dust extinction, containing on average 5-10% of the total IR luminosity in galaxies. I use a sample of 105 star-forming galaxies covering a range of total IR luminosity, LIR = L(8-1000μm) = 109 - 1012 L⊙ and redshift 0 < z < 0.4, with mid-IR spectroscopy from the Spitzer Infrared Spectrograph (IRS), and data covering other SFR indicators (Hα emission and rest-frame 24μm continuum emission). The PAH luminosity correlates linearly with the SFR as measured by the Hα luminosity (corrected for attenuation using the mono-chromatic rest-frame 24μm emission), with a tight scatter of <0.15 dex. The scatter is comparable to that between SFRs derived from the Paα and dust-corrected Hα emission lines. We present a case study in advance of JWST, which will be capable of measuring SFRs (from 8μm rest-frame photometry, i.e. PAHs) in distant galaxies (z ≤ 2) with JWST/MIRI to SFRs as low as ~10 M⊙yr-1, because the PAH features are so bright. We use Spitzer/IRS observations of PAH features in lensed star-forming galaxies at 1 < z < 3 to demonstrate the utility of the PAHs to derive SFRs that agree with

  4. c2d Spitzer IRS spectra of embedded low-mass young stars: gas-phase emission lines

    NASA Astrophysics Data System (ADS)

    Lahuis, F.; van Dishoeck, E. F.; Jørgensen, J. K.; Blake, G. A.; Evans, N. J.

    2010-09-01

    Context. A survey of mid-infrared gas-phase emission lines of H2, H2O and various atoms toward a sample of 43 embedded low-mass young stars in nearby star-forming regions is presented. The sources are selected from the Spitzer “Cores to Disks” (c2d) legacy program. Aims: The environment of embedded protostars is complex both in its physical structure (envelopes, outflows, jets, protostellar disks) and the physical processes (accretion, irradiation by UV and/or X-rays, excitation through slow and fast shocks) which take place. The mid-IR spectral range hosts a suite of diagnostic lines which can distinguish them. A key point is to spatially resolve the emission in the Spitzer-IRS spectra to separate extended PDR and shock emission from compact source emission associated with the circumstellar disk and jets. Methods: An optimal extraction method is used to separate both spatially unresolved (compact, up to a few hundred AU) and spatially resolved (extended, thousand AU or more) emission from the IRS spectra. The results are compared with the c2d disk sample and literature PDR and shock models to address the physical nature of the sources. Results: Both compact and extended emission features are observed. Warm (T_ex few hundred K) H2, observed through the pure rotational H2 S(0), S(1) and S(2) lines, and [S i] 25 μm emission is observed primarily in the extended component. [S i] is observed uniquely toward truly embedded sources and not toward disks. On the other hand hot (T_ex ⪆ 700 K) H2, observed primarily through the S(4) line, and [Ne ii] emission is seen mostly in the spatially unresolved component. [Fe ii] and [Si ii] lines are observed in both spatial components. Hot H2O emission is found in the spatially unresolved component of some sources. Conclusions: The observed emission on ≥1000 AU scales is characteristic of PDR emission and likely originates in the outflow cavities in the remnant envelope created by the stellar wind and jets from the embedded

  5. A search for excess mid-IR emission from cataclysmic variables

    NASA Astrophysics Data System (ADS)

    Dubus, G.; Campbell, R.; Kern, B.; Taam, R.; Spruit, H.

    Cataclysmic variables (CVs) regularly eject matter through winds and novae outbursts. A small fraction of this material may stay bound and accumulate around the binary in a disk. The strong braking exerted on the red dwarf by such a circumbinary (CB) disk would explain several puzzles in our current understanding of CV evolution. Thermal emission from CB disks could easily have gone unnoticed since the mid-IR emission of CVs remains largely unexplored. We present the results of a near- and mid-IR survey of 8 CVs obtained at the Keck I in Sep. 2002.

  6. The origin of the diffuse galactic IR/submm emission: Revisited after IRAS

    NASA Technical Reports Server (NTRS)

    Cox, P.; Mezger, P. G.

    1987-01-01

    Balloon observations are compared with Infrared Astronomy Satellite observations. There was good agreement for the longitudinal profiles. However, the dust emission observed by IRAS, contrary to the balloon observations which show dust emission only within the absolute value of b is equal to or less than 3 degrees, extends all the way to the galactic pole. The model fits were repeated using more recent parameters for the distribution of interstellar matter in the galactic disk and central region. The IR luminosities are derived for the revised galactic distance scale of solar radius - 8.5 Kpc. A total IR luminosity of 1.2 E10 solar luminosity is obtained, which is about one third of the estimated stellar luminosity of the Galaxy. The dust emission spectrum lambdaI(sub lambda) attains it maximum at 100 microns. A secondary maximum in the dust emission spectrum occurs at 10 microns, which contains 15% of the total IR luminosity of the Galaxy. The galactic dust emission spectrum was compared with the dust emission spectra of external IRAS galaxies. The warm dust luminosity relates to the present OB star formation rate, while flux densities observed at longer submm wavelengths are dominated by cold dust emission and thus can be used to estimate gas masses.

  7. Internal thermal emission analysis of an IR seeker

    NASA Astrophysics Data System (ADS)

    Brown, Daniel M.

    1992-09-01

    The focal plane of an infrared seeker was plagued with ghost images and nonuniform stray light irradiance. Teledyne Brown Engineering was tasked to determine the irradiance source and propose inexpensive solutions to the problems. First order analysis approximately modeled the focal plane irradiance and showed a serious flaw in the design. A design flaw allowed normal internally emitted thermal radiation to develop into a high level, nonuniform, focal plane irradiance. Exact ray tracing software, developed by the author, computed focal plane irradiance distributions which closely matched measured distributions. The software performs a non-sequential surface ray trace, splitting rays at partially reflecting surfaces (using a recursive algorithm), and computes internal thermal emission. The stray light problems could have been avoided in a design with the cold stop as the system aperture stop. This paper shows the method of analysis, results, and proposed solutions to the problem. This work demonstrates how infrared optical design requires precautions and considerations. Methods and tools which work well in visible optical design may not work in infrared optical design.

  8. AGN are cooler than you think: the intrinsic far-IR emission from QSOs

    NASA Astrophysics Data System (ADS)

    Symeonidis, M.; Giblin, B. M.; Page, M. J.; Pearson, C.; Bendo, G.; Seymour, N.; Oliver, S. J.

    2016-06-01

    We present an intrinsic AGN spectral energy distribution (SED) extending from the optical to the submm, derived with a sample of unobscured, optically luminous (νLν,5100 > 1043.5 erg s-1) QSOs at z < 0.18 from the Palomar Green survey. The intrinsic AGN SED was computed by removing the contribution from stars using the 11.3 μm polycyclic aromatic hydrocarbon (PAH) feature in the QSOs' mid-IR spectra; the 1σ uncertainty on the SED ranges between 12 and 45 per cent as a function of wavelength and is a combination of PAH flux measurement errors and the uncertainties related to the conversion between PAH luminosity and star-forming luminosity. Longwards of 20 μm, the shape of the intrinsic AGN SED is independent of the AGN power indicating that our template should be applicable to all systems hosting luminous AGN (νLν, 5100 or L_X(2-10 keV) ≳ 1043.5 erg s-1). We note that for our sample of luminous QSOs, the average AGN emission is at least as high as, and mostly higher than, the total stellar powered emission at all wavelengths from the optical to the submm. This implies that in many galaxies hosting powerful AGN, there is no `safe' broad-band photometric observation (at λ < 1000 μm) which can be used in calculating star formation rates without subtracting the AGN contribution. Roughly, the AGN contribution may be ignored only if the intrinsic AGN luminosity at 5100 AA is at least a factor of 4 smaller than the total infrared luminosity (LIR, 8-1000 μm) of the galaxy. Finally, we examine the implication of our work in statistical studies of star formation in AGN host galaxies.

  9. Positron emission tomography features of hidradenitis suppurativa

    PubMed Central

    Simpson, R C; Dyer, M J S; Entwisle, J; Harman, K E

    2011-01-01

    A 35-year-old male with classical Hodgkin's lymphoma (nodular sclerosing, grade 1 histology, clinical stage 2A) underwent a positron emission tomography (PET) scan to assess response to treatment. Half body CT PET imaging was obtained using a Siemens Biograph scanner from eyes to thighs. 405 MBq of 18-fluorodeoxyglucose (FDG) was injected with acquisition starting at 60 min. There was unexpected intense focal uptake in the superficial subcutaneous tissues of the abdomen, pelvis and lateral chest wall with overlying skin thickening seen on the CT component. This was initially of concern, but the patient was known to have a history of hidradenitis suppurativa (HS). On further examination, the radiological abnormalities corresponded to the clinical sites of involvement. To the best of our knowledge, this is the first documentation of the appearance of HS on PET scan. PMID:21750134

  10. Detecting early IR emission from dust heated by a tidal disruption flare

    NASA Astrophysics Data System (ADS)

    van Velzen, Sjoert; Gezari, Suvi; Hung, Tiara; Cenko, Bradley; Gorjian, Varoujan

    2016-06-01

    A stellar tidal disruption flare (TDF) occurs when a star gets too close to a supermassive black hole and is shredded into streams that are accreted. New TDFs can be discovered by their transient optical or X-ray emission. We have recently made a discovery that opens a new wavelength regime for the study of these flares: transient emission at 3 micron in WISE multi-epoch imaging. This emission is best understood as originating from dust that has been heated by the intense UV and X-ray emission of the flare. However, the 6-month cadence of the WISE observations is too low to critically test this dust reprocessing model. Using optical observations of the iPTF survey, we recently discovered a very strong TDF candidate that is currenlty only a few weeks past maximum light. Since TDFs are rare, this new source provides an unique oppurtunity for Spitzer to make a very important contribution to this field. We proposed 7 Spitzer follow-up observations of this flare, which would yield the first early-time light curve of IR emission from a tidal flare. This data will be crucial to estabilish (or rule-out) dust reprocessing as the origin of IR emission from TDFs.

  11. Features of gallstone and kidney stone fragmentation by IR-pulsed Nd:YAG laser radiation

    NASA Astrophysics Data System (ADS)

    Batishche, Sergei A.

    1995-05-01

    It is shown that infra-red ((lambda) equals 1064 nm) long pulse (approximately 100 microsecond(s) ) radiation of YAG:Nd laser, operating in free generation regime, effectively fragments gallstones, urinary calculus and kidney stones. The features of the mechanism of this process are investigated. Laser lithotripsy is nowadays a method widely used for fragmentation of gallstones, urinary calculus and kidney stones. Flashlamp pumped dye lasers of microsecond duration are most often used for such purposes. Nevertheless, there are some reports on lithotripsies with nanosecond duration laser pulses (for example, Q-switched YAG:Nd laser). The mechanism of the laser fragmentation of such stones was supposed to be the next. The laser powerful radiation, delivered through the optical fiber, is absorbed by the material of the stone. As a result of such highly localized energy absorption, dense plasma is formed, which expands. Such plasma and vapor, liquid confined, forms a cavitation bubble. This bubble grows, reaches its most dimension and then collapses on itself in some hundreds of micro seconds. Shock waves generated during the growth and the collapse of these bubbles are the origin of fragmentation of the stone. It is necessary to say that there are rather confined data on the hundreds microsecond laser pulse fragmentation especially what concerns the usage of infra-red (IR) YAG:Nd lasers with long laser pulses. Clearing this problem would result in better understanding of the fragmentation mechanism and it could favor development of simple and more reliable laser systems for lithotripsy. In this work we report about investigation of features of an effective fragmentation of gallstones, urinary calculus and kidney stones under exposure of IR ((lambda) equals 1064 nm) radiation of repetitive YAG:Nd laser working in free generation regime.

  12. Characterization of protein and carbohydrate mid-IR spectral features in crop residues

    NASA Astrophysics Data System (ADS)

    Xin, Hangshu; Zhang, Yonggen; Wang, Mingjun; Li, Zhongyu; Wang, Zhibo; Yu, Peiqiang

    2014-08-01

    To the best of our knowledge, a few studies have been conducted on inherent structure spectral traits related to biopolymers of crop residues. The objective of this study was to characterize protein and carbohydrate structure spectral features of three field crop residues (rice straw, wheat straw and millet straw) in comparison with two crop vines (peanut vine and pea vine) by using Fourier transform infrared spectroscopy (FTIR) technique with attenuated total reflectance (ATR). Also, multivariate analyses were performed on spectral data sets within the regions mainly related to protein and carbohydrate in this study. The results showed that spectral differences existed in mid-IR peak intensities that are mainly related to protein and carbohydrate among these crop residue samples. With regard to protein spectral profile, peanut vine showed the greatest mid-IR band intensities that are related to protein amide and protein secondary structures, followed by pea vine and the rest three field crop straws. The crop vines had 48-134% higher spectral band intensity than the grain straws in spectral features associated with protein. Similar trends were also found in the bands that are mainly related to structural carbohydrates (such as cellulosic compounds). However, the field crop residues had higher peak intensity in total carbohydrates region than the crop vines. Furthermore, spectral ratios varied among the residue samples, indicating that these five crop residues had different internal structural conformation. However, multivariate spectral analyses showed that structural similarities still exhibited among crop residues in the regions associated with protein biopolymers and carbohydrate. Further study is needed to find out whether there is any relationship between spectroscopic information and nutrition supply in various kinds of crop residue when fed to animals.

  13. Characterization of protein and carbohydrate mid-IR spectral features in crop residues.

    PubMed

    Xin, Hangshu; Zhang, Yonggen; Wang, Mingjun; Li, Zhongyu; Wang, Zhibo; Yu, Peiqiang

    2014-08-14

    To the best of our knowledge, a few studies have been conducted on inherent structure spectral traits related to biopolymers of crop residues. The objective of this study was to characterize protein and carbohydrate structure spectral features of three field crop residues (rice straw, wheat straw and millet straw) in comparison with two crop vines (peanut vine and pea vine) by using Fourier transform infrared spectroscopy (FTIR) technique with attenuated total reflectance (ATR). Also, multivariate analyses were performed on spectral data sets within the regions mainly related to protein and carbohydrate in this study. The results showed that spectral differences existed in mid-IR peak intensities that are mainly related to protein and carbohydrate among these crop residue samples. With regard to protein spectral profile, peanut vine showed the greatest mid-IR band intensities that are related to protein amide and protein secondary structures, followed by pea vine and the rest three field crop straws. The crop vines had 48-134% higher spectral band intensity than the grain straws in spectral features associated with protein. Similar trends were also found in the bands that are mainly related to structural carbohydrates (such as cellulosic compounds). However, the field crop residues had higher peak intensity in total carbohydrates region than the crop vines. Furthermore, spectral ratios varied among the residue samples, indicating that these five crop residues had different internal structural conformation. However, multivariate spectral analyses showed that structural similarities still exhibited among crop residues in the regions associated with protein biopolymers and carbohydrate. Further study is needed to find out whether there is any relationship between spectroscopic information and nutrition supply in various kinds of crop residue when fed to animals.

  14. The luminous polycyclic aromatic hydrocarbon emission features: Applications to high redshift galaxies and active galactic nuclei

    NASA Astrophysics Data System (ADS)

    Shipley, Heath Vernon

    The co-evolution of star-formation and supermassive black hole (SMBH) accretion in galaxies is one of the key problems in galaxy formation theory. Understanding the formation of galaxies, and their subsequent evolution, will be coupled to intensive study of the evolution of SMBHs. This thesis focuses on studying diagnostics of star-formation and SMBH accretion to develop tools to study this co-evolution. Chapter 2 consists of using mid-infrared (mid-IR) spectroscopy from the Spitzer Infrared Spectrograph (IRS) to study the nature of star-formation and SMBH accretion. The mid-IR spectra cover wavelengths 5-38mum, spanning the polycyclic aromatic hydrocarbon (PAH) features and important atomic diagnostic lines. We divide our sample into a subsample of galaxies with Spitzer IRAC colors indicative of warm dust heated by an AGN (IRAGN) and those galaxies whose colors indicate star-formation processes (non-IRAGN). In both the IRAGN and star-forming samples, the luminosity in the PAH features correlates strongly with [Ne II]lambda12.8&mum emission line, from which we conclude that the PAH luminosity directly traces the instantaneous star-formation rate (SFR) in both the IRAGN and star-forming galaxies. There is no measurable difference between the PAH luminosity ratios of L11:3/L7:7 and L6:2/L7:7 for the IRAGN and non-IRAGN, suggesting that AGN do not significantly excite or destroy PAH molecules on galaxy-wide scales. In chapter 3, I calibrate the PAH luminosity as a SFR indicator. We provide a new robust SFR calibration using the luminosity emitted from PAH molecules at 6.2mum, 7.7mum and 11.3mum. The PAH features emit strongly in the mid-IR mitigating dust extinction, containing on average 5--10% of the total IR luminosity in galaxies. We use mid-IR spectroscopy from the Spitzer/IRS, and data covering other SFR indicators (Halpha emission and rest-frame 24mum continuum emission). The PAH luminosity correlates linearly with the SFR as measured by the Halpha luminosity

  15. C-H Hot Bands in the Near-IR Emission Spectra of Leonids

    NASA Technical Reports Server (NTRS)

    Freund, F. T.; Scoville, J.; Holm, R.; Seelemann, R.; Freund, M. M.

    2002-01-01

    The reported infrared (IR) emission spectra from 1999 Leonid fireballs show a 3.4 micron C-H emission band and unidentified bands at longer wavelengths. Upon atmospheric entry, the Leonid meteorites were flash-heated to temperatures around 2400K, which would destroy any organics on the surface of the meteorite grains. We propose that the nu(sub )CH emission band in the Leonid emission spectra arises from matrix-embedded C(sub n)-H-O entities that are protected from instant pyrolysis. Our model is based on IR absorption nu(sub )CH bands, which we observed in laboratory-grown MgO and natural olivine single crystals, where they arise from C(sub n)-H-O units imbedded in the mineral matrix, indicative of aliphatic -CH2- and -CH3 organics. Instead of being pyrolyzed, the C(sub n)-H-O entities in the Leonid trails become vibrationally excited to higher levels n = 1, 2, 3 etc. During de-excitation they emit at 3.4 microns, due to the (0 => 1) transition, and at longer wavelengths, due to hot bands. As a first step toward verifying this hypothesis we measured the C-H vibrational manifold of hexane (C6H14). The calculated positions of the (2 => l ) , (3 => 2), and possibly (4 => 3) hot bands agree with the Leonid emission bands at 3.5, 3.8 and 4.l microns.

  16. Evaluation of angle dependence in spectral emissivity of ceramic tiles measured by FT-IR

    NASA Astrophysics Data System (ADS)

    Kobayashi, C.; Ogasawara, N.; Yamada, H.; Yamada, S.; Kikuchi, T.

    2015-05-01

    Ceramic tiles are widely used for building walls. False detections are caused in inspections by infrared thermography because of the infrared reflection and angle dependence of emissivity. As the first problem, ceramic tile walls are influenced from backgrounds reflection. As the second problem, in inspection for tall buildings, the camera angles are changed against the height. Thus, to reveal the relation between the emissivity and angles is needed. However, there is very little data about it. It is impossible to decrease the false detection on ceramic tile walls without resolving these problems; background reflection and angle dependence of emissivity. In this study, the angle problem was investigated. The purpose is to establish a revision method in the angle dependence of the emissivity for infrared thermography. To reveal the relation between the emissivity and angles, the spectral emissivity of a ceramic tile at various angles was measured by FT-IR and infrared thermographic instrument. These two experimental results were compared with the emissivity-angle curves from the theoretical formula. In short wavelength range, the two experimental results showed similar behavior, but they did not agree with the theoretical curve. This will be the subject of further study. In long wavelength range, the both experimental results almost obeyed the theoretical curve. This means that it is possible to revise the angle dependence of spectral emissivity, for long wavelength range.

  17. Spatial variations of the 3 micron emission features within nebulae

    NASA Technical Reports Server (NTRS)

    Moorhouse, Alan; Geballe, T. R.; Allamandola, Louis J.

    1989-01-01

    The 3 micron spectra is presented for the Orion bar region and the Red Rectangle. In both objects spectra were obtained at more than one location, corresponding to different distances from the excitation source. The well known 3.3 and 3.4 micron emission bands are seen in both objects as well as the recently discovered features at 3.46, 3.51, and 3.57 microns in the Orion bar spectra. The spectra show that the relative strengths of the 3 micron emission features vary within the Orion bar. As distance from the exciting star increases, the 3.4 and 3.51 micron features increase, and the 3.46 micron feature decreases in strength, relative to the strong 3.3 micron feature. These are two possible interpretations which are postulated, each of which involves the breaking of bonds by UV radiation, which removes the modes responsible for the 3.4 micron emission near the star. The two possible bond ruptures are the CH bond in small polycyclic aromatic hydrocarbons (PAHs), or the bond to an aliphatic subgroup. It has to be pointed out that neither interpretation appears entirely satisfactory. The vibrational overtone interpretation cannot explain the presence or behavior of the 3.46 micron feature, whereas the laboratory spectra of aliphatic sidegroups contain many more features in the 3 micron region than are observed in the astronomical sources.

  18. Investigating the origin of emissivity features in airless body spectra

    NASA Astrophysics Data System (ADS)

    Greenhagen, B. T.; Bowles, N. E.; Thomas, I.; Donaldson Hanna, K. L.

    2013-12-01

    It has long been noted that mid-infrared emissivity features remote observations of airless bodies do not generally match reflectance and ambient thermal emission laboratory measurements. Recently Vernazza et al., (2012) conducted reflectance experiments and successfully reproduced spectral differences by doping a fine (<30 micron) particulate samples of meteorite and/or minerals with KBr (potassium bromide) powder, which is transparent in the infrared. Their results suggest that porosity and/or cavity effects are significant in modifying the observed spectra of asteroids and derived values of surface thermal inertia. At similar wavelengths, the lunar community has long supported the theory that radiative transfer was a driving phenomenon through the creation of strong thermal gradients in the upper 100 microns of a particulate surface (e.g. Logan et al., 1973; Henderson et al., 1995). These thermal gradients are steep within the depth of thermal emission causing a strong wavelength dependence to the observed thermal emission spectrum. For example, strong absorptions like Reststrahlen Bands emit from the colder, shallower surface while strongly transparent features such as the Christiansen Feature emit from the warmer, deeper surface. To study these effects, we have built simulated airless body thermal emission chambers at University of Oxford and JPL (Thomas et al., 2012). In this study we investigate both radiative transfer and porosity phenomenon by measuring KBr-doped samples in reflectance and both ambient and simulated airless body emission.

  19. Unusual features in the persistent emission of the Rapid Burster

    NASA Technical Reports Server (NTRS)

    Lubin, Lori M.; Lewin, Walter H. G.; Van Paradijs, Jan; Van Der Klis, Michiel

    1993-01-01

    Several distinct features in the persistent X-ray emission after long (greater than 30 s) type II bursts from the Rapid Burster were discovered in August 1985. A specific pattern characterized by a 'hump' was observed in the early portion of the persistent emission after type II bursts with integrated fluxes less than about 4.8 x 10 exp -6 erg/sq cm. This hump which typically lasts about 200 s is almost never observed after bursts with fluences greater than this value. The emission during the hump is found to be always harder than the average persistent emission. Quasi-periodic oscillations with frequencies of about 40 mHz observed in 10 cases occur exclusively during a hump. The persistent emission also exhibited sharp 'glitches' and small 'bumps' lasting about 20-100 s. The glitches always occurred at the same phase in the intervals between bursts. In seven cases the glitches were followed by a bump.

  20. Toward Unraveling the Nature of the Mysterious 21 and 30 Micrometer Emission Features of Evolved Stars

    NASA Astrophysics Data System (ADS)

    Mishra, Ajay; Li, A.

    2014-01-01

    The mysterious "21 micrometer" emission feature seen almost exclusively in the short-lived protoplanetary nebula (PPN) phase of stellar evolution remains unidentified since its discovery two decades ago. This feature is always accompanied by the equally mysterious, unidentified "30 micrometer" feature and the so-called “unidentified infrared” (UIR) features generally attributed to polycyclic aromatic hydrocarbon (PAH) molecules. The 30 micrometer feature is commonly observed in all stages of stellar evolution from the asymptotic giant branch (AGB) through PPN to the planetary nebula phase. We explore the interrelations among the mysterious 21 micrometer, 30 micrometer, and UIR features in the Galactic and Magellanic Cloud 21 micrometer sources. We derive the fluxes emitted in the observed UIR, 21 micrometer, and 30 micrometer features from published ISO or Spitzer/IRS spectra. To derive the stellar mass loss rates of these 21 micrometer sources, we use the 2-dust radiative transfer code for axisymmetric dusty systems to model their dust infrared emission. We found that --- (1) The 30 micrometer feature does not seem to positively correlate with the 21 micrometer feature. This argues against the hypothesis of thiourea and aliphatic chains (attached to various carbonaceous structures) as the common carriers for both the 21 and 30 micrometer features; (2) The 21 micrometer feature does not correlate with the UIR features. This argues against large PAH clusters as a possible carrier for the 21 micrometer feature. (3) The 30 micrometer feature and the UIR features appear to weakly correlate, suggesting that the UIR carriers (e.g. PAHs) may result from the decomposition or shattering of the 30 micrometer feature carrier; and (4) The 21 micrometer feature and UIR features seem to weakly correlate with the stellar mass loss rates while the 30 micrometer feature appears to weakly anti-correlate with the stellar mass loss rates, suggesting that the UIR and 21 micrometer

  1. Single photon infrared emission spectroscopy: a study of IR emission from UV laser excited PAHs between 3 and 15 micrometers.

    PubMed

    Cook, D J; Schlemmer, S; Balucani, N; Wagner, D R; Harrison, J A; Steiner, B; Saykally, R J

    1998-02-26

    Single-photon infrared emission spectroscopy (SPIRES) has been used to measure emission spectra from polycyclic aromatic hydrocarbons (PAHs). A supersonic free-jet expansion has been used to provide emission spectra of rotationally cold and vibrationally excited naphthalene and benzene. Under these conditions, the observed width of the 3.3-micrometers (C-H stretch) band resembles the bandwidths observed in experiments in which emission is observed from naphthalene with higher rotational energy. To obtain complete coverage of IR wavelengths relevant to the unidentified infrared bands (UIRs), UV laser-induced desorption was used to generate gas-phase highly excited PAHs. Lorentzian band shapes were convoluted with the monochromator-slit function in order to determine the widths of PAH emission bands under astrophysically relevant conditions. Bandwidths were also extracted from bands consisting of multiple normal modes blended together. These parameters are grouped according to the functional groups mostly involved in the vibration, and mean bandwidths are obtained. These bandwidths are larger than the widths of the corresponding UIR bands. However, when the comparison is limited to the largest PAHs studied, the bandwidths are slightly smaller than the corresponding UIR bands. These parameters can be used to model emission spectra from PAH cations and cations of larger PAHs, which are better candidate carriers of the UIRs.

  2. Single photon infrared emission spectroscopy: a study of IR emission from UV laser excited PAHs between 3 and 15 micrometers

    NASA Technical Reports Server (NTRS)

    Cook, D. J.; Schlemmer, S.; Balucani, N.; Wagner, D. R.; Harrison, J. A.; Steiner, B.; Saykally, R. J.

    1998-01-01

    Single-photon infrared emission spectroscopy (SPIRES) has been used to measure emission spectra from polycyclic aromatic hydrocarbons (PAHs). A supersonic free-jet expansion has been used to provide emission spectra of rotationally cold and vibrationally excited naphthalene and benzene. Under these conditions, the observed width of the 3.3-micrometers (C-H stretch) band resembles the bandwidths observed in experiments in which emission is observed from naphthalene with higher rotational energy. To obtain complete coverage of IR wavelengths relevant to the unidentified infrared bands (UIRs), UV laser-induced desorption was used to generate gas-phase highly excited PAHs. Lorentzian band shapes were convoluted with the monochromator-slit function in order to determine the widths of PAH emission bands under astrophysically relevant conditions. Bandwidths were also extracted from bands consisting of multiple normal modes blended together. These parameters are grouped according to the functional groups mostly involved in the vibration, and mean bandwidths are obtained. These bandwidths are larger than the widths of the corresponding UIR bands. However, when the comparison is limited to the largest PAHs studied, the bandwidths are slightly smaller than the corresponding UIR bands. These parameters can be used to model emission spectra from PAH cations and cations of larger PAHs, which are better candidate carriers of the UIRs.

  3. Variations of the Mid-IR Aromatic Features Inside and Among Galaxies

    NASA Technical Reports Server (NTRS)

    Galliano, F.; Madden, S.C.; Tielens, A. G. G. M.; Peeters, E.; Jones, A. P.

    2007-01-01

    We present the results of a systematic study of mid-IR spectra of Galactic regions, Magellanic H II regions, and galaxies of various types (dwarf, spiral, starburst), observed by the satellites ISO and Spitzer. We study the relative variations of the 6.2, 7.7, 8.6 and 11.3 micron features inside spatially resolved objects (such as M 82, M 51, 30 Doradus, M 17 and the Orion bar), as well as among 90 integrated spectra of 50 objects. Our main results are that the 6.2, 7.7 and 8.6 micron bands are essentially tied together, while the ratios between these bands and the 11.3 micron band varies by one order of magnitude. This implies that the properties of the PAHs are remarkably universal throughout our sample, and that the relative variations of the band ratios are mainly controlled by the fraction of ionized PAHs. In particular, we show that we can rule out the modification of the PAH size distribution as an explanation of these variations. Using a few well-studied Galactic regions (including the spectral image of the Orion bar), we give an empirical relation between the I(6.2)/I(11.3) ratio and the ionization/recombination ratio Go/n(sub e) x square root of(T(sub gas)). Finally, we discuss the physical interpretation of the I(6.2)/I(11.3) ratio, on galactic size scales.

  4. Dual emission from an ortho-metalated Ir(III) complex

    SciTech Connect

    King, K.A.; Watts, R.J.

    1987-03-04

    Several complexes of Ir(III) containing both the bidentate N-coordinating ligand 2,2'-bipyridine (bpy) and the N,C-orthometalating ligand 2-phenylpyridine (ppy) have recently been prepared; these include the two species Ir(ppy)/sub 2/(bpy)/sup +/ (A) and Ir(ppy)(bpy)/sub 2//sup 2 +/ (B). The former was prepared from the dichloro-bridged dimer, (Ir(ppy)/sub 2/Cl)/sub 2/, by modification of the procedure of Nonoyama while the latter was obtained by reaction of cis-(Ir(bpy)/sub 2/(OSO/sub 2/CF/sub 3/)/sub 2/) (CF/sub 3/SO/sub 3/) with ppy in refluxing 2-ethoxyethanol. The purity of the complexes was monitored with thin-layer chromatography using silica gel plates and 1:1:1 acetone/methanol/water mixtures for elution. Samples of the complexes used in these studies showed only one component in thin-layer chromatography. While only one isomer of B is possible, there are three possible isomers of A. Data from /sup 1/H and /sup 13/C NMR experiments indicate that A has C/sub 2/ symmetry. The NMR spectrum indicates, as does thin-layer chromatography, that only a single isomer of A is present with no detectable impurities due to a mixture of isomers. While X-ray structural data for A are lacking, structural data for related complexes suggest that A is the isomer with cisoid metal-carbon bonds and bpy metal-nitrogen bonds transoid to the metal-carbon bonds and bpy metal-nitrogen bonds transoid to the metal-carbon bonds. These species were prepared in order to probe further the effects of metal-carbon bonding on energy-transfer processes and electron-transfer reactions of metal complexes. Emission spectroscopic studies reported here reveal unusual and distinct intramolecular energy-transfer behavior in these complexes. Whereas dual emission from the former is observed in glasses at 77 K, a single emission is observed in the latter.

  5. Supporting Ease-of-Use and User Control: Desired Features and Structure of Web-Based Online IR Systems.

    ERIC Educational Resources Information Center

    Xie, Hong

    2003-01-01

    Describes a study that investigated users' perceptions of ease of use versus user control in Web-based online information retrieval (IR) systems. Discusses desired features and functionalities as well as desired interface structures that support both ease of use and user control. (Author/LRW)

  6. Foreground Bias from Parametric Models of Far-IR Dust Emission

    NASA Astrophysics Data System (ADS)

    Kogut, A.; Fixsen, D. J.

    2016-08-01

    We use simple toy models of far-IR dust emission to estimate the accuracy to which the polarization of the cosmic microwave background can be recovered using multi-frequency fits, if the parametric form chosen for the fitted dust model differs from the actual dust emission. Commonly used approximations to the far-IR dust spectrum yield CMB residuals comparable to or larger than the sensitivities expected for the next generation of CMB missions, despite fitting the combined CMB + foreground emission to precision 0.1% or better. The Rayleigh-Jeans approximation to the dust spectrum biases the fitted dust spectral index by {{Δ }}{β }d=0.2 and the inflationary B-mode amplitude by {{Δ }}r=0.03. Fitting the dust to a modified blackbody at a single temperature biases the best-fit CMB by {{Δ }}r\\gt 0.003 if the true dust spectrum contains multiple temperature components. A 13-parameter model fitting two temperature components reduces this bias by an order of magnitude if the true dust spectrum is in fact a simple superposition of emission at different temperatures, but fails at the level {{Δ }}r=0.006 for dust whose spectral index varies with frequency. Restricting the observing frequencies to a narrow region near the foreground minimum reduces these biases for some dust spectra but can increase the bias for others. Data at THz frequencies surrounding the peak of the dust emission can mitigate these biases while providing a direct determination of the dust temperature profile.

  7. Foreground Bias from Parametric Models of Far-IR Dust Emission

    NASA Technical Reports Server (NTRS)

    Kogut, A.; Fixsen, D. J.

    2016-01-01

    We use simple toy models of far-IR dust emission to estimate the accuracy to which the polarization of the cosmic microwave background can be recovered using multi-frequency fits, if the parametric form chosen for the fitted dust model differs from the actual dust emission. Commonly used approximations to the far-IR dust spectrum yield CMB residuals comparable to or larger than the sensitivities expected for the next generation of CMB missions, despite fitting the combined CMB plus foreground emission to precision 0.1 percent or better. The Rayleigh-Jeans approximation to the dust spectrum biases the fitted dust spectral index by (Delta)(Beta)(sub d) = 0.2 and the inflationary B-mode amplitude by (Delta)(r) = 0.03. Fitting the dust to a modified blackbody at a single temperature biases the best-fit CMB by (Delta)(r) greater than 0.003 if the true dust spectrum contains multiple temperature components. A 13-parameter model fitting two temperature components reduces this bias by an order of magnitude if the true dust spectrum is in fact a simple superposition of emission at different temperatures, but fails at the level (Delta)(r) = 0.006 for dust whose spectral index varies with frequency. Restricting the observing frequencies to a narrow region near the foreground minimum reduces these biases for some dust spectra but can increase the bias for others. Data at THz frequencies surrounding the peak of the dust emission can mitigate these biases while providing a direct determination of the dust temperature profile.

  8. A Systematic Search for the Spectra with Features of Crystalline Silicates in the Spitzer IRS Enhanced Products

    NASA Astrophysics Data System (ADS)

    Chen, Rui; Luo, Ali; Liu, Jiaming; Jiang, Biwei

    2016-06-01

    The crystalline silicate features are mainly reflected in infrared bands. The Spitzer Infrared Spectrograph (IRS) collected numerous spectra of various objects and provided a big database to investigate crystalline silicates in a wide range of astronomical environments. We apply the manifold ranking algorithm to perform a systematic search for the spectra with crystalline silicate features in the Spitzer IRS Enhanced Products available. In total, 868 spectra of 790 sources are found to show the features of crystalline silicates. These objects are cross-matched with the SIMBAD database as well as with the Large Sky Area Multi-object Fiber Spectroscopic Telescope (LAMOST)/DR2. The average spectrum of young stellar objects shows a variety of features dominated either by forsterite or enstatite or neither, while the average spectrum of evolved objects consistently present dominant features of forsterite in AGB, OH/IR, post-AGB, and planetary nebulae. They are identified optically as early-type stars, evolved stars, galaxies and so on. In addition, the strength of spectral features in typical silicate complexes is calculated. The results are available through CDS for the astronomical community to further study crystalline silicates.

  9. A High Spatial Resolution Study of Far IR Emission of Galaxies

    NASA Technical Reports Server (NTRS)

    Caldwell, Barrie A.

    2000-01-01

    This grant funded observations, data reduction, professional publications and travel for scientific efforts on the Kuiper Airborne Observatory. The research project was successfully completed. New insights into the distribution of far infrared emission across star forming regions was obtained, and student training was achieved. The efforts contributed towards new observing strategies, such as calibration and intercomparison of data from different infrared astronomical observing platforms, that will impact future NASA missions, such as SOFIA. The results of the effort have been presented in several papers in the refereed literature, including: "The Structure of IR Luminous Galaxies at 100 Microns". " Far Infrared Thermal Emission from the Inner Cooling Flow Region of NGC1275". "Distribution of Light in the "Dusty Hand" Galaxy NGC2146".

  10. Improving HJ-1B IRS land surface temperature product using ASTER global emissivity database

    NASA Astrophysics Data System (ADS)

    Li, H.; Hu, T.; Meng, X.; Yongming, D.; Cao, B.; Liu, Q.

    2015-12-01

    Land surface temperature (LST) is a key parameter for hydrological, meteorological, climatological and environmental studies. Currently many operational LST products have been generated using European and American satellite data, i.e., the Advanced Very High Resolution Radiometer (AVHRR), Advanced Along-Track Scanning Radiometer (AATSR) and Moderate Resolution Imaging Spectroradiometer (MODIS). However, few LST product has been produced using Chinese satellite data. Thus, the objective of this study is to generate reliable LST product using Chinese HJ-1B satellite data. The HJ-1B satellite of China, were launched on September 6, 2008, which are used for disaster and environment monitoring. IRS (Infrared Scanner) is one of the key instruments onboard HJ-1B satellite, it can scan the earth every four days, has four spectral bands ranging from the near-infrared to thermal infrared bands (band 1 0.75 - 1.10μm, band 2 1.55-1.75μm, MIR band 3 3.50 - 3.90μm, band 4 10.5-12.5μm) with 720 km swath. It scans ±29° from nadir and the spatial resolution for band1-3 is 150m and 300m for band4. In this study, a single-channel parametric model (SC-PM) algorithm were used to produce 300m LST product from HJ-1B IRS data. The NCEP atmospheric profiles and a parametric model were used for atmospheric correction. In order to improve the accuracy of the land surface emissivity (LSE), the 1km ASTER Global Emissivity Database (GED) and self-developed 5-day 1km vegetation cover product were used for estimating the LSE based on the Vegetation Cover Method. Two years of HJ-1B IRS LST product in Heihe River basin (Gansu province, China) from June 2012 to June 2014 were generated. The LST products were evaluated against ground observations in an arid area of northwest China during the Heihe Watershed Allied Telemetry Experimental Research (HiWATER) experiment. Four barren surface sites and ten vegetated sites were chosen for the evaluation. The results show that the developed HJ-1B IRS

  11. Error analysis for retrieval of Venus' IR surface emissivity from VIRTIS/VEX measurements

    NASA Astrophysics Data System (ADS)

    Kappel, David; Haus, Rainer; Arnold, Gabriele

    2015-08-01

    Venus' surface emissivity data in the infrared can serve to explore the planet's geology. The only global data with high spectral, spatial, and temporal resolution and coverage at present is supplied by nightside emission measurements acquired by the Visible and InfraRed Thermal Imaging Spectrometer VIRTIS-M-IR (1.0 - 5.1 μm) aboard ESA's Venus Express. A radiative transfer simulation and a retrieval algorithm can be used to determine surface emissivity in the nightside spectral transparency windows located at 1.02, 1.10, and 1.18 μm. To obtain satisfactory fits to measured spectra, the retrieval pipeline also determines auxiliary parameters describing cloud properties from a certain spectral range. But spectral information content is limited, and emissivity is difficult to retrieve due to strong interferences from other parameters. Based on a selection of representative synthetic VIRTIS-M-IR spectra in the range 1.0 - 2.3 μm, this paper investigates emissivity retrieval errors that can be caused by interferences of atmospheric and surface parameters, by measurement noise, and by a priori data, and which retrieval pipeline leads to minimal errors. Retrieval of emissivity from a single spectrum is shown to fail due to extremely large errors, although the fits to the reference spectra are very good. Neglecting geologic activity, it is suggested to apply a multi-spectrum retrieval technique to retrieve emissivity relative to an initial value as a parameter that is common to several measured spectra that cover the same surface bin. Retrieved emissivity maps of targets with limited extension (a few thousand km) are then additively renormalized to remove spatially large scale deviations from the true emissivity map that are due to spatially slowly varying interfering parameters. Corresponding multi-spectrum retrieval errors are estimated by a statistical scaling of the single-spectrum retrieval errors and are listed for 25 measurement repetitions. For the best of the

  12. A New Star Formation Rate Calibration from Polycyclic Aromatic Hydrocarbon Emission Features and Application to High-redshift Galaxies

    NASA Astrophysics Data System (ADS)

    Shipley, Heath V.; Papovich, Casey; Rieke, George H.; Brown, Michael J. I.; Moustakas, John

    2016-02-01

    We calibrate the integrated luminosity from the polycyclic aromatic hydrocarbon (PAH) features at 6.2, 7.7, and 11.3 μm in galaxies as a measure of the star formation rate (SFR). These features are strong (containing as much as 5%-10% of the total infrared luminosity) and suffer minimal extinction. Our calibration uses Spitzer Infrared Spectrograph (IRS) measurements of 105 galaxies at 0 < z < 0.4, infrared (IR) luminosities of 109-1012 {L}⊙ , combined with other well-calibrated SFR indicators. The PAH luminosity correlates linearly with the SFR as measured by the extinction-corrected Hα luminosity over the range of luminosities in our calibration sample. The scatter is 0.14 dex, comparable to that between SFRs derived from the Paα and extinction-corrected Hα emission lines, implying that the PAH features may be as accurate an SFR indicator as hydrogen recombination lines. The PAH SFR relation depends on gas-phase metallicity, for which we supply an empirical correction for galaxies with 0.2 < Z ≲ 0.7 {Z}⊙ . We present a case study in advance of the James Webb Space Telescope (JWST), which will be capable of measuring SFRs from PAHs in distant galaxies at the peak of the SFR density in the universe (z ˜ 2) with SFRs as low as ˜10 {M}⊙ {{yr}}-1. We use Spitzer/IRS observations of the PAH features and Paα emission plus Hα measurements in lensed star-forming galaxies at 1 < z < 3 to demonstrate the ability of the PAHs to derive accurate SFRs. We also demonstrate that because the PAH features dominate the mid-IR fluxes, broadband mid-IR photometric measurements from JWST will both trace the SFR and provide a way to exclude galaxies dominated by an active galactic nucleus.

  13. SiO and H2O maser emission in OH/IR objects and late-type variable stars

    NASA Technical Reports Server (NTRS)

    Nyman, L.-A.; Johansson, L. E. B.; Booth, R. S.

    1986-01-01

    A four-year search for 86-GHz SiO and H2O maser emission towards about 20 unidentified OH/IR objects and about 35 optically identified variable stars has yielded information on the temporal variations of many of these sources. The SiO maser emission is noted to behave differently in OH/IR objects as compared with Mira variables. An attempt is made to explain the appearance of strong masers in both vibrational states solely at the 43 GHz transition, under the assumption that an intrinsically weak pump mechanism generates weak (v=1, J=2-1) emission.

  14. Investigating the Enigmatic Ultraviolet 2175 A Extinction Feature and Correlation with Infrared Aromatic/PAH emission in M101

    NASA Astrophysics Data System (ADS)

    Gordon, Karl

    2011-10-01

    The 2175 Angstrom ultraviolet dust extinction feature has been known for more than 45 years, but the source of the extinction has yet to be positively identified. One of the leading contenders in dust grain models is small aromatic/PAHs grains. Through IR observations of HII regions in the spiral galaxy M101, PAHs have measured emission strengths that dramatically weaken at large radii and ionizations. The parameter space of these HII regions in terms of metallicity, ionization, and PAH emission strengths is the largest of any known galaxy. To explore the connection between the 2175 A extinction feature and IR aromatic/PAH emission strengths, we propose to observe the six regions in M101 {5 HII and the nucleus} using near-UV and far-UV gratings {G230L/G140L} with the MAMA detectors on STIS. The STIS instrument provides the opportunity to obtain high S/N UV spectra integrated over the same large spatial scales of the previous IR observations { 78 square arcsec} in minimal time {2 orbits per region}. From the measured spectra, we will employ stellar evolutionary synthesis and radiative transfer models to extract the intrinsic strength of the 2175 A extinction feature. The 2175 A features strengths will be compared with the published emission strengths of five different aromatic/PAH features in all six regions. If the 2175 A feature is associated with aromatic/PAHs grains, we will see a strong correlation. The lack of a strong correlation will imply the need for significant modification of leading dust models.

  15. Particular features of the application of IR reflection spectroscopy methods in studies in archeology and paleontology

    NASA Astrophysics Data System (ADS)

    Zolotarev, V. M.; Khlopachev, G. A.

    2013-06-01

    We have considered an optical model of a porous rough surface with optical properties of objects (bone, flint) that are typical of archeology and paleontology. We have formulated an approach that makes it possible to perform mathematical processing of the IR reflection spectra of objects of this kind using standard algorithms and determine criteria that ensure obtaining reliable information on objects with a rough surface in the course of interpretation of frequencies in their IR reflection spectra. The potential of the approach has been demonstrated using as an example an investigation by the IR Fourier-transform reflection spectroscopy of mineralization processes of mammoth tusks from two paleolithic sites (14000 and 16000 BCE) located by the town of Yudinovo, Bryansk oblast, Russia.

  16. Physiological and genomic characterization of Arcobacter anaerophilus IR-1 reveals new metabolic features in Epsilonproteobacteria

    PubMed Central

    Roalkvam, Irene; Drønen, Karine; Stokke, Runar; Daae, Frida L.; Dahle, Håkon; Steen, Ida H.

    2015-01-01

    In this study we characterized and sequenced the genome of Arcobacter anaerophilus strain IR-1 isolated from enrichment cultures used in nitrate-amended corrosion experiments. A. anaerophilus IR-1 could grow lithoautotrophically on hydrogen and hydrogen sulfide and lithoheterothrophically on thiosulfate and elemental sulfur. In addition, the strain grew organoheterotrophically on yeast extract, peptone, and various organic acids. We show for the first time that Arcobacter could grow on the complex organic substrate tryptone and oxidize acetate with elemental sulfur as electron acceptor. Electron acceptors utilized by most Epsilonproteobacteria, such as oxygen, nitrate, and sulfur, were also used by A. anaerophilus IR-1. Strain IR-1 was also uniquely able to use iron citrate as electron acceptor. Comparative genomics of the Arcobacter strains A. butzleri RM4018, A. nitrofigilis CI and A. anaerophilus IR-1 revealed that the free-living strains had a wider metabolic range and more genes in common compared to the pathogen strain. The presence of genes for NAD+-reducing hydrogenase (hox) and dissimilatory iron reduction (fre) were unique for A. anaerophilus IR-1 among Epsilonproteobacteria. Finally, the new strain had an incomplete denitrification pathway where the end product was nitrite, which is different from other Arcobacter strains where the end product is ammonia. Altogether, our study shows that traditional characterization in combination with a modern genomics approach can expand our knowledge on free-living Arcobacter, and that this complementary approach could also provide invaluable knowledge about the physiology and metabolic pathways in other Epsilonproteobacteria from various environments. PMID:26441916

  17. Diogenite-like Features in the Spitzer IRS (5-35 micrometers) Spectrum of 956 ELISA

    NASA Technical Reports Server (NTRS)

    Lim, Lucy F.; Emery, Joshua P.; Moskovitz, Nicholas A.

    2009-01-01

    We report preliminary results from the Spitzer Infrared Spectrograph (IRS) observations of the V-type asteroid 956 Elisa. Elisa was observed as part of a campaign to measure the 5.2-38 micron spectra of small basaltic asteroids with the Spitzer IRS. Targets include members of the dynamical family of the unique large differentiated asteroid 4 Vesta ("Vesroids"), several outer-main-belt basaltic asteroids whose orbits exclude them from originating on 4 Vesta, and the basaltic near-Earth asteroid 4055 Magellan.

  18. Parks Medical Flo-Lab 2100-SX may interpret IR emissions from CenTrak RTLS as user commands.

    PubMed

    2010-09-01

    The Parks Medical Flo-Lab 2100-SX vascular laboratory system may react to infrared (IR) emissions from the CenTrak real-time locating system (RTLS) as if they were remote-control commands, causing the Flo-Lab to operate without user action. Parks Medical plans to offer a redesigned remote control to eliminate susceptibility of its product to IR interference. In addition, CenTrak has designed an assessment tool that will help identify devices that may be vulnerable to IR interference from its RTLS.

  19. Surface Emissivity Retrieved with Satellite Ultraspectral IR Measurements for Monitoring Global Change

    NASA Technical Reports Server (NTRS)

    Zhou, Daniel K.; Larar, Allen M.; Liu, Xu; Smith, William L.; Schluessel, Peter

    2009-01-01

    Surface and atmospheric thermodynamic parameters retrieved with advanced ultraspectral remote sensors aboard Earth observing satellites are critical to general atmospheric and Earth science research, climate monitoring, and weather prediction. Ultraspectral resolution infrared radiance obtained from nadir observations provide atmospheric, surface, and cloud information. Presented here is the global surface IR emissivity retrieved from Infrared Atmospheric Sounding Interferometer (IASI) measurements under "clear-sky" conditions. Fast radiative transfer models, applied to the cloud-free (or clouded) atmosphere, are used for atmospheric profile and surface parameter (or cloud parameter) retrieval. The inversion scheme, dealing with cloudy as well as cloud-free radiances observed with ultraspectral infrared sounders, has been developed to simultaneously retrieve atmospheric thermodynamic and surface (or cloud microphysical) parameters. Rapidly produced surface emissivity is initially evaluated through quality control checks on the retrievals of other impacted atmospheric and surface parameters. Surface emissivity and surface skin temperature from the current and future operational satellites can and will reveal critical information on the Earth s ecosystem and land surface type properties, which can be utilized as part of long-term monitoring for the Earth s environment and global climate change.

  20. Layer-like IR limb emission enhancement observed by SABER/TIMED in the mesosphere and lower thermosphere region

    NASA Astrophysics Data System (ADS)

    Goldberg, R. A.; Kutepov, A.; Janches, D.; Rezac, L.; Plane, J. M.; Gordley, L. L.; Marshall, T.; Russell, J. M.

    2012-12-01

    We report first results of our study of characteristics and variability of the layer-like IR limb 4.3 mm daytime emission enhancement observed by SABER/TIMED utilizing nearly a decade of SABER observations. The enhancement is observed in a localized region of the mesosphere and lower thermosphere (MLT) at a tangent height between 85 and 95 km. Also, it has a distinct spatial and temporal variability, and is not predicted by current Non-Local Thermal Equilibrium (NLTE) models for generation of the IR molecular emissions in the MLT. We discuss the characteristics and variability of this layer, compare them with similar effects detected by other instruments, and consider possible physical processes which may influence formation of the IR radiation in the MLT to explain the observed emission enhancement.

  1. Solid State FT-IR and (31)P NMR Spectral Features of Phosphate Compounds

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Solid-state spectroscopic techniques, including Fourier transform infrared (FT-IR) and solid-state 31P magic angle spinning nuclear magnetic resonance (MAS NMR) spectroscopies, are powerful tools for evaluating metal speciation and transformation mechanisms of P compounds in the environment. Studie...

  2. The discovery of a new infrared emission feature at 1905 wavenumbers (5.25 microns) in the spectrum of BD + 30 deg 3639 and its relation to the polycyclic aromatic hydrocarbon model

    NASA Technical Reports Server (NTRS)

    Allamandola, L. J.; Bregman, J. D.; Sandford, S. A.; Tielens, A. G. G. M.; Witteborn, F. C.

    1989-01-01

    A new IR emission feature at 1905/cm (5.25 microns) has been discovered in the spectrum of BD + 30 deg 3639. This feature joins the family of well-known IR emission features at 3040, 2940, 1750, 1610, '1310', 1160, and 890/cm. The origin of this new feature is discussed and it is assigned to an overtone or combination band involving C-H bending modes of polycyclic aromatic hydrocarbons (PAHs). Laboratory work suggests that spectral studies of the 2000-1650/cm region may be very useful in elucidating the molecular structure of interstellar PAHs. The new feature, in conjunction with other recently discovered spectral structures, suggests that the narrow IR emission features originate in PAH molecules rather than large carbon grains.

  3. Discussing the processes constraining the Jovian synchrotron radio emission's features

    NASA Astrophysics Data System (ADS)

    Santos-Costa, Daniel; Bolton, Scott J.

    2008-03-01

    Our recent analysis and understanding of the Jovian synchrotron radio emission with a radiation-belt model is presented. In this work, the electron population is determined by solving the Fokker-Planck diffusion equation and considering different physical processes. The results of the modeling are first compared to in situ particle data, brightness distributions, radio spectrum, and beaming curves to verify the simulated particle distributions. The dynamics of high-energy electrons in Jupiter's inner magnetosphere and their related radio emission are then examined. The results demonstrate that the Jovian moons set the extension and intensity of the synchrotron emission's brightness distribution along the magnetic equator. Simulations show that moons and dust both control the transport toward the planet by significantly reducing the abundance of particles constrained to populate, near the equator and inside 1.8 Jovian radii, the innermost region of the magnetosphere. Due to interactions with dust and synchrotron mechanism, radiation-belt electrons are moved along field lines, between Metis (1.79 Jovian radii) and Amalthea (2.54 Jovian radii), toward high latitudes. The quantity of particles transported away from the equator is sufficient to produce measurable secondary radio emissions. Among all the phenomena acting in the inner magnetosphere, the moons (Amalthea and Thebe) are the primary moderator for the radiation's intensity at high latitudes. Moon losses also affect the characteristics of the total radio flux with longitude. The sweeping effect amplifies the 10-h modulation of the beaming curve's amplitude while energy resonances occurring near Amalthea and Thebe belong to phenomena adjusting it to the right level. Interactions with dust do not significantly constrain radio spectrum features. Resonances near Amalthea and Thebe are responsible for the Jovian radio spectrum's particular slope.

  4. The Spectacular Radio-near-IR-X-Ray Jet of 3C 111: The X-Ray Emission Mechanism and Jet Kinematics

    NASA Astrophysics Data System (ADS)

    Clautice, Devon; Perlman, Eric S.; Georganopoulos, Markos; Lister, Matthew L.; Tombesi, Francesco; Cara, Mihai; Marshall, Herman L.; Hogan, Brandon; Kazanas, Demos

    2016-08-01

    Relativistic jets are the most energetic manifestation of the active galactic nucleus (AGN) phenomenon. AGN jets are observed from the radio through gamma-rays and carry copious amounts of matter and energy from the sub-parsec central regions out to the kiloparsec and often megaparsec scale galaxy and cluster environs. While most spatially resolved jets are seen in the radio, an increasing number have been discovered to emit in the optical/near-IR and/or X-ray bands. Here we discuss a spectacular example of this class, the 3C 111 jet, housed in one of the nearest, double-lobed FR II radio galaxies known. We discuss new, deep Chandra and Hubble Space Telescope (HST) observations that reveal both near-IR and X-ray emission from several components of the 3C 111 jet, as well as both the northern and southern hotspots. Important differences are seen between the morphologies in the radio, X-ray, and near-IR bands. The long (over 100 kpc on each side), straight nature of this jet makes it an excellent prototype for future, deep observations, as it is one of the longest such features seen in the radio, near-IR/optical, and X-ray bands. Several independent lines of evidence, including the X-ray and broadband spectral shape as well as the implied velocity of the approaching hotspot, lead us to strongly disfavor the EC/CMB model and instead favor a two-component synchrotron model to explain the observed X-ray emission for several jet components. Future observations with NuSTAR, HST, and Chandra will allow us to further constrain the emission mechanisms.

  5. Highly selective and responsive visible to near-IR ytterbium emissive probe for monitoring mercury(II).

    PubMed

    Zhang, Tao; Chan, Chi-Fai; Lan, Rongfeng; Wong, Wai-Kwok; Wong, Ka-Leung

    2014-01-20

    A new lanthanide probe based on the fluorescence resonance energy transfer (FRET) process with the combination of ytterbium porphyrinate complex and a rhodamine B derivative unit was synthesized to detect the Hg(2+) ion with responsive emission in the visible and near-IR region with a detection limit of 10 μM.

  6. Comet Grains: Their IR Emission and Their Relation to ISM Grains

    NASA Technical Reports Server (NTRS)

    Wooden, Diane H.; DeVincenzi, Donald (Technical Monitor)

    2002-01-01

    Comets and the chodritic, porous interplanetary dust particles (CP IDPs) that they shed in their comae are reservoirs of primitive solar nebula materials. The high porosity and fragility of cometary grains and CP IDPs, and anomalously high deuterium contents of highly fragile, pyroxene-rich Cluster IDPs imply these aggregate particles contain significant abundances of grains from the interstellar medium (ISM). IR spectra of comets (3 - 40 micron) reveal the presence of a warm (nearIR) featureless emission modeled by amorphous carbon grains. Broad and narrow resonances near 10 and 20 microns are modeled by warm chondritic (50% Fe and 50% Mg) amorphous silicates and cooler Mg-rich crystalline silicate minerals, respectively. Cometary amorphous silicates resonances are well matched by IR spectra of CP IDPs dominated by GEMS (0.1 micron silicate spherules) that are thought to be the interstellar Fe-bearing amorphous silicates produced in AGB stars. Acid-etched ultramicrotomed CP IDP samples, however, show that both the carbon phase (amorphous and aliphatic) and the Mg-rich amorphous silicate phase in GEMS are not optically absorbing. Rather, it is Fe and FeS nanoparticles embedded in the GEMS that makes the CP IDPs dark. Therefore, CP IDPs suggest significant processing has occurred in the ISM. ISM processing probably includes in He' ion bombardment in supernovae shocks. Laboratory experiments show He+ ion bombardment amorphizes crystalline silicates, increases porosity, and reduces Fe into nanoparticles. Cometary crystalline silicate resonances are well matched by IR spectra of laboratory submicron Mg-rich olivine crystals and pyroxene crystals. Discovery of a Mg-pure olivine crystal in a Cluster IDP with isotopically anomalous oxygen indicates that a small fraction of crystalline silicates may have survived their journey from AGB stars through the ISM to the early solar nebula. The ISM does not have enough crystalline silicates (<5%) , however, to account for the

  7. Exploring the Physical Conditions in 30 Doradus, using the Aromatic Feature Emission

    NASA Astrophysics Data System (ADS)

    Galliano, Frédéric; Madden, S.; Hony, S.; Indebetouw, R.; Consortium, S.

    2010-01-01

    30 Doradus is the most powerful star forming region in the LMC. It contains also the most nearby massive star cluster. It presents a unique opportunity to study the effect of intense star formation on the surrounding ISM, and understand the details of the physics in distant starburst galaxies. Using Spitzer spectral mapping of the region, we extracted both the spatial variations of the PAH-to-continuum intensity ratio and of the PAH band-to-band intensity ratios. We first showed that the latter quantities are a tracer of the charge of the molecules and therefore of the physical conditions, by ruling out other causes of variations, like variations in the size distribution or radiative transfer effects (selective extinction, variations of the local mean intensity). One of the striking features of this region is that the PAH band ratios span a significantly smaller range of variations than in other, Galactic, regions and extragalactic sources, such as M 17, the Orion bar or M 82 (Galliano et al. 2008, ApJ, 679, 310). This is an indication of differences in morphology of the ISM. It implies that the regions dominating the PAH emission are subject to more uniform conditions than in solar metallicity environments. Then, to quantify the variations of the physical conditions, we combined the results from the modeling of the ionic lines in 30 Doradus (Indebetouw et al. 2009, ApJ, 694, 84) with the far-IR SED. This modeling allows us to estimate the contribution of diffuse ionized gas and dense PDRs to the IR emission. By comparing those quantities to the measured PAH band ratios, we constrain the relation of the band ratio to the physical conditions.

  8. Polycyclic Aromatic Hydrocarbon Emission in Spitzer/IRS Maps. I. Catalog and Simple Diagnostics

    NASA Astrophysics Data System (ADS)

    Stock, D. J.; Choi, W. D.-Y.; Moya, L. G. V.; Otaguro, J. N.; Sorkhou, S.; Allamandola, L. J.; Tielens, A. G. G. M.; Peeters, E.

    2016-03-01

    We present a sample of resolved galactic H ii regions and photodissociation regions (PDRs) observed with the Spitzer infrared spectrograph in spectral mapping mode between the wavelengths of 5-15 μm. For each object we have spectral maps at a spatial resolution of ˜4″ in which we have measured all of the mid-infrared emission and absorption features. These include the polycyclic aromatic hydrocarbon (PAH) emission bands, primarily at 6.2, 7.7, 8.6, 11.2, and 12.7 μm, as well as the spectral emission lines of neon and sulfur and the absorption band caused by silicate dust at around 9.8 μm. In this work we describe the data in detail, including the data reduction and measurement strategies, and subsequently present the PAH emission band intensity correlations for each of the objects and the sample as a whole. We find that there are distinct differences between the sources in the sample, with two main groups: the first comprising the H ii regions and the second the reflection nebulae (RNe). Three sources—the reflection nebula NGC 7023, the Horsehead nebula PDR (an interface between the H ii region IC 434 and the Orion B molecular cloud), and M17—resist this categorization, with the Horsehead PDR points mimicking the RNe and the NGC 7023 fluxes displaying a unique bifurcated appearance in our correlation plots. These discrepancies seem to be due to the very low radiation field experienced by the Horsehead PDR and the very clean separation between the PDR environment and a diffuse environment in the NGC 7023 observations.

  9. Mid-IR Properties of an Unbiased AGN Sample of the Local Universe. 1; Emission-Line Diagnostics

    NASA Technical Reports Server (NTRS)

    Weaver, K. A.; Melendez, M.; Muhotzky, R. F.; Kraemer, S.; Engle, K.; Malumuth. E.; Tueller, J.; Markwardt, C.; Berghea, C. T.; Dudik, R. P.; Winter, L. M.; Armus, L.

    2010-01-01

    \\Ve compare mid-IR emission-lines properties, from high-resolution Spitzer IRS spectra of a statistically-complete hard X-ray (14-195 keV) selected sample of nearby (z < 0.05) AGN detected by the Burst Alert Telescope (BAT) aboard Swift. The luminosity distribution for the mid-infrared emission-lines, [O IV] 25.89 microns, [Ne II] 12.81 microns, [Ne III] 15.56 microns and [Ne V] 14.32 microns, and hard X-ray continuum show no differences between Seyfert 1 and Seyfert 2 populations, although six newly discovered BAT AGNs are shown to be under-luminous in [O IV], most likely the result of dust extinction in the host galaxy. The overall tightness of the mid-infrared correlations and BAT luminosities suggests that the emission lines primarily arise in gas ionized by the AGN. We also compared the mid-IR emission-lines in the BAT AGNs with those from published studies of star-forming galaxies and LINERs. We found that the BAT AGN fall into a distinctive region when comparing the [Ne III]/[Ne II] and the [O IV]/[Ne III] quantities. From this we found that sources that have been previously classified in the mid-infrared/optical as AGN have smaller emission line ratios than those found for the BAT AGNs, suggesting that, in our X-ray selected sample, the AGN represents the main contribution to the observed line emission. Overall, we present a different set of emission line diagnostics to distinguish between AGN and star forming galaxies that can be used as a tool to find new AGN.

  10. Energetic electrons, hard x-ray emission and MHD activity studies in the IR-T1 tokamak.

    PubMed

    Agah, K Mikaili; Ghoranneviss, M; Elahi, A Salar

    2015-01-01

    Determinations of plasma parameters as well as the Magnetohydrodynamics (MHD) activity, energetic electrons energy and energy confinement time are essential for future fusion reactors experiments and optimized operation. Also some of the plasma information can be deduced from these parameters, such as plasma equilibrium, stability, and MHD instabilities. In this contribution we investigated the relation between energetic electrons, hard x-ray emission and MHD activity in the IR-T1 Tokamak. For this purpose we used the magnetic diagnostics and a hard x-ray spectroscopy in IR-T1 tokamak. A hard x-ray emission is produced by collision of the runaway electrons with the plasma particles or limiters. The mean energy was calculated from the slope of the energy spectrum of hard x-ray photons.

  11. Complex infrared emission features in the spectrum of beta Lyrae

    NASA Technical Reports Server (NTRS)

    Morgan, T. H.; Potter, A. E.; Kondo, Y.

    1974-01-01

    Spectra of beta Lyrae over the spectral region from 5800 to 11,000 per cm (1.76 to 0.9 micron) at two different phases have been obtained. They show a remarkable emission-absorption complex at 9231 per cm, a highly structured emission at P beta, and several additional broad weak emissions.

  12. Broadband near-IR emission from cubic perovskite KZnF(3):Ni(2+) nanocrystals embedded glass-ceramics.

    PubMed

    Lin, Changgui; Liu, Chao; Zhao, Zhiyong; Li, Legang; Bocker, Christian; Rüssel, Christian

    2015-11-15

    Transparent KF-ZnF(2)-SiO(2) glass-ceramics were prepared with the precipitation of KZnF(3)Ni(2+) nanocrystals. During excitation with a wavelength of 405 nm at room temperature, a broadband near-IR emission centered at 1695 nm with the FWHM of more than 350 nm was observed, which is originated from the T(2g)3(F3)→A(2g)3(F3) transition of octahedral Ni(2+) incorporated in the KZnF(3) crystalline phase. In comparison to oxide glass-ceramics, a redshift of the luminescence is observed, which is due to the low crystal field of these octahedral Ni(2+). The shift and extension of near-IR emission in the KZnF(3):Ni(2+) nanocrystals embedded in a glassy matrix do not only complete the broadband emission in the whole near-IR region for the Ni(2+) ions-based photonics, but also open an easy way to approach the broadband optical amplifier and tunable lasers operating in the wavelength region near 1800 nm, which was up to now achieved by codoping of several types of active ions. PMID:26565850

  13. Regioselective aromatic substitution reactions of cyclometalated Ir(III) complexes: synthesis and photochemical properties of substituted Ir(III) complexes that exhibit blue, green, and red color luminescence emission.

    PubMed

    Aoki, Shin; Matsuo, Yasuki; Ogura, Shiori; Ohwada, Hiroki; Hisamatsu, Yosuke; Moromizato, Shinsuke; Shiro, Motoo; Kitamura, Masanori

    2011-02-01

    In this manuscript, the regioselective halogenation, nitration, formylation, and acylation of Ir(tpy)(3) and Ir(ppy)(3) (tpy = 2-(4'-tolyl)pyridine and ppy = 2-phenylpyridine) and the subsequent conversions are described. During attempted bromination of the three methyl groups in fac-Ir(tpy)(3) using N-bromosuccinimide (NBS) and benzoyl peroxide (BPO), three protons at the 5'-position (p-position with respect to the C-Ir bond) of phenyl rings in tpy units were substituted by Br, as confirmed by (1)H NMR spectra, mass spectra, and X-ray crystal structure analysis. It is suggested that such substitution reactions of Ir complexes proceed via an ionic mechanism rather than a radical mechanism. UV-vis and luminescence spectra of the substituted Ir(III) complexes are reported. The introduction of electron-withdrawing groups such as CN and CHO groups at the 5'-position of tpy induces a blue shift of luminescence emission to about 480 nm, and the introduction of electron-donating groups such as an amino group results in a red shift to about 600 nm. A reversible change of emission for the 5'-amino derivative of Ir(tpy)(3), Ir(atpy)(3), between red and green occurs upon protonation and deprotonation. PMID:21214169

  14. Multi-spectrum retrieval of Venus IR surface emissivity maps from VIRTIS/VEX nightside measurements at Themis Regio

    NASA Astrophysics Data System (ADS)

    Kappel, David; Arnold, Gabriele; Haus, Rainer

    2016-02-01

    Surface emissivity maps in the infrared can contribute to explore Venus' geology. Nightside radiance spectra at Themis Regio acquired by the IR mapping channel of the Visible and InfraRed Thermal Imaging Spectrometer (VIRTIS-M-IR) aboard Venus EXpress (VEX) are used to derive emissivity data from the three accessible spectral surface windows at 1.02, 1.10, and 1.18 μm. The measured spectra are simulated by applying a full radiative transfer model. Neglecting geologic activity, a multi-spectrum retrieval algorithm is utilized to determine the emissivity maps of the surface target as parameter vectors that are common to many spectrally resolved images that cover this target. Absolute emissivity values are difficult to obtain due to strong interferences from other parameters. The true emissivity mean of the target cannot be retrieved, nor can the emissivity mean of a retrieved map be strictly preset. The retrieved map can exhibit trends with latitude and topography that are probably artificial. Once the trends have been removed in a post-processing step, it can be observed that the magnitude of the resulting spatial emissivity fluctuations around their mean value increases with increasing mean value. A linear transformation is applied that converts the de-trended map to exhibit a defined emissivity mean value called reference emissivity, here 0.5, yielding the 'renormalized emissivity map' with accordingly transformed fluctuations. It is verified that renormalized emissivity maps are largely independent of the emissivity mean before renormalization, of modifications to interfering atmospheric, surface, and instrumental parameters, and of selected details of the retrieval pipeline and data calibration and preprocessing. Extremely large emissivity retrieval errors due to imperfect or unconsidered forward model parameters are effectively avoided. If the absolute emissivity at a given bin of the target were known, the absolute emissivity map of the entire target could be

  15. A Red to Near-IR Fluorogen: Aggregation-Induced Emission, Large Stokes Shift, High Solid Efficiency and Application in Cell-Imaging.

    PubMed

    Wang, Yi Jia; Shi, Yang; Wang, Zhaoyang; Zhu, Zhenfeng; Zhao, Xinyuan; Nie, Han; Qian, Jun; Qin, Anjun; Sun, Jing Zhi; Tang, Ben Zhong

    2016-07-01

    A tetraphenylethene (TPE) derivative modified with the strong electron acceptor 2-dicyano-methylene-3-cyano-4,5,5-trimethyl-2,5-dihydrofuran (TCF) was obtained in high yield by a simple two-step reaction. The resultant TPE-TCF showed evident aggregation-induced emission (AIE) features and pronounced solvatochromic behavior. Changing the solvent from apolar cyclohexane to highly polar acetonitrile, the emission peak shifted from 560 to 680 nm (120 nm redshift). In an acetonitrile solution and in the solid powder, the Stokes shifts are as large as 230 and 190 nm, respectively. The solid film emits red to near-IR (red-NIR) fluorescence with an emission peak at 670 nm and a quantum efficiency of 24.8 %. Taking the advantages of red-NIR emission and high efficiency, nanoparticles (NPs) of TPE-TCF were fabricated by using tat-modified 1,2-distearoylsn-glycero-3-phosphor-ethanol-amine-N-[methoxy-(polyethyl-eneglycol)-2000] as the encapsulation matrix. The obtained NPs showed perfect membrane penetrability and high fluorescent imaging quality of cell cytoplasm. Upon co-incubation with 4,6-diamidino-2-phenylindole (DAPI) in the presence of tritons, the capsulated TPE-TCF nanoparticles could enter into the nucleus and displayed similar staining properties to those of DAPI.

  16. A Red to Near-IR Fluorogen: Aggregation-Induced Emission, Large Stokes Shift, High Solid Efficiency and Application in Cell-Imaging.

    PubMed

    Wang, Yi Jia; Shi, Yang; Wang, Zhaoyang; Zhu, Zhenfeng; Zhao, Xinyuan; Nie, Han; Qian, Jun; Qin, Anjun; Sun, Jing Zhi; Tang, Ben Zhong

    2016-07-01

    A tetraphenylethene (TPE) derivative modified with the strong electron acceptor 2-dicyano-methylene-3-cyano-4,5,5-trimethyl-2,5-dihydrofuran (TCF) was obtained in high yield by a simple two-step reaction. The resultant TPE-TCF showed evident aggregation-induced emission (AIE) features and pronounced solvatochromic behavior. Changing the solvent from apolar cyclohexane to highly polar acetonitrile, the emission peak shifted from 560 to 680 nm (120 nm redshift). In an acetonitrile solution and in the solid powder, the Stokes shifts are as large as 230 and 190 nm, respectively. The solid film emits red to near-IR (red-NIR) fluorescence with an emission peak at 670 nm and a quantum efficiency of 24.8 %. Taking the advantages of red-NIR emission and high efficiency, nanoparticles (NPs) of TPE-TCF were fabricated by using tat-modified 1,2-distearoylsn-glycero-3-phosphor-ethanol-amine-N-[methoxy-(polyethyl-eneglycol)-2000] as the encapsulation matrix. The obtained NPs showed perfect membrane penetrability and high fluorescent imaging quality of cell cytoplasm. Upon co-incubation with 4,6-diamidino-2-phenylindole (DAPI) in the presence of tritons, the capsulated TPE-TCF nanoparticles could enter into the nucleus and displayed similar staining properties to those of DAPI. PMID:27265326

  17. Emission features in the spectrum of NGC 7027 near 3. 3 microns at very high resolution

    SciTech Connect

    Lowe, R.P.; Moorhead, J.M.; Wehlau, W.H.; Maillard, J.P. CNRS, Institut d'Astrophysique, Paris )

    1991-02-01

    A very high resolution spectrum is presented of the planetary nebula NGC 7027 over a 200/cm interval centered at 2950/cm, and the features found are described: (1) nebular continuum, (2) atomic recombination lines of H and He II, and (3) three broader emission features of uncertain origin. For the latter the first evidence is presented that the 3.46 micron feature and possibly the 3.40 micron feature are resolvable into a sequence of narrower features. The interpretation of the broader features is discussed in terms of the hypothesis of identification with emission by polycyclic aromatic hydrocarbons. 18 refs.

  18. The influence of the spectral emissivity of flat-plate calibrators on the calibration of IR thermometers

    SciTech Connect

    Cárdenas-García, D.; Méndez-Lango, E.

    2013-09-11

    Flat Calibrators (FC) are an option for calibration of infrared thermometers (IT) with a fixed large target. FCs are neither blackbodies, nor gray-bodies; their spectral emissivity is lower than one and depends on wavelength. Nevertheless they are used as gray-bodies with a nominal emissivity value. FCs can be calibrated radiometrically using as reference a calibrated IR thermometer (RT). If an FC will be used to calibrate ITs that work in the same spectral range as the RT then its calibration is straightforward: the actual FC spectral emissivity is not required. This result is valid for any given fixed emissivity assessed to the FC. On the other hand, when the RT working spectral range does not match with that of the ITs to be calibrated with the FC then it is required to know the FC spectral emissivity as part of the calibration process. For this purpose, at CENAM, we developed an experimental setup to measure spectral emissivity in the infrared spectral range, based on a Fourier transform infrared spectrometer. Not all laboratories have emissivity measurement capability in the appropriate wavelength and temperature ranges to obtain the spectral emissivity. Thus, we present an estimation of the error introduced when the spectral range of the RT used to calibrate an FC and the spectral ranges of the ITs to be calibrated with the FC do not match. Some examples are developed for the cases when RT and IT spectral ranges are [8,13] μm and [8,14] μm respectively.

  19. THE 217.5 nm BAND, INFRARED ABSORPTION, AND INFRARED EMISSION FEATURES IN HYDROGENATED AMORPHOUS CARBON NANOPARTICLES

    SciTech Connect

    Duley, W. W.; Hu, Anming E-mail: a2hu@uwaterloo.ca

    2012-12-20

    We report on the preparation of hydrogenated amorphous carbon nanoparticles whose spectral characteristics include an absorption band at 217.5 nm with the profile and characteristics of the interstellar 217.5 nm feature. Vibrational spectra of these particles also contain the features commonly observed in absorption and emission from dust in the diffuse interstellar medium. These materials are produced under ''slow'' deposition conditions by minimizing the flux of incident carbon atoms and by reducing surface mobility. The initial chemistry leads to the formation of carbon chains, together with a limited range of small aromatic ring molecules, and eventually results in carbon nanoparticles having an sp {sup 2}/sp {sup 3} ratio Almost-Equal-To 0.4. Spectroscopic analysis of particle composition indicates that naphthalene and naphthalene derivatives are important constituents of this material. We suggest that carbon nanoparticles with similar composition are responsible for the appearance of the interstellar 217.5 nm band and outline how these particles can form in situ under diffuse cloud conditions by deposition of carbon on the surface of silicate grains. Spectral data from carbon nanoparticles formed under these conditions accurately reproduce IR emission spectra from a number of Galactic sources. We provide the first detailed fits to observational spectra of Type A and B emission sources based entirely on measured spectra of a carbonaceous material that can be produced in the laboratory.

  20. Analysis of the emitting states of an Ir(III) complex with strong blue emission

    NASA Astrophysics Data System (ADS)

    Liew, Jane Y.; Lo, Shih-Chun; Burn, Paul L.; Krausz, Elmars R.; Hall, Jeremy D.; Moore, Evan G.; Riley, Mark J.

    2015-11-01

    Temperature dependent luminescence, lifetimes and magnetic circularly polarised luminescence (MCPL) are reported between 1.7 and 80 K and in magnetic fields of 0-5 T for [Ir(ptz)3]. Data analysis reveals the temperature and field dependent behaviour is due to the sublevel structure of the emitting state. We have determined energy separations of ΔEII,I = 10 cm-1 and ΔEIII,I = 45 cm-1 between three triplet sublevels, with intrinsic luminescence lifetimes of τI = 160 μs, τII = 10 μs and τIII = 800 ns. We compare these with values for the green emitter, [Ir(ppy)3] and discuss implications for the excited state geometries.

  1. UV-stimulated near-IR emission of Pr3+ in phosphate glass via twofold-coordinated Sn centers

    NASA Astrophysics Data System (ADS)

    Jiménez, José A.; Sendova, Mariana; Rosim Fachini, Esteban

    2014-11-01

    The optical properties of Pr2O3 and SnO co-doped barium-phosphate glass prepared by the melt-quenching technique have been investigated. Optical absorption and X-ray photoelectron spectroscopy (XPS) are employed in the characterization of tin species. The prevalence of divalent tin is indicated by the XPS data in accord with a conspicuous absorption band detected around 287 nm ascribed to twofold-coordinated Sn centers (isoelectronic with Sn2+). Upon ultraviolet (UV) photoexcitation of the tin centers, near-infrared (IR) emission from Pr3+ ions is realized. An excitation spectrum acquired by monitoring Pr3+ emission from the 1D2 state at 1.03 μm revealed a broad band around 290 nm consistent with a Snsbnd Pr donor-acceptor energy transfer channel. The data supports a mechanism starting with the singlet-to-singlet UV excitation of Sn centers, followed by the intersystem crossing populating their triplet states emitting in the visible. From these, energy transfer occurs to 3P0, 3P1, 1I6, and 3P2 resonant states in Pr3+, from which the near-IR emitting states 1D2 and 1G4 are populated.

  2. Unravelling thermal emissivity spectra of the main minerals on Mercury's surface by comparison with ab initio calculated IR-HT vibrational frequencies

    NASA Astrophysics Data System (ADS)

    Stangarone, C.; Helbert, J.; Tribaudino, M.; Maturilli, A.; D'Amore, M.; Ferrari, S.; Prencipe, M.

    2015-12-01

    Spectral signatures of minerals are intimately related to the crystal structure; therefore they may represent a remote sensing model to determine surface composition of planetary bodies, by analysing their spectral reflectance and emission. However, one of the most critical point is data interpretation considering planetary surfaces, as Mercury, where the changes in spectral characteristics are induced by the high temperatures conditions (Helbert et al., 2013). The aim of this work is to interpret the experimental thermal emissivity spectra with an innovative approach: simulating IR spectra of the main mineral families that compose the surface of Mercury, focusing on pyroxenes (Sprague et al., 2002), both at room and high temperature, exploiting the accuracy of ab initio quantum mechanical calculations, by means of CRYSTAL14 code (Dovesi et al., 2014). The simulations will be compared with experimental emissivity measurements of planetary analogue samples at temperature up to 1000K, performed at Planetary Emissivity Laboratory (PEL) by Institute of Planetary Research (DLR, Berlin). Results will be useful to create a theoretical background to interpret HT-IR emissivity spectra that will be collected by the Mercury Radiometer and Thermal Infrared Spectrometer (MERTIS), a spectrometer developed by DLR that will be on board of the ESA BepiColombo Mercury Planetary Orbiter (MPO) scheduled for 2017. The goal is to point out the most interesting spectral features for a geological mapping of Mercury and other rocky bodies, simulating the environmental conditions of the inner planets of Solar System. Dovesi R., Saunders V. R., Roetti C., Orlando R., Zicovich-Wilson C. M., Pascale F., Civalleri B., Doll K., Harrison N. M., Bush I. J., D'Arco P., Llunell M., Causà M. & Noël Y. 2014. CRYSTAL14 User's Manual, University of Torino. Sprague, A. L., Emery, J. P., Donaldson, K. L., Russell, R. W., Lynch, D. K., & Mazuk, A. L. (2002). Mercury: Mid-infrared (3-13.5

  3. Superbroadband near-IR emission from praseodymium-doped bismuth gallate glasses.

    PubMed

    Zhou, Bo; Pun, Edwin Yue-Bun

    2011-08-01

    Superbroadband near-infrared (NIR) emission covering 1250 to 1680 nm wavelength has been obtained in praseodymium (Pr(3+)) singly doped bismuth gallate glasses. The emission originates from the (1)G(4)→(3)H(5) and (1)D(2)→(1)G(4) transitions at 1330 and 1490 nm wavelengths, respectively, and is due to the extremely low phonon energy (∼690 cm(-1)) and the unique ligand field of the glasses. It is shown that the emission line shape can be modified by adjusting the Pr(3+) concentration and the energy transfers involved. The results confirm that other than bismuth (Bi), chromium (Cr), nickel (Ni), and other chemical elements, Pr(3+) singly doped system is a promising alternative in achieving superbroadband NIR emission.

  4. On the origin of the 3.2 to 3.6-micron emission features in comets.

    NASA Astrophysics Data System (ADS)

    Bockelée-Morvan, D.; Brooke, T. Y.; Crovisier, J.

    1995-07-01

    We investigate the contribution of the v2, v3 , and v9 CH-stretching bands of methanol to the 3.2- to 3.6-μm emission feature observed in seven comets at a range of heliocentric distances and analyze the residual emission spectra. The comets examined are P/Halley, Wilson 1987 VII, Bradfield 1987 XXIX, P/Brorsen-Metcalf, Okazaki-Levy-Rudenko 1989 XIX, Austin 1990 V, and Levy 1990 XX. From the fitting of its v3 band at 3.52 μm, we infer that methanol is present in all of the comets with abundances ranging from 0.6 to 5% with respect to water. We do not see strong evidence for a bimodal distribution of methanol-rich and methanol-poor comets, though Levy appears to be relatively low. The methanol fundamental bands are found to contribute up to 60% of the total 3.2 to 3.6-μm emission flux. All 7 comets have residual emission with a distinct feature centered at 3.43 μm. The flux of this 3.43-μm feature is correlated with the water production rate, suggesting a gaseous origin, but the correlation with the methanol production rate is even tighter, suggesting a connection between the 3.43-μm emitter and methanol. Another residual emission feature at 3.28 μm is roughly correlated with the water production rate, but is stronger in dustier comets. If the 3.28-μm feature is due to ultraviolet-pumped IR fluorescence of aromatic molecules, abundances between 1.5 and 10 × 10 -6 are estimated. These abundances are at least 100 times smaller than the value deduced from UV observations of P/Halley (G. Moreels et al., 1994, Astron. Astrophy. 282, 643-656), but both the UV- and IR-derived abundances depend on modeling assumptions which are still uncertain. Additional residual emission features between 3.30 and 3.40 μm and near 3.24 μm vary among the comets examined. In addition to the v2, v3, and v9 fundamental bands, overtones, and combination bands of methanol are present in the 3.2 to 3.6-μm spectral region and may be enhanced due to Fermi resonances with the CH

  5. Anthracene Clusters and the Interstellar Infrared Emission Features

    NASA Astrophysics Data System (ADS)

    Roser, J. E.; Ricca, A.; Allamandola, L. J.

    2014-03-01

    The unidentified infrared bands are ubiquitous in the interstellar medium and typically attributed to emission from neutral and ionized polycyclic aromatic hydrocarbons (or PAHs). The contribution of neutral PAH clusters to these bands has been impossible to determine due to a paucity of infrared spectral data. Here we investigated neutral clusters of the three-ring PAH anthracene using FTIR absorption spectroscopy of anthracene matrix-isolated at varying concentrations in solid argon. In order to determine likely cluster structures of the embedded molecules, we also calculated theoretical absorption spectra for the anthracene monomer through hexamer using density functional theory with a dispersion correction (DFT-D). The DFT-D calculations have been calibrated for the anthracene dimer using the second-order Møller-Plesset approach. Because there is some support for the hypothesis that three or four-ring PAHs are present in the Red Rectangle nebula, we discuss the application of our results to this nebula in particular as well as to the interstellar infrared emission in general.

  6. Anthracene clusters and the interstellar infrared emission features

    SciTech Connect

    Roser, J. E.; Ricca, A.; Allamandola, L. J.

    2014-03-10

    The unidentified infrared bands are ubiquitous in the interstellar medium and typically attributed to emission from neutral and ionized polycyclic aromatic hydrocarbons (or PAHs). The contribution of neutral PAH clusters to these bands has been impossible to determine due to a paucity of infrared spectral data. Here we investigated neutral clusters of the three-ring PAH anthracene using FTIR absorption spectroscopy of anthracene matrix-isolated at varying concentrations in solid argon. In order to determine likely cluster structures of the embedded molecules, we also calculated theoretical absorption spectra for the anthracene monomer through hexamer using density functional theory with a dispersion correction (DFT-D). The DFT-D calculations have been calibrated for the anthracene dimer using the second-order Møller-Plesset approach. Because there is some support for the hypothesis that three or four-ring PAHs are present in the Red Rectangle nebula, we discuss the application of our results to this nebula in particular as well as to the interstellar infrared emission in general.

  7. The contribution of CHONS particles to the diffuse high-Galactic-latitude IR emission

    NASA Astrophysics Data System (ADS)

    Papoular, R.

    2014-05-01

    This work purports to model the far-infrared grey-body emission in the spectra of high-Galactic-latitude clouds. Several carbonaceous laboratory materials are tested for their fitness as carriers of this modified blackbody emission which, according to data delivered by the Planck satellite, and others before, is best fitted with temperature 17.9 K and spectral index β = 1.78. Some of these materials were discarded for insufficient emissivity, others for inadequate β. By contrast, CHONS clusters (β = 1.4, T = 19 K) combine nicely with magnesium silicate (β = 2, T = 18.7 K) to give a spectrum which falls well within the observational error bars (total emission cross-section at 250 μm: 8.6 × 10-26 cm2 per H atom). Only 15 per cent of all Galactic carbon atoms are needed for this purpose. The CHONS particles that were considered and described have a disordered (amorphous) structure but include a sizeable fraction of aromatic rings, although they are much less graphitized than a-C:H/hydrogenated amorphous carbon. They can be seen as one embodiment of `astronomical graphite' deduced earlier on from the then available astronomical observations. Grain heating by H atom capture is proposed as a contributor to the observed residual emissions that do not follow the dust/H I correlation.

  8. The Non-LTE Model of IR Emissions of Methane in the Titan'sAtmosphere

    NASA Astrophysics Data System (ADS)

    Kutepov, Alexander; Rezac, Ladislav; Feofilov, Artem; Rey, Michael; Nikitin, Andrei; Tyuterev, Vladimir

    2015-11-01

    Above about 400-450 km in Titan's atmosphere, the assumption of local thermodynamic equilibrium (LTE) breaks down for molecular vibrational levels of methane and various trace gases. Above this altitude non-LTE significantly impacts the formation of infrared ro-vibrational band emissions of these species observed in the limb viewing geometry. We present detailed model of the non-LTE in methane in the Titan's atmosphere based on a new extended database of the CH4 spectroscopic parameters calculated for this study. We analyze vibrational temperatures of various 12CH4 and 13CH4 levels as well as CH4 limb emissions in the 7.6 and 3.3 um spectral regions. The impact on these emissions of many weak one-quantum and combinational bands, which are missing in current databases, is studied. Implications for the non-LTE diagnostics of the Cassini CIRS and VIMS measurements are discussed.

  9. A TALE OF THREE MYSTERIOUS SPECTRAL FEATURES IN CARBON-RICH EVOLVED STARS: THE 21 μm, 30 μm, AND “UNIDENTIFIED INFRARED” EMISSION FEATURES

    SciTech Connect

    Mishra, Ajay; Li, Aigen; Jiang, B. W. E-mail: lia@missouri.edu

    2015-03-20

    The mysterious “21 μm” emission feature seen almost exclusively in the short-lived protoplanetary nebula (PPN) phase of stellar evolution remains unidentified since its discovery two decades ago. This feature is always accompanied by the equally mysterious, unidentified “30 μm” feature and the so-called “unidentified infrared” (UIR) features at 3.3, 6.2, 7.7, 8.6, and 11.3 μm which are generally attributed to polycyclic aromatic hydrocarbon (PAH) molecules. The 30 μm feature is commonly observed in all stages of stellar evolution from the asymptotic giant branch through PPN to the planetary nebula phase. We explore the interrelations among the mysterious 21, 30 μm, and UIR features of the 21 μm sources. We derive the fluxes emitted in the observed UIR, 21, and 30 μm features from published Infrared Space Observatory or Spitzer/IRS spectra. We find that none of these spectral features correlate with each other. This argues against a common carrier (e.g., thiourea) for both the 21 μm feature and the 30 μm feature. This also does not support large PAH clusters as a possible carrier for the 21 μm feature.

  10. A Tale of Three Mysterious Spectral Features in Carbon-rich Evolved Stars: The 21 μm, 30 μm, and “Unidentified Infrared” Emission Features

    NASA Astrophysics Data System (ADS)

    Mishra, Ajay; Li, Aigen; Jiang, B. W.

    2015-03-01

    The mysterious “21 μm” emission feature seen almost exclusively in the short-lived protoplanetary nebula (PPN) phase of stellar evolution remains unidentified since its discovery two decades ago. This feature is always accompanied by the equally mysterious, unidentified “30 μm” feature and the so-called “unidentified infrared” (UIR) features at 3.3, 6.2, 7.7, 8.6, and 11.3 μm which are generally attributed to polycyclic aromatic hydrocarbon (PAH) molecules. The 30 μm feature is commonly observed in all stages of stellar evolution from the asymptotic giant branch through PPN to the planetary nebula phase. We explore the interrelations among the mysterious 21, 30 μm, and UIR features of the 21 μm sources. We derive the fluxes emitted in the observed UIR, 21, and 30 μm features from published Infrared Space Observatory or Spitzer/IRS spectra. We find that none of these spectral features correlate with each other. This argues against a common carrier (e.g., thiourea) for both the 21 μm feature and the 30 μm feature. This also does not support large PAH clusters as a possible carrier for the 21 μm feature.

  11. Sportswear textiles emissivity measurement: comparison of IR thermography and emissometry techniques

    NASA Astrophysics Data System (ADS)

    Bison, P.; Grinzato, E.; Libbra, A.; Muscio, A.

    2012-06-01

    Three sportswear textiles are compared, one normal and two 'special' with Ag+ ions and Carbon powder added, with different colors. The emissivity of the textiles has been measured to determine if it is increased in the 'special' textiles with respect to the normal one. The test implied some non-standard procedure due to the semitransparent nature of the textiles, in comparison with the normal procedure that is commonly used on opaque surfaces. The test is also carried out by a standard emissometry technique, based on a comparative approach with reference samples having known thermal emissivity. The results are compared and discussed.

  12. Optical Emission Studies of Copper Plasma Induced Using Infrared Transversely Excited Atmospheric (IR TEA) Carbon Dioxide Laser Pulses.

    PubMed

    Momcilovic, Milos; Kuzmanovic, Miroslav; Rankovic, Dragan; Ciganovic, Jovan; Stoiljkovic, Milovan; Savovic, Jelena; Trtica, Milan

    2015-04-01

    Spatially resolved, time-integrated optical emission spectroscopy was applied for investigation of copper plasma produced by a nanosecond infrared (IR) transversely excited atmospheric (TEA) CO2 laser, operating at 10.6 μm. The effect of surrounding air pressure, in the pressure range 0.1 to 1013 mbar, on plasma formation and its characteristics was investigated. A linear dependence of intensity threshold for plasma formation on logarithm of air pressure was found. Lowering of the air pressure reduces the extent of gas breakdown, enabling better laser-target coupling and thus increases ablation. Optimum air pressure for target plasma formation was 0.1 mbar. Under that pressure, the induced plasma consisted of two clearly distinguished and spatially separated regions. The maximum intensity of emission, with sharp and well-resolved spectral lines and negligibly low background emission, was obtained from a plasma zone 8 mm from the target surface. The estimated excitation temperature in this zone was around 7000 K. The favorable signal to background ratio obtained in this plasma region indicates possible analytical application of TEA CO2 laser produced copper plasma. Detection limits of trace elements present in the Cu sample were on the order of 10 ppm (parts per million). Time-resolved measurements of spatially selected plasma zones were used to find a correlation between the observed spatial position and time delay. PMID:25741748

  13. Orientation effects on spectral emission features of quasars

    NASA Astrophysics Data System (ADS)

    Bisogni, Susanna; Marconi, Alessandro; Risaliti, Guido

    2016-09-01

    We present an analysis of the orientation effects in SDSS quasar composite spectra. In a previous work we have shown that the equivalent width EW of the [OIII] λ5008Å line is a reliable indicator of the inclination of the accretion disk. Here, we have selected a sample of ˜15,000 quasars from the SDSS 7th Data Release and divided it in sub-samples with different values of EW[OIII]. We find inclination effects both on broad and narrow quasars emission lines, among which an increasing broadening from low to high EW for the broad lines and a decreasing importance of the blue component for the narrow lines. These effects are naturally explained with a variation of source inclination from nearly face-on to edge-on, confirming the goodness of EW[OIII]as an orientation indicator. Moreover, we suggest that orientation effects could explain, at least partially, the origin of the anticorrelation between [OIII] and FeII intensities, i.e. the well known Eigenvector 1.

  14. A study of extreme carbon stars. I - Silicon carbide emission features

    NASA Technical Reports Server (NTRS)

    Cohen, M.

    1984-01-01

    10-micron spectra of many extreme carbon stars reveal a prominent emission feature near 11 microns. This is compared with laboratory spectra of SiC grains. Two distinct types of features are found, perhaps indicative of different mechanisms of grain formation in different stars. Estimates are made of probable column densities and total masses of SiC in the circumstellar shells.

  15. HST WFC3 Early Release Science: Emission-Line Galaxies from IR Grism Observations

    NASA Technical Reports Server (NTRS)

    Straughn, A. N.; Kuntschner, H.; Kuemmel, M.; Walsh, J. R.; Cohen, S. H.; Gardner, J. P.; Windhorst, R. A.; O'Connell, R. W.; Pirzkal, N.; Meurer, G.; McCarthy, P. J.; Hathi, N. P.; Malhotra, S.; Rhoads, J.; Balick, B.; Bond, H. E.; Calzetti, D.; Disney, M. J.; Dopita, M. A.; Frogel, J. A.; Hall, D. N. B.; Holtzman, J. A.; Kimlbe, R. A.; Trauger, J. T.; Young, E. T.

    2010-01-01

    We present grism spectra of emission line galaxies (ELGs) from 0.6-1.6 microns from the Wide Field Camera 3 (WFC3) on the Hubble Space Telescope (HST). These new infrared grism data augment previous optical Advanced Camera for Surveys G800L (0.6-0.95 micron) grism data in GOODS South, extending the wavelength coverage well past the G800L red cutoff. The ERS grism field was observed at a depth of 2 orbits per grism, yielding spectra of hundreds of faint objects, a subset of which are presented here. ELGs are studied via the Ha, [O III ], and [OII] emission lines detected in the redshift ranges 0.2 less than or equal to z less than or equal to 1.6, 1.2 less than or equal to z less than or equal to 2.4 and 2.0 less than or equal to z less than or equal to 3.6 respectively in the G102 (0.8-1.1 microns; R approximately 210) and C141 (1.1-1.6 microns; R approximately 130) grisms. The higher spectral resolution afforded by the WFC3 grisms also reveals emission lines not detectable with the G800L grism (e.g., [S II] and [S III] lines). From these relatively shallow observations, line luminosities, star formation rates, and grism spectroscopic redshifts are determined for a total of 25 ELGs to M(sub AB)(F098M) approximately 25 mag. The faintest source in our sample with a strong but unidentified emission line--is MAB(F098M)=26.9 mag. We also detect the expected trend of lower specific star formation rates for the highest mass galaxies in the sample, indicative of downsizing and discovered previously from large surveys. These results demonstrate the remarkable efficiency and capability of the WFC3 NIR grisms for measuring galaxy properties to faint magnitudes.

  16. HST WFC3 Early Release Science: Emission-line Galaxies from IR Grism Observations

    NASA Astrophysics Data System (ADS)

    Straughn, Amber; Kuntschner, H.; Kuemmel, M.; Walsh, J.; Cohen, S.; Gardner, J. P.; Windhorst, R. A.; O'Connell, R. W.; Pirzkal, N.; Meurer, G.; McCarthy, P. J.; Hathi, N. P.; Malhotra, S.; Rhoads, J.; SOC, WFC3

    2011-01-01

    The Early Release Science II program for HST WFC3 includes one pointing observed with the G102 (0.8-1.1 microns; R 210) and G141 (1.1-1.6 microns; R 130) infrared grisms at a depth of 2 orbits/grism. From this data we detect 48 actively star-forming emission-line galaxies and measure the galaxies' redshifts, line fluxes, star-formation rates, and masses. In particular, the prominent emission lines Ha, [OII], and [OIII] fall into the two infrared grism bandpasses over a redshift range z=0.2-3.6, and the majority of galaxies have at least two lines in the observable wavelength range resulting in secure line identification and redshift determination. We detect galaxies with line fluxes to 3 x 10-17 erg/s/cm2 as well as several sources with very high EW lines. The higher spectral resolution and sensitivity of the WFC3 grisms over previous instrumentation also allows detection of other emission lines in some galaxies. The average magnitude of the emission-line galaxy sample is mAB(F098M)=23.6 mag with more than 20% of the sample fainter than mAB(F098M)=25 mag, demonstrating the remarkable efficiency and capability of the WFC3 NIR grisms for measuring galaxy properties to faint magnitudes and intermediate redshifts. Our results point to the promising potential for future science with WFC3 grism spectroscopy, as well as upcoming missions such as JWST and WFIRST. This paper is based on Early Release Science observations made by the WFC3 Scientific Oversight Committee. We are grateful to the Director of the Space Telescope Science Institute for awarding Director's Discretionary time for this program. This research was supported in part by an appointment to the NASA Postdoctoral Program at Goddard Space Flight Center, administered by Oak Ridge Associated Universities through a contract with NASA (ANS).

  17. Infrared Emission of Normal Galaxies from 2.5 to 12 Micron: Infrared Space Observatory Spectra, Near-Infrared Continuum, and Mid-Infrared Emission Features

    NASA Astrophysics Data System (ADS)

    Lu, Nanyao; Helou, George; Werner, Michael W.; Dinerstein, Harriet L.; Dale, Daniel A.; Silbermann, Nancy A.; Malhotra, Sangeeta; Beichman, Charles A.; Jarrett, Thomas H.

    2003-05-01

    We present ISOPHOT spectra of the regions 2.5-4.9 μm and 5.8-11.6 μm for a sample of 45 disk galaxies from the US Infrared Space Observatory Key Project on Normal Galaxies. The galaxies were selected to span the range in global properties of normal, star-forming disk galaxies in the local universe. The spectra can be decomposed into three spectral components: (1) continuum emission from stellar photospheres, which dominates the near-infrared (NIR; 2.5-4.9 μm) spectral region; (2) a weak NIR excess continuum, which has a color temperature of ~103 K, carries a luminosity of a few percent of the total far-infrared (FIR) dust luminosity LFIR and most likely arises from the interstellar medium (ISM); and (3) the well-known broad emission features at 6.2, 7.7, 8.6, and 11.3 μm, which are generally attributed to aromatic carbon particles. These aromatic features in emission (AFEs) dominate the mid-infrared (MIR; 5.8-11.6 μm) part of the spectrum and resemble the so-called type A spectra observed in many nonstellar sources and the diffuse ISM in our own Galaxy. The few notable exceptions include NGC 4418, where a dust continuum replaces the AFEs in MIR, and NGC 1569, where the AFEs are weak and the strongest emission feature is [S IV] 10.51 μm. The relative strengths of the AFEs vary by 15%-25% among the galaxies. However, little correlation is seen between these variations and either IRAS 60 μm/100 μm flux density ratio R(60/100) or the FIR/blue luminosity ratio LFIR/LB, two widely used indicators of the current star formation activity, suggesting that the observed variations are not a consequence of the radiation field differences among the galaxies. We demonstrate that the NIR excess continuum and AFE emission are correlated, suggesting that they are produced by similar mechanisms and similar (or the same) material. On the other hand, as the current star formation activity increases, the overall strengths of the AFEs and the NIR excess continuum drop

  18. High-power THz to IR emission by femtosecond laser irradiation of random 2D metallic nanostructures

    NASA Astrophysics Data System (ADS)

    Zhang, Liangliang; Mu, Kaijun; Zhou, Yunsong; Wang, Hai; Zhang, Cunlin; Zhang, X.-C.

    2015-07-01

    Terahertz (THz) spectroscopic sensing and imaging has identified its potentials in a number of areas such as standoff security screening at portals, explosive detection at battle fields, bio-medical research, and so on. With these needs, the development of an intense and broadband THz source has been a focus of THz research. In this work, we report an intense (~10 mW) and ultra-broadband (~150 THz) THz to infrared (IR) source with a Gaussian wavefront, emitted from nano-pore-structured metallic thin films with femtosecond laser pulse excitation. The underlying mechanism has been proposed as thermal radiation. In addition, an intense coherent THz signal was generated through the optical rectification process simultaneously with the strong thermal signal. This unique feature opens up new avenues in biomedical research.

  19. High-power THz to IR emission by femtosecond laser irradiation of random 2D metallic nanostructures

    PubMed Central

    Zhang, Liangliang; Mu, Kaijun; Zhou, Yunsong; Wang, Hai; Zhang, Cunlin; Zhang, X.-C.

    2015-01-01

    Terahertz (THz) spectroscopic sensing and imaging has identified its potentials in a number of areas such as standoff security screening at portals, explosive detection at battle fields, bio-medical research, and so on. With these needs, the development of an intense and broadband THz source has been a focus of THz research. In this work, we report an intense (~10 mW) and ultra-broadband (~150 THz) THz to infrared (IR) source with a Gaussian wavefront, emitted from nano-pore-structured metallic thin films with femtosecond laser pulse excitation. The underlying mechanism has been proposed as thermal radiation. In addition, an intense coherent THz signal was generated through the optical rectification process simultaneously with the strong thermal signal. This unique feature opens up new avenues in biomedical research. PMID:26205611

  20. The discovery of a new infrared emission feature at 1905 wavenumbers (5.25 microns) in the spectrum of BD +30 degrees 3639 and its relation to the polycyclic aromatic hydrocarbon model

    NASA Technical Reports Server (NTRS)

    Allamandola, L. J.; Bregman, J. D.; Sandford, S. A.; Tielens, A. G.; Witteborn, F. C.; Wooden, D. H.; Rank, D.

    1989-01-01

    We have discovered a new IR emission feature at 1905 cm-1 (5.25 microns) in the spectrum of BD +30 degrees 3639. This feature joins the family of well-known IR emission features at 3040, 2940, 1750, 1610, "1310," 1160, and 890 cm-1 (3.3, 3.4, 5.7, 6.2, "7.7," 8.6, and 11.2 microns). The origin of this new feature is discussed and it is assigned to an overtone or combination band involving C-H bending modes of polycyclic aromatic hydrocarbons (PAHs). Laboratory work suggests that spectral studies of the 2000-1650 cm-1 (5.0-6.1 microns) region may be very useful in elucidating the molecular structure of interstellar PAHs. The new feature, in conjunction with other recently discovered spectral structure, suggests that the narrow IR emission features originate in PAH molecules rather than large carbon grains. Larger species are likely to be the source of the broad underlying "plateaus" seen in many of the spectra.

  1. IR Windstreaks

    NASA Technical Reports Server (NTRS)

    2005-01-01

    [figure removed for brevity, see original site]

    Windstreaks are features caused by the interaction of wind and topographic landforms. The raised rims and bowls of impact craters causes a complex interaction such that the wind vortex in the lee of the crater can both scour away the surface dust and deposit it back in the center of the lee. If you look closely, you will see evidence of this in a darker 'rim' enclosing a brighter interior.

    This infrared image shows windstreaks in the region between Gordii Dorsum and Amazonis Mensa.

    Image information: IR instrument. Latitude -15.8, Longitude 215 East (145 West). 97 meter/pixel resolution.

    Note: this THEMIS visual image has not been radiometrically nor geometrically calibrated for this preliminary release. An empirical correction has been performed to remove instrumental effects. A linear shift has been applied in the cross-track and down-track direction to approximate spacecraft and planetary motion. Fully calibrated and geometrically projected images will be released through the Planetary Data System in accordance with Project policies at a later time.

    NASA's Jet Propulsion Laboratory manages the 2001 Mars Odyssey mission for NASA's Office of Space Science, Washington, D.C. The Thermal Emission Imaging System (THEMIS) was developed by Arizona State University, Tempe, in collaboration with Raytheon Santa Barbara Remote Sensing. The THEMIS investigation is led by Dr. Philip Christensen at Arizona State University. Lockheed Martin Astronautics, Denver, is the prime contractor for the Odyssey project, and developed and built the orbiter. Mission operations are conducted jointly from Lockheed Martin and from JPL, a division of the California Institute of Technology in Pasadena.

  2. On the Relation between the Mysterious 21 μm Emission Feature of Post-asymptotic Giant Branch Stars and Their Mass-loss Rates

    NASA Astrophysics Data System (ADS)

    Mishra, Ajay; Li, Aigen; Jiang, B. W.

    2016-07-01

    Over two decades ago, a prominent, mysterious emission band peaking at ˜20.1 μm was serendipitously detected in four preplanetary nebulae (PPNe; also known as “protoplanetary nebulae”). To date, this spectral feature, designated as the “21 μm” feature, has been seen in 27 carbon-rich PPNe in the Milky Way and the Magellanic Clouds. The nature of its carriers remains unknown although many candidate materials have been proposed. The 21 μm sources also exhibit an equally mysterious, unidentified emission feature peaking at 30 μm. While the 21 μm feature is exclusively seen in PPNe, a short-lived evolutionary stage between the end of the asymptotic giant branch (AGB) and planetary nebula (PN) phases, the 30 μm feature is more commonly observed in all stages of stellar evolution from the AGB through PPN to PN phases. We derive the stellar mass-loss rates (\\dot{M}) of these sources from their infrared (IR) emission, using the “2-DUST” radiative transfer code for axisymmetric dusty systems which allows one to distinguish the mass-loss rates of the AGB phase ({\\dot{M}}{AGB}) from that of the superwind ({\\dot{M}}{SW}) phase. We examine the correlation between {\\dot{M}}{AGB} or {\\dot{M}}{SW} and the fluxes emitted from the 21 and 30 μm features. We find that both features tend to correlate with {\\dot{M}}{AGB}, suggesting that their carriers are probably formed in the AGB phase. The nondetection of the 21 μm feature in AGB stars suggests that, unlike the 30 μm feature, the excitation of the carriers of the 21 μm feature may require ultraviolet photons which are available in PPNe but not in AGB stars.

  3. ON THE VIABILITY OF THE PAH MODEL AS AN EXPLANATION OF THE UNIDENTIFIED INFRARED EMISSION FEATURES

    SciTech Connect

    Zhang, Yong; Kwok, Sun E-mail: sunkwok@hku.hk

    2015-01-01

    Polycyclic aromatic hydrocarbon (PAH) molecules are widely considered the preferred candidate for the carrier of the unidentified infrared emission bands observed in the interstellar medium and circumstellar envelopes. In this paper, we report the results of fitting a variety of non-PAH spectra (silicates, hydrogenated amorphous carbon, coal, and even artificial spectra) using the theoretical infrared spectra of PAHs from the NASA Ames PAH IR Spectroscopic Database. We show that these non-PAH spectra can be well fitted by PAH mixtures. This suggests that a general match between astronomical spectra and those of PAH mixtures does not necessarily provide definitive support for the PAH hypothesis.

  4. Detection of the Near-IR Cosmic Infrared Background Using Alternative Models of Near-IR Galactic Emission in the DIRBE Data

    NASA Technical Reports Server (NTRS)

    Arendt, Richard G.; Dwek, Eli; Oliversen, Ronald J. (Technical Monitor)

    2000-01-01

    The analysis portion of this task has been completed. New models were developed for the removal of the near-infrared emission of Galactic stars in the DIRBE data. Subtraction of these models from the observed emission attempted to achieve a better detection of the Cosmic Infrared Background at near-infrared wavelengths. The new models were found to provide a large improvement in the isotropy of the residual emission, however constraints on the intensity of the emission are not significantly improved. A paper detailing the procedures and results has been drafted, and will be completed next year. The draft of this paper is included as the final report on the contract.

  5. Dust Around R Coronae Borealis Stars. II. Infrared Emission Features in an H-poor Environment

    NASA Astrophysics Data System (ADS)

    García-Hernández, D. A.; Rao, N. Kameswara; Lambert, D. L.

    2013-08-01

    Residual Spitzer/Infrared Spectrograph spectra for a sample of 31 R Coronae Borealis (RCB) stars are presented and discussed in terms of narrow emission features superimposed on the quasi-blackbody continuous infrared emission. A broad ~6-10 μm dust emission complex is seen in the RCBs showing an extreme H-deficiency. A secondary and much weaker ~11.5-15 μm broad emission feature is detected in a few RCBs with the strongest ~6-10 μm dust complex. The Spitzer infrared spectra reveal for the first time the structure within the ~6-10 μm dust complex, showing the presence of strong C-C stretching modes at ~6.3 and 8.1 μm as well as of other dust features at ~5.9, 6.9, and 7.3 μm, which are attributable to amorphous carbonaceous solids with little or no hydrogen. The few RCBs with only moderate H-deficiencies display the classical "unidentified infrared bands (UIRs)" and mid-infrared features from fullerene-related molecules. In general, the characteristics of the RCB infrared emission features are not correlated with the stellar and circumstellar properties, suggesting that the RCB dust features may not be dependent on the present physical conditions around RCB stars. The only exception seems to be the central wavelength of the 6.3 μm feature, which is blueshifted in those RCBs showing also the UIRs, i.e., the RCBs with the smallest H deficiency.

  6. DUST AROUND R CORONAE BOREALIS STARS. II. INFRARED EMISSION FEATURES IN AN H-POOR ENVIRONMENT

    SciTech Connect

    Garcia-Hernandez, D. A.; Lambert, D. L. E-mail: nkrao@iiap.res.in

    2013-08-20

    Residual Spitzer/Infrared Spectrograph spectra for a sample of 31 R Coronae Borealis (RCB) stars are presented and discussed in terms of narrow emission features superimposed on the quasi-blackbody continuous infrared emission. A broad {approx}6-10 {mu}m dust emission complex is seen in the RCBs showing an extreme H-deficiency. A secondary and much weaker {approx}11.5-15 {mu}m broad emission feature is detected in a few RCBs with the strongest {approx}6-10 {mu}m dust complex. The Spitzer infrared spectra reveal for the first time the structure within the {approx}6-10 {mu}m dust complex, showing the presence of strong C-C stretching modes at {approx}6.3 and 8.1 {mu}m as well as of other dust features at {approx}5.9, 6.9, and 7.3 {mu}m, which are attributable to amorphous carbonaceous solids with little or no hydrogen. The few RCBs with only moderate H-deficiencies display the classical ''unidentified infrared bands (UIRs)'' and mid-infrared features from fullerene-related molecules. In general, the characteristics of the RCB infrared emission features are not correlated with the stellar and circumstellar properties, suggesting that the RCB dust features may not be dependent on the present physical conditions around RCB stars. The only exception seems to be the central wavelength of the 6.3 {mu}m feature, which is blueshifted in those RCBs showing also the UIRs, i.e., the RCBs with the smallest H deficiency.

  7. The Effect of Radiation Timing on Patients With High-Risk Features of Parameningeal Rhabdomyosarcoma: An Analysis of IRS-IV and D9803

    SciTech Connect

    Spalding, Aaron C.; Hawkins, Douglas S.; Anderson, James R.; Lyden, Elizabeth; Laurie, Fran; Wolden, Suzanne L.; Arndt, Carola A.S.; Michalski, Jeff M.

    2013-11-01

    Purpose: Radiation therapy remains an essential treatment for patients with parameningeal rhabdomyosarcoma (PMRMS), and early radiation therapy may improve local control for patients with intracranial extension (ICE). Methods and Materials: To address the role of radiation therapy timing in PMRMS in the current era, we reviewed the outcome from 2 recent clinical trials for intermediate-risk RMS: Intergroup Rhabdomyosarcoma Study (IRS)-IV and Children's Oncology Group (COG) D9803. The PMRMS patients on IRS-IV with any high-risk features (cranial nerve palsy [CNP], cranial base bony erosion [CBBE], or ICE) were treated immediately at day 0, and PMRMS patients without any of these 3 features received week 6-9 radiation therapy. The D9803 PMRMS patients with ICE received day 0 X-Ray Therapy (XRT) as well; however, those with either CNP or CBBE had XRT at week 12. Results: Compared with the 198 PMRMS patients from IRS-IV, the 192 PMRMS patients from D9803 had no difference (P<.05) in 5-year local failure (19% vs 19%), failure-free-survival (70% vs 67%), or overall survival (75% vs 73%) in aggregate. The 5-year local failure rates by subset did not differ when patients were classified as having no risk features (None, 15% vs 19%, P=.25), cranial nerve palsy/cranial base of skull erosion (CNP/CBBE, 15% vs 28%, P=.22), or intracranial extension (ICE, 21% vs 15%, P=.27). The D9083 patients were more likely to have received initial staging by magnetic resonance imaging (71% vs 53%). Conclusions: These data support that a delay in radiation therapy for high-risk PMRMS features of CNP/CBBE does not compromise clinical outcomes.

  8. Specific features of diffuse reflection of human face skin for laser and non-laser sources of visible and near-IR light

    SciTech Connect

    Dolotov, L E; Sinichkin, Yu P; Tuchin, Valerii V; Al'tshuler, G B; Yaroslavskii, I V

    2011-04-30

    The specific features of diffuse reflection from different areas of human face skin for laser and non-laser sources of visible and near-IR light have been investigated to localise the closed-eye (eyelid) region. In the visible spectral range the reflection from the eyelid skin surface can be differentiated by measuring the slope of the spectral dependence of the effective optical density of skin in the wavelength range from 650 to 700nm. In the near-IR spectral range the reflectances of the skin surface at certain wavelengths, normalised to the forehead skin reflectance, can be used as a criterion for differentiating the eyelid skin. In this case, a maximum discrimination is obtained when measuring the skin reflectances at laser wavelengths of 1310 and 1470nm, which correspond to the spectral ranges of maximum and minimum water absorption. (optical technologies in biophysics and medicine)

  9. Specific features of diffuse reflection of human face skin for laser and non-laser sources of visible and near-IR light

    NASA Astrophysics Data System (ADS)

    Dolotov, L. E.; Sinichkin, Yu P.; Tuchin, Valerii V.; Al'tshuler, G. B.; Yaroslavskii, I. V.

    2011-04-01

    The specific features of diffuse reflection from different areas of human face skin for laser and non-laser sources of visible and near-IR light have been investigated to localise the closed-eye (eyelid) region. In the visible spectral range the reflection from the eyelid skin surface can be differentiated by measuring the slope of the spectral dependence of the effective optical density of skin in the wavelength range from 650 to 700nm. In the near-IR spectral range the reflectances of the skin surface at certain wavelengths, normalised to the forehead skin reflectance, can be used as a criterion for differentiating the eyelid skin. In this case, a maximum discrimination is obtained when measuring the skin reflectances at laser wavelengths of 1310 and 1470nm, which correspond to the spectral ranges of maximum and minimum water absorption.

  10. The effect of emissive biased limiter on the magnetohydrodynamic modes in the IR-T1 tokamak

    SciTech Connect

    Ghasemloo, M.; Ghoranneviss, M.; Salem, M. K.; Arvin, R.; Mohammadi, S.; Nik Mohammadi, A.

    2013-03-15

    A moveable emissive biased limiter (EBL) for the investigation of spatial and temporal structure of MHD modes in IR-T1 tokamak, based on mirnov oscillations, was designed and constructed. The biasing has been considered to improve the global confinement by setting up an electric field at the plasma edge. Radial electric field (E{sub r}) modifies edge plasma turbulence, plasma rotation, and transport. Mirnov oscillations using singular value decomposition (SVD) and wavelet techniques were analyzed. SVD algorithm has been employed to analyze the frequency and wavenumber harmonics of the MHD fluctuations. The time-resolved frequency component analysis has been performed using wavelets. The EBL was applied to plasma at 10 ms with negative polarity. The results show that after applying EBL, the m = 2 mode is grown, m = 3 mode is suppressed, and H{sub {alpha}} radiation is decreased. Furthermore, results of the wavelet analysis of mirnov coil in the time range of 8-12 ms indicate that 1.5 ms after applying EBL, the MHD frequency is reduced from 45 kHz to 25 kHz.

  11. Review of features of stimulated electromagnetic emission (see): Recent results obtained at the ``sura'' heating facility

    NASA Astrophysics Data System (ADS)

    Frolov, V. L.; Kagan, L. M.; Sergeev, E. N.

    1999-07-01

    We present a short review of the features of the main components (DM, UM, NC, BC, BUM, and BUS) of stimulated electromagnetic emission (SEE). We discuss variations of these components in the case where additional X-mode heating is used. The experiments were performed at the “Sura” heating facility (Nizhny Novgorod, Russia) during the last few years.

  12. Spatial variations of the 3-micron emission features within Orion's Bar

    NASA Technical Reports Server (NTRS)

    Moorhouse, A.; Brand, P. W. J. L.; Geballe, T. R.; Allamandola, L. J.; Tielens, A. G. G. M.

    1988-01-01

    3-micron spectra of the Orion Bar region have been obtained at three positions corresponding to different distances from the exciting source. The recently discovered unidentified features at 3.46, 3.51, and 3.57 microns are clearly visible. The spectra show that the 3.4 and 3.51-micron emission features increase in intensity relative to the strong 3.3-micron feature as the distance from the exciting source increases. The implications for polycyclic aromatic hydrocarbons and recent ideas concerning their ultraviolet excitation and spatial evolution are discussed.

  13. Application of a radiometric calibration method to lunar Fourier transform IR spectra by using a liquid-nitrogen-cooled high-emissivity blackbody.

    PubMed

    Schreiber, J; Blumenstock, T; Hase, F

    1997-11-01

    Since winter 1994/1995 the Moon has been used in addition to the Sun as an IR source of radiation to measure atmospheric absorption spectra with a Bruker IR Fourier transform spectrometer IFS 120M located near Kiruna, Sweden. A two-point radiometric calibration method with blackbody references was applied to lunar spectra in the long-wave detector channel to improve the accuracy of evaluation of the column amounts of different atmospheric trace gases. A new liquid-nitrogen-cooled high-emissivity blackbody without an entrance window is described that is used for this calibration method.

  14. The Luminous Polycyclic Aromatic Hydrocarbon Emission Features: Applications to High Redshift Galaxies and Active Galactic Nuclei

    NASA Astrophysics Data System (ADS)

    Shipley, Heath; Papovich, Casey

    2015-08-01

    We provide a new robust star-formation rate (SFR) calibration using the luminosity from polycyclic aromatic hydrogen (PAH) molecules. The PAH features emit strongly in the mid-infrared (mid-IR; 3-19μm), mitigating dust extinction, and they are very luminous, containing 5-10% of the total IR luminosity in galaxies. We derive the calibration of the PAH luminosity as a SFR indicator using a sample of 105 star-forming galaxies covering a range of total IR luminosity, LIR = L(8-1000μm) = 109 - 1012 L⊙ and redshift 0 < z < 0.6. The PAH luminosity correlates linearly with the SFR as measured by the dust-corrected Hα luminosity (using the sum of the Hα and rest-frame 24μm luminosity from Kennicutt et al. 2009), with tight scatter of ~0.15 dex, comparable to the scatter in the dust-corrected Hα SFRs and Paα SFRs. We show this relation is sensitive to galaxy metallicity, where the PAH luminosity of galaxies with Z < 0.7 Z⊙ departs from the linear SFR relationship but in a behaved manor. We derive for this a correction to galaxies below solar metallicity. As a case study for observations with JWST, we apply the PAH SFR calibration to a sample of lensed galaxies at 1 < z < 3 with Spitzer Infrared Spectrograph (IRS) data, and we demonstrate the utility of PAHs to derive SFRs as accurate as those available from any other indicator. This new SFR indicator will be useful for probing the peak of the SFR density of the universe (1 < z < 3) and for studying the coevolution of star-formation and supermassive blackhole accretion contemporaneously in a galaxy.

  15. Separation of Atmospheric and Surface Spectral Features in Mars Global Surveyor Thermal Emission Spectrometer (TES) Spectra

    NASA Technical Reports Server (NTRS)

    Smith, Michael D.; Bandfield, Joshua L.; Christensen, Philip R.

    2000-01-01

    We present two algorithms for the separation of spectral features caused by atmospheric and surface components in Thermal Emission Spectrometer (TES) data. One algorithm uses radiative transfer and successive least squares fitting to find spectral shapes first for atmospheric dust, then for water-ice aerosols, and then, finally, for surface emissivity. A second independent algorithm uses a combination of factor analysis, target transformation, and deconvolution to simultaneously find dust, water ice, and surface emissivity spectral shapes. Both algorithms have been applied to TES spectra, and both find very similar atmospheric and surface spectral shapes. For TES spectra taken during aerobraking and science phasing periods in nadir-geometry these two algorithms give meaningful and usable surface emissivity spectra that can be used for mineralogical identification.

  16. Probing the terrestrial regions of planetary systems: warm debris disks with emission features

    SciTech Connect

    Ballering, Nicholas P.; Rieke, George H.; Gáspár, András

    2014-09-20

    Observations of debris disks allow for the study of planetary systems, even where planets have not been detected. However, debris disks are often only characterized by unresolved infrared excesses that resemble featureless blackbodies, and the location of the emitting dust is uncertain due to a degeneracy with the dust grain properties. Here, we characterize the Spitzer Infrared Spectrograph spectra of 22 debris disks exhibiting 10 μm silicate emission features. Such features arise from small warm dust grains, and their presence can significantly constrain the orbital location of the emitting debris. We find that these features can be explained by the presence of an additional dust component in the terrestrial zones of the planetary systems, i.e., an exozodiacal belt. Aside from possessing exozodiacal dust, these debris disks are not particularly unique; their minimum grain sizes are consistent with the blowout sizes of their systems, and their brightnesses are comparable to those of featureless warm debris disks. These disks are in systems of a range of ages, though the older systems with features are found only around A-type stars. The features in young systems may be signatures of terrestrial planet formation. Analyzing the spectra of unresolved debris disks with emission features may be one of the simplest and most accessible ways to study the terrestrial regions of planetary systems.

  17. Mixed aromatic-aliphatic organic nanoparticles as carriers of unidentified infrared emission features.

    PubMed

    Kwok, Sun; Zhang, Yong

    2011-11-01

    Unidentified infrared emission bands at wavelengths of 3-20 micrometres are widely observed in a range of environments in our Galaxy and in others. Some features have been identified as the stretching and bending modes of aromatic compounds, and are commonly attributed to polycyclic aromatic hydrocarbon molecules. The central argument supporting this attribution is that single-photon excitation of the molecule can account for the unidentified infrared emission features observed in 'cirrus' clouds in the diffuse interstellar medium. Of the more than 160 molecules identified in the circumstellar and interstellar environments, however, not one is a polycyclic aromatic hydrocarbon molecule. The detections of discrete and broad aliphatic spectral features suggest that the carrier of the unidentified infrared emission features cannot be a pure aromatic compound. Here we report an analysis of archival spectroscopic observations and demonstrate that the data are most consistent with the carriers being amorphous organic solids with a mixed aromatic-aliphatic structure. This structure is similar to that of the organic materials found in meteorites, as would be expected if the Solar System had inherited these organic materials from interstellar sources.

  18. Studies of the jet in BL Lacertae. I. Recollimation shock and moving emission features

    SciTech Connect

    Cohen, M. H.; Hovatta, T.; Meier, D. L.; Arshakian, T. G.; Homan, D. C.; Kovalev, Y. Y.; Pushkarev, A. B.; Savolainen, T.

    2014-06-01

    Parsec-scale VLBA images of BL Lac at 15 GHz show that the jet contains a permanent quasi-stationary emission feature 0.26 mas (0.34 pc projected) from the core, along with numerous moving features. In projection, the tracks of the moving features cluster around an axis at a position angle of –166.°6 that connects the core with the standing feature. The moving features appear to emanate from the standing feature in a manner strikingly similar to the results of numerical two-dimensional relativistic magneto-hydrodynamic (RMHD) simulations in which moving shocks are generated at a recollimation shock (RCS). Because of this, and the close analogy to the jet feature HST-1 in M87, we identify the standing feature in BL Lac as an RCS. We assume that the magnetic field dominates the dynamics in the jet, and that the field is predominantly toroidal. From this we suggest that the moving features are compressions established by slow and fast mode magneto-acoustic MHD waves. We illustrate the situation with a simple model in which the slowest moving feature is a slow-mode wave, and the fastest feature is a fast-mode wave. In the model, the beam has Lorentz factor Γ{sub beam}{sup gal}≈3.5 in the frame of the host galaxy and the fast mode wave has Lorentz factor Γ{sub Fwave}{sup beam}≈1.6 in the frame of the beam. This gives a maximum apparent speed for the moving features, β{sub app} = v{sub app}/c = 10. In this model the Lorentz factor of the pattern in the galaxy frame is approximately three times larger than that of the beam itself.

  19. Emission intensity in the visible and IR spectral ranges from Si-based structures formed by direct bonding with simultaneous doping with erbium (Er) and europium (Eu)

    SciTech Connect

    Mezdrogina, M. M. Kostina, L. S.; Beliakova, E. I.; Kuzmin, R. V.

    2013-09-15

    The photo- and electroluminescence spectra of silicon-based structures formed by direct bonding with simultaneous doping with rare-earth metals are studied. It is shown that emission in the visible and IR spectral ranges can be obtained from n-Si:Er/p-Si and n-Si:Eu/p-Si structures fabricated by the method suggested in the study. The results obtained make this method promising for the fabrication of optoelectronic devices.

  20. THE 5.25 AND 5.7 {mu}m ASTRONOMICAL POLYCYCLIC AROMATIC HYDROCARBON EMISSION FEATURES

    SciTech Connect

    Boersma, C.; Tielens, A. G. G. M.; Mattioda, A. L.; Allamandola, L. J.; Bauschlicher, C. W.; Peeters, E.

    2009-01-10

    Astronomical mid-IR spectra show two minor polycyclic aromatic hydrocarbon (PAH) features at 5.25 and 5.7 {mu}m (1905 and 1754 cm{sup -1}) that hitherto have been little studied, but contain information about the astronomical PAH population that complements that of the major emission bands. Here, we report a study involving both laboratory and theoretical analysis of the fundamentals of PAH spectroscopy that produce features in this region and use these to analyze the astronomical spectra. The Infrared Space Observatory Short Wavelength Spectrograph spectra of 15 objects showing these PAH features were considered for this study, however only four (HD 44179; NGC 7027; Orion Bar, two positions) have sufficient signal-to-noise between 5 and 6 {mu}m to allow for an in-depth analysis. All four astronomical spectra show similar peak positions and profiles. The 5.25 {mu}m feature is peaked and asymmetric, with an FWHM of about 0.12 {+-} 0.01 {mu}m ({approx}40 {+-} 6.5 cm{sup -1}), while the 5.7 {mu}m feature is broader and flatter, with an FWHM of about 0.17 {+-} 0.02 {mu}m (50 {+-} 5.6 cm{sup -1}). Detailed analysis of the laboratory spectra and quantum-chemical calculations show that the astronomical 5.25 and 5.7 {mu}m bands are a blend of combination, difference and overtone bands primarily involving CH stretching and CH in-plane and CH out-of-plane bending fundamental vibrations. The experimental and computational spectra show that, of all the hydrogen adjacency classes that are possible on PAHs, solo and duo hydrogens consistently produce prominent bands at the observed positions, whereas quartet hydrogens do not. In all, this study supports the picture that astronomical PAHs are large with compact, regular structures. From the coupling with primarily strong CH out-of-plane bending modes, one might surmise that the 5.25 and 5.7 {mu}m bands track the neutral PAH population. However, theory suggests that the role of charge in these astronomical bands might also be

  1. The 5.25 and 5.7 μm Astronomical Polycyclic Aromatic Hydrocarbon Emission Features

    NASA Astrophysics Data System (ADS)

    Boersma, C.; Mattioda, A. L.; Bauschlicher, C. W., Jr.; Peeters, E.; Tielens, A. G. G. M.; Allamandola, L. J.

    2009-01-01

    Astronomical mid-IR spectra show two minor polycyclic aromatic hydrocarbon (PAH) features at 5.25 and 5.7 μm (1905 and 1754 cm-1) that hitherto have been little studied, but contain information about the astronomical PAH population that complements that of the major emission bands. Here, we report a study involving both laboratory and theoretical analysis of the fundamentals of PAH spectroscopy that produce features in this region and use these to analyze the astronomical spectra. The Infrared Space Observatory Short Wavelength Spectrograph spectra of 15 objects showing these PAH features were considered for this study, however only four (HD 44179; NGC 7027; Orion Bar, two positions) have sufficient signal-to-noise between 5 and 6 μm to allow for an in-depth analysis. All four astronomical spectra show similar peak positions and profiles. The 5.25 μm feature is peaked and asymmetric, with an FWHM of about 0.12 ± 0.01 μm (~40 ± 6.5 cm-1), while the 5.7 μm feature is broader and flatter, with an FWHM of about 0.17 ± 0.02 μm (50 ± 5.6 cm-1). Detailed analysis of the laboratory spectra and quantum-chemical calculations show that the astronomical 5.25 and 5.7 μm bands are a blend of combination, difference and overtone bands primarily involving CH stretching and CH in-plane and CH out-of-plane bending fundamental vibrations. The experimental and computational spectra show that, of all the hydrogen adjacency classes that are possible on PAHs, solo and duo hydrogens consistently produce prominent bands at the observed positions, whereas quartet hydrogens do not. In all, this study supports the picture that astronomical PAHs are large with compact, regular structures. From the coupling with primarily strong CH out-of-plane bending modes, one might surmise that the 5.25 and 5.7 μm bands track the neutral PAH population. However, theory suggests that the role of charge in these astronomical bands might also be important. Based on observations with Infrared Space

  2. Long-lived room-temperature deep-red-emissive intraligand triplet excited state of naphthalimide in cyclometalated Ir(III) complexes and its application in triplet-triplet annihilation-based upconversion.

    PubMed

    Sun, Jifu; Wu, Wanhua; Zhao, Jianzhang

    2012-06-25

    Cyclometalated Ir(III) complexes with acetylide ppy and bpy ligands were prepared (ppy = 2-phenylpyridine, bpy = 2,2'-bipyridine) in which naphthal (Ir-2) and naphthalimide (NI) were attached onto the ppy (Ir-3) and bpy ligands (Ir-4) through acetylide bonds. [Ir(ppy)(3)] (Ir-1) was also prepared as a model complex. Room-temperature phosphorescence was observed for the complexes; both neutral and cationic complexes Ir-3 and Ir-4 showed strong absorption in the visible range (ε=39,600  M(-1)  cm(-1) at 402 nm and ε=25,100  M(-1)  cm(-1) at 404 nm, respectively), long-lived triplet excited states (τ(T)=9.30 μs and 16.45 μs) and room-temperature red emission (λ(em)=640 nm, Φ(p)=1.4 % and λ(em)=627 nm, Φ(p)=0.3 %; cf. Ir-1: ε=16,600  M(-1)  cm(-1) at 382 nm, τ(em)=1.16 μs, Φ(p)=72.6 %). Ir-3 was strongly phosphorescent in non-polar solvent (i.e., toluene), but the emission was completely quenched in polar solvents (MeCN). Ir-4 gave an opposite response to the solvent polarity, that is, stronger phosphorescence in polar solvents than in non-polar solvents. Emission of Ir-1 and Ir-2 was not solvent-polarity-dependent. The T(1) excited states of Ir-2, Ir-3, and Ir-4 were identified as mainly intraligand triplet excited states ((3)IL) by their small thermally induced Stokes shifts (ΔE(s)), nanosecond time-resolved transient difference absorption spectroscopy, and spin-density analysis. The complexes were used as triplet photosensitizers for triplet-triplet annihilation (TTA) upconversion and quantum yields of 7.1 % and 14.4 % were observed for Ir-2 and Ir-3, respectively, whereas the upconversion was negligible for Ir-1 and Ir-4. These results will be useful for designing visible-light-harvesting transition-metal complexes and for their applications as triplet photosensitizers for photocatalysis, photovoltaics, TTA upconversion, etc.

  3. A far-infrared emission feature in carbon-rich stars and planetary nebulae

    NASA Technical Reports Server (NTRS)

    Forrest, W. J.; Houck, J. R.; Mccarthy, J. F.

    1981-01-01

    The 16-30 micron spectra of several carbon stars and the planetary nebulae IC 418 and NGC 6572 have been obtained using the NASA C-141 Kuiper Airborne Observatory. A newly observed emission feature appears in the spectrum of IRC +10216 and several other carbon stars at wavelengths greater than 24 microns. The feature is interpreted as resulting from a solid-state resonance in the dust grains which have condensed around these stars. A similar feature appears in the spectra of IC 418 and NGC 6572, implying that the same type of dust is present. Since the dust probably condensed from a carbon-rich gas, this indicates an evolutionary link between carbon stars and these planetary nebulae. No identification for the grain material has been found, but some clues are apparent which could aid in the identification.

  4. Laboratory simulation of infrared astrophysical features. Ph.D. Thesis; [emission spectra of comets

    NASA Technical Reports Server (NTRS)

    Rose, L. A.

    1977-01-01

    Intermediate resolution emission spectroscopy was used to study a group of 9 terrestrial silicates, 1 synthetic silicate, 6 meteorites and 2 lunar soils; comparisons were made with the intermediate resolution spectra of Comet Kohoutek in order to determine which materials best simulate the 10um astrophysical feature. Mixtures of silicates which would yield spectra matching the spectrum of the comet in the 10um region include: (1) A hydrous layer lattice silicate in combination with a high temperature condensate; (2) an amorphous magnesium silicate in combination with a high temperature condensate and (3) glassy olivine and glassy anorthite in approximately equal proportions.

  5. Preseismic electromagnetic emissions: demystifying the features of the last stages of fracture process

    NASA Astrophysics Data System (ADS)

    Eftaxias, Konstantinos; Potirakis, Stelios M.; Peratzakis, Athanasios; Nomicos, Constantinos

    2013-04-01

    In recent years, the wind prevailing in the scientific community does not appear to be favorable for earthquake (EQ) prediction research, in particular for the research of short term prediction. Sometimes the arguments were extended to the extreme claim that any precursory activity is impossible. Importantly, negative views originate from certain systematically observed features, currently considered as "paradoxes". Fracture-induced electromagnetic emissions (EME) in a wide range of frequency bands are sensitive to the micro-structural chances. Thus, their study constitutes a nondestructive method for the monitoring of the evolution of damage process at the laboratory scale. It has been suggested that fracture induced MHz-kHz electromagnetic (EM) emissions, which emerge from a few days up to a few hours before the main seismic shock occurrence permit a real time monitoring of the damage process during the last stages of earthquake preparation, as it happens at the laboratory scale. Despite fairly abundant evidence, EM precursors have not been adequately accepted as credible physical quantities. These negative views are enhanced by the fact that certain "puzzling features" are consistently observed in candidate pre-seismic EM emissions. More precisely: (i) EM silence in all frequency bands appears before the main seismic shock occurrence, as well as during the aftershock period. (ii) Absence of strong strain changes is observed during the emergence of EM precursors. We argue that experiments by means of EME at the large, geophysical, scale would probably reveal features of the last stages of failure process not clearly observable at the small, laboratory, scale, allowing thus the monitoring in real-time and step-by-step of the EQ generation. The observed EM precursors have been interpreted through a shift in thinking towards the basic science. Strict criteria have been established for the definition of an emerged EM anomaly as a pre-seismic one by means of a

  6. On the puzzling feature of the silence of precursory electromagnetic emissions

    NASA Astrophysics Data System (ADS)

    Eftaxias, K.; Potirakis, S. M.; Chelidze, T.

    2013-09-01

    It has been suggested that fracture-induced MHz-kHz electromagnetic emissions (EME), which emerge from a few days up to a few hours before the main seismic shock occurrence permit a real-time monitoring of the damage process during the last stages of earthquake preparation, as it happens at the laboratory scale. Despite fairly abundant evidence, electromagnetic (EM) precursors have not been adequately accepted as credible physical phenomena. These negative views are enhanced by the fact that certain "puzzling features" are repetitively observed in candidate fracture-induced pre-seismic EME. More precisely, EM silence in all frequency bands appears before the main seismic shock occurrence, as well as during the aftershock period. Actually, the view that "acceptance of "precursive" EM signals without convincing co-seismic signals should not be expected" seems to be reasonable. In this work we focus on this point. We examine whether the aforementioned features of EM silence are really puzzling ones or, instead, reflect well-documented characteristic features of the fracture process, in terms of universal structural patterns of the fracture process, recent laboratory experiments, numerical and theoretical studies of fracture dynamics, critical phenomena, percolation theory, and micromechanics of granular materials. Our analysis shows that these features should not be considered puzzling.

  7. Spectroscopic observations of bright and dark emission features on the night side of venus.

    PubMed

    Bell, J F; Crisp, D; Lucey, P G; Ozoroski, T A; Sinton, W M; Willis, S C; Campbell, B A

    1991-05-31

    Near-infrared spectra of a bright and a dark thermal emission feature on the night side of Venus have been obtained from 2.2 to 2.5 micrometers (microm) at a spectral resolution of 1200 to 1500. Both bright and dark features show numerous weak absorption bands produced by CO(2), CO, water vapor, and other gases. The bright feature (hot spot) emits more radiation than the dark feature (cold spot) throughout this spectral region, but the largest contrasts occur between 2.21 and 2.32 microm, where H(2)SO(4) clouds and a weak CO(2) band provide the only known sources of extinction. The contrast decreases by 55 to 65 percent at wavelengths longer than 2.34 microm, where CO, clouds, and water vapor also absorb and scatter upwelling radiation. This contrast reduction may provide direct spectroscopic evidence for horizontal variations in the water vapor concentrations in the Venus atmosphere at levels below the cloud tops. PMID:17842954

  8. Spectroscopic observations of bright and dark emission features on the night side of venus.

    PubMed

    Bell, J F; Crisp, D; Lucey, P G; Ozoroski, T A; Sinton, W M; Willis, S C; Campbell, B A

    1991-05-31

    Near-infrared spectra of a bright and a dark thermal emission feature on the night side of Venus have been obtained from 2.2 to 2.5 micrometers (microm) at a spectral resolution of 1200 to 1500. Both bright and dark features show numerous weak absorption bands produced by CO(2), CO, water vapor, and other gases. The bright feature (hot spot) emits more radiation than the dark feature (cold spot) throughout this spectral region, but the largest contrasts occur between 2.21 and 2.32 microm, where H(2)SO(4) clouds and a weak CO(2) band provide the only known sources of extinction. The contrast decreases by 55 to 65 percent at wavelengths longer than 2.34 microm, where CO, clouds, and water vapor also absorb and scatter upwelling radiation. This contrast reduction may provide direct spectroscopic evidence for horizontal variations in the water vapor concentrations in the Venus atmosphere at levels below the cloud tops.

  9. Intrinsic fluorescence excitation-emission matrix spectral features of cottonseed protein fractions and the effects of denaturants

    Technology Transfer Automated Retrieval System (TEKTRAN)

    To better understand the functional and physicochemical properties of cottonseed protein, we investigated the intrinsic fluorescence excitation-emission matrix (EEM) spectral features of cottonseed protein isolate (CSPI) and sequentially extracted water (CSPw) and alkali (CSPa) protein fractions, an...

  10. THE CARRIERS OF THE INTERSTELLAR UNIDENTIFIED INFRARED EMISSION FEATURES: AROMATIC OR ALIPHATIC?

    SciTech Connect

    Li Aigen; Draine, B. T. E-mail: draine@astro.princeton.edu

    2012-12-01

    The unidentified infrared emission (UIE) features at 3.3, 6.2, 7.7, 8.6, and 11.3 {mu}m, commonly attributed to polycyclic aromatic hydrocarbon (PAH) molecules, have been recently ascribed to coal- or kerogen-like organic nanoparticles with a mixed aromatic-aliphatic structure. However, we show in this Letter that this hypothesis is inconsistent with observations. We estimate the aliphatic fraction of the UIE carriers based on the observed intensities of the 3.4 {mu}m and 6.85 {mu}m emission features by attributing them exclusively to aliphatic C-H stretch and aliphatic C-H deformation vibrational modes, respectively. We derive the fraction of carbon atoms in aliphatic form to be <15%. We conclude that the UIE emitters are predominantly aromatic, with aliphatic material at most a minor part of the UIE carriers. The PAH model is consistent with astronomical observations and PAHs dominate the strong UIE bands.

  11. ON THE ORIGIN OF THE 11.3 MICRON UNIDENTIFIED INFRARED EMISSION FEATURE

    SciTech Connect

    Sadjadi, SeyedAbdolreza; Zhang, Yong; Kwok, Sun

    2015-07-01

    The 11.3 μm emission feature is a prominent member of the family of unidentified infrared emission (UIE) bands and is frequently attributed to out-of-plane bending modes of polycyclic aromatic hydrocarbon (PAH) molecules. We have performed quantum mechanical calculations of 60 neutral PAH molecules and found that it is difficult to reconcile the observed astronomical feature with any or a mix of these PAH molecules. We have further analyzed the fitting of spectra of several astronomical objects by the NASA PAH database program and found that reasonable fittings to the observed spectra are only possible by including significant contributions from oxygen- and/or magnesium-containing molecules in the mix. A mix of pure PAH molecules, even including units of different sizes, geometry, and charged states, is unable to fit the astronomical spectra. Preliminary theoretical results on the vibrational spectra of simple molecules with mixed aromatic/aliphatic structures show that these structures have consistent clusters of vibrational modes and could be viable carriers of the UIE bands.

  12. ON THE 2012 OCTOBER 23 CIRCULAR RIBBON FLARE: EMISSION FEATURES AND MAGNETIC TOPOLOGY

    SciTech Connect

    Yang, Kai; Guo, Yang; Ding, M. D. E-mail: dmd@nju.edu.cn

    2015-06-20

    Circular ribbon flares are usually related to spine-fan type magnetic topology containing null points. In this paper, we investigate an X-class circular ribbon flare on 2012 October 23, using the multiwavelength data from the Solar Dynamics Observatory, Hinode, and RHESSI. In Ca ii H emission, the flare showed three ribbons with two highly elongated ones inside and outside a quasi-circular one, respectively. A hot channel was displayed in the extreme-ultraviolet emissions that infers the existence of a magnetic flux rope. Two hard X-ray (HXR) sources in the 12–25 keV energy band were located at the footpoints of this hot channel. Using a nonlinear force-free magnetic field extrapolation, we identify three topological structures: (1) a three-dimensional null point, (2) a flux rope below the fan of the null point, and (3) a large-scale quasi-separatrix layer (QSL) induced by the quadrupolar-like magnetic field of the active region. We find that the null point is embedded within the large-scale QSL. In our case, all three identified topological structures must be considered to explain all the emission features associated with the observed flare. Besides, the HXR sources are regarded as the consequence of the reconnection within or near the border of the flux rope.

  13. Hard X-ray emission and {sup 44}Ti line features of the Tycho supernova remnant

    SciTech Connect

    Wang, Wei; Li, Zhuo E-mail: zhuo.li@pku.edu.cn

    2014-07-10

    A deep hard X-ray survey of the International Gamma-Ray Astrophysics Laboratory (INTEGRAL) satellite has detected for the first time non-thermal emission up to 90 keV in the Tycho supernova (SN) remnant. Its 3-100 keV spectrum is fitted with a thermal bremsstrahlung of kT ∼ 0.81 ± 0.45 keV plus a power-law model of Γ ∼ 3.01 ± 0.16. Based on diffusive shock acceleration theory, this non-thermal emission, together with radio measurements, implies that the Tycho remnant may not accelerate protons up to >PeV but to hundreds TeV. Only heavier nuclei may be accelerated to the cosmic ray spectral 'knee'. In addition, using INTEGRAL, we search for soft gamma-ray lines at 67.9 and 78.4 keV that come from the decay of radioactive {sup 44}Ti in the Tycho remnant. A bump feature in the 60-90 keV energy band, potentially associated with the {sup 44}Ti line emission, is found with a marginal significance level of ∼2.6σ. The corresponding 3σ upper limit on the {sup 44}Ti line flux amounts to 1.5 × 10{sup –5} photon cm{sup –2} s{sup –1}. Implications on the progenitor of the Tycho SN, considered to be a Type Ia SN prototype, are discussed.

  14. Emission features and expansion dynamics of nanosecond laser ablation plumes at different ambient pressures

    SciTech Connect

    Farid, N.; Harilal, S. S. Hassanein, A.; Ding, H.

    2014-01-21

    The influence of ambient pressure on the spectral emission features and expansion dynamics of a plasma plume generated on a metal target has been investigated. The plasma plumes were generated by irradiating Cu targets using 6 ns, 1064 nm pulses from a Q-switched Nd:YAG laser. The emission and expansion dynamics of the plasma plumes were studied by varying air ambient pressure levels ranging from vacuum to atmospheric pressure. The ambient pressure levels were found to affect both the line intensities and broadening along with the signal to background and signal to noise ratios and the optimum pressure conditions for analytical applications were evaluated. The characteristic plume parameters were estimated using emission spectroscopy means and noticed that the excitation temperature peaked ∼300 Torr, while the electron density showed a maximum ∼100 Torr. Fast-gated images showed a complex interaction between the plume and background air leading to changes in the plume geometry with pressure as well as time. Surface morphology of irradiated surface showed that the pressure of the ambient gas affects the laser-target coupling significantly.

  15. On the aliphatic versus aromatic content of the carriers of the `unidentified' infrared emission features

    NASA Astrophysics Data System (ADS)

    Yang, X. J.; Glaser, R.; Li, Aigen; Zhong, J. X.

    2016-10-01

    Although it is generally accepted that the unidentified infrared emission (UIE) features at 3.3, 6.2, 7.7, 8.6, and 11.3 μm are characteristic of the stretching and bending vibrations of aromatic hydrocarbon materials, the exact nature of their carriers remains unknown: whether they are free-flying, predominantly aromatic gas-phase molecules, or amorphous solids with a mixed aromatic/aliphatic composition are being debated. Recently, the 3.3 and 3.4 μm features which are commonly respectively attributed to aromatic and aliphatic C-H stretches have been used to place an upper limit of ˜2 per cent on the aliphatic fraction of the UIE carriers (i.e. the number of C atoms in aliphatic chains to that in aromatic rings). Here we further explore the aliphatic versus aromatic content of the UIE carriers by examining the ratio of the observed intensity of the 6.2 μm aromatic C-C feature (I6.2) to that of the 6.85 μm aliphatic C-H deformation feature (I6.85). To derive the intrinsic oscillator strengths of the 6.2 μm stretch (A6.2) and the 6.85 μm deformation (A6.85), we employ density functional theory to compute the vibrational spectra of seven methylated polycyclic aromatic hydrocarbon molecules and their cations. By comparing I6.85/I6.2 with A6.85/A6.2, we derive the fraction of C atoms in methyl(ene) aliphatic form to be at most ˜10 per cent, confirming the earlier finding that the UIE emitters are predominantly aromatic. We have also computed the intrinsic strength of the 7.25 μm feature (A7.25), another aliphatic C-H deformation band. We find that A6.85 appreciably exceeds A7.25. This explains why the 6.85 μm feature is more frequently detected in space than the 7.25 μm feature.

  16. IR nanoscale spectroscopy and imaging

    NASA Astrophysics Data System (ADS)

    Kennedy, Eamonn; Yarrow, Fiona; Rice, James H.

    2011-10-01

    Sub diffraction limited infrared absorption imaging was applied to hemoglobin by coupling IR optics with an atomic force microscope. Comparisons between the AFM topography and IR absorption images of micron sized hemoglobin features are presented, along with nanoscale IR spectroscopic analysis of the metalloprotein.

  17. Features for instantaneous emissions of low-level infrared signals of glucokinase enzyme from Pyrococcus furiosus.

    PubMed

    Torres, Sergio; Mella, Héctor; Reyes, Claudio; Meza, Pablo; Gallardo, Maria J; Staforelli, Juan P

    2015-03-10

    A noncontact infrared (IR) imaging-based methodology and signal recovery tools are applied on an enzyme reaction as a test target. The method is implemented by a long-wave (8-12 μm) IR microbolometer imaging array and a germanium-based IR optical vision. The reaction is carried out by the glucokinase, which produces a rapid exothermal release of energy that is weak, and, even worse, the IR video captured by the uncooled microbolometer detector is affected by spatial and temporal noise with specific complexities. Hitherto, IR-based signal recovery tools have worked with a standard acquisition frequency, which is clearly beyond the time scale of a real scenario. The implications of this (and similar) rapid reactions motivate the designs of a signal recovery method using prior information of the processes to extract and quantify the spontaneity of the enzymatic reaction in a three-dimensional (space and time) single and noncontact online measurement. PMID:25968383

  18. Spatial variations of the 3 micron emission features within UV-excited nebulae - Photochemical evolution of interstellar polycyclic aromatic hydrocarbons

    NASA Technical Reports Server (NTRS)

    Geballe, T. R.; Tielens, A. G. G. M.; Allamandola, L. J.; Moorhouse, A.; Brand, P. W. J. L.

    1989-01-01

    Spectra at 3 microns have been obtained at several positions in the Orion Bar region and in the nebula surrounding HD 44179. Weak emission features at 3.40, 3.46, 3.51, and 3.57 microns are prominent in the Orion Bar region. The 3.40- and 3.51-micron features increase in intensity relative to the dominant 3.29-micron feature. The spectrum obtained in the Red Rectangle region 5 arcsecs north of HD 44179 are similar to those in the Orion Bar, with a weak, broad 3.40-micron feature at the position of HD 44179. The spatial behavior of the weak emission features is explained in terms of hot bands of the CH stretch and overtones, and combination bands of other fundamental vibrations in simple PAHs. Based on the susceptibility of PAHs to destruction by the far UV fields in both regions, PAH sizes are estimated at 20-50 carbon atoms.

  19. First detection of Mars atmospheric hydroxyl: CRISM Near-IR measurement versus LMD GCM simulation of OH Meinel band emission in the Mars polar winter atmosphere

    NASA Astrophysics Data System (ADS)

    Clancy, R. Todd; Sandor, Brad J.; García-Muñoz, Antonio; Lefèvre, Franck; Smith, Michael D.; Wolff, Michael J.; Montmessin, Franck; Murchie, Scott L.; Nair, Hari

    2013-09-01

    Visible and near-IR Meinel band emissions originate from excited OH in the terrestrial upper atmosphere (Meinel, I.A.B. [1950]. Astrophys. J. 111, 555. http://dx.doi.org/10.1086/145296), and have recently been detected in the Venus nightside upper mesosphere (Piccioni, G. et al. [2008]. Astron. Astrophys. 483, L29-L33. http://dx.doi.org/10.1051/0004-6361:200809761). Meinel band observations support key studies of transport and photochemistry in both of these atmospheres. In the case of Mars, OH regulates the basic stability of the CO2 atmosphere to photolytic decomposition (to CO and O2, e.g. Parkinson, T.D., Hunten, D.M. [1972]. J. Atmos. Sci. 29, 1380-1390. http://dx.doi.org/10.1175/1520-0469(1972)029<1380:SAAOOO>2.0.CO;2), and yet has never been measured. We present the first detection of Mars atmospheric OH, associated with CRISM near-IR spectral limb observations of polar night Meinel band emissions centered at 1.45 and 2.9 μm. Meinel band (1-0), (2-1), and (2-0) average limb intensities of 990 ± 280, 1060 ± 480, and 200 ± 100 kiloRayleighs (kR), respectively, are determined for 70-90 NS polar winter latitudes over altitudes of 40-56 km. Additional OH bands, such as (3-2), (3-1), and (4-2), present ⩽1σ measurements. Uncertainty in the (4-2) band emission rate contributes to increased uncertainty in the determination of the O2(1Δg) (0-0)/(0-1) band emission ratio A00/A01=47-12+26. An average profile retrieval for Mars OH polar nightglow indicates 45-55 km altitude levels for volume emission rates (VER) of 0.4 (2-0) to 2 (1-0, 2-1) × 104 photons/(cm3 s). Similar to polar night O2(1Δg) emission (e.g. Clancy, R.T. et al. [2012]. J. Geophys. Res. (Planets) 117, E00J10. http://dx.doi.org/10.1029/2011JE004018), Meinel OH band emission is supported by upper level, winter poleward transport of O and H in the deep Hadley solsticial circulations of Mars. The retrieved OH emission rates are compared to polar winter OH nightglow simulated by the LMD (Laboratoire

  20. First detection of Mars atmospheric hydroxyl: CRISM Near-IR measurement versus LMD GCM simulation of OH Meinel band emission in the Mars polar winter atmosphere

    NASA Astrophysics Data System (ADS)

    Todd Clancy, R.; Sandor, Brad J.; García-Muñoz, Antonio; Lefèvre, Franck; Smith, Michael D.; Wolff, Michael J.; Montmessin, Franck; Murchie, Scott L.; Nair, Hari

    2013-09-01

    Visible and near-IR Meinel band emissions originate from excited OH in the terrestrial upper atmosphere (Meinel, I.A.B. [1950]. Astrophys. J. 111, 555. http://dx.doi.org/10.1086/145296), and have recently been detected in the Venus nightside upper mesosphere (Piccioni, G. et al. [2008]. Astron. Astrophys. 483, L29-L33. http://dx.doi.org/10.1051/0004-6361:200809761). Meinel band observations support key studies of transport and photochemistry in both of these atmospheres. In the case of Mars, OH regulates the basic stability of the CO2 atmosphere to photolytic decomposition (to CO and O2, e.g. Parkinson, T.D., Hunten, D.M. [1972]. J. Atmos. Sci. 29, 1380-1390. http://dx.doi.org/10.1175/1520-0469(1972)029<1380:SAAOOO>2.0.CO;2), and yet has never been measured. We present the first detection of Mars atmospheric OH, associated with CRISM near-IR spectral limb observations of polar night Meinel band emissions centered at 1.45 and 2.9 μm. Meinel band (1-0), (2-1), and (2-0) average limb intensities of 990 ± 280, 1060 ± 480, and 200 ± 100 kiloRayleighs (kR), respectively, are determined for 70-90 NS polar winter latitudes over altitudes of 40-56 km. Additional OH bands, such as (3-2), (3-1), and (4-2), present ⩽1σ measurements. Uncertainty in the (4-2) band emission rate contributes to increased uncertainty in the determination of the O2(1Δg) (0-0)/(0-1) band emission ratio A00/A01=47-12+26. An average profile retrieval for Mars OH polar nightglow indicates 45-55 km altitude levels for volume emission rates (VER) of 0.4 (2-0) to 2 (1-0, 2-1) × 104 photons/(cm3 s). Similar to polar night O2(1Δg) emission (e.g. Clancy, R.T. et al. [2012]. J. Geophys. Res. (Planets) 117, E00J10. http://dx.doi.org/10.1029/2011JE004018), Meinel OH band emission is supported by upper level, winter poleward transport of O and H in the deep Hadley solsticial circulations of Mars. The retrieved OH emission rates are compared to polar winter OH nightglow simulated by the LMD (Laboratoire

  1. In Vivo Quantification of 5-HT2A Brain Receptors in Mdr1a KO Rats with 123I-R91150 Single-Photon Emission Computed Tomography.

    PubMed

    Dumas, Noé; Moulin-Sallanon, Marcelle; Fender, Pascal; Tournier, Benjamin B; Ginovart, Nathalie; Charnay, Yves; Millet, Philippe

    2015-01-01

    Our goal was to identify suitable image quantification methods to image 5-hydroxytryptamine2A (5-HT2A) receptors in vivo in Mdr1a knockout (KO) rats (i.e., P-glycoprotein KO) using 123I-R91150 single-photon emission computed tomography (SPECT). The 123I-R91150 binding parameters estimated with different reference tissue models (simplified reference tissue model [SRTM], Logan reference tissue model, and tissue ratio [TR] method) were compared to the estimates obtained with a comprehensive three-tissue/seven-parameter (3T/7k)-based model. The SRTM and Logan reference tissue model estimates of 5-HT2A receptor (5-HT2AR) nondisplaceable binding potential (BPND) correlated well with the absolute receptor density measured with the 3T/7k gold standard (r > .89). Quantification of 5-HT2AR using the Logan reference tissue model required at least 90 minutes of scanning, whereas the SRTM required at least 110 minutes. The TR method estimates were also highly correlated to the 5-HT2AR density (r > .91) and only required a single 20-minute scan between 100 and 120 minutes postinjection. However, a systematic overestimation of the BPND values was observed. The Logan reference tissue method is more convenient than the SRTM for the quantification of 5-HT2AR in Mdr1a KO rats using 123I-R91150 SPECT. The TR method is an interesting and simple alternative, despite its bias, as it still provides a valid index of 5-HT2AR density. PMID:26105563

  2. DETECTION OF POWERFUL MID-IR H{sub 2} EMISSION IN THE BRIDGE BETWEEN THE TAFFY GALAXIES

    SciTech Connect

    Peterson, B. W.; Struck, C.; Appleton, P. N.; Helou, G.; Jarrett, T. H.; Guillard, P.; Cluver, M. E.; Ogle, P.; Boulanger, F.

    2012-05-20

    We report the detection of strong, resolved emission from warm H{sub 2} in the Taffy galaxies and bridge. Relative to the continuum and faint polyclic aromatic hydrocarbon (PAH) emission, the H{sub 2} emission is the strongest in the connecting bridge, approaching L(H{sub 2})/L(PAH 8 {mu}m) = 0.1 between the two galaxies, where the purely rotational lines of H{sub 2} dominate the mid-infrared spectrum in a way very reminiscent of the group-wide shock in the interacting group Stephan's Quintet (SQ). The surface brightness in the 0-0 S(0) and S(1) H{sub 2} lines in the bridge is more than twice that observed at the center of the SQ shock. We observe a warm H{sub 2} mass of 4.2 Multiplication-Sign 10{sup 8} M{sub Sun} in the bridge, but taking into account the unobserved bridge area, the total warm mass is likely to be twice this value. We use excitation diagrams to characterize the warm molecular gas, finding an average surface mass of {approx}5 Multiplication-Sign 10{sup 6} M{sub Sun} kpc{sup -2} and typical excitation temperatures of 150-175 K. H{sub 2} emission is also seen in the galaxy disks, although there the emission is more consistent with normal star-forming galaxies. We investigate several possible heating mechanisms for the bridge gas but favor the conversion of kinetic energy from the head-on collision via turbulence and shocks as the main heating source. Since the cooling time for the warm H{sub 2} is short ({approx}5000 yr), shocks must be permeating the molecular gas in the bridge region in order to continue heating the H{sub 2}.

  3. The Galactic disc distribution of planetary nebulae with warm dust emission features - II

    NASA Astrophysics Data System (ADS)

    Casassus, S.; Roche, P. F.

    2001-02-01

    We address the question of whether the distribution of warm-dust compositions in IR-bright Galactic disc PNe (Paper I, Casassus et al.) can be linked to the underlying stellar population. The PNe with warm dust emission represent a homogeneous population, which is presumably young and minimally affected by a possible dependence of PN lifetime on progenitor mass. The sample in Paper I thus allows testing of the predictions of single-star evolution, through a comparison with synthetic distributions and under the assumption that tip-of-the-AGB and PN statistics are similar. We construct a schematic model for AGB evolution (adapted from Groenewegen & de Jong), the free parameters of which are calibrated with the luminosity function (LF) of C stars in the LMC, the initial-final mass relation and the range of PN compositions. The observed metallicity gradient and distribution of star-forming regions with Galactocentric radius (Bronfman et al.) allow us to synthesize the Galactic disc PN progenitor population. We find that the fraction of O-rich PNe, f(0), is a tight constraint on AGB parameters. For our best model, a minimum PN progenitor mass Mmin=1 M⊙ predicts that about 50per cent of all young PNe should be O-rich, compared with an observed fraction of 22per cent; thus Mmin=1.2 M⊙, at a 2σ confidence level Mmin=1.3 M⊙ at 1σ). By contrast, current AGB models for single stars can account neither for the continuous range of N enrichment (Leisy & Dennefeld) nor for the observation that the majority of very C-rich PNe have Peimbert type I (Paper I). f(O) is thus an observable quantity much easier to model. The decrease in f(O) with Galactocentric radius, as reported in Paper I, is a strong property of the synthetic distribution, independent of Mmin. This trend reflects the sensitivity of the surface temperature of AGB stars and of the core mass at the first thermal pulse to the Galactic metallicity gradient.

  4. Risk assessment of an old landfill regarding the potential of gaseous emissions--a case study based on bioindication, FT-IR spectroscopy and thermal analysis.

    PubMed

    Tintner, Johannes; Smidt, Ena; Böhm, Katharina; Matiasch, Lydia

    2012-12-01

    Risk assessment of two sections (I and II) of an old landfill (ALH) in Styria (Austria) in terms of reactivity of waste organic matter and the related potential of gaseous emissions was performed using conventional parameters and innovative tools to verify their effectiveness in practice. The ecological survey of the established vegetation at the landfill surface (plant sociological relevés) indicated no relevant emissions over a longer period of time. Statistical evaluation of conventional parameters reveals that dissolved organic carbon (DOC), respiration activity (RA(4)), loss of ignition (LOI) and total inorganic carbon (TIC) mostly influence the variability of the gas generation sum (GS(21)). According to Fourier Transform Infrared (FT-IR) spectral data and the results of the classification model the reactivity potential of the investigated sections is very low which is in accordance with the results of plant sociological relevés and biological tests. The interpretation of specific regions in the FT-IR spectra was changed and adapted to material characteristics. Contrary to mechanically-biologically treated (MBT) materials, where strong aliphatic methylene bands indicate reactivity, they are rather assigned to the C-H vibrations of plastics in old landfill materials. This assumption was confirmed by thermal analysis and the characteristic heat flow profile of plastics containing landfill samples. Therefore organic carbon contents are relatively high compared to other stable landfills as shown by a prediction model for TOC contents based on heat flow profiles and partial least squares regression (PLS-R). The stability of the landfill samples, expressed by the relation of CO(2) release and enthalpies, was compared to unreactive landfills, archeological samples, earthlike materials and hardly degradable organic matter. Due to the material composition and the aging process the landfill samples are located between hardly degradable, but easily combustible

  5. Risk assessment of an old landfill regarding the potential of gaseous emissions--a case study based on bioindication, FT-IR spectroscopy and thermal analysis.

    PubMed

    Tintner, Johannes; Smidt, Ena; Böhm, Katharina; Matiasch, Lydia

    2012-12-01

    Risk assessment of two sections (I and II) of an old landfill (ALH) in Styria (Austria) in terms of reactivity of waste organic matter and the related potential of gaseous emissions was performed using conventional parameters and innovative tools to verify their effectiveness in practice. The ecological survey of the established vegetation at the landfill surface (plant sociological relevés) indicated no relevant emissions over a longer period of time. Statistical evaluation of conventional parameters reveals that dissolved organic carbon (DOC), respiration activity (RA(4)), loss of ignition (LOI) and total inorganic carbon (TIC) mostly influence the variability of the gas generation sum (GS(21)). According to Fourier Transform Infrared (FT-IR) spectral data and the results of the classification model the reactivity potential of the investigated sections is very low which is in accordance with the results of plant sociological relevés and biological tests. The interpretation of specific regions in the FT-IR spectra was changed and adapted to material characteristics. Contrary to mechanically-biologically treated (MBT) materials, where strong aliphatic methylene bands indicate reactivity, they are rather assigned to the C-H vibrations of plastics in old landfill materials. This assumption was confirmed by thermal analysis and the characteristic heat flow profile of plastics containing landfill samples. Therefore organic carbon contents are relatively high compared to other stable landfills as shown by a prediction model for TOC contents based on heat flow profiles and partial least squares regression (PLS-R). The stability of the landfill samples, expressed by the relation of CO(2) release and enthalpies, was compared to unreactive landfills, archeological samples, earthlike materials and hardly degradable organic matter. Due to the material composition and the aging process the landfill samples are located between hardly degradable, but easily combustible

  6. Highly Emissive Far Red/Near-IR Fluorophores Based on Borylated Fluorene-Benzothiadiazole Donor-Acceptor Materials.

    PubMed

    Crossley, Daniel L; Vitorica-Yrezabal, Inigo; Humphries, Martin J; Turner, Michael L; Ingleson, Michael J

    2016-08-22

    Stille, Suzuki-Miyaura and Negishi cross-coupling reactions of bromine-functionalised borylated precursors enable the facile, high yielding, synthesis of borylated donor-acceptor materials that contain electron-rich aromatic units and/or extended effective conjugation lengths. These materials have large Stokes shifts, low LUMO energies, small band-gaps and significant fluorescence emission >700 nm in solution and when dispersed in a host polymer. PMID:27460768

  7. IR fiber sources for scene projection

    NASA Astrophysics Data System (ADS)

    Shaw, L. B.; Sanghera, J. S.; Aggarwal, I. D.

    2007-04-01

    Naval Research Laboratory has developed IR transmitting fiber and IR fiber sources which can be used for HWIL testing. IR transmitting fiber is capable of broad transmission from near IR to LWIR and can be formed into bundles for imaging. IR fiber sources are based on rare earth doped glass or nonlinear processes in the glass and are cable of high brightness IR emission. Recently, NRL developed a four emitter MWIR fiber source which is capable of high temperature simulation, high dynamic range, and fast response. New broadband fiber sources based upon IR supercontinuum generation in IR fibers are also being developed. In this paper, we will report on these technologies.

  8. Quantification of microstructural features in tempered carbon steel using magnetic Barkhausen emission parameters

    NASA Astrophysics Data System (ADS)

    Moorthy, V.; Raj, Baldev; Vaidyanathan, S.; Jayakumar, T.; Kashyap, B. P.

    2000-05-01

    In ferromagnetic materials, the magnetic Barkhausen emission (MBE) during magnetization has been found to be highly sensitive with good and repeatable correlations to microstructural variations. Thus, MBE technique is complementary to the microscopy techniques and is superior for on-line characterization of ferromagnetic materials. However, this micro-magnetic non-destructive evaluation (NDE) technique could not be developed, so far, to a level of resolving and quantifying the individual microstructural features such as grain size and second phase precipitate size which vary simultaneously during heat treatment or thermal aging. In the present study, it has been shown that, in a carbon steel, on carefully optimizing the experimental parameters, the MBE profile systematically changes from a single peak to two peaks, when the quenched martensite structure dominated by high dislocation density is heat treated to produce well differentiated ferrite grain boundaries and second phase precipitates. The first MBE peak at lower current/magnetic field has been attributed to the influence of grain boundaries and the second MBE peak at higher current/magnetic field to that of second phase precipitates. To substantiate this, it has also been shown that the variations in the position of the two MBE peaks match well with the kinetics of tempering, the changes in the average size of the grains and carbides. The excellent quantitative correlation reveals that MBE technique has matured as a powerful technique for rapid on-line evaluation of metallurgical quality of as fabricated and service exposed ferromagnetic materials through finer microstructural characterization.

  9. Thermal emission spectroscopy of microcrystalline sedimentary phases: Effects of natural surface roughness on spectral feature shape

    NASA Astrophysics Data System (ADS)

    Hardgrove, C. J.; Rogers, A. D.; Glotch, T. D.; Arnold, J. A.

    2016-03-01

    Distinguishing between microcrystalline and macrocrystalline mineral phases can help constrain the conditions under which those minerals formed or the degree of postdepositional alteration. This study demonstrates the effects of crystal size and surface roughness on thermal infrared emission spectra of micro and macrocrystalline phases of the two most common minerals on Earth, quartz and calcite. Given the characteristic depositional and environmental conditions under which microcrystalline minerals form, and the recent observations of high-silica deposits on Mars, it is important to understand how these unique materials can be identified using remote infrared spectroscopy techniques. We find that (a) microcrystalline minerals exhibit naturally rough surfaces compared to their macrocrystalline counterparts at the 10 µm scale; and that (b) this roughness causes distinct spectral differences within the Reststrahlen bands of each mineral. These spectral differences occur for surfaces that are rough on the wavelength scale, where the absorption coefficient (k) is large. Specifically, the wavelength positions of the Reststrahlen features for microcrystalline phases are narrowed and shifted compared to macrocrystalline counterparts. The spectral shape differences are small enough that the composition of the material is still recognizable, but large enough such that a roughness effect could be detected. Petrographic and topographic analyses of microcrystalline samples suggest a relationship between crystal size and surface roughness. Together, these observations suggest it may be possible to make general inferences about microcrystallinity from the thermal infrared spectral character of samples, which could aid in reconstructions of sedimentary rock diagenesis where corresponding petrographic or microimaging is not available.

  10. Fatigue features study on the crankshaft material of 42CrMo steel using acoustic emission

    NASA Astrophysics Data System (ADS)

    Shi, Yue; Dong, Lihong; Wang, Haidou; Li, Guolu; Liu, Shenshui

    2016-09-01

    Crankshaft is regarded as an important component of engines, and it is an important application of remanufacturing because of its high added value. However, the fatigue failure research of remanufactured crankshaft is still in its primary stage. Thus, monitoring and investigating the fatigue failure of the remanufacturing crankshaft is crucial. In this paper, acoustic emission (AE) technology and machine vision are used to monitor the four-point bending fatigue of 42CrMo, which is the material of crankshaft. The specimens are divided into two categories, namely, pre-existing crack and non-preexisting crack, which simulate the crankshaft and crankshaft blank, respectively. The analysis methods of parameter-based AE techniques, wavelet transform (WT) and SEM analysis are combined to identify the stage of fatigue failure. The stage of fatigue failure is the basis of using AE technology in the field of remanufacturing crankshafts. The experiment results show that the fatigue crack propagation style is a transgranular fracture and the fracture is a brittle fracture. The difference mainly depends on the form of crack initiation. Various AE signals are detected by parameter analysis method. Wavelet threshold denoising and WT are combined to extract the spectral features of AE signals at different fatigue failure stages.

  11. Sensing Properties of Multiwalled Carbon Nanotubes Grown in MW Plasma Torch: Electronic and Electrochemical Behavior, Gas Sensing, Field Emission, IR Absorption

    PubMed Central

    Majzlíková, Petra; Sedláček, Jiří; Prášek, Jan; Pekárek, Jan; Svatoš, Vojtěch; Bannov, Alexander G.; Jašek, Ondřej; Synek, Petr; Eliáš, Marek; Zajíčková, Lenka; Hubálek, Jaromír

    2015-01-01

    Vertically aligned multi-walled carbon nanotubes (VA-MWCNTs) with an average diameter below 80 nm and a thickness of the uniform VA-MWCNT layer of about 16 μm were grown in microwave plasma torch and tested for selected functional properties. IR absorption important for a construction of bolometers was studied by Fourier transform infrared spectroscopy. Basic electrochemical characterization was performed by cyclic voltammetry. Comparing the obtained results with the standard or MWCNT‐modified screen-printed electrodes, the prepared VA-MWCNT electrodes indicated their high potential for the construction of electrochemical sensors. Resistive CNT gas sensor revealed a good sensitivity to ammonia taking into account room temperature operation. Field emission detected from CNTs was suitable for the pressure sensing application based on the measurement of emission current in the diode structure with bending diaphragm. The advantages of microwave plasma torch growth of CNTs, i.e., fast processing and versatility of the process, can be therefore fully exploited for the integration of surface-bound grown CNTs into various sensing structures. PMID:25629702

  12. Sensing properties of multiwalled carbon nanotubes grown in MW plasma torch: electronic and electrochemical behavior, gas sensing, field emission, IR absorption.

    PubMed

    Majzlíková, Petra; Sedláček, Jiří; Prášek, Jan; Pekárek, Jan; Svatoš, Vojtěch; Bannov, Alexander G; Jašek, Ondřej; Synek, Petr; Eliáš, Marek; Zajíčková, Lenka; Hubálek, Jaromír

    2015-01-01

    Vertically aligned multi-walled carbon nanotubes (VA-MWCNTs) with an average diameter below 80 nm and a thickness of the uniform VA-MWCNT layer of about 16 µm were grown in microwave plasma torch and tested for selected functional properties. IR absorption important for a construction of bolometers was studied by Fourier transform infrared spectroscopy. Basic electrochemical characterization was performed by cyclic voltammetry. Comparing the obtained results with the standard or MWCNT‑modified screen-printed electrodes, the prepared VA-MWCNT electrodes indicated their high potential for the construction of electrochemical sensors. Resistive CNT gas sensor revealed a good sensitivity to ammonia taking into account room temperature operation. Field emission detected from CNTs was suitable for the pressure sensing application based on the measurement of emission current in the diode structure with bending diaphragm. The advantages of microwave plasma torch growth of CNTs, i.e., fast processing and versatility of the process, can be therefore fully exploited for the integration of surface-bound grown CNTs into various sensing structures. PMID:25629702

  13. Highly strained InAs quantum wells on InP substrates for mid-IR emission

    NASA Astrophysics Data System (ADS)

    Kim, Sangho; Kirch, Jeremy; Mawst, Luke

    2010-04-01

    Optical emission characteristics of indium arsenide (InAs) quantum wells were studied using organometallic vapor phase epitaxy (OMVPE). Low growth temperature (<500 °C) and tertiarybutylarsine (TBA) and/or arsine precursors were applied for this study. Several growth parameters such as growth temperature, growth rate, interruption time between growths of layers, and mixture of group V precursors were investigated. It was found that relatively high growth rate of InAs (0.3 nm/s) and a mixture flow of TBA and AsH 3, allowed growth of up to 9 nm thick InAs quantum wells without significant strain relaxation. Photoluminescence (PL) wavelengths of 2.52 μm were observed at room temperature (RT) from a 9 nm InAs double quantum well (DQW) in a separate confinement hetero-structure (SCH) structure.

  14. Spectral features of guanidinium-carboxylate salt bridges. The combined ATR-IR and theoretical studies of aqueous solution of guanidinium acetate

    NASA Astrophysics Data System (ADS)

    Levina, Elena O.; Lokshin, Boris V.; Mai, Bich D.; Vener, Mikhail V.

    2016-08-01

    The spectrum of guanidinium acetate in aqueous solution has been recorded by attenuated total reflectance infrared spectroscopy (ATR-IR). Assignments of the bands have been done using the polarizable continuum model (PCM). Three IR intensive bands at 1670, 1550, and 1410 cm-1 are associated with stretching and bending vibrations of the groups forming a ring of six heavy atoms of the bidentate configuration of guanidinium acetate. The relatively weak broad band near 2200 cm-1 is tentatively assigned to the stretching vibration of the Nsbnd H⋯O fragment of the hydrogen-bonded ion pairs.

  15. Lunar Mare Basalts as Analogues for Martian Volcanic Compositions: Evidence from Visible, Near-IR, and Thermal Emission Spectroscopy

    NASA Technical Reports Server (NTRS)

    Graff, T. G.; Morris, R. V.; Christensen, P. R.

    2003-01-01

    The lunar mare basalts potentially provide a unique sample suite for understanding the nature of basalts on the martian surface. Our current knowledge of the mineralogical and chemical composition of the basaltic material on Mars comes from studies of the basaltic martian meteorites and from orbital and surface remote sensing observations. Petrographic observations of basaltic martian meteorites (e.g., Shergotty, Zagami, and EETA79001) show that the dominant phases are pyroxene (primarily pigeonite and augite), maskelynite (a diaplectic glass formed from plagioclase by shock), and olivine [1,2]. Pigeonite, a low calcium pyroxene, is generally not found in abundance in terrestrial basalts, but does often occur on the Moon [3]. Lunar samples thus provide a means to examine a variety of pigeonite-rich basalts that also have bulk elemental compositions (particularly low-Ti Apollo 15 mare basalts) that are comparable to basaltic SNC meteorites [4,5]. Furthermore, lunar basalts may be mineralogically better suited as analogues of the martian surface basalts than the basaltic martian meteorites because the plagioclase feldspar in the basaltic Martian meteorites, but not in the lunar surface basalts, is largely present as maskelynite [1,2]. Analysis of lunar mare basalts my also lead to additional endmember spectra for spectral libraries. This is particularly important analysis of martian thermal emission spectra, because the spectral library apparently contains a single pigeonite spectrum derived from a synthetic sample [6].

  16. Emission from water vapor and absorption from other gases at 5-7.5 μm in Spitzer-IRS Spectra Of Protoplanetary Disks

    SciTech Connect

    Sargent, B. A.; Forrest, W.; Watson, Dan M.; Kim, K. H.; Richter, I.; Tayrien, C.; D'Alessio, P.; Calvet, N.; Furlan, E.; Green, J.; Pontoppidan, K.

    2014-09-10

    We present spectra of 13 T Tauri stars in the Taurus-Auriga star-forming region showing emission in Spitzer Space Telescope Infrared Spectrograph 5-7.5 μm spectra from water vapor and absorption from other gases in these stars' protoplanetary disks. Seven stars' spectra show an emission feature at 6.6 μm due to the ν{sub 2} = 1-0 bending mode of water vapor, with the shape of the spectrum suggesting water vapor temperatures >500 K, though some of these spectra also show indications of an absorption band, likely from another molecule. This water vapor emission contrasts with the absorption from warm water vapor seen in the spectrum of the FU Orionis star V1057 Cyg. The other 6 of the 13 stars have spectra showing a strong absorption band, peaking in strength at 5.6-5.7 μm, which for some is consistent with gaseous formaldehyde (H{sub 2}CO) and for others is consistent with gaseous formic acid (HCOOH). There are indications that some of these six stars may also have weak water vapor emission. Modeling of these stars' spectra suggests these gases are present in the inner few AU of their host disks, consistent with recent studies of infrared spectra showing gas in protoplanetary disks.

  17. New emission features in the 11-13 micron region and their relationship to polycyclic aromatic hydrocarbons.

    PubMed

    Witteborn, F C; Sandford, S A; Bregman, J D; Allamandola, L J; Cohen, M; Wooden, D H; Graps, A L

    1989-06-01

    If the "11.3 microns" emission feature seen in the spectra of many planetary nebulae, H II regions, and reflection nebulae is due to polycyclic aromatic hydrocarbons (PAHs), then additional features should be present between 11.3 and 13.0 microns (885 and 770 cm-1). Moderate-resolution spectra of NGC 7027, HD 44179, IRAS 21282+5050, and BD + 30 degrees 3639 are presented which show that the "11.3 microns" feature actually peaks at 11.22 microns (891 cm-1). The spectra also show evidence of new emission features near 11.9 and 12.7 microns (840 and 787 cm-1). These are consistent with an origin from PAHs and can be used to constrain the molecular structure of the family of PAHs responsible for the infrared features. The observed asymmetry of the "11.3 microns" band is consistent with the slight anharmonicity expected in the C--H out-of-plane bending mode in PAHs. Laboratory experiments show that the intensity of this mode relative to the higher frequency modes depends on the extent of molecular "clustering." The observed strengths of the "11.3 microns" interstellar bands relative to the higher frequency bands are most consistent with the features originating from free molecular PAHs. The intensity and profile of the underlying broad structure, however, may well arise from PAH clusters and amorphous carbon particles. Analysis of the 11-13 microns (910-770 cm-1) emission suggests that the molecular structures of the most intensity emitting free PAHs vary somewhat between the high-excitation environment in NGC 7027 and the low-excitation but high-flux environment close to HD 44179. Finally, a previously undetected series of regularly spaced features between 10 and 11 microns (1000 and 910 cm-1) in the spectrum of HD 44179 suggests that a simple polyatomic hydride is present in the gas phase in this object. PMID:11542169

  18. Spatial variations of the 3 micron emission features within UV-excited nebulae: photochemical evolution of interstellar polycyclic aromatic hydrocarbons.

    PubMed

    Geballe, T R; Tielens, A G; Allamandola, L J; Moorhouse, A; Brand, P W

    1989-06-01

    We have obtained 3 microns spectra at several positions in the Orion Bar region and in the "Red Rectangle," the nebula surrounding HD 44179. The recently discovered weak emission features at 3.40, 3.46, 3.51, and 3.57 microns (2940, 2890, 2850, and 2800 cm-1) are prominent in the Orion Bar region. The 3.40 microns and 3.51 microns features increases in intensity relative to the dominant 3.29 microns (3040 cm-1) feature when going from the ionized to the neutral zone across the Orion Bar. However, only a weak and rather broad 3.40 microns feature is present at the position of HD 44179. These spectra demonstrate that some of the 3 microns emission components vary independently of each other and in a systematic way within UV-excited nebulae. This spatial variation is discussed in terms of the UV excitation and photochemical evolution of polycyclic aromatic hydrocarbons and related molecular structures. The spatial behavior of the weak emission features can be understood qualitatively in terms of hot bands of the CH stretch and overtones and combination bands of other fundamental vibrations in simple PAHs. An explanation in terms of emission by molecular sidegroups attached to the PAHs is less straightforward, particularly in the case of the Red Rectangle and other evolved mass-losing objects. We estimate PAH sizes of 20-50 carbon atoms based on the susceptibility of PAHs to destruction by the far ultraviolet fields present in the Orion Bar and the Red Rectangle; the size range is similar to independent estimates made previously. PMID:11542168

  19. Spatial variations of the 3 micron emission features within UV-excited nebulae: photochemical evolution of interstellar polycyclic aromatic hydrocarbons.

    PubMed

    Geballe, T R; Tielens, A G; Allamandola, L J; Moorhouse, A; Brand, P W

    1989-06-01

    We have obtained 3 microns spectra at several positions in the Orion Bar region and in the "Red Rectangle," the nebula surrounding HD 44179. The recently discovered weak emission features at 3.40, 3.46, 3.51, and 3.57 microns (2940, 2890, 2850, and 2800 cm-1) are prominent in the Orion Bar region. The 3.40 microns and 3.51 microns features increases in intensity relative to the dominant 3.29 microns (3040 cm-1) feature when going from the ionized to the neutral zone across the Orion Bar. However, only a weak and rather broad 3.40 microns feature is present at the position of HD 44179. These spectra demonstrate that some of the 3 microns emission components vary independently of each other and in a systematic way within UV-excited nebulae. This spatial variation is discussed in terms of the UV excitation and photochemical evolution of polycyclic aromatic hydrocarbons and related molecular structures. The spatial behavior of the weak emission features can be understood qualitatively in terms of hot bands of the CH stretch and overtones and combination bands of other fundamental vibrations in simple PAHs. An explanation in terms of emission by molecular sidegroups attached to the PAHs is less straightforward, particularly in the case of the Red Rectangle and other evolved mass-losing objects. We estimate PAH sizes of 20-50 carbon atoms based on the susceptibility of PAHs to destruction by the far ultraviolet fields present in the Orion Bar and the Red Rectangle; the size range is similar to independent estimates made previously.

  20. Radio continuum and X-ray emission from the most extreme far-IR-excess galaxy NGC 1377. An extremely obscured AGN revealed

    NASA Astrophysics Data System (ADS)

    Costagliola, F.; Herrero-Illana, R.; Lohfink, A.; Pérez-Torres, M.; Aalto, S.; Muller, S.; Alberdi, A.

    2016-10-01

    Context. Galaxies which strongly deviate from the radio-far infrared (FIR) correlation are of great importance for studies of galaxy evolution as they may be tracing early, short-lived stages of starbursts and active galactic nuclei (AGNs). The most extreme FIR-excess galaxy NGC 1377 has long been interpreted as a young dusty starburst, but millimeter observations of CO lines revealed a powerful collimated molecular outflow which cannot be explained by star formation alone. Aims: This paper aims to determine the nature of the energy source in the nucleus of NGC 1377 and to study the driving mechanism of the collimated CO outflow. Methods: We present new radio observations of NGC 1377 at 1.5 and 10 GHz obtained with the Jansky Very Large Array (JVLA) and Chandra X-ray observations. The observations are compared to synthetic starburst models to constrain the properties of the central energy source. Results: We obtained the first detection of the cm radio continuum and X-ray emission in NGC 1377. We found that the radio emission is distributed in two components, one on the nucleus and another offset by 4.5 arcsec to the south-west. We confirm the extreme FIR-excess of the galaxy, with a qFIR ≃ 4.2, which deviates by more than 7σ from the radio-FIR correlation. Soft X-ray emission is detected on the off-nucleus component. From the radio emission we estimated for a young (<10 Myr) starburst a star formation rate (SFR) of <0.1 M⊙ yr-1. Such a SFR is not sufficient to power the observed IR luminosity and to drive the CO outflow. Conclusions: We found that a young starburst cannot reproduce all the observed properties of the nucleus of NGC 1377. We suggest that the galaxy may be harboring a radio-quiet, obscured AGN of 106M⊙, accreting at near-Eddington rates. We speculate that the off-nucleus component may be tracing an hot-spot in the AGN jet.

  1. Variations in the Peak Position of the 6.2 micron Interstellar Emission Feature: A Tracer of N in the Interstellar Polycyclic Aromatic Hydrocarbon Population

    NASA Technical Reports Server (NTRS)

    Hudgins, Douglas M.; Bauschlicher, Charles W.; Allamandola, L. J.

    2005-01-01

    more nitrogen atoms within the interior of the carbon skeleton of a PAH cation induces a significant blueshift in the position of the dominant CC stretching feature of these compounds that is suf6cient to account for the position of the interstellar bands. Subsequent studies of the effects of substitution by other heteroatoms (O and Si), metal ion complexation (Fe(+), Mg(+), and Mg(2+)), and molecular symmetry variation-all of which fail to reproduce the blueshift observed in the PANH cations-indicate that N appears to be unique in its ability to accommodate the position of the interstellar 6.2 micron bands while simultaneously satisfying the other constraints of the astrophysical problem. This result implies that the peak position of the interstellar feature near 6.2 micron traces the degree of nitrogen substitution in the population, that most of the PAHs responsible for the interstellar IR emission features incorporate nitrogen within their aromatic networks, and that a lower limit of 1%-2% of the cosmic nitrogen is sequestered within the interstellar PAH population. Finally, in view of the ubiquity and abundance of interstellar PAHs and the permanent dipoles and distinctive electronic structures of these nitrogen-substituted variants, this work impacts a wide range of observational phenomena outside of the infrared region of the spectrum including the forest of unidentified molecular rotational features and the anomalous Galactic foreground emission in the microwave, and the diffuse interstellar bands (DIBs) and other structure in the interstellar extinction curve in the ulhviolet/visible. These astrophysical ramifications are discussed, and the dipole moments and rotational constants are tabulated to facilitate further investigations of the astrophysical role of nitrogen-substituted aromatic compounds.

  2. Variations in the Peak Position of the 6.2 μm Interstellar Emission Feature: A Tracer of N in the Interstellar Polycyclic Aromatic Hydrocarbon Population

    NASA Astrophysics Data System (ADS)

    Hudgins, Douglas M.; Bauschlicher, Charles W., Jr.; Allamandola, L. J.

    2005-10-01

    within the interior of the carbon skeleton of a PAH cation induces a significant blueshift in the position of the dominant CC stretching feature of these compounds that is sufficient to account for the position of the interstellar bands. Subsequent studies of the effects of substitution by other heteroatoms (O and Si), metal ion complexation (Fe+, Mg+, and Mg2+), and molecular symmetry variation-all of which fail to reproduce the blueshift observed in the PANH cations-indicate that N appears to be unique in its ability to accommodate the position of the interstellar 6.2 μm bands while simultaneously satisfying the other constraints of the astrophysical problem. This result implies that the peak position of the interstellar feature near 6.2 μm traces the degree of nitrogen substitution in the population, that most of the PAHs responsible for the interstellar IR emission features incorporate nitrogen within their aromatic networks, and that a lower limit of 1%-2% of the cosmic nitrogen is sequestered within the interstellar PAH population. Finally, in view of the ubiquity and abundance of interstellar PAHs and the permanent dipoles and distinctive electronic structures of these nitrogen-substituted variants, this work impacts a wide range of observational phenomena outside of the infrared region of the spectrum including the forest of unidentified molecular rotational features and the anomalous Galactic foreground emission in the microwave, and the diffuse interstellar bands (DIBs) and other structure in the interstellar extinction curve in the ultraviolet/visible. These astrophysical ramifications are discussed, and the dipole moments and rotational constants are tabulated to facilitate further investigations of the astrophysical role of nitrogen-substituted aromatic compounds.

  3. Features of the Amplitude-Frequency Characteristics of Electromagnetic Emission during Uniaxial Compression of Dielectric Composites

    NASA Astrophysics Data System (ADS)

    Surzhikov, V. P.; Khorsov, N. N.

    2015-04-01

    We have studied the electromagnetic emission from samples of epoxy resin filled with sand subjected to uniaxial compression. Capacitive sensor measures the electrical component of the response when excited electromagnetic emission of ultrasonic pulse using a differential amplifier. It was shown the influence of the load on the spectral signal characteristics: with increasing pressure, the formation of bands at frequencies corresponding to possibly quasi-Rayleigh waves generation. It is concluded that the use of the experimental geometry studies the main contribution to the response of electromagnetic emissions create born normal vibrations, which are damped standing waves.

  4. Distinctive features of Coulomb-related emissions in peripheral heavy ion collisions at Fermi energies

    NASA Astrophysics Data System (ADS)

    Piantelli, S.; Maurenzig, P. R.; Olmi, A.; Bardelli, L.; Bini, M.; Casini, G.; Mangiarotti, A.; Pasquali, G.; Poggi, G.; Stefanini, A. A.

    2007-12-01

    Light charged particles emitted at about 90° in the frame of the projectile-like fragment in semiperipheral collisions of Nb93+Nb93 at 38A MeV give evidence for the occurrence, in the same class of events, of two different production mechanisms. This is demonstrated by differences in the kinetic energy spectra and in the isotopic composition of the particles. The emission with a softer kinetic energy spectrum and a low N/Z ratio for the hydrogen isotopes is attributed to an evaporation process. The harder emission, with a much higher N/Z ratio, can be attributed to a midvelocity process consisting of a nonisotropic emission, on a short time-scale, from the projectile-like fragment.

  5. New features of excitonic emission in metal nanoparticle/semiconductor quantum dot nanosystem

    NASA Astrophysics Data System (ADS)

    Kryuchenko, Yu. V.; Korbutyak, D. V.

    2016-10-01

    We study theoretically the excitonic emission properties of a hybrid nanosystem composed of a spherical metal nanoparticle (NP) and a spherical quantum dot (QD). We show that electromagnetic field (EMF) emitted by a single QD has only dipole, quadrupole, and octupole components, i.e., QD cannot in principle be regarded as an oscillating point dipole, which emits infinite series of multipoles. This leads to a substantial deviation of the characteristics of QD excitonic emission from the emission characteristics of point dipole (molecular fluorophore) located in a vicinity of metal NP at small interparticle distances. The observed fluorescence spectra of the CdTe QD/Ag NP nanostructure are found to be in good agreement with the calculated ones.

  6. UV and IR measurements of sulphur dioxide emissions during and after the 2014-2015 Bárðarbunga eruption, Iceland

    NASA Astrophysics Data System (ADS)

    Simmons, Isla C.; Whitty, Rachel C. W.; Pfeffer, Melissa A.; Thomas, Helen; Galle, Bo; Calder, Eliza; Arellano, Santiago; Prata, Fred; Pumphrey, Hugh C.

    2016-04-01

    A basaltic fissure eruption of the Bárðarbunga volcanic system, Iceland, occurred from 31st August 2014 until 28th February 2015. This flood basalt eruption produced 1.6 km3 of lava and emitted sulphur dioxide (SO2) from the vents at rates of up to 3800 kg/s forming an eruption plume that could easily be detected from space. SO2 was also released by the cooling lava flows forming a low level haze. SO2 emissions were monitored using multiple techniques including scanning differential optical absorption spectrometers (DOAS), mobile DOAS traverses, and a NicAIR II infrared camera. UV DOAS data have been processed to distinguish the SO2 released by the degassing lava field as it cooled, both during and after the eruption. Initial results show that during February, the final month of the eruption, the lava field released about 3 kg/s of SO2. The lava field continued to emit detectable levels of SO2 at lower quantities in March, following the end of the eruption. Brightness temperature differences using 8.62 and 10.87 μm channels on the IR camera have been processed to calculate the column amounts of SO2 within the eruption plume. SO2 path lengths of over 700 ppm-m have been retrieved in November. This has been achieved despite the challenges of high H2O concentrations in the plume and high gas concentrations above the lava field. Poor meteorological conditions often resulted in a lack of clear sky within the images causing difficulties constraining background SO2 levels.

  7. Herschel-PACS Observations of Far-IR CO Line Emission in NGC 1068: Highly Excited Molecular Gas in the Circumnuclear Disk

    NASA Astrophysics Data System (ADS)

    Hailey-Dunsheath, S.; Sturm, E.; Fischer, J.; Sternberg, A.; Graciá-Carpio, J.; Davies, R.; González-Alfonso, E.; Mark, D.; Poglitsch, A.; Contursi, A.; Genzel, R.; Lutz, D.; Tacconi, L.; Veilleux, S.; Verma, A.; de Jong, J. A.

    2012-08-01

    We report the detection of far-IR CO rotational emission from the prototypical Seyfert 2 galaxy NGC 1068. Using Herschel-PACS, we have detected 11 transitions in the J upper = 14-30 (E upper/kB = 580-2565 K) range, all of which are consistent with arising from within the central 10'' (700 pc). The detected transitions are modeled as arising from two different components: a moderate-excitation (ME) component close to the galaxy systemic velocity and a high-excitation (HE) component that is blueshifted by ~80 km s-1. We employ a large velocity gradient model and derive n H2 ~ 105.6 cm-3, T kin ~ 170 K, and M H2 ~ 106.7 M ⊙ for the ME component and n H2 ~ 106.4 cm-3, T kin ~ 570 K, and M H2 ~ 105.6 M ⊙ for the HE component, although for both components the uncertainties in the density and mass are ±(0.6-0.9) dex. Both components arise from denser and possibly warmer gas than traced by low-J CO transitions, and the ME component likely makes a significant contribution to the mass budget in the nuclear region. We compare the CO line profiles with those of other molecular tracers observed at higher spatial and spectral resolution and find that the ME transitions are consistent with these lines arising in the ~200 pc diameter ring of material traced by H2 1-0 S(1) observations. The blueshift of the HE lines may also be consistent with the bluest regions of this H2 ring, but a better kinematic match is found with a clump of infalling gas ~40 pc north of the active galactic nucleus (AGN). We consider potential heating mechanisms and conclude that X-ray- or shock heating of both components is viable, while far-UV heating is unlikely. We discuss the prospects of placing the HE component near the AGN and conclude that while the moderate thermal pressure precludes an association with the ~1 pc radius H2O maser disk, the HE component could potentially be located only a few parsecs more distant from the AGN and might then provide the N H ~ 1025 cm-2 column obscuring the

  8. Detailed Analysis of Near-IR Water (H2O) Emission in Comet C/2014 Q2 (Lovejoy) with the GIANO/TNG Spectrograph

    NASA Astrophysics Data System (ADS)

    Faggi, S.; Villanueva, G. L.; Mumma, M. J.; Brucato, J. R.; Tozzi, G. P.; Oliva, E.; Massi, F.; Sanna, N.; Tozzi, A.

    2016-10-01

    We observed the Oort cloud comet C/2014 Q2 (Lovejoy) on 2015 January 31 and February 1 and 2 at a heliocentric distance of 1.3 au and geocentric distance of 0.8 au during its approach to the Sun. Comet Lovejoy was observed with GIANO, the near-infrared high-resolution spectrograph mounted at the Nasmyth-A focus of the TNG (Telescopio Nazionale Galileo) telescope in La Palma, Canary Islands, Spain. We detected strong emissions of radical CN and water, along with many emission features of unidentified origin, across the 1–2.5 μm region. Spectral lines from eight ro-vibrational bands of H2O were detected, six of them for the first time. We quantified the water production rate [Q(H2O), (3.11 ± 0.14) × 1029 s‑1] by comparing the calibrated line fluxes with the Goddard full non-resonance cascade fluorescence model for H2O. The production rates of ortho-water [Q(H2O)ORTHO, (2.33 ± 0.11) × 1029 s‑1] and para-water [Q(H2O)PARA, (0.87 ± 0.21) × 1029 s‑1] provide a measure of the ortho-to-para ratio (2.70 ± 0.76)). The confidence limits are not small enough to provide a critical test of the nuclear spin temperature.

  9. Solid-State Chemistry as a Formation Mechanism for C 4N 2 Ice and Possibly the Haystack (220 cm -1 ice emission feature) in Titan's Stratosphere as Observed by Cassini CIRS

    NASA Astrophysics Data System (ADS)

    Anderson, Carrie; Samuelson, Robert E.; McLain, Jason L.; Nna Mvondo, Delphine; Romani, Paul; Flasar, F. Michael

    2016-10-01

    A profusion of organic ices containing hydrocarbons, nitriles, and combinations of their mixtures comprise Titan's complex stratospheric cloud systems, and are typically formed via vapor condensation. These ice particles are then distributed throughout the mid-to-lower stratosphere, with an increased abundance near the winter poles (see Anderson et al., 2016). The cold temperatures and the associated strong circumpolar winds that isolate polar air act in much the same way as on Earth, giving rise to compositional anomalies and stratospheric clouds that provide heterogeneous chemistry sites.Titan's C4N2 ice emission feature at 478 cm-1 and "the Haystack," a strong unidentified stratospheric ice emission feature centered at 220 cm-1, share a common characteristic. Even though both are distinctive ice emission features evident in Cassini Composite InfraRed (CIRS) far-IR spectra, no associated vapor emission features can be found in Titan's atmosphere. Without a vapor phase, solid-state chemistry provides an alternate mechanism beside vapor condensation for producing these observed stratospheric ices.Anderson et al., (2016) postulated that C4N2 ice formed in Titan's stratosphere via the solid-state photochemical reaction HCN + HC3N → C4N2 + H2 can occur within extant HCN-HC3N composite ice particles. Such a reaction, and potentially similar reactions that may produce the Haystack ice, are specific examples of solid-state chemistry in solar system atmospheres. This is in addition to the reaction HCl + ClONO2 → HNO3 + Cl2, which is known to produce HNO3 coatings on terrestrial water ice particles, a byproduct of the catalytic chlorine chemistry that produces ozone holes in Earth's polar stratosphere (see for example, Molina et al., 1987 Soloman, 1999).A combination of radiative transfer modeling of CIRS far-IR spectra, coupled with optical constants derived from thin film transmittance spectra of organic ice mixtures obtained in our Spectroscopy for Planetary ICes

  10. Mapping vegetation types with the multiple spectral feature mapping algorithm in both emission and absorption

    NASA Technical Reports Server (NTRS)

    Clark, Roger N.; Swayze, Gregg A.; Koch, Christopher; Ager, Cathy

    1992-01-01

    Vegetation covers a large portion of the Earth's land surface. Remotely sensing quantitative information from vegetation has proven difficult because in a broad sense, all vegetation is similar from a chemical viewpoint, and most healthy plants are green. Plant species are generally characterized by the leaf and flower or fruit morphology, not by remote sensing spectral signatures. But to the human eye, many plants show varying shades of green, so there is direct evidence for spectral differences between plant types. Quantifying these changes in a predictable manner has not been easy. The Clark spectral features mapping algorithm was applied to mapping spectral features in vegetation species.

  11. Cryptography based on the absorption/emission features of multicolor semiconductor nanocrystal quantum dots.

    PubMed

    Zhou, Ming; Chang, Shoude; Grover, Chander

    2004-06-28

    Further to the optical coding based on fluorescent semiconductor quantum dots (QDs), a concept of using mixtures of multiple single-color QDs for creating highly secret cryptograms based on their absorption/emission properties was demonstrated. The key to readout of the optical codes is a group of excitation lights with the predetermined wavelengths programmed in a secret manner. The cryptograms can be printed on the surfaces of different objects such as valuable documents for security purposes.

  12. Spectral features of stimulated electromagnetic emission, measured in the 4.3-9.5 MHz pump wave frequency range

    NASA Astrophysics Data System (ADS)

    Frolov, V. L.; Sergeev, E. N.; Ermakova, E. N.; Komrakov, G. P.; Stubbe, P.

    Steady state spectral features of stimulated electromagnetic emissions (SEEs) for their major emission components (DM, NC, BC, BUM, and BUS) are studied in a wide pump wave frequency range, from 4.3 to 9.5 MHz, i.e., from slightly above the 3rd to slightly above the 7th gyroharmonic frequency. Based on these systematic experimental data, new peculiarities in the behaviour of the SEE intensity and of the spectral properties, in relation to the gyroharmonic mode number, have been found. The experimental results, discussed in the paper, were collected during the years 1996-2000 at the Sura heating facility in Russia by modification of the ionospheric F region, using ordinary mode HF pump waves.

  13. Possible Detection of an Emission Cyclotron Resonance Scattering Feature from the Accretion-Powered Pulsar 4U 1626-67

    NASA Technical Reports Server (NTRS)

    Iwakiri, W. B.; Terada, Y.; Tashiro, M. S.; Mihara, T.; Angelini, L.; Yamada, S.; Enoto, T.; Makishima, K.; Nakajima, M.; Yoshida, A.

    2012-01-01

    We present analysis of 4U 1626-67, a 7.7 s pulsar in a low-mass X-ray binary system, observed with the hard X-ray detector of the Japanese X-ray satellite Suzaku in 2006 March for a net exposure of 88 ks. The source was detected at an average 10-60 keY flux of approx 4 x 10-10 erg / sq cm/ s. The phase-averaged spectrum is reproduced well by combining a negative and positive power-law times exponential cutoff (NPEX) model modified at approx 37 keY by a cyclotron resonance scattering feature (CRSF). The phase-resolved analysis shows that the spectra at the bright phases are well fit by the NPEX with CRSF model. On the other hand. the spectrum in the dim phase lacks the NPEX high-energy cutoff component, and the CRSF can be reproduced by either an emission or an absorption profile. When fitting the dim phase spectrum with the NPEX plus Gaussian model. we find that the feature is better described in terms of an emission rather than an absorption profile. The statistical significance of this result, evaluated by means of an F test, is between 2.91 x 10(exp -3) and 1.53 x 10(exp -5), taking into account the systematic errors in the background evaluation of HXD-PIN. We find that the emission profile is more feasible than the absorption one for comparing the physical parameters in other phases. Therefore, we have possibly detected an emission line at the cyclotron resonance energy in the dim phase.

  14. Why the oxygen IR emission at 1.27 μm is not the best way for ozone retrieval in the mesosphere?

    NASA Astrophysics Data System (ADS)

    Manuilova, Rada O.; Yankovsky, Valentine A.

    2016-04-01

    In the framework of model of electronic vibrational kinetics of excited products of O3 and O2 photolysis in the MLT of the Earth, YM2011, we have tried to answer the formulated above question. In our study we propose to retrieve the [O3] using as proxies electronic-vibrationally excited levels of oxygen molecule, namely O2(b1, v=0, 1), O2(a1, v=0) and excited atom O(1D). Concerning the [O3] retrieval in the range of 50-100 km, the emissions at 1.27 μm formed by transition from O2(a1, v=0) and at 762 nm formed by transition from O2(b1, v=0) are the most intensive ones among all emissions under consideration. However, considering the complexity of kinetics of the excited components: choosing O(1D) as a proxy for [O3] retrieval, requires taking into account five aeronomical reactions. For other proxies the number of aeronomical reactions is as follows: O2(b1, v=1) - 13; O2(b1, v=0) - 18; O2(a1, v=0) - 25. Increasing the number of reactions that must be considered when using a proxy from O(1D) to O2(a1, v=0) depends on the fact that, calculating the population of each of the underlying electronic-vibrationally excited state requires considering the mechanisms of the population of the upper levels. Using the O2(a1, v=0) is also associated with the problem of poorly known rate coefficients for some important processes. For example, the rate constant of reaction O₂( a1, v=0) + O(³P) -> products is known with uncertainty 200%. The next criterion of a "good" proxy is the value of [O3] retrieval uncertainty. Above 90 km, O2(a1, v=0) becomes the worst proxy among all under consideration with the uncertainty exceeding 100%. In the interval 50-98 km O2(b1, v=1) is the "good" proxy with the value of uncertainty less than 20% below 90 km and less than 25% up to 98 km. Therefore, O2(b1, v=1) is the preferable proxy at the altitudes of 50-98 km. Commonly used [O3] retrieval proxy, O2(a1, v=0), transition from which forms the 1.27 μm O2 IR Atmospheric band, has more than one

  15. Applying light-emitting diodes with narrowband emission features in differential spectroscopy.

    PubMed

    Sihler, Holger; Kern, Christoph; Pöhler, Denis; Platt, Ulrich

    2009-12-01

    LEDs are a promising new type of light source for differential optical absorption spectroscopy (DOAS). Varying differential structures in the emission spectrum of LEDs, however, display a potentially severe problem. We show that the structures, which originate from a Fabry-Pérot etalon, may be removed by tilting the emitter, which at the same time increases the radiant flux coupled into the subsequent optical system. The results of long-path DOAS measurements, where we apply our method on a blue LED for the suppression of periodic structures, are also presented. PMID:19953172

  16. Dissociative excitation of vacuum ultraviolet emission features by electron impact on molecular gases. 3: CO2

    NASA Technical Reports Server (NTRS)

    Mumma, M. J.; Borst, W. L.; Zipf, E. C.

    1972-01-01

    Vacuum ultraviolet multiplets of C I, C II, and O I were produced by electron impact on CO2. Absolute emission cross sections for these multiplets were measured from threshold to 350 eV. The electrostatically focused electron gun used is described in detail. The atomic multiplets which were produced by dissociative excitation of CO2 and the cross sections at 100 eV are presented. The dependence of the excitation functions on electron energy shows that these multiplets are produced by electric-dipole-allowed transitions in CO2.

  17. Features of space-charge-limited emission in foil-less diodes

    SciTech Connect

    Wu, Ping; Yuan, Keliang; Liu, Guozhi; Sun, Jun

    2014-12-15

    Space-charge-limited (SCL) current can always be obtained from the blade surface of annular cathodes in foil-less diodes which are widely used in O-type relativistic high power microwave generators. However, there is little theoretical analysis regarding it due to the mathematical complexity, and almost all formulas about the SCL current in foil-less diodes are based on numerical simulation results. This paper performs an initial trial in calculation of the SCL current from annular cathodes theoretically under the ultra-relativistic assumption and the condition of infinitely large guiding magnetic field. The numerical calculation based on the theoretical research is coherent with the particle-in-cell (PIC) simulation result to some extent under a diode voltage of 850 kV. Despite that the theoretical research gives a much larger current than the PIC simulation (41.3 kA for the former and 9.7 kA for the latter), which is induced by the ultra-relativistic assumption in the theoretical research, they both show the basic characteristic of emission from annular cathodes in foil-less diodes, i.e., the emission enhancement at the cathode blade edges, especially at the outer edge. This characteristic is confirmed to some extent in our experimental research of cathode plasma photographing under the same diode voltage and a guiding magnetic field of 4 T.

  18. Modeling emission features of salicylidene aniline molecular crystals: A QM/QM' approach.

    PubMed

    Presti, Davide; Labat, Frédéric; Pedone, Alfonso; Frisch, Michael J; Hratchian, Hrant P; Ciofini, Ilaria; Cristina Menziani, Maria; Adamo, Carlo

    2016-04-01

    A new computational protocol relying on the use of electrostatic embedding, derived from QM/QM' ONIOM calculations, to simulate the effect of the crystalline environment on the emission spectra of molecular crystals is here applied to the β-form of salicylidene aniline (SA). The first singlet excited states (S1 ) of the SA cis-keto and trans-keto conformers, surrounded by a cluster of other molecules representing the crystalline structure, were optimized by using a QM/QM' ONIOM approach with and without electronic embedding. The model system consisting of the central salicylidene aniline molecule was treated at the DFT level by using either the B3LYP, PBE0, or the CAM-B3LYP functional, whereas the real system was treated at the HF level. The CAM-B3LYP/HF level of theory provides emission energies in good agreement with experiment with differences of -20/-32 nm (cis-keto form) and -8/-14 nm (trans-keto form), respectively, whereas notably larger differences are obtained using global hybrids. Though such differences on the optical properties arise from the density functional choice, the contribution of the electronic embedding is rather independent of the functional used. This plays in favor of a more general applicability of the present protocol to other crystalline molecular systems. PMID:26919703

  19. Influence of laser pulse duration on extreme ultraviolet and ion emission features from tin plasmas

    SciTech Connect

    Roy, A. E-mail: aroy@barc.gov.in; Harilal, S. S.; Polek, M. P.; Hassan, S. M.; Hassanein, A.; Endo, A.

    2014-03-15

    We investigated the role of laser pulse duration and intensity on extreme ultraviolet (EUV) generation and ion emission from a laser produced Sn plasma. For producing plasmas, planar slabs of pure Sn were irradiated with 1064 nm Nd:YAG laser pulses with varying pulse duration (5–20 ns) and intensity. Experimental results performed at CMUXE indicate that the conversion efficiency (CE) of the EUV radiation strongly depend on laser pulse width and intensity, with a maximum CE of ∼2.0% measured for the shortest laser pulse width used (5 ns). Faraday Cup ion analysis of Sn plasma showed that the ion flux kinetic profiles are shifted to higher energy side with the reduction in laser pulse duration and narrower ion kinetic profiles are obtained for the longest pulse width used. However, our initial results showed that at a constant laser energy, the ion flux is more or less constant regardless of the excitation laser pulse width. The enhanced EUV emission obtained at shortest laser pulse duration studied is related to efficient laser-plasma reheating supported by presence of higher energy ions at these pulse durations.

  20. IR Asterisms

    NASA Astrophysics Data System (ADS)

    Riess, Adam

    2010-09-01

    Observing asterisms for photometric calibration provides a "happy medium" between observing single stars which areobservable from the ground but lack statistics, and star clusters which have excellent statistics but are too crowded to observe from the ground.Asterisms in the IR for calibration have been less available than in the optical, e.g., Landolt's standard fields.While ad-hoc asterisms for calibration could be formed from 2MASS calibration, the photometric precision of 2MASSis relatively low, 0.02-0.05, for the fainter stars, m=9-13, that can still be observed without saturation in WFC3-IR.However, IR monitoring of variable phenomena {e.g., AGN SNe, stellar variables} from the ground has produced calibration of stars in asterisms with m=9-13 with a relative uncertainty of 0.001 to 0.01 mag due to the high frequency of monitoring. We have selected 4 such asterisms to observe. Because the stars are bright we need to use subarrays of 64x64 or 128x128 to get read out short enough to avoid saturation. The observations are obtained in pairs of 3 close stars, i.e., 2x3=6 stars per orbit in F125W and F160W as well as a F555W full frame to verify astrometry. In all we expect to measure 24 stars with m=9 to 14. The goal is to provide 2 calibrations, an independent zeropoint and its uncertainty as well as a measure of count rate non linearity. For the latter, an expected CRNL over 2 dex {5 mag} is expected tobe 0.02 mag.

  1. The infrared spectrum of comet Bradfield (1987s) and the silicate emission feature.

    PubMed

    Hanner, M S; Newburn, R L; Gehrz, R D; Harrison, T; Ney, E P; Hayward, T L

    1990-01-01

    Infrared (1-20 micrometers) observations of comet Bradfield (1987s) from three observatories are reported. Silicate emission is prominent in all the data, from heliocentric distance r=0.87 to 1.45 AU. A CVF spectrum at r=1.45 AU shows a peak at 11.3 micrometers identified as crystalline olivine; the spectral shape is similar to that in Halley. Dust optical properties are similar to those of the grains in Halley's jets. Dust production rate near perihelion was approximately 10(6) g s-1 and varied in proportion to (r-2). We suggest that some differences in grain properties among comets could result from differences in the thermal history of the nuclear surface and the relative fraction of the dust particles originating in the subsurface icy layer versus the devolatilized mantle.

  2. Features of the Earth surface deformations in Kamchatka peninsula and their relation with geoacoustic emission

    NASA Astrophysics Data System (ADS)

    Larionov, I. A.; Marapulets, Yu. V.; Shevtsov, B. M.

    2014-08-01

    The paper presents the results of investigations of deformation process in the near surface sedimentary rocks, which has been carried out in a seismically active region of Kamchatka peninsular since 2007. The peculiarity of the experiments on registration of geodeformations is the application of a laser strainmeter-interferometer constructed according to the Michelson interferometer scheme. Besides rock deformations, geoacoustic emission in the frequency range from several hertz to the first tens of kilohertz is under the investigation. Piezoceramic hydrophones installed in artificial water reservoirs are applied. It is shown that periods of primary rock compression and tension with the duration up to several months are distinguished in the geodeformation process at the observation site. During the direction change in the deformations, when geodeformation process rate grows, the increase of geoacoustic radiation is observed.

  3. Specific features of thermocouple calorimeter application for measurements of pulsed X-ray emission from plasma

    SciTech Connect

    Gavrilov, V. V.; Fasakhov, I. K.

    2012-01-15

    It is shown that the accuracy of time-integrated measurements of pulsed X-ray emission from hot plasma with calibrated thermocouple calorimeters is mainly determined by two factors. The first and the most important factor is heating of the filter by the absorbed X-rays; as a result, the calorimeter measures the thermal radiation of the filter, which causes appreciable distortion of the temporal profile and amplitude of the recorded signal. The second factor is the dependence of the effective depth of X-ray absorption in the dielectric that covers the entrance window of the calorimeter on the energy of X-ray photons, i.e., on the recorded radiation spectrum. The results of model calculations of the calorimeter signal are compared with the experimental data.

  4. Salient features of otoacoustic emissions are common across tetrapod groups and suggest shared properties of generation mechanisms.

    PubMed

    Bergevin, Christopher; Manley, Geoffrey A; Köppl, Christine

    2015-03-17

    Otoacoustic emissions (OAEs) are faint sounds generated by healthy inner ears that provide a window into the study of auditory mechanics. All vertebrate classes exhibit OAEs to varying degrees, yet the biophysical origins are still not well understood. Here, we analyzed both spontaneous (SOAE) and stimulus-frequency (SFOAE) otoacoustic emissions from a bird (barn owl, Tyto alba) and a lizard (green anole, Anolis carolinensis). These species possess highly disparate macromorphologies of the inner ear relative to each other and to mammals, thereby allowing for novel insights into the biomechanical mechanisms underlying OAE generation. All ears exhibited robust OAE activity, and our chief observation was that SFOAE phase accumulation between adjacent SOAE peak frequencies clustered about an integral number of cycles. Being highly similar to published results from human ears, we argue that these data indicate a common underlying generator mechanism of OAEs across all vertebrates, despite the absence of morphological features thought essential to mammalian cochlear mechanics. We suggest that otoacoustic emissions originate from phase coherence in a system of coupled oscillators, which is consistent with the notion of "coherent reflection" but does not explicitly require a mammalian-type traveling wave. Furthermore, comparison between SFOAE delays and auditory nerve fiber responses for the barn owl strengthens the notion that most OAE delay can be attributed to tuning. PMID:25737537

  5. HERSCHEL-PACS OBSERVATIONS OF FAR-IR CO LINE EMISSION IN NGC 1068: HIGHLY EXCITED MOLECULAR GAS IN THE CIRCUMNUCLEAR DISK

    SciTech Connect

    Hailey-Dunsheath, S.; Sturm, E.; Gracia-Carpio, J.; Davies, R.; Poglitsch, A.; Contursi, A.; Genzel, R.; Lutz, D.; Tacconi, L.; De Jong, J. A.; Fischer, J.; Sternberg, A.; Mark, D.; Gonzalez-Alfonso, E.; Veilleux, S.; Verma, A.

    2012-08-10

    We report the detection of far-IR CO rotational emission from the prototypical Seyfert 2 galaxy NGC 1068. Using Herschel-PACS, we have detected 11 transitions in the J{sub upper} = 14-30 (E{sub upper}/k{sub B} = 580-2565 K) range, all of which are consistent with arising from within the central 10'' (700 pc). The detected transitions are modeled as arising from two different components: a moderate-excitation (ME) component close to the galaxy systemic velocity and a high-excitation (HE) component that is blueshifted by {approx}80 km s{sup -1}. We employ a large velocity gradient model and derive n{sub H2} {approx} 10{sup 5.6} cm{sup -3}, T{sub kin} {approx} 170 K, and M{sub H2} {approx} 10{sup 6.7} M{sub Sun} for the ME component and n{sub H2} {approx} 10{sup 6.4} cm{sup -3}, T{sub kin} {approx} 570 K, and M{sub H2} {approx} 10{sup 5.6} M{sub Sun} for the HE component, although for both components the uncertainties in the density and mass are {+-}(0.6-0.9) dex. Both components arise from denser and possibly warmer gas than traced by low-J CO transitions, and the ME component likely makes a significant contribution to the mass budget in the nuclear region. We compare the CO line profiles with those of other molecular tracers observed at higher spatial and spectral resolution and find that the ME transitions are consistent with these lines arising in the {approx}200 pc diameter ring of material traced by H{sub 2} 1-0 S(1) observations. The blueshift of the HE lines may also be consistent with the bluest regions of this H{sub 2} ring, but a better kinematic match is found with a clump of infalling gas {approx}40 pc north of the active galactic nucleus (AGN). We consider potential heating mechanisms and conclude that X-ray- or shock heating of both components is viable, while far-UV heating is unlikely. We discuss the prospects of placing the HE component near the AGN and conclude that while the moderate thermal pressure precludes an association with the {approx}1 pc

  6. Persistent time intervals between features in solar flare hard X-ray emission

    NASA Technical Reports Server (NTRS)

    Desai, Upendra D.; Kouveliotou, Chryssa; Barat, C.; Hurley, K.; Niel, M.; Talon, R.; Vedrenne, G.

    1986-01-01

    Several solar hard X-ray events (greater than 100 keV) were observed simultaneously with identical instruments on the Venera 11, 12, 13, 14, and Prognoz spacecraft. High time resolution (= 2 ms) data were stored in memory when a trigger occurred. The observations of modulation are presented with a period of 1.6 s for the event on December 3, 1978. Evidence is also presented for fast time fluctuations from an event on November 6, 1979, observed from Venera 12 and another on September 6, 1981, observed from the Solar Maximum Mission. Power spectrum analysis, epoch folding, and Monte Carlo simulation were used to evaluate the statistical significance of persistent time delays between features. The results are discussed in light of the MHD model proposed by Zaitsev and Stepanov.

  7. Using ATR-FT/IR to detect carbohydrate-related molecular structure features of carinata meal and their in situ residues of ruminal fermentation in comparison with canola meal

    NASA Astrophysics Data System (ADS)

    Xin, Hangshu; Yu, Peiqiang

    2013-10-01

    There is no information on the co-products from carinata bio-fuel and bio-oil processing (carinata meal) in molecular structural profiles mainly related to carbohydrate biopolymers in relation to ruminant nutrition. Molecular analyses with Fourier transform infrared spectroscopy (FT/IR) technique with attenuated total reflectance (ATR) and chemometrics enable to detect structural features on a molecular basis. The objectives of this study were to: (1) determine carbohydrate conformation spectral features in original carinata meal, co-products from bio-fuel/bio-oil processing; and (2) investigate differences in carbohydrate molecular composition and functional group spectral intensities after in situ ruminal fermentation at 0, 12, 24 and 48 h compared to canola meal as a reference. The molecular spectroscopic parameters of carbohydrate profiles detected were structural carbohydrates (STCHO, mainly associated with hemi-cellulosic and cellulosic compounds; region and baseline ca. 1483-1184 cm-1), cellulosic compounds (CELC, region and baseline ca. 1304-1184 cm-1), total carbohydrates (CHO, region and baseline ca. 1193-889 cm-1) as well as the spectral ratios calculated based on respective spectral intensity data. The results showed that the spectral profiles of carinata meal were significantly different from that of canola meal in CHO 2nd peak area (center at ca. 1091 cm-1, region: 1102-1083 cm-1) and functional group peak intensity ratios such as STCHO 1st peak (ca. 1415 cm-1) to 2nd peak (ca. 1374 cm-1) height ratio, CHO 1st peak (ca. 1149 cm-1) to 3rd peak (ca. 1032 cm-1) height ratio, CELC to total CHO area ratio and STCHO to CELC area ratio, indicating that carinata meal may not in full accord with canola meal in carbohydrate utilization and availability in ruminants. Carbohydrate conformation and spectral features were changed by significant interaction of meal type and incubation time and almost all the spectral parameters were significantly decreased (P < 0

  8. Spitzer IRS Observations of ``Mature'' Novae

    NASA Astrophysics Data System (ADS)

    Helton, L. Andrew; Woodward, C. E.; Evans, A.; Gehrz, R. D.; Lynch, D. L.; Rudy, R.; Schwarz, G. J.; Vanlandingham, K.; Spitzer Nova Team

    2009-01-01

    Many facets of astrophysics are captured in classical nova (CN) eruptions, making them unique laboratories in which we may observe several poorly understood astrophysical processes including mass transfer, thermonuclear runaway, optically thick winds, common envelope evolution, molecule and grain formation, coronal line emission, and gas cooling by fine structure lines. Many of these phenomena evolve in real time. Therefore, a better understanding of CNe has far-reaching applications and underpins several related and important areas of astrophysics. Here we present preliminary results of our Cycle 5 Spitzer IRS study of ``mature'' novae (several 100s of days post-outburst), complemented by extensive multi-wavelength data from other facilities. We present data on V2361 Cyg, V2467 Cyg and V378 Ser. In particular, V2361 Cyg displays a strong dust continuum with possible Aromatic Emission Features (AEF) superimposed, the first dusty CN observed to do so since 1993 and the first to be observed spectroscopically in the far IR. This object presents us with an outstanding opportunity to investigate how the dust is processed by the UV radiation from the stellar remnant. Support for this work was provided in part by NASA through Spitzer contracts issued by JPL/Caltech to the University of Minnesota.

  9. Nighttime IR Ejecta

    NASA Technical Reports Server (NTRS)

    2004-01-01

    [figure removed for brevity, see original site]

    Today's crater is slightly older than one shown yesterday. The ballistically emplaced ejecta is now a uniform gray tone in this nighttime IR image. With time dust will cover young surfaces and control the IR image tone. This crater is located east of Huygens Crater.

    Image information: IR instrument. Latitude -10.6, Longitude 64.3 East (295.7 West). 100 meter/pixel resolution.

    Note: this THEMIS visual image has not been radiometrically nor geometrically calibrated for this preliminary release. An empirical correction has been performed to remove instrumental effects. A linear shift has been applied in the cross-track and down-track direction to approximate spacecraft and planetary motion. Fully calibrated and geometrically projected images will be released through the Planetary Data System in accordance with Project policies at a later time.

    NASA's Jet Propulsion Laboratory manages the 2001 Mars Odyssey mission for NASA's Office of Space Science, Washington, D.C. The Thermal Emission Imaging System (THEMIS) was developed by Arizona State University, Tempe, in collaboration with Raytheon Santa Barbara Remote Sensing. The THEMIS investigation is led by Dr. Philip Christensen at Arizona State University. Lockheed Martin Astronautics, Denver, is the prime contractor for the Odyssey project, and developed and built the orbiter. Mission operations are conducted jointly from Lockheed Martin and from JPL, a division of the California Institute of Technology in Pasadena.

  10. Gas-emission crater in Central Yamal, West Siberia, Russia, a new permafrost feature

    NASA Astrophysics Data System (ADS)

    Leibman, Marina; Kizyakov, Alexandr; Khomutov, Artem; Dvornikov, Yury; Streletskaya, Irina; Gubarkov, Anatoly

    2016-04-01

    The Yamal crater is a hole funnel-shaped on top and cylinder-shaped down to the bottom, surrounded by a parapet. Field study of the crater included size measurements, photo- video-documentation of the feature and the surrounding environment, and geochemical sampling. The upper part of the geological section within the crater consisted of stratified icy sediments, underlain by almost pure stratified ice of nearly vertical orientation of the layers. The volume of discharged material (volume of the void of the crater) was 6 times larger than the volume of material in the parapet. The difference was due to a significant amount of ice exposed in the walls of the crater, emitted to the surface and melted there. Remote sensing data was processes and validated by field observations to reveal the date of crater formation, previous state of the surface, evolution of the crater and environmental conditions of the surrounding area. Crater formed between 9 October and 1 November 2013. The initial size derived from Digital Elevation Model (DEM) had diameter of the vegetated rim 25-29 m. It turned through a sharp bend into a cylinder with close to vertical sides and diameter 15-16 m. Depth of the hole was impossible to estimate from DEM because of no light reaching walls in the narrow hole. By the time of initial observation in July 2014, water was found at the depth exceeding 50 m below the rim. In November 2014 this depth was 26 m. By September 2015 almost all the crater was flooded, with water surface about 5 m below the rim. The plan dimensions of the crater increased dramatically from initial 25-29 to 47-54 m in 2015. Thus, it took two warm seasons to almost entirely fill in the crater. We suppose that during the next 1-2 years parapet will be entirely destroyed, and as a result the crater will look like an ordinary tundra lake. Excluding impossible and improbable versions of the crater's development, the authors conclude that the origin of this crater can be attributed to

  11. The Synthesis and Characterization of a Group of Transition Metal Octabutoxynaphthalocyanines and the Absorption and Emission Properties of the Co, Rh, Ir, Ni, Pd and Pt Members of This Group.

    PubMed

    Kim, Junhwan; Soldatova, Alexandra V; Rodgers, Michael A J; Kenney, Malcolm E

    2013-07-01

    The synthesis and photophysical properties of new metallo-octabutoxynaphthalocyanines with Rh(III), Ir(III), and Pt(II) are reported. Various metals were inserted into the metal-free octabutoxynaphthalocyanine and the resultant metal complexes were fully characterized by NMR, UV-vis spectroscopy, and mass spectrometry. The absorption and emission properties of these new complexes were also examined and compared to those of Co(II), Ni(II), and Pd(II) octabutoxynaphthalocyanines. The results provide useful information to understand the effect of these transition metals on the properties of this macrocyclic ring. PMID:23745014

  12. The Synthesis and Characterization of a Group of Transition Metal Octabutoxynaphthalocyanines and the Absorption and Emission Properties of the Co, Rh, Ir, Ni, Pd and Pt Members of This Group

    PubMed Central

    Kim, Junhwan; Soldatova, Alexandra V.; Rodgers, Michael A. J.; Kenney, Malcolm E.

    2013-01-01

    The synthesis and photophysical properties of new metallo-octabutoxynaphthalocyanines with Rh(III), Ir(III), and Pt(II) are reported. Various metals were inserted into the metal-free octabutoxynaphthalocyanine and the resultant metal complexes were fully characterized by NMR, UV-vis spectroscopy, and mass spectrometry. The absorption and emission properties of these new complexes were also examined and compared to those of Co(II), Ni(II), and Pd(II) octabutoxynaphthalocyanines. The results provide useful information to understand the effect of these transition metals on the properties of this macrocyclic ring. PMID:23745014

  13. FE K EMISSION AND ABSORPTION FEATURES IN THE XMM-EPIC SPECTRUM OF THE SEYFERT GALAXY IC 4329A

    NASA Technical Reports Server (NTRS)

    Markowitz, A.; Reeves, J. N.; Braito, V.

    2001-01-01

    We present a re-analysis of the XMM-Newton long-look of the X-ray bright Seyfert galaxy IC 4329a. The Fe K bandpass is dominated by two peaks, consistent with emission from neutral or near-neutral Fe Ka and KP. A relativistic diskline model whereby both peaks are the result of one doubly-peaked diskline profile is found to be a poor description of the data. Models using two relativistic disklines are found to describe the emission profile well. A low-inclination, moderately-relativistic dual-diskline model is possible if the contribution from narrow components, due to distant material, is small or absent. A high-inclination, moderately relativistic profile for each peak is possible if there are roughly equal contributions from both the broad and narrow components. Upper limits on Fe XXV and Fe XXVI emission and absorption at the systemic velocity of IC 4329a are obtained. We also present the results of RXTE monitoring of this source obtained so far; the combined XMM-Newton and RXTE data sets allow us to explore the time-resolved spectral behavior of this source on time scales ranging from hours to 2 years. We find no strong evidence for variability of the Fe Ka emission line on any time scale probed, likely due to the minimal level of continuum variability. We detect a narrow absorption line, at a energy of 7.68 keV in the rest frame of the source; its significance has been confirmed using Monte Carlo simulations. This feature is most likely due to absorption from Fe XXVI blueshifted to approximately 0.1c relative to the systemic velocity, making IC 4329a the lowest-redshift AGN known with a high-velocity, highly-ionized outflow component. As is often the case with similar outflows seen in high-luminosity quasars, the estimated mass outflow rate is larger than the inflow accretion rate, signaling that the outflow represents a substantial portion of the total energy budget of the AGN. The outflow could arise from a radiatively-driven disk wind, or it may be in the

  14. Far-infrared emission spectra of selected gas-phase PAHs: Spectroscopic fingerprints

    SciTech Connect

    Zhang, K.; Guo, B.; Colarusso, P.; Bernath, P.F.

    1996-10-25

    The emission spectra of the gaseous polycyclic aromatic hydrocarbons (PAHs) naphthalene, chrysene, and pyrene were recorded in the far-infrared (far-IR) region. The vibrational bands that lie in the far IR are unique for each PAH molecule and allow discrimination among the three PAH molecules. The far-IR PAH spectra, therefore, may prove useful in the assignment of unidentified spectral features from astronomical objects. 23 refs., 1 fig., 1 tab.

  15. Temperature and current dependencies of terahertz emission from stacks of intrinsic Josephson junctions with thin electrodes revealed by a high-resolution FT-IR spectrometer

    NASA Astrophysics Data System (ADS)

    Kakeya, Itsuhiro; Hirayama, Nobuo; Nakagawa, Takuto; Omukai, Yuta; Suzuki, Minoru

    2013-08-01

    We report on emission of electromagnetic wave in a frequency range of 1012 hertz (THz) from stacks of intrinsic Josephson junctions (IJJ) made of superconducting Bi2Sr2CaCu2O8+δ single crystals. A home-built high-resolution Fourier-transfer-infrared spectrometer reveals that the emission spectrum is monochromatic and the width is as sharp as its resolution limit (∼1 GHz). The THz emission is obtained in a broad temperature and current range depending on the mesa. The emission frequency is tuned from 0.55 to 0.45 THz by changing temperature from 20 to 55 K.

  16. Spitzer IRS Observations of FU Orionis Objects

    NASA Astrophysics Data System (ADS)

    Green, J. D.; Hartmann, L.; Calvet, N.; Watson, D. M.; Ibrahimov, M.; Furlan, E.; Sargent, B.; Forrest, W. J.

    2006-09-01

    We present 5-35 μm spectra, taken with the Infrared Spectrograph (IRS) on the Spitzer Space Telescope, of five FU Orionis objects: FU Ori, V1515 Cyg, V1057 Cyg, BBW 76, and V346 Nor. All but V346 Nor reveal amorphous silicate grains in emission at 10 and 20 μm, and show water-vapor absorption bands at 5.8 and 6.8 μm and SiO or possibly methane absorption at 8 μm. These absorption features closely match these bands in model stellar photospheres-signs of the gaseous photospheres of the inner regions of these objects' accretion disks. The continuum emission at 5-8 μm is also consistent with such disks, and, for FU Orionis and BBW 76, longer wavelength emission may be fit by a model that includes moderate disk flaring. V1057 Cyg and V1515 Cyg have much more emission at longer wavelengths than the others, perhaps evidence of a substantial remnant of their natal, infalling envelopes.

  17. Magmatic gas emissions at Holocene volcanic features near Mono Lake, California, and their relation to regional magmatism

    USGS Publications Warehouse

    Bergfeld, D.; Evans, William C.; Howle, James F.; Hunt, Andrew G.

    2015-01-01

    Silicic lavas have erupted repeatedly in the Mono Basin over the past few thousand years, forming the massive domes and coulees of the Mono Craters chain and the smaller island vents in Mono Lake. We report here on the first systematic study of magmatic CO2 emissions from these features, conducted during 2007–2010. Most notably, a known locus of weak steam venting on the summit of North Coulee is actually enclosed in a large area (~ 0.25 km2) of diffuse gas discharge that emits 10–14 t/d of CO2, mostly at ambient temperature. Subsurface gases sampled here are heavily air-contaminated, but after standard corrections are applied, show average δ13C-CO2 of − 4.72‰, 3He/4He of 5.89RA, and CO2/3He of 0.77 × 1010, very similar to the values in fumarolic gas from Mammoth Mountain and the Long Valley Caldera immediately to the south of the basin. If these values also characterize the magmatic gas source at Mono Lake, where CO2 is captured by the alkaline lake water, a magmatic CO2 upflow beneath the lake of ~ 4 t/d can be inferred. Groundwater discharge from the Mono Craters area transports ~ 13 t/d of 14C-dead CO2 as free gas and dissolved carbonate species, and adding in this component brings the estimated total magmatic CO2 output to 29 t/d for the two silicic systems in the Mono Basin. If these emissions reflect intrusion and degassing of underlying basalt with 0.5 wt.% CO2, a modest intrusion rate of 0.00075 km3/yr is indicated. Much higher intrusion rates are required to account for CO2 emissions from Mammoth Mountain and the West Moat of the Long Valley Caldera.

  18. Modelling the Emission And/or Absorption Features in the High Resolution Spectra of the Southern Binary System: HH Car

    NASA Astrophysics Data System (ADS)

    Koseoglu, Dogan; Bakış, Hicran

    2016-07-01

    High-resolution spectra (R=48000) of the southern close binary system, HH Car, has been analyzed with modern analysis techniques. Precise absolute parameters were derived from the simultaneous solution of the radial velocity, produced in this study and the light curves, published. According to the results of these analyses, the primary component is an O9 type main sequence star while the secondary component is a giant/subgiant star with a spectral type of B0. Hα emissions can be seen explicitly in the spectra of HH Car. These features were modelled using the absolute parameters of the components. Since components of HH Car are massive early-type stars, mass loss through stellar winds can be expected. This study revealed that the components of HH Car have stellar winds and the secondary component loses mass to the primary. Stellar winds and the gas stream between the components were modelled as a hot shell around the system. It is determined that the interaction between the winds and the gas stream leads to formation of a high temperature impact region.

  19. Near-IR imaging toward a puzzling young stellar object precessing jet

    NASA Astrophysics Data System (ADS)

    Paron, S.; Fariña, C.; Ortega, M. E.

    2016-10-01

    Aims: The study of jets that are related to stellar objects in formation is important because it enables us to understand the history of how the stars have built up their mass. Many studies currently examine jets towards low-mass young stellar objects, while equivalent studies toward massive or intermediate-mass young stellar objects are rare. In a previous study, based on 12CO J = 3-2 and public near-IR data, we found highly misaligned molecular outflows toward the infrared point source UGPS J185808.46+010041.8 (IRS) and some infrared features suggesting the existence of a precessing jet. Methods: Using near-IR data acquired with Gemini-NIRI at the JHKs broad- and narrowbands centered on the emission lines of [FeII], H2 1-0 S(1), H2 2-1 S(1), Brγ, and CO 2-0 (bh), we studied the circumstellar environment of IRS with an angular resolution between 0.̋35 and 0.̋45. Results: The emission in the JHKs broadbands shows in great detail a cone-shaped nebula extending to the north-northeast of the point source, which appears to be attached to it by a jet-like structure. In the three bands the nebula is resolved in a twisted-shaped feature composed of two arc-like features and a bow-shock-like structure seen mainly in the Ks band, which strongly suggests the presence of a precessing jet. An analysis of proper motions based on our Gemini observations and UKIDSS data additionally supports the precession scenario. We present one of the best-resolved cone-like nebula that is most likely related to a precessing jet up to date. The analysis of the observed near-IR lines shows that the H2 is collisionally excited, and the spatially coincidence of the [FeII] and H2 emissions in the closer arc-like feature suggests that this region is affected by a J shock. The second arc-like feature presents H2 emission without [FeII], which suggests a nondissociated C shock or a less energetic J shock. The H2 1-0 S(1) continuum-subtracted image reveals several knots and filaments at a larger

  20. The emission/absorption FE 2 spectrum of HD 45677

    NASA Technical Reports Server (NTRS)

    Stalio, R.; Selvelli, P. L.

    1981-01-01

    The complex behavior of the emission/absorption spectrum of Fe II is analyzed. The far UV spectrum is characterized almost solely by absorption lines, while, in the near UV, strong emissions are predominant. Radiative excitation from the ground to the highest levels (chi is approximately 10 eV) with re-emission in the near UV, visible and I.R. seems to be the main mechanism capable of explaining the observed spectral features.

  1. FAST X-RAY/IR CROSS-CORRELATIONS AND RELATIVISTIC JET FORMATION IN GRS 1915+105

    SciTech Connect

    Lasso-Cabrera, N. M.; Eikenberry, S. S.

    2013-10-01

    We present cross-correlation analyses of simultaneous X-ray and near-infrared (near-IR) observations of the microquasar GRS 1915+105 during relativistic jet-producing epochs (X-ray class α and β). While previous studies have linked the large amplitude IR flares and X-ray behaviors to jet formation in these states, our new analyses are sensitive to much lower amplitude IR variability, providing more sensitive probes of the jet formation process. The X-ray to IR cross-correlation function (CCF) shows significant correlations that vary in form between the different X-ray states. During low/hard dips in both classes, we find no significant X-ray/IR correlation. During high-variability epochs, we find consistently significant correlations in both α and β classes, but with strong differences in the CCF structure. The high variability α CCF shows strong anti-correlation between X-ray/IR, with the X-ray preceding the IR by ∼13 ± 2 s. The high variability β state shows a time-variable CCF structure, which is statistically significant but without a clearly consistent lag. Our simulated IR light curves, designed to match the observed CCFs, show variably flickering IR emission during the class β high-variability epoch, while class α can be fit by IR flickering with frequencies in the range 0.1-0.3 Hz, strengthening ∼10 s after every X-ray subflare. We interpret these features in the context of the X-ray-emitting accretion disk and IR emission from relativistic jet formation in GRS 1915+105, concluding that the CCF analysis places the origin in a synchrotron-emitting relativistic compact jet at a distance from the compact object of ∼0.02 AU.

  2. IR Thermography NDE of ISS Radiator Panels

    NASA Technical Reports Server (NTRS)

    Koshti, Ajay; Winfree, William; Morton, Richard; Wilson, Walter; Reynolds, Gary

    2010-01-01

    The presentation covers an active and a passive infrared (IR) thermography for detection of delaminations in the radiator panels used for the International Space Station (ISS) program. The passive radiator IR data was taken by a NASA astronaut in an extravehicular activity (EVA) using a modified FLIR EVA hand-held camera. The IR data could be successfully analyzed to detect gross facesheet disbonds. The technique used the internal hot fluid tube as the heat source in analyzing the IR data. Some non-flight ISS radiators were inspected using an active technique of IR flash thermography to detect disbond of face sheet with honeycomb core, and debonds in facesheet overlap areas. The surface temperature and radiated heat emission from flight radiators is stable during acquisition of the IR video data. This data was analyzed to detect locations of unexpected surface temperature gradients. The flash thermography data was analyzed using derivative analysis and contrast evolutions. Results of the inspection are provided.

  3. Efficient conversion from UV light to near-IR emission in Yb{sup 3+}-doped triple-layered perovskite CaLaNb{sub 3}O{sub 10}

    SciTech Connect

    Lu, Yuting; Li, Yuze; Qin, Lin; Huang, Yanlin; Qin, Chuanxiang; Tsuboi, Taiju; Huang, Wei

    2015-04-15

    Graphical abstract: CaRNb{sub 3}O{sub 10} is a self-activated oxide due to charge transfer transition in octahedral NbO{sub 6} groups. CaLaNb{sub 3}O{sub 10}:Yb{sup 3+} presents intense IR emission due to the cooperative energy transfer from host (NbO{sub 6}) to Yb{sup 3+} is responsible. It could be expected to be potentially applicable for enhancing photovoltaic conversion efficiency of Si-based solar cells. - Abstract: Yb{sup 3+}-doped triple-layered perovskite CaLaNb{sub 3}O{sub 10} micro-particles were synthesized via the solid-state reaction method. The crystal structure and morphology of the polycrystalline samples were investigated by X-ray powder diffraction (XRD) and scanning electron microscopy (SEM) measurements, respectively. The reflectance spectra, photoluminescence (PL) excitation and emission spectra, the decay curves, and the absolute quantum efficiency (QE) of the near-infrared (NIR) emission (910–1100 nm) were measured. Under excitation of UV light, Yb{sup 3+}-doped perovskite shows an intense NIR emission attributed to the {sup 2}F{sub 5/2} → {sup 2}F{sub 7/2} transitions of Yb{sup 3+} ions, which could match maximum spectral response of a Si-based solar cell. This is beneficial for its possible application in an enhancement of the photovoltaic conversion efficiency of solar energy utilization. The efficient energy transfer in Yb{sup 3+}-doped CaLaNb{sub 3}O{sub 10} from NbO{sub 6} groups into Yb{sup 3+} ions was confirmed by the spectra and fluorescent decay measurements. Cooperative energy transfer (CET) was supposed to be the NIR emission mechanism.

  4. Surface-induced brightness temperature variations and their effects on detecting thin cirrus clouds using IR emission channels in the 8-12 microns region

    NASA Technical Reports Server (NTRS)

    Gao, Bo-Cai; Wiscombe, W. J.

    1994-01-01

    A method for detecting cirrus clouds in terms of brightness temperature differences between narrowbands at 8, 11, and 12 microns has been proposed by Ackerman et al. In this method, the variation of emissivity with wavelength for different surface targets was not taken into consideration. Based on state-of-the-art laboratory measurements of reflectance spectra of terrestrial materials by Salisbury and D'Aria, it is found that the brightness temperature differences between the 8- and 11-microns bands for soils, rocks, and minerals, and dry vegetation can vary between approximately -8 and +8 K due solely to surface emissivity variations. The large brightness temperature differences are sufficient to cause false detection of cirrus clouds from remote sensing data acquired over certain surface targets using the 8-11-12-microns method directly. It is suggested that the 8-11-12-microns method should be improved to include the surface emissivity effects. In addition, it is recommended that in the future the variation of surface emissivity with wavelength should be taken into account in algorithms for retrieving surface temperatures and low-level atmospheric temperature and water vapor profiles.

  5. Northern Polar Spring in IR

    NASA Technical Reports Server (NTRS)

    2004-01-01

    [figure removed for brevity, see original site]

    Released 12 March 2004

    The Odyssey spacecraft has completed a full Mars year of observations of the red planet. For the next several weeks the Image of the Day will look back over this first mars year. It will focus on four themes: 1) the poles - with the seasonal changes seen in the retreat and expansion of the caps; 2) craters - with a variety of morphologies relating to impact materials and later alteration, both infilling and exhumation; 3) channels - the clues to liquid surface flow; and 4) volcanic flow features. While some images have helped answer questions about the history of Mars, many have raised new questions that are still being investigated as Odyssey continues collecting data as it orbits Mars.

    Infrared images taken during the daytime exhibit both the morphological and thermophysical properties of the surface of Mars. Morphologic details are visible due to the effect of sun-facing slopes receiving more energy than antisun-facing slopes. This creates a warm (bright) slope and cool (dark) slope appearance that mimics the light and shadows of a visible wavelength image. Thermophysical properties are seen in that dust heats up more quickly than rocks. Thus dusty areas are bright and rocky areas are dark.

    This image was collected October 19, 2002 during the northern spring season. The top half of this daytime IR image shows the North Polar sand sea.

    Image information: IR instrument. Latitude 76.2, Longitude 226.8 East (133.2 West). 19 meter/pixel resolution.

    Note: this THEMIS visual image has not been radiometrically nor geometrically calibrated for this preliminary release. An empirical correction has been performed to remove instrumental effects. A linear shift has been applied in the cross-track and down-track direction to approximate spacecraft and planetary motion. Fully calibrated and geometrically projected images will be released through the Planetary Data System in

  6. Photometric study of NGC 2023 in the 3500 A to 10000 A region - Confirmation of a near-IR emission process in reflection nebulae

    NASA Technical Reports Server (NTRS)

    Schild, R. E.; Kraiman, J. B.; Witt, A. N.

    1984-01-01

    A surface brightness study of the reflection nebula NGC 2023 covering the 3500-10,000 A wavelength region performed with uvby photoelectric photometry and BVRI imaging with a CCD detector is reported along with VRI photometry of a cluster of embedded red stars. The nebular radiation in the 3500-5500 A region is dust-scattered starlight originating in the star HD 37903. The embedded red stars are probably pre-main sequence stars. The nebular surface brightness in R and I exceeds that expected on the basis of a reasonable radiative transfer model by factors of two and more than three, respectively. The excess radiation is extended across the nebula in a manner similar to the scattered light. The extended red emission may be interpreted as the high-frequency extension of extended emission discovered by Sellgren, Werner, and Dinerstein (1983) in the 2-5 micron region in NGC 2023 and two other reflection nebulae.

  7. Surface-induced brightness temperature variations and their effects on detecting thin cirrus clouds using IR emission channels in the 8-12 micrometer region

    NASA Technical Reports Server (NTRS)

    Gao, Bo-Cai; Wiscombe, W. J.

    1993-01-01

    A method for detecting cirrus clouds in terms of brightness temperature differences between narrow bands at 8, 11, and 12 mu m has been proposed by Ackerman et al. (1990). In this method, the variation of emissivity with wavelength for different surface targets was not taken into consideration. Based on state-of-the-art laboratory measurements of reflectance spectra of terrestrial materials by Salisbury and D'Aria (1992), we have found that the brightness temperature differences between the 8 and 11 mu m bands for soils, rocks and minerals, and dry vegetation can vary between approximately -8 K and +8 K due solely to surface emissivity variations. We conclude that although the method of Ackerman et al. is useful for detecting cirrus clouds over areas covered by green vegetation, water, and ice, it is less effective for detecting cirrus clouds over areas covered by bare soils, rocks and minerals, and dry vegetation. In addition, we recommend that in future the variation of surface emissivity with wavelength should be taken into account in algorithms for retrieving surface temperatures and low-level atmospheric temperature and water vapor profiles.

  8. From Ultrafast Structure Determination to Steering Reactions: Mixed IR/Non-IR Multidimensional Vibrational Spectroscopies.

    PubMed

    van Wilderen, Luuk J G W; Bredenbeck, Jens

    2015-09-28

    Ultrafast multidimensional infrared spectroscopy is a powerful method for resolving features of molecular structure and dynamics that are difficult or impossible to address with linear spectroscopy. Augmenting the IR pulse sequences by resonant or nonresonant UV, Vis, or NIR pulses considerably extends the range of application and creates techniques with possibilities far beyond a pure multidimensional IR experiment. These include surface-specific 2D-IR spectroscopy with sub-monolayer sensitivity, ultrafast structure determination in non-equilibrium systems, triggered exchange spectroscopy to correlate reactant and product bands, exploring the interplay of electronic and nuclear degrees of freedom, investigation of interactions between Raman- and IR-active modes, imaging with chemical contrast, sub-ensemble-selective photochemistry, and even steering a reaction by selective IR excitation. We give an overview of useful mixed IR/non-IR pulse sequences, discuss their differences, and illustrate their application potential. PMID:26394274

  9. Late Time Multi-wavelength Observations of Swift J1644+5734: A Luminous Optical/IR Bump and Quiescent X-Ray Emission

    NASA Astrophysics Data System (ADS)

    Levan, A. J.; Tanvir, N. R.; Brown, G. C.; Metzger, B. D.; Page, K. L.; Cenko, S. B.; O'Brien, P. T.; Lyman, J. D.; Wiersema, K.; Stanway, E. R.; Fruchter, A. S.; Perley, D. A.; Bloom, J. S.

    2016-03-01

    We present late time multi-wavelength observations of Swift J1644+57, suggested to be a relativistic tidal disruption flare (TDF). Our observations extend to >4 years from discovery and show that 1.4 years after outburst the relativistic jet switched off on a timescale less than tens of days, corresponding to a power-law decay faster than t-70. Beyond this point weak X-rays continue to be detected at an approximately constant luminosity of LX ˜ 5 × 1042 erg s-1 and are marginally inconsistent with a continuing decay of t-5/3, similar to that seen prior to the switch-off. Host photometry enables us to infer a black hole mass of MBH = 3 × 106 M⊙, consistent with the late time X-ray luminosity arising from sub-Eddington accretion onto the black hole in the form of either an unusually optically faint active galactic nucleus or a slowly varying phase of the transient. Optical/IR observations show a clear bump in the light curve at timescales of 30-50 days, with a peak magnitude (corrected for host galaxy extinction) of MR ˜ -22 to -23. The luminosity of the bump is significantly higher than seen in other, non-relativistic TDFs and does not match any re-brightening seen at X-ray or radio wavelengths. Its luminosity, light curve shape, and spectrum are broadly similar to those seen in superluminous supervnovae, although subject to large uncertainties in the correction of the significant host extinction. We discuss these observations in the context of both TDF and massive star origins for Swift J1644+5734 and other candidate relativistic tidal flares.

  10. Spectral reflectance and emissivity features of broad leaf plants: Prospects for remote sensing in the thermal infrared (8.0-14.0 μm)

    USGS Publications Warehouse

    Ribeiro da Luz, Beatriz; Crowley, James K.

    2007-01-01

    In contrast to visible and short-wave infrared data, thermal infrared spectra of broad leaf plants show considerable spectral diversity, suggesting that such data eventually could be utilized to map vegetation composition. However, remotely measuring the subtle emissivity features of leaves still presents major challenges. To be successful, sensors operating in the 8–14 μm atmospheric window must have high signal-to-noise and a small enough instantaneous field of view to allow measurements of only a few leaf surfaces. Methods for atmospheric compensation, temperature–emissivity separation, and spectral feature analysis also will need to be refined to allow the recognition, and perhaps, exploitation of leaf thermal infrared spectral properties.

  11. Occurrence of global-scale emissions on Jupiter - Proposed identification of Jovian dimer H2 emission

    NASA Technical Reports Server (NTRS)

    Trafton, L. M.; Wartson, J. K. G.

    1992-01-01

    Two occasions of exceptionally widespread but distinct emission activity were observed in Jupiter's near-IR K-band spectrum during September and November of 1988. Two different sets of emission features were involved on the two dates of observation. During these occasions, the normally absent emission features extended from the South polar limb to at least the equator, over a large range of longitudes. Meanwhile, Jupiter's auroral H2 and H3(+) emissions remained confined to their usual magnetic polar domains. The global-scale emission features observed during those periods appear to have originated from the H2 dimer, (H2)2, during two different excitation modes. Inverse predissociation may have driven the November event. The September event probably originated deeper within the Jovian atmosphere, where excited H2 is more likely to combine with an unexcited H2 before radiating. Unusual magnetospheric loading probably precipitated these events.

  12. IR Variability of Eta Carinae

    NASA Astrophysics Data System (ADS)

    Smith, Nathan

    2007-02-01

    Every 5.5 years, η Carinae experiences a dramatic ``spectroscopic event'' when high-excitation lines in its UV, optical, and IR spectrum disappear, and its hard X-ray and radio continuum flux crash. This periodicity has been attributed to an eccentric binary system with a shell ejection occurring at periastron. In addition, η Car shows long term changes as it is still recovering from its giant 19th century outburst. Both types of variability are directly linked to the current mass-loss rate and dust formation in its wind. Mid-IR images and spectra with T-ReCS provide a direct measure of changes in the current bolometric luminosity and trace dust formation episodes. This will provide a direct measurement of the mass ejected. Near-IR emission lines trace related changes in the post-event wind and ionization changes in the circumstellar environment needed to test specific models for the cause of η Car's variability as it recovers from its recent ``event''. High resolution near-IR spectra with GNIRS will continue the important work of HST/STIS, investigating changes in the direct and reflected spectrum of the stellar wind, and ionization changes in the nebula.

  13. IR Variability of Eta Carinae

    NASA Astrophysics Data System (ADS)

    Smith, Nathan

    2008-02-01

    Every 5.5 years, η Carinae experiences a dramatic ``spectroscopic event'' when high-excitation lines in its UV, optical, and IR spectrum disappear, and its hard X-ray and radio continuum flux crash. This periodicity has been attributed to an eccentric binary system with a shell ejection occurring at periastron, and the next periastron event will occur at the very end of 2008. In addition, η Car shows long term changes as it is still recovering from its giant 19th century outburst. Both types of variability are directly linked to the current mass-loss rate and dust formation in its wind. Mid-IR images and spectra with T-ReCS provide a direct measure of changes in the current bolometric luminosity and a direct measure of the massw in dust formation episodes that may occur at periastron in the colliding wind shock. Near-IR emission lines trace related changes in the post-event wind and ionization changes in the circumstellar environment needed to test specific models for the cause of η Car's variability as it recovers from its recent ``event''. High resolution near-IR spectra with Phoenix will continue the important work of HST/STIS, investigating changes in the direct and reflected spectrum of the stellar wind, and ionization changes in the nebula.

  14. Development of an Extra-vehicular (EVA) Infrared (IR) Camera Inspection System

    NASA Technical Reports Server (NTRS)

    Gazarik, Michael; Johnson, Dave; Kist, Ed; Novak, Frank; Antill, Charles; Haakenson, David; Howell, Patricia; Pandolf, John; Jenkins, Rusty; Yates, Rusty

    2006-01-01

    Designed to fulfill a critical inspection need for the Space Shuttle Program, the EVA IR Camera System can detect crack and subsurface defects in the Reinforced Carbon-Carbon (RCC) sections of the Space Shuttle s Thermal Protection System (TPS). The EVA IR Camera performs this detection by taking advantage of the natural thermal gradients induced in the RCC by solar flux and thermal emission from the Earth. This instrument is a compact, low-mass, low-power solution (1.2cm3, 1.5kg, 5.0W) for TPS inspection that exceeds existing requirements for feature detection. Taking advantage of ground-based IR thermography techniques, the EVA IR Camera System provides the Space Shuttle program with a solution that can be accommodated by the existing inspection system. The EVA IR Camera System augments the visible and laser inspection systems and finds cracks and subsurface damage that is not measurable by the other sensors, and thus fills a critical gap in the Space Shuttle s inspection needs. This paper discusses the on-orbit RCC inspection measurement concept and requirements, and then presents a detailed description of the EVA IR Camera System design.

  15. New IR detectors pig-tailed with IR fibers

    NASA Astrophysics Data System (ADS)

    Artiouchenko, Viatcheslav G.; Chekanova, Galina V.; Lartsev, Ivan Y.; Lobachev, Vladimir A.; Nikitine, Mikhail S.

    2003-09-01

    New generation of Mercury-Cadmium-Telluride (MCT) high performance infrared radiation (IR) detectors with IR-fiber input has been developed and fabricated. This new product is originated from 25 years experience in MCT detectors and IR fiber optics technologies. Range of products includes single- and multi-element detectors designed for registration of optical signals in spectral range from 2 to 18 μm. Detectors design is integrated or modular and includes package, sensitive element, cooling system, operating temperature sensor, optical components such as narrow band-pass filter and/or lens and/or different kind of optical window, optical connection unit and fiber pig-tail or fiber cable. Cooling system options include thermoelectric cooler, long-holding time dewar filled with liquid nitrogen, Joule-Thomson micro-liquidizer and Stirling-cycle cooler. Registered infrared radiation is delivered to sensitive area of detector through either Polycrystalline InfraRed (PIR-) Fiber (4 - 18 μm) or Chalcogenide IR-glass (CIR-) Fiber (2 - 6 μm). Unique feature intrinsic to Hg1-xCdxTe (MCT) alloys to form continuous series of alloy compositions "x" with proportionally changed energy gap Eg(x,T) allows to tune spectral responsivity of detector sensitive element with ordered spectral range and hence to use every time the highest sensitive detector.

  16. Influence of modifier oxide on emission features of Dy3+ ion in Pb3O4 ‒ZnO‒P2O5 glasses

    NASA Astrophysics Data System (ADS)

    Ravi kumar, Valluri; Giridhar, G.; Veeraiah, N.

    2016-10-01

    Glasses of the composition Pb2O3‒ZnO‒P2O5: Dy3+ mixed with three different modifier oxides viz., MgO, CaO and SrO are prepared. The influence of modifier oxide on the luminescence characteristics of Dy3+ ions has been investigated. Using the intensities of various absorption bands of Dy3+ ions, the Judd-Ofelt parameters Ω2, Ω4 and Ω6 have been evaluated. Together with the J‒O parameters and the luminescence spectra, various radiative properties like transition probability A, branching ratio βr, the radiative life time τr, and the emission cross-section σE for various emission levels of Dy3+ ions have been evaluated and reported. The values of these parameters were found to be influenced by modifier oxides. Among the three modifier oxides mixed glasses, the glasses mixed with CaO mixed glasses exhibited the highest luminescence efficiency. The results have been analyzed in the light of structural modifications taking place in the glass network with the help of IR spectral studies.

  17. Enhancement mechanism of field electron emission properties in hybrid carbon nanotubes with tree- and wing-like features

    SciTech Connect

    Yang, G.M.; Yang, C.C.; Xu, Q.; Zheng, W.T.; Li, S.

    2009-12-15

    In this work, the tree-like carbon nanotubes (CNTs) with branches of different diameters and the wing-like CNTs with graphitic-sheets of different densities were synthesized by using plasma enhanced chemical vapor deposition. The nanostructures of the as-prepared hybrid carbon materials were characterized by scanning electron microscopy and transmission electron microscopy. The structural dependence of field electron emission (FEE) property was also investigated. It is found that both of the tree- and wing-like CNTs exhibit a lower turn-on field and higher emission current density than the pristine CNTs, which can be ascribed to the effects of branch size, crystal orientation, and graphitic-sheet density. - Graphical abstract: Tree-like carbon nanotubes (CNTs) with branches and the wing-like CNTs with graphitic-sheets were synthesized by using plasma enhanced chemical vapor deposition. The structural dependence of field electron emission property was also investigated.

  18. Characterization of Vertical and Horizontal Wave Features in Dayglow Emissions as Observed from a Low-latitude Station, Hyderabad, INDIA.

    NASA Astrophysics Data System (ADS)

    Islam Laskar, Fazlul; Pallamraju, Duggirala; Chakrabarti, Supriya; Raghavarao, Ravipati; Vijaya Lakshmi, Thatiparthi; Anji Reddy, M.

    2012-07-01

    Due to the unique geomagnetic field configuration, equatorial upper atmosphere of the earth is affected by various electro-dynamical processes, such as, equatorial electrojet (EEJ), equatorial ionization anomaly (EIA), equatorial spread-F (ESF), equatorial temperature and wind anomaly (ETWA). Each of these processes leave their imprint on both the neutral and ionised components of the upper atmosphere. The plasma dynamics can be investigated by radio probing methods. Investigations on the neutral dynamics, however, are possible mainly through the optical measurements. As these phenomena spread over a large spatial extent, it is extremely important to measure their variability over a large field-of-view. Here, we present the results of the wave characteristics observed over a low latitude location, Hyderabad (Geographic: 17.5° N, 78.5° E; Geomagnetic: 8.6° N, 151.8° E), which were obtained using a high spectral-resolution multi-wavelength echelle-grating spectrograph. This instrument obtains oxygen dayglow emissions at 557.7 nm, 630.0 nm, and 777.4 nm wavelengths over a large field-of-view ( of about 140 degrees) that originate from peak altitudes of around 130 km, 230 km, and 300 km, respectively. Initial results from a total of 52 days of data reveal that the dominant wave periodicities in the intensities of these emissions are different for different emission heights. Significant latitudinal dependency is seen in case of 557.7 nm and 630.0 nm. The latitudinal behavior of the emissions show the influence of both the neutral dynamics and electrodynamics of the equatorial origin. The emission variabilities are compared with the empirical and physics based models to discern the dynamical component in them in order to understand the nature of the vertical coupling of atmospheric regions. These results will be presented in light of the electrodynamic effects on them.

  19. Temperature profile retrieval in axisymmetric combustion plumes using multilayer perceptron modeling and spectral feature selection in the infrared CO2 emission band.

    PubMed

    García-Cuesta, Esteban; de Castro, Antonio J; Galván, Inés M; López, Fernando

    2014-01-01

    In this work, a methodology based on the combined use of a multilayer perceptron model fed using selected spectral information is presented to invert the radiative transfer equation (RTE) and to recover the spatial temperature profile inside an axisymmetric flame. The spectral information is provided by the measurement of the infrared CO2 emission band in the 3-5 μm spectral region. A guided spectral feature selection was carried out using a joint criterion of principal component analysis and a priori physical knowledge of the radiative problem. After applying this guided feature selection, a subset of 17 wavenumbers was selected. The proposed methodology was applied over synthetic scenarios. Also, an experimental validation was carried out by measuring the spectral emission of the exhaust hot gas plume in a microjet engine with a Fourier transform-based spectroradiometer. Temperatures retrieved using the proposed methodology were compared with classical thermocouple measurements, showing a good agreement between them. Results obtained using the proposed methodology are very promising and can encourage the use of sensor systems based on the spectral measurement of the CO2 emission band in the 3-5 μm spectral window to monitor combustion processes in a nonintrusive way.

  20. Transmission of IR light by light guides made of silver halide solid solutions

    NASA Astrophysics Data System (ADS)

    Shmygalev, A. S.; Zhilkin, B. P.; Korsakov, A. S.; Nizovtsev, M. I.; Sterlyagov, A. N.; Terekhov, V. I.

    2016-09-01

    The possibility of transferring IR emission by light guides made of silver halide solid solutions has been experimentally studied. The energy loss in transmission of the heat radiation through a light guide in various wavelength ranges of IR light was determined. The possibility of using IR light guides for transport of thermal energy and temperature measurements by IR thermography was considered.

  1. Hydrogenated polycyclic aromatic hydrocarbons and the 2940 and 2850 wavenumber (3.40 and 3.51 micron) infrared emission features.

    PubMed

    Bernstein, M P; Sandford, S A; Allamandola, L J

    1996-12-01

    The 3150-2700 cm-1 (3.17-3.70 microns) range of the spectra of a number of Ar-matrix-isolated PAHs containing excess H atoms (Hn-PAHs) are presented. This region covers features produced by aromatic and aliphatic C-H stretching vibrations as well as overtone and combination bands involving lower lying fundamentals. The aliphatic C-H stretches in molecules of this type having low to modest excess H coverage provide excellent fits to a number of the weak emission features superposed on the plateau between 3080 and 2700 cm-1 (3.25 and 3.7 microns) in the spectra of many planetary nebulae, reflection nebulae, and H II regions. Higher H coverage is implied for a few objects. We compare these results in context with the other suggested identifications of the emission features in the 2950-2700 cm-1 (3.39-3.70 microns) region and briefly discuss their astrophysical implications. PMID:11541245

  2. New features in Saturn's atmosphere revealed by high-resolution thermal infrared images

    NASA Technical Reports Server (NTRS)

    Gezari, D. Y.; Mumma, M. J.; Espenak, F.; Deming, D.; Bjoraker, G.; Woods, L.; Folz, W.

    1989-01-01

    Observations of the stratospheric IR emission structure on Saturn are presented. The high-spatial-resolution global images show a variety of new features, including a narrow equatorial belt of enhanced emission at 7.8 micron, a prominent symmetrical north polar hotspot at all three wavelengths, and a midlatitude structure which is asymmetrically brightened at the east limb. The results confirm the polar brightening and reversal in position predicted by recent models for seasonal thermal variations of Saturn's stratosphere.

  3. Characterization of the Etna volcanic emissions through an active biomonitoring technique (moss-bags): part 2--morphological and mineralogical features.

    PubMed

    Calabrese, S; D'Alessandro, W

    2015-01-01

    Volcanic emissions were studied at Mount Etna (Italy) by using moss-bags technique. Mosses were exposed around the volcano at different distances from the active vents to evaluate the impact of volcanic emissions in the atmosphere. Morphology and mineralogy of volcanic particulate intercepted by mosses were investigated using scanning electron microscopy (SEM) equipped with energy dispersive spectrometer (EDS). Particles emitted during passive degassing activity from the two active vents, Bocca Nuova and North East Crater (BNC and NEC), were identified as silicates, sulfates and halide compounds. In addition to volcanic particles, we found evidences also of geogenic, anthropogenic and marine spray input. The study has shown the robustness of this active biomonitoring technique to collect particles, very useful in active volcanic areas characterized by continuous degassing and often not easily accessible to apply conventional sampling techniques.

  4. Characterization of the Etna volcanic emissions through an active biomonitoring technique (moss-bags): part 2--morphological and mineralogical features.

    PubMed

    Calabrese, S; D'Alessandro, W

    2015-01-01

    Volcanic emissions were studied at Mount Etna (Italy) by using moss-bags technique. Mosses were exposed around the volcano at different distances from the active vents to evaluate the impact of volcanic emissions in the atmosphere. Morphology and mineralogy of volcanic particulate intercepted by mosses were investigated using scanning electron microscopy (SEM) equipped with energy dispersive spectrometer (EDS). Particles emitted during passive degassing activity from the two active vents, Bocca Nuova and North East Crater (BNC and NEC), were identified as silicates, sulfates and halide compounds. In addition to volcanic particles, we found evidences also of geogenic, anthropogenic and marine spray input. The study has shown the robustness of this active biomonitoring technique to collect particles, very useful in active volcanic areas characterized by continuous degassing and often not easily accessible to apply conventional sampling techniques. PMID:25311770

  5. Nonlinear reflection from the surface of neutron stars and features of radio emission from the pulsar in the Crab nebula

    NASA Astrophysics Data System (ADS)

    Kontorovich, V. M.

    2016-08-01

    There are no explanations for the high-frequency component of the emission from the pulsar in the Crab nebula, but it may be a manifestation of instability in nonlinear reflection from the star's surface. Radiation from relativistic positrons flying from the magnetosphere to the star and accelerated by the electric field of the polar gap is reflected. The instability involves stimulated scattering on surface waves.

  6. The UV to Near-IR Optical Properties of PAHs: A Semi-Empirical Model

    NASA Technical Reports Server (NTRS)

    Mattioda, A. L.; Allamandola, L. J.; Hudgins, D. M.

    2005-01-01

    Interstellar Polycyclic Aromatic Hydrocarbon (PAH) infrared emission features represent an important and unique diagnostic tool of the chemical and physical conditions throughout the universe. However, one challenge facing the widely accepted PAH emission model has been the detection of infrared features in regions of low UV flux. Utilizing recently published laboratory Near Infrared VIR) PAH ion absorption data measured in our laboratory, we build upon previous models for PAH ion absorption in the UV-Vis to extrapolate a new model which incorporates PAH ion absorption in the NIR. This model provides a basis for comparing the relative energy absorption of PAH ions in the UV-Vis and NIR regions for a wide variety of stellar types. This model demonstrates that the radiation from late-type stars can pump the mid-IR PAH features.

  7. Infrared emission features: probing the interstellar PAH population and circumstellar environment of Herbig Ae/Be stars

    NASA Astrophysics Data System (ADS)

    Boersma, Christiaan

    2009-12-01

    AKs zijn alom vertegenwoordigd en bieden een uitstekend middel om de veelheid aan objecten verspreid over het heelal te bestuderen. Met name in gebieden waar zich sterren en planeten vormen, helpen ze bij het ontwarren van de grootschalige structuur. PAKs staat voor polycyclische aromatische koolwaterstoffen en ze vormen een familie van grote kippengaasvormige moleculen opgebouwd uit koolstof en waterstof. Op aarde worden ze onderander aangetroffen in de verbrandingsproducten van fossiele brandstoffen. PAKs vormen het overgangsgebied van stofdeeltjes ter grote van een micron naar moleculair "gas". PAKs zijn uniek op twee manieren. Allereerst, PAKs fluoresceren na de absorptie van een enkel ultraviolet foton, waardoor ze te zien zijn in zeer koude gebieden, ver weg van de aanstralende bron. In de tweede plaats, gegeven de complexiteit van deze moleculen, kunnen ze een belangrijke rol hebben gespeeld in het ontstaan van leven. Met behulp van topklasse ruimte- en grond gestationeerde observatoria, zoals bijvoorbeeld Spitzer en de 10-meter klasse telescopen in Chili, is de PAK-emissie afkomstig van middelzware, zich vormende, sterren onderzocht. Door gebruik van zowel beeldvorming als spectroscopie, zijn morfologische en evolutionaire aspecten van de PAK-emissie vastgesteld. De NASA Ames PAK IR Spectroscopische Database is een verzameling van meer dan 600 berekend en ongeveer 200 experimenteel bepaalde spectra. Deze unieke database gaat eind 2009 publiek. Gebruikmakend van deze database is een systematische zoektocht gedaan naar kandidaten die verantwoordelijk kunnen worden gehouden voor de emissie in twee, tot op heden, niet goed bestudeerde regio's van het PAKs-spectra.

  8. Gale Crater in IR Color

    NASA Technical Reports Server (NTRS)

    2004-01-01

    [figure removed for brevity, see original site]

    Released August 4, 2004 This image shows two representations of the same infra-red image of Gale Crater. On the left is a grayscale image showing surface temperature, and on the right is a false-color composite made from 3 individual THEMIS bands. The false-color image is colorized using a technique called decorrelation stretch (DCS), which emphasizes the spectral differences between the bands to highlight compositional variations.

    In the bottom of the crater, surrounding the central mound, there are extensive basaltic sand deposits. The basaltic sand spectral signature combined with the warm surface (due to the low albedo of basaltic sand) produces a very strong pink/magenta color. This color signature contrasts with the green/yellow color of soil and dust in the top of the image, and the cyan color due to the presence of water ice clouds at the bottom of the image. This migrating sand may be producing the erosional features seen on the central mound.

    Image information: IR instrument. Latitude -4.4, Longitude 137.4 East (222.6 West). 100 meter/pixel resolution.

    Note: this THEMIS visual image has not been radiometrically nor geometrically calibrated for this preliminary release. An empirical correction has been performed to remove instrumental effects. A linear shift has been applied in the cross-track and down-track direction to approximate spacecraft and planetary motion. Fully calibrated and geometrically projected images will be released through the Planetary Data System in accordance with Project policies at a later time.

    NASA's Jet Propulsion Laboratory manages the 2001 Mars Odyssey mission for NASA's Office of Space Science, Washington, D.C. The Thermal Emission Imaging System (THEMIS) was developed by Arizona State University, Tempe, in collaboration with Raytheon Santa Barbara Remote Sensing. The THEMIS investigation is led by Dr. Philip Christensen at Arizona State University

  9. A FEATURE MOVIE OF SiO EMISSION 20-100 AU FROM THE MASSIVE YOUNG STELLAR OBJECT ORION SOURCE I

    SciTech Connect

    Matthews, L. D.; Greenhill, L. J.; Goddi, C.; Humphreys, E. M. L.; Chandler, C. J.; Kunz, M. W.

    2010-01-01

    We present multi-epoch Very Long Baseline Array imaging of the {sup 28}SiO v = 1 and v = 2, J = 1-0 maser emission toward the massive young stellar object (YSO) Orion Source I. Both SiO transitions were observed simultaneously with an angular resolution of approx0.5 mas (approx0.2 AU for d = 414 pc) and a spectral resolution of approx0.2 km s{sup -1}. Here we explore the global properties and kinematics of the emission through two 19-epoch animated movies spanning 21 months (from 2001 March 19 to 2002 December 10). These movies provide the most detailed view to date of the dynamics and temporal evolution of molecular material within approx20-100 AU of a massive (approx>8 M{sub sun}) YSO. As in previous studies, we find that the bulk of the SiO masers surrounding Source I lie in an X-shaped locus; the emission in the south and east arms is predominantly blueshifted, and emission in the north and west is predominantly redshifted. In addition, bridges of intermediate-velocity emission are observed connecting the red and blue sides of the emission distribution. We have measured proper motions of over 1000 individual maser features and found that these motions are characterized by a combination of radially outward migrations along the four main maser-emitting arms and motions tangent to the intermediate-velocity bridges. We interpret the SiO masers as arising from a wide-angle bipolar wind emanating from a rotating, edge-on disk. The detection of maser features along extended, curved filaments suggests that magnetic fields may play a role in launching and/or shaping the wind. Our observations appear to support a picture in which stars with masses as high as at least 8 M{sub sun} form via disk-mediated accretion. However, we cannot yet rule out that the Source I disk may have been formed or altered following a recent close encounter.

  10. Infrared absorption and emission characteristics of interstellar PAHs

    NASA Technical Reports Server (NTRS)

    Barker, J. R.; Allamandola, Louis J.; Tielens, Alexander G. G. M.; Barker, J. R.; Barker, J. R.

    1986-01-01

    The mid-infrared interstellar emission spectrum with features at 3.28, 6.2, 7.7, 8.7 and 11.3 microns is discussed in terms of the Polycyclic Aromatic Hydrocarbon (PAH) hypothesis, which is based on the suggestive, but inconclusive comparison between the interstellar emission spectrum with the infrared absorption and Raman spectra of a few PAHs. The fundamental vibrations of PAHs and PAH-like species which determine the IR and Raman properties are discussed. Interstellar IR band emission is due to relaxation from highly vibrationally excited PAHs excited by ultraviolet photons. The excitation/emission process is described and the IR fluorescence from one PAH, chrysene, is traced. Generally, there is sufficient energy to populate several vibrational levels in each mode. Molecular vibrational potentials are anharmonic and emission from these higher levels will fall at lower frequencies and produce weak features to the red of the stronger fundamentals. This process is also described and can account for some spectroscopic details of the interstellar emission spectra previously unexplained. Analysis of the interstellar spectrum shows that PAHs contain between 20 and 30 carbon atoms are responsible for the emission.

  11. IOT Overview: IR Instruments

    NASA Astrophysics Data System (ADS)

    Mason, E.

    In this instrument review chapter the calibration plans of ESO IR instruments are presented and briefly reviewed focusing, in particular, on the case of ISAAC, which has been the first IR instrument at VLT and whose calibration plan served as prototype for the coming instruments.

  12. Stimulated Raman scattering as an explanation for the extreme high-velocity features of water maser emission

    NASA Astrophysics Data System (ADS)

    Deguchi, Shuji

    1994-01-01

    Extreme high-velocity features in the water maser spectra with velocity shifts of about +/- 900 km/s have recently been detected in the extragalactic water maser source, NGC 4258. We explain these extreme high-velocity features of water masers by stimulated Raman scattering in the plasma of the electron density of about 106-107/cu cm. For the Raman masers to occur, the brightness temperature of the original masers must be greater than about 1016-1019 K (depending on the maser beam solid angles, etc.), and the amplification path length of the maser must be about 3 x 1014 cm. We show that the frequency-downshifted (Stokes) photons are produced by the backward scattering and that upshifted (anti-Stokes) photons are created by interacting intersecting masers in the plasma. The intensity of the upshifted component is slightly lower than the intensity of the downshifted component. Time variations of upshifted and downshifted features must be independent. A crucial test for the Raman maser model is proposed.

  13. The mid-IR and near-IR interferometry of AGNs: key results and their implications

    NASA Astrophysics Data System (ADS)

    Kishimoto, M.

    2015-09-01

    Infrared interferometry has been very productive in directly probing the structure of AGNs at sub-pc scales. With tens of objects already probed in the mid-IR and near-IR, I will summarize the key results and im- plications from this direct exploration. The Keck interferometry in the near-IR and VLTI in the mid-IR shaped the luminosity dependence of the torus size and structure, while the latter also revealed an equatorial structure at several Rsub (dust sublimation radius), and a polar-elongated region at a few tens of Rsub. Notably, this polar component seems to dominate the compact mid-IR flux. This component can persuasively be attributed to a polar outflow. However, interferometry, through emissivity estimations, also indicates that it is not a UV-optically-thin cloud but participating in the obscuration of the nucleus. I will discuss how to accommodate all these facts to build a consistent picture.

  14. Mid-IR Spectra Herbig Ae/Be Stars

    NASA Technical Reports Server (NTRS)

    Wooden, Diane; Witteborn, Fred C. (Technical Monitor)

    1997-01-01

    Herbig Ae/Be stars are intermediate mass pre-main sequence stars, the higher mass analogues to the T Tauri stars. Because of their higher mass, they are expected form more rapidly than the T Tauri stars. Whether the Herbig Ae/Be stars accrete only from collapsing infalling envelopes or whether accrete through geometrically flattened viscous accretion disks is of current debate. When the Herbig Ae/Be stars reach the main sequence they form a class called Vega-like stars which are known from their IR excesses to have debris disks, such as the famous beta Pictoris. The evolutionary scenario between the pre-main sequence Herbig Ae/Be stars and the main sequence Vega-like stars is not yet revealed and it bears on the possibility of the presence of Habitable Zone planets around the A stars. Photometric studies of Herbig Ae/Be stars have revealed that most are variable in the optical, and a subset of stars show non-periodic drops of about 2 magnitudes. These drops in visible light are accompanied by changes in their colors: at first the starlight becomes reddened, and then it becomes bluer, the polarization goes from less than 0.1 % to roughly 1% during these minima. The theory postulated by V. Grinnin is that large cometary bodies on highly eccentric orbits occult the star on their way to being sublimed, for systems that are viewed edge-on. This theory is one of several controversial theories about the nature of Herbig Ae/Be stars. A 5 year mid-IR spectrophotometric monitoring campaign was begun by Wooden and Butner in 1992 to look for correlations between the variations in visible photometry and mid-IR dust emission features. Generally the approximately 20 stars that have been observed by the NASA Ames HIFOGS spectrometer have been steady at 10 microns. There are a handful, however, that have shown variable mid-IR spectra, with 2 showing variations in both the continuum and features anti-correlated with visual photometry, and 3 showing variations in the emission

  15. IR laser chemistry

    NASA Astrophysics Data System (ADS)

    Quack, Martin

    1995-01-01

    Recent progress in IR laser chemistry is reviewed with stress on the conceptual background and experimental advances from our research group. In particular we discuss various experimental schemes in laser chemistry as related to thermal reactions and ordinary photochemistry, and new results in time and frequency resolved kinetic IR spectroscopy at the limit defined by the uncertainty relation. The recent detection of hyperfine effects in IR laser chemistry is reviewed as well as nonlinear intensity dependence over many orders of magnitude including observations of nonlinear intensity fall-off and IR laser ionization of molecules. An outlook is presented on different time scales for intramolecular processes and the resulting future possibilities of IR laser chemical reaction control.

  16. IR Hot Wave

    SciTech Connect

    Graham, T. B.

    2010-04-01

    The IR Hot Wave{trademark} furnace is a breakthrough heat treatment system for manufacturing metal components. Near-infrared (IR) radiant energy combines with IR convective heating for heat treating. Heat treatment is an essential process in the manufacture of most components. The controlled heating and cooling of a metal or metal alloy alters its physical, mechanical, and sometimes chemical properties without changing the object's shape. The IR Hot Wave{trademark} furnace offers the simplest, quickest, most efficient, and cost-effective heat treatment option for metals and metal alloys. Compared with other heat treatment alternatives, the IR Hot Wave{trademark} system: (1) is 3 to 15 times faster; (2) is 2 to 3 times more energy efficient; (3) is 20% to 50% more cost-effective; (4) has a {+-}1 C thermal profile compared to a {+-}10 C thermal profile for conventional gas furnaces; and (5) has a 25% to 50% smaller footprint.

  17. Novel lanthanide pH fluorescent probes based on multiple emissions and its visible-light-sensitized feature.

    PubMed

    Lin, Jintai; Zheng, Yuhui; Wang, Qianming; Zeng, Zhi; Zhang, Cheng Cheng

    2014-08-11

    A new type of Eu(III) ofloxacin complex as the fluorescent pH indicator has been presented. Compared to pure ligand, the complex offers more distinguished color changes (green-red-blue) derived from both lanthanide line emissions and the secondary ionization steps of ofloxacin. During the concentration dependence experiments, the photoluminescence studies on the complex showed that the excitation of this pH probe can occur at a very long wavelength which extends to visible range (Ex=427 nm). Furthermore, the functional complex was successfully incorporated into soft networks and two novel luminescent hydrogels (rod and film) were fabricated. The soft materials also exhibited specific responses towards the pH variation. Finally, the onion cell-stain experiments were carried out to further confirm the validity of pH dependence and the results support the idea that the material will be suitable for monitoring biological samples in the future. PMID:25066718

  18. Novel lanthanide pH fluorescent probes based on multiple emissions and its visible-light-sensitized feature.

    PubMed

    Lin, Jintai; Zheng, Yuhui; Wang, Qianming; Zeng, Zhi; Zhang, Cheng Cheng

    2014-08-11

    A new type of Eu(III) ofloxacin complex as the fluorescent pH indicator has been presented. Compared to pure ligand, the complex offers more distinguished color changes (green-red-blue) derived from both lanthanide line emissions and the secondary ionization steps of ofloxacin. During the concentration dependence experiments, the photoluminescence studies on the complex showed that the excitation of this pH probe can occur at a very long wavelength which extends to visible range (Ex=427 nm). Furthermore, the functional complex was successfully incorporated into soft networks and two novel luminescent hydrogels (rod and film) were fabricated. The soft materials also exhibited specific responses towards the pH variation. Finally, the onion cell-stain experiments were carried out to further confirm the validity of pH dependence and the results support the idea that the material will be suitable for monitoring biological samples in the future.

  19. Coma morphology and dust-emission pattern of periodic Comet Halley. II - Nucleus spin vector and modeling of major dust features in 1910

    NASA Astrophysics Data System (ADS)

    Sekanina, Z.; Larson, S. M.

    1984-09-01

    The continuous ejection of dust from discrete emission sources on the rotating nucleus of the Comet Halley is modelled in order to explain the evolution of spiral jets which unwind from the nucleus condensation into envelopes or halos in the comet head. The model is applied to digitally processed images of three features of the comet taken from Mount Wilson plates during the 1910 fly-by. The model permits a determination of the motion and spin vector for each emission source, its cometocentric coordinates, and a function relating particle ejection velocity to the solar radiation pressure exerted on the ejecta. It is found that the obliquity of the comet orbit's plane to its equatorial plane is 45 deg, the axis of rotation period of 17.3 days. The derived function of particle ejection velocity to the solar radiation pressure implied no contribution from grains larger than 10 microns in radius. High dust loading of gas flows from the June 1910 emission sources is indicated. It is estimated that because of the favorable approach geometry of the Gioto spacecraft during its 1986 flyby, the likelihood of encountering dense jets of dust is small.

  20. Visualizing Infrared (IR) Spectroscopy with Computer Animation

    NASA Technical Reports Server (NTRS)

    Abrams, Charles B.; Fine, Leonard W.

    1996-01-01

    IR Tutor, an interactive, animated infrared (IR) spectroscopy tutorial has been developed for Macintosh and IBM-compatible computers. Using unique color animation, complicated vibrational modes can be introduced to beginning students. Rules governing the appearance of IR absorption bands become obvious because the vibrational modes can be visualized. Each peak in the IR spectrum is highlighted, and the animation of the corresponding normal mode can be shown. Students can study each spectrum stepwise, or click on any individual peak to see its assignment. Important regions of each spectrum can be expanded and spectra can be overlaid for comparison. An introduction to the theory of IR spectroscopy is included, making the program a complete instructional package. Our own success in using this software for teaching and research in both academic and industrial environments will be described. IR Tutor consists of three sections: (1) The 'Introduction' is a review of basic principles of spectroscopy. (2) 'Theory' begins with the classical model of a simple diatomic molecule and is expanded to include larger molecules by introducing normal modes and group frequencies. (3) 'Interpretation' is the heart of the tutorial. Thirteen IR spectra are analyzed in detail, covering the most important functional groups. This section features color animation of each normal mode, full interactivity, overlay of related spectra, and expansion of important regions. This section can also be used as a reference.

  1. One-Dimensional Fluorescent Silicon Nanorods Featuring Ultrahigh Photostability, Favorable Biocompatibility, and Excitation Wavelength-Dependent Emission Spectra.

    PubMed

    Song, Bin; Zhong, Yiling; Wu, Sicong; Chu, Binbin; Su, Yuanyuan; He, Yao

    2016-04-13

    We herein report a kind of one-dimensional biocompatible fluorescent silicon nanorods (SiNRs) with tunable lengths ranging ∼100-250 nm, which can be facilely prepared through one-pot microwave synthesis. In addition to the strong fluorescence (quantum yield value: ∼15%) and negligible toxicity, the resultant SiNRs exhibit excitation wavelength-dependent photoluminescence whose maximum emission wavelength ranges from ∼450 to ∼600 nm under serial excitation wavelengths from 390 to 560 nm, providing feasibility for multicolor biological imaging. More significantly, the SiNRs are ultrahighly photostable, preserving strong and nearly unchanged fluorescence under 400 min high-power UV irradiation, which is in sharp contrast to severe fluorescence quenching of organic dyes (e.g., FITC) or II-VI quantum dots (QDs) (e.g., CdTe QDs and CdSe/ZnS QDs) within 15 or 160 min UV treatment under the same experiment conditions, respectively. Taking advantage of these attractive merits, we further exploit the SiNRs as a novel type of color converters for the construction of white light-emitting diodes (LED), which is the first proof-of-concept demonstration of LED device fabricated using the one-dimensional fluorescent silicon nanostructures. PMID:27010956

  2. Features of Excitation of Stimulated Electromagnetic Emission of the Ionosphere Modified by an Oblique High-Power Radio Wave

    NASA Astrophysics Data System (ADS)

    Frolov, V. L.; Nedzvetsky, D. I.; Komrakov, G. P.

    2005-09-01

    We present the results of measuring the characteristics of the stimulated electromagnetic emission (SEE) of the ionosphere with variation in the zenith angle of a pump beam of high-power O-mode radio waves in the geomagnetic-meridian plane. The experiments were performed at the midlatitude heating facility “Sura.” It is established that the maximum intensity of the DM and BC components of SEE is observed for southward inclination angles θ ≈ 8°--12° of the antenna beam, for which the most intense generation of artificial small-scale ionospheric irregularities also takes place. Based on the results of measurements near the fourth and fifth harmonics of the electron gyrofrequency, it is found that the first component of the BUM (BUM-1) is generated only when the pump wave reaches the plasma-resonance region. This allows one to assume that, unlike the second component of the BUM (BUM-2), whose generation is determined by development of instability in the upper-hybrid resonance region, the BUM-1 generation mechanism should be related to processes of interaction between a high-power radio wave and the plasma in the plasma-resonance region.

  3. Naval target classification by fusion of IR and EO sensors

    NASA Astrophysics Data System (ADS)

    Giompapa, S.; Croci, R.; Di Stefano, R.; Farina, A.; Gini, F.; Graziano, A.; Lapierre, F.

    2007-10-01

    This paper describes the classification function of naval targets performed by an infrared camera (IR) and an electro-optical camera (EO) that operate in a more complex multisensor system for the surveillance of a coastal region. The following naval targets are considered: high speed dinghy, motor boat, fishing boat, oil tanker. Target classification is automatically performed by exploiting the knowledge of the sensor confusion matrix (CM). The CM is analytically computed as a function of the sensor noise features, the sensor resolution, and the dimension of the involved image database. For both the sensors, a database of images is generated exploiting a three-dimensional (3D) Computer Aided Design (CAD) of the target, for the four types of ship mentioned above. For the EO camera, the image generation is simply obtained by the projection of the 3D CAD on the camera focal plane. For the IR images simulation, firstly the surface temperatures are computed using an Open-source Software for Modelling and Simulation of Infrared Signatures (OSMOSIS) that efficiently integrates the dependence of the emissivity upon the surface temperature, the wavelength, and the elevation angle. The software is applicable to realistic ship geometries. Secondly, these temperatures and the environment features are used to predict realistic IR images. The local decisions on the class are made using the elements of the confusion matrix of each sensor and they are fused according to a maximum likelihood (ML) rule. The global performance of the classification process is measured in terms of the global confusion matrix of the integrated system. This analytical approach can effectively reduce the computational load of a Monte Carlo simulation, when the sensors described here are introduced in a more complex multisensor system for the maritime surveillance.

  4. Assessment of COTS IR image simulation tools for ATR development

    NASA Astrophysics Data System (ADS)

    Seidel, Heiko; Stahl, Christoph; Bjerkeli, Frode; Skaaren-Fystro, Paal

    2005-05-01

    Following the tendency of increased use of imaging sensors in military aircraft, future fighter pilots will need onboard artificial intelligence e.g. ATR for aiding them in image interpretation and target designation. The European Aeronautic Defence and Space Company (EADS) in Germany has developed an advanced method for automatic target recognition (ATR) which is based on adaptive neural networks. This ATR method can assist the crew of military aircraft like the Eurofighter in sensor image monitoring and thereby reduce the workload in the cockpit and increase the mission efficiency. The EADS ATR approach can be adapted for imagery of visual, infrared and SAR sensors because of the training-based classifiers of the ATR method. For the optimal adaptation of these classifiers they have to be trained with appropriate and sufficient image data. The training images must show the target objects from different aspect angles, ranges, environmental conditions, etc. Incomplete training sets lead to a degradation of classifier performance. Additionally, ground truth information i.e. scenario conditions like class type and position of targets is necessary for the optimal adaptation of the ATR method. In Summer 2003, EADS started a cooperation with Kongsberg Defence & Aerospace (KDA) from Norway. The EADS/KDA approach is to provide additional image data sets for training-based ATR through IR image simulation. The joint study aims to investigate the benefits of enhancing incomplete training sets for classifier adaptation by simulated synthetic imagery. EADS/KDA identified the requirements of a commercial-off-the-shelf IR simulation tool capable of delivering appropriate synthetic imagery for ATR development. A market study of available IR simulation tools and suppliers was performed. After that the most promising tool was benchmarked according to several criteria e.g. thermal emission model, sensor model, targets model, non-radiometric image features etc., resulting in a

  5. Spitzer Space Telescope IRS Spectral Mapping of Photoionized Columns in M16 and the Carina HII Regions

    NASA Astrophysics Data System (ADS)

    Cotera, Angela; Simpson, J. P.; Sellgren, K.; Stolovy, S. R.

    2013-01-01

    Photoevaporated columns of dust and gas - also called elephant trunks, pillars or fingers - are found in the periphery of many H II regions. They have been observed within the Galaxy, the SMC and the LMC. These features are thought to be sites of current star formation, but the question remains whether the columns persist because stars formed in the denser regions prior to interactions with the UV radiation and stellar winds of nearby massive stars, or because of core collapse resulting from these interactions. We have obtained Spitzer IRS spectral maps of three columns within M 16 and three columns within the Carina nebula, to test our understanding of the impact on these transitory features of differing stellar populations and initial conditions. We use the wealth of molecular, atomic and PAH emission lines located within the spectral range of the high resolution IRS modes (9.9-37.2 micron) to determine the excitation state, dust and gas temperatures, and probe the shock characteristics within the columns as a function of location. Using the IRS spectral mapping mode, in conjunction with the CUBISM tool and the CLOUDY H II region model code, we have constructed detailed maps of the accessible emission lines and derived parameters for each column. Mapping the distribution of the physical states of the dust and gas in these columns is enhancing our understanding of the competing processes within these dynamic objects. The data presented here represent the only IRS spectral maps of photoionized pillars.

  6. IRS Scan-mapping of the Wasp-waist Nebula (IRAS 16253-2429). I. Derivation of Shock Conditions from H2 Emission and Discovery of 11.3 μm PAH Absorption

    NASA Astrophysics Data System (ADS)

    Barsony, Mary; Wolf-Chase, Grace A.; Ciardi, David R.; O'Linger, JoAnn

    2010-09-01

    The outflow driven by the Class 0 protostar, IRAS 16253-2429, is associated with bipolar cavities visible in scattered mid-infrared light, which we refer to as the Wasp-Waist Nebula. InfraRed Spectometer (IRS) scan mapping with the Spitzer Space Telescope of a ~1' × 2' area centered on the protostar was carried out. The outflow is imaged in six pure rotational (0-0 S(2) through 0-0 S(7)) H2 lines, revealing a distinct, S-shaped morphology in all maps. A source map in the 11.3 μm polycyclic aromatic hydrocarbon (PAH) feature is presented in which the protostellar envelope appears in absorption. This is the first detection of absorption in the 11.3 μm PAH feature. Spatially resolved excitation analysis of positions in the blue- and redshifted outflow lobes, with extinction-corrections determined from archival Spitzer 8 μm imaging, shows remarkably constant temperatures of ~1000 K in the shocked gas. The radiated luminosity in the observed H2 transitions is found to be 1.94 ± 0.05 × 10-5 L sun in the redshifted lobe and 1.86 ± 0.04 × 10-5 L sun in the blueshifted lobe. These values are comparable to the mechanical luminosity of the flow. By contrast, the mass of hot (T ~ 1000 K) H2 gas is 7.95 ± 0.19 × 10-7 M sun in the redshifted lobe and 5.78 ± 0.17 × 10-7 M sun in the blueshifted lobe. This is just a tiny fraction, of order 10-3, of the gas in the cold (30 K), swept-up gas mass derived from millimeter CO observations. The H2 ortho/para ratio of 3:1 found at all mapped points in this flow suggests previous passages of shocks through the gas. Comparison of the H2 data with detailed shock models of Wilgenbus et al. shows the emitting gas is passing through Jump (J-type) shocks. Pre-shock densities of 104 cm-3<= n H <= 105 cm-3 are inferred for the redshifted lobe and n H <= 103 cm-3 for the blueshifted lobe. Shock velocities are 5 km s-1 <= vs <= 10 km s-1 for the redshifted gas and vs = 10 km s-1 for the blueshifted gas. Initial transverse (to the shock

  7. IRS SCAN-MAPPING OF THE WASP-WAIST NEBULA (IRAS 16253-2429). I. DERIVATION OF SHOCK CONDITIONS FROM H{sub 2} EMISSION AND DISCOVERY OF 11.3 {mu}m PAH ABSORPTION

    SciTech Connect

    Barsony, Mary; Wolf-Chase, Grace A.; Ciardi, David R.

    2010-09-01

    The outflow driven by the Class 0 protostar, IRAS 16253-2429, is associated with bipolar cavities visible in scattered mid-infrared light, which we refer to as the Wasp-Waist Nebula. InfraRed Spectometer (IRS) scan mapping with the Spitzer Space Telescope of a {approx}1' x 2' area centered on the protostar was carried out. The outflow is imaged in six pure rotational (0-0 S(2) through 0-0 S(7)) H{sub 2} lines, revealing a distinct, S-shaped morphology in all maps. A source map in the 11.3 {mu}m polycyclic aromatic hydrocarbon (PAH) feature is presented in which the protostellar envelope appears in absorption. This is the first detection of absorption in the 11.3 {mu}m PAH feature. Spatially resolved excitation analysis of positions in the blue- and redshifted outflow lobes, with extinction-corrections determined from archival Spitzer 8 {mu}m imaging, shows remarkably constant temperatures of {approx}1000 K in the shocked gas. The radiated luminosity in the observed H{sub 2} transitions is found to be 1.94 {+-} 0.05 x 10{sup -5} L{sub sun} in the redshifted lobe and 1.86 {+-} 0.04 x 10{sup -5} L{sub sun} in the blueshifted lobe. These values are comparable to the mechanical luminosity of the flow. By contrast, the mass of hot (T {approx} 1000 K) H{sub 2} gas is 7.95 {+-} 0.19 x 10{sup -7} M{sub sun} in the redshifted lobe and 5.78 {+-} 0.17 x 10{sup -7} M{sub sun} in the blueshifted lobe. This is just a tiny fraction, of order 10{sup -3}, of the gas in the cold (30 K), swept-up gas mass derived from millimeter CO observations. The H{sub 2} ortho/para ratio of 3:1 found at all mapped points in this flow suggests previous passages of shocks through the gas. Comparison of the H{sub 2} data with detailed shock models of Wilgenbus et al. shows the emitting gas is passing through Jump (J-type) shocks. Pre-shock densities of 10{sup 4} cm{sup -3{<=}} n {sub H{<=}} 10{sup 5} cm{sup -3} are inferred for the redshifted lobe and n {sub H{<=}} 10{sup 3} cm{sup -3} for the

  8. Transition from the infalling envelope to the Keplerian disk around L1551 IRS 5

    SciTech Connect

    Chou, Ti-Lin; Takakuwa, Shigehisa; Yen, Hsi-Wei; Ohashi, Nagayoshi; Ho, Paul T. P.

    2014-11-20

    We present combined Submillimeter Array (SMA) +Atacama Submillimeter Telescope Experiment (ASTE) images of the Class I protobinary L1551 IRS 5 in the CS (J = 7-6) line, the submillimeter images of L1551 IRS 5 with the most complete spatial sampling ever achieved (0.''9-36''). The SMA image of L1551 IRS 5 in the 343 GHz dust-continuum emission is also presented, which shows an elongated feature along the northwest to southeast direction (∼160 AU × 80 AU), perpendicular to the associated radio jets. The combined SMA+ASTE images show that the high-velocity (≳1.5 km s{sup –1}) CS emission traces the structure of the dust component and shows a velocity gradient along the major axis, which is reproduced by a geometrically thin Keplerian-disk model with a central stellar mass of ∼0.5 M {sub ☉}. The low-velocity (≲1.3 km s{sup –1}) CS emission shows an extended (∼1000 AU) feature that exhibits slight south (blueshifted) to north (redshifted) emission offsets, which is modeled with a rotating and infalling envelope with a conserved angular momentum. The rotational motion of the envelope connects smoothly to the inner Keplerian rotation at a radius of ∼64 AU. The infalling velocity of the envelope is ∼three times lower than the free-fall velocity toward the central stellar mass of 0.5 M {sub ☉}. These results demonstrate transition from the infalling envelope to the Keplerian disk, consistent with the latest theoretical studies of disk formation. We suggest that sizable (r ∼ 50-200 AU) Keplerian disks are already formed when the protostars are still deeply embedded in the envelopes.

  9. Synthesis, spectral (FT-IR, UV-visible, NMR) features, biological activity prediction and theoretical studies of 4-Amino-3-(4-hydroxybenzyl)-1H-1,2,4-triazole-5(4H)-thione and its tautomer

    NASA Astrophysics Data System (ADS)

    Srivastava, Ambrish Kumar; Kumar, Abhishek; Misra, Neeraj; Manjula, P. S.; Sarojini, B. K.; Narayana, B.

    2016-03-01

    Triazole compounds constitute an important class of organic chemistry due to their various biological and corrosion inhibition activities. The synthesis scheme of a new triazole compound namely, 4-Amino-3-(4-hydroxybenzyl)-1H-1,2,4-triazole-5(4H)-thione (4AHT) has been theoretically analyzed. Our density functional theory (DFT) based calculations show that the synthesis of 4AHT is energetically feasible at the room temperature as the reaction is exothermic, spontaneous as well as favored in forward direction. The calculated bond-lengths are found to be in good agreement with corresponding crystallographic values. We have considered two possible tautomers of 4AHT viz. thione and thiol forms. The FT-IR (KBr disc), UV-visible (ethanol) and 1H-NMR (DMSO) spectra of 4AHT have been recorded. The vibrational modes have been assigned on the basis of their potential energy distributions and scaled wavenumbers agree well with the FT-IR wavenumbers. Time dependent DFT calculations are performed to analyze the electronic transitions for various excited states which reproduce the experimental peak observed in UV-visible spectrum. Using gauge independent atomic orbital method 1H-NMR chemical shifts have been calculated and correlated with the experimental chemical shifts with the linear correlation coefficient of 0.9453. Our spectral analyses reveal the dominance of thione over thiol form of 4AHT. The chemical reactivity of 4AHT has been discussed by molecular electrostatic potential surface as well as various electronic parameters. The biological activities of 4AHT have also been explored theoretically and it has been found that the title molecule can act as a potential inhibitor of cyclin-dependent kinase 5 enzyme. These findings may guide the synthesis and design of new triazole compounds with interesting biological activity.

  10. Arsia Mons Collapse Pits in IR

    NASA Technical Reports Server (NTRS)

    2004-01-01

    [figure removed for brevity, see original site]

    We will be looking at collapse pits for the next two weeks. Collapse pits on Mars are formed in several ways. In volcanic areas, channelized lava flows can form roofs which insulate the flowing lava. These features are termed lava tubes on Earth and are common features in basaltic flows. After the lava has drained, parts of the roof of the tube will collapse under its own weight. These collapse pits will only be as deep as the bottom of the original lava tube. Another type of collapse feature associated with volcanic areas arises when very large eruptions completely evacuate the magma chamber beneath the volcano. The weight of the volcano will cause the entire edifice to subside into the void space below it. Structural features including fractures and graben will form during the subsidence. Many times collapse pits will form within the graben. In addition to volcanic collapse pits, Mars has many collapse pits formed when volatiles (such as subsurface ice) are released from the surface layers. As the volatiles leave, the weight of the surrounding rock causes collapse pits to form.

    These collapse pits are found on the flank of Arsia Mons and are related to lava tube collapse.

    Image information: IR instrument. Latitude -8.8, Longitude 240.4 East (119.6 West). 100 meter/pixel resolution.

    Note: this THEMIS visual image has not been radiometrically nor geometrically calibrated for this preliminary release. An empirical correction has been performed to remove instrumental effects. A linear shift has been applied in the cross-track and down-track direction to approximate spacecraft and planetary motion. Fully calibrated and geometrically projected images will be released through the Planetary Data System in accordance with Project policies at a later time.

    NASA's Jet Propulsion Laboratory manages the 2001 Mars Odyssey mission for NASA's Office of Space Science, Washington, D.C. The Thermal

  11. Coprates Chasma Landslides in IR

    NASA Technical Reports Server (NTRS)

    2005-01-01

    [figure removed for brevity, see original site]

    Today's daytime IR image is of a portion of Coprates Chasma, part of Valles Marineris. As with yesterday's image, this image shows multiple large landslides.

    Image information: IR instrument. Latitude -8.2, Longitude 300.2 East (59.8 West). 100 meter/pixel resolution.

    Note: this THEMIS visual image has not been radiometrically nor geometrically calibrated for this preliminary release. An empirical correction has been performed to remove instrumental effects. A linear shift has been applied in the cross-track and down-track direction to approximate spacecraft and planetary motion. Fully calibrated and geometrically projected images will be released through the Planetary Data System in accordance with Project policies at a later time.

    NASA's Jet Propulsion Laboratory manages the 2001 Mars Odyssey mission for NASA's Office of Space Science, Washington, D.C. The Thermal Emission Imaging System (THEMIS) was developed by Arizona State University, Tempe, in collaboration with Raytheon Santa Barbara Remote Sensing. The THEMIS investigation is led by Dr. Philip Christensen at Arizona State University. Lockheed Martin Astronautics, Denver, is the prime contractor for the Odyssey project, and developed and built the orbiter. Mission operations are conducted jointly from Lockheed Martin and from JPL, a division of the California Institute of Technology in Pasadena.

  12. Xanthe Terra Landslide in IR

    NASA Technical Reports Server (NTRS)

    2005-01-01

    [figure removed for brevity, see original site]

    This is a daytime IR image of a chaos region within Xanthe Terra. As with earlier images, the landslide in this image is caused by the failure of steep slopes releasing material to form the landslide deposit.

    Image information: IR instrument. Latitude 3.1, Longitude 309.7 East (50.3 West). 100 meter/pixel resolution.

    Note: this THEMIS visual image has not been radiometrically nor geometrically calibrated for this preliminary release. An empirical correction has been performed to remove instrumental effects. A linear shift has been applied in the cross-track and down-track direction to approximate spacecraft and planetary motion. Fully calibrated and geometrically projected images will be released through the Planetary Data System in accordance with Project policies at a later time.

    NASA's Jet Propulsion Laboratory manages the 2001 Mars Odyssey mission for NASA's Office of Space Science, Washington, D.C. The Thermal Emission Imaging System (THEMIS) was developed by Arizona State University, Tempe, in collaboration with Raytheon Santa Barbara Remote Sensing. The THEMIS investigation is led by Dr. Philip Christensen at Arizona State University. Lockheed Martin Astronautics, Denver, is the prime contractor for the Odyssey project, and developed and built the orbiter. Mission operations are conducted jointly from Lockheed Martin and from JPL, a division of the California Institute of Technology in Pasadena.

  13. Photonics of a conjugated organometallic Pt-Ir polymer and its model compounds exhibiting hybrid CT excited states.

    PubMed

    Soliman, Ahmed M; Fortin, Daniel; Zysman-Colman, Eli; Harvey, Pierre D

    2012-04-13

    Trans- dichlorobis(tri-n-butylphosphine)platinum(II) reacts with bis(2- phenylpyridinato)-(5,5'-diethynyl-2,2'-bipyridine)iridium(III) hexafluorophosphate to form the luminescent conjugated polymer poly[trans-[(5,5'-ethynyl-2,2'-bipyridine)bis(2- phenylpyridinato)-iridium(III)]bis(tri-n-butylphosphine)platinum(II)] hexafluorophosphate ([Pt]-[Ir])n. Gel permeation chromatography indicates a degree of polymerization of 9 inferring the presence of an oligomer. Comparison of the absorption and emission band positions and their temperature dependence, emission quantum yields, and lifetimes with those for models containing only the [Pt] or the [Ir] units indicates hybrid excited states including features from both chromophores.

  14. Effect of Eriophrum spp. on Methane Emission and Methane Production Potential in a Melt Feature Within the Discontinuous Permafrost Region of Northern Alberta, Canada

    NASA Astrophysics Data System (ADS)

    Harrison, M. D.; Whiting, G. J.

    2003-12-01

    provide a conduit for CH4 may contribute to the increased CH4 production and emission observed in these melt features.

  15. Microcavity array IR photodetector

    SciTech Connect

    Esman, A K; Kuleshov, V K; Zykov, G L

    2009-12-31

    An original microcavity array IR photodetector is proposed and the sensitivity and response time of its pixels are calculated. A photosensitive element represents a composite silicon microcavity made of two optically coupled closed waveguides on a dielectric substrate whose resonance wave depends on its temperature. This dependence is used to detect IR radiation which heats an absorbing element and the composite microcavity thermally coupled with this element. It is shown that for a spatial resolution of 45 {mu}m, the time response is 30 ms and the sensitivity is 10{sup -3} K at the IR radiation power of {approx} 4.7 x 10{sup -8} W element{sup -1}. (photodetectors)

  16. Dust Content in Compact HII Regions (NGC 7538 -- IRS 1, IRS 2, and IRS 3)

    NASA Astrophysics Data System (ADS)

    Akabane, K.; Kuno, N.

    The luminosity of the central star in compact HII regions was estimated from the solid angle of the nearby IR sources subtended at the central star, to be 5 ˜ 10 times as intense as that of the IR sources. The luminosity gives the stellar UV photon rate, Nu(*)(s-1), under the assumption of a single star approximation. For gas of standard dust content, Nu(*) and the observed electron density, ne, provide the dust opacity of the ionizing photons, τSdn, along the optical path to the Strömgren sphere of radius rs. The ionizing photon opacity over the same optical path but with the actual dust content, τSdi, is also derived from Nu(*) and the observed emission measure, ne2(4 π/3)ri3, with ri of the radius of the ionized sphere. A relationship γNu(*)/(4 π ri2)1/2˜= 1.3 × 109 (s-1/2m-1) with γ= τSdi/ τSdn was obtained as an observational trend for the 4 compact HII regions of NGC7538(N). Fourteen selected compact HII regions from the data catalogued by VLA observations were examined for this trend, and a similar result was shown. A confined area within 1050 >= Nu (s-1, radio) >= 1044 and 15 >= γ >= 0.1 was proposed for the location of compact HII regions in their (ne - D) diagram.

  17. Infrared Emissions from Shock Heated Hydrocarbons

    NASA Technical Reports Server (NTRS)

    Stephens, K. M.; Bauer, S. H.

    1994-01-01

    The primary objective of this study was to ascertain whether low molecular weight hydrocarbons (LMWH) in the range C4 to C7, upon heating to temperatures above 900 K, emit IR radiations at frequencies that correspond to the 'unidentified infrared' (UIR) features - the recorded emissions from a variety of astronomical sources - reflection nebulae, HII regions, planetary nebulae, spiral galaxies and other extra galactic objects. We describe IR emission spectra recorded from shock-heated gases (C2H2; (H3C)2C = CH2; H2C = C(CH3) - C(CH3) = CH2; (H3C)2C = CH - C(CH3) = CH2), that arise from excitation of the fundamental C-H stretching vibrations. While the IR emissions from LMWH, anticipated over the entire spectra range, do not present a perfect match to UIR, the correspondence over several wavelength regions is better than the emissions anticipated from polycyclic aromatic hydrocarbon (PAH) species. Finally, we briefly review the range of proposals that have been presented for the origin of the UIR bands.

  18. A SPITZER/IRS SPECTRUM OF THE 2008 LUMINOUS TRANSIENT IN NGC 300: CONNECTION TO PROTO-PLANETARY NEBULAE

    SciTech Connect

    Prieto, Jose L.; Sellgren, Kris; Thompson, Todd A.; Kochanek, Christopher S.

    2009-11-10

    We present a Spitzer/IRS low-resolution mid-infrared (mid-IR) spectrum (5-14 mum) of the luminous transient discovered in the nearby galaxy NGC 300 in 2008 May. This transient had peak luminosity M{sub V} approx = -13, showed an optical spectrum dominated by relatively narrow Balmer and Ca II lines in emission, and its progenitor was identified in pre-explosion images as a dust-enshrouded approx10 M {sub sun} star, characteristics that make it a twin of SN 2008S. The Spitzer spectrum, obtained three months after discovery, shows that the transient is very luminous in the mid-IR. Furthermore, the spectrum shows strong, broad emission features at 8 mum and 12 mum that are observed in Galactic carbon-rich proto-planetary nebulae. Combining these data with published optical and near-IR photometry obtained at the same epoch, we find that the mid-IR excess traced by the Spitzer spectrum accounts for approx20% of the total energy output. This component can be well explained by emission from approx3 x 10{sup -4} M{sub sun} of pre-existing progenitor dust at temperature T approx 400 K. The spectral energy distribution of the transient also shows a near-IR excess that can be explained by emission from newly formed dust in the ejecta. Alternatively, both the near-IR and mid-IR excesses can together be explained by a single pre-existing geometrically thick dust shell. In light of the new observations obtained with Spitzer, we revisit the analysis of the optical spectra and kinematics, which were compared to the massive yellow-hypergiant IRC+10420 in previous studies. We show that proto-planetary nebulae share many properties with the NGC 300 transient and SN 2008S. We conclude that even though the explosion of a massive star (M approx> 10 M{sub sun}) cannot be ruled out, an explosive event on a massive (M approx 6-10 M{sub sun}) carbon-rich AGB/super-AGB or post-AGB star is consistent with all observations of the transients and their progenitors presented thus far.

  19. RADIO JETS AND DISKS IN THE INTERMEDIATE-MASS STAR-FORMING REGION NGC2071IR

    SciTech Connect

    Trinidad, M. A.; Rodriguez, T.; Rodriguez, L. F.

    2009-11-20

    We report the results of simultaneous radio continuum and water maser observations toward the NGC 2071IR star-forming region, carried out with the VLA in its A configuration. We detect continuum emission toward the infrared sources IRS 1 and IRS 3 at 1.3 and 3.6 cm. In addition, a new continuum source, VLA 1, is also detected at both wavelengths, which is located between IRS 1 and IRS 3. IRS 1 breaks up into three continuum peaks (IRS 1E, 1C, and 1W), aligned in the east-west direction (P.A. = 100{sup 0}). IRS 1 is the central source, while the sources E and W seem to be condensations ejected by IRS 1. In the same way, IRS 3 is also forming a triple system (IRS 3N, 3C and 3S), which is elongated in the northeast-southwest direction and the condensations, IRS 3N and IRS 3S, are symmetrically located along the major axis. Based on the morphology and the continuum emission, we suggest that both IRS 1 and IRS 3 are radio jets, which have ejected condensations into the interstellar medium. Moreover, IRS 1 and IRS 3 seem to be the driving sources of the large-scale outflows observed in H{sub 2} and CO, respectively. In addition, we also detected water emission toward the systems IRS 1, IRS 3, and the new source VLA 1. Based on the spatial-kinematic distribution of the water masers, we find evidence that the water masers are tracing part of circumstellar disks around IRS 1C and IRS 3C. Moreover, we estimate that the sources IRS 1C and IRS 3C have central masses of approx5 and approx1 M {sub sun}, respectively. We conclude that the radio continuum and water maser emission are tracing disk-YSO-outflow systems toward IRS 1 and IRS 3, which are low- and intermediate-mass young stellar objects, respectively.

  20. CBSD Version II component models of the IR celestial background. Technical report

    SciTech Connect

    Kennealy, J.P.; Glaudell, G.A.

    1990-12-07

    CBSD Version II addresses the development of algorithms and software which implement realistic models of all the primary celestial background phenomenologies, including solar system, galactic, and extra-galactic features. During 1990, the CBSD program developed and refined IR scene generation models for the zodiacal emission, thermal emission from asteroids and planets, and the galactic point source background. Chapters in this report are devoted to each of those areas. Ongoing extensions to the point source module for extended source descriptions of nebulae and HII regions are briefly discussed. Treatment of small galaxies will also be a natural extension of the current CBSD point source module. Although no CBSD module yet exists for interstellar IR cirrus, MRC has been working closely with the Royal Aerospace Establishment in England to achieve a data-base understanding of cirrus fractal characteristics. The CBSD modules discussed in Chapters 2, 3, and 4 are all now operational and have been employed to generate a significant variety of scenes. CBSD scene generation capability has been well accepted by both the IR astronomy community and the DOD user community and directly supports the SDIO SSGM program.

  1. Luminescent cyanometallates based on phenylpyridine-Ir(III) units: solvatochromism, metallochromism, and energy-transfer in Ir/Ln and Ir/Re complexes.

    PubMed

    Ali, Noorshida Mohd; MacLeod, Voirrey L; Jennison, Petter; Sazanovich, Igor V; Hunter, Christopher A; Weinstein, Julia A; Ward, Michael D

    2012-02-28

    [Ir(ppy)(2)(CN)(2)](-) (ppy = anion of 2-phenylpyridine) and some substituted derivatives have been investigated for their ability to interact with additional metal cations, both in solution and the solid state, via the externally-directed cyanide lone pairs, and to act as energy-donors in the resulting assemblies. [Ir(ppy)(2)(CN)(2)](-) is slightly solvatochromic, showing a blue-shift of the lowest energy absorption manifold in water compared to organic solvents, and the solubilised (t)Bu-substituted analogue [Ir((t)Buppy)(2)(CN)(2)](-) [(t)Buppy = anion of 2-(4-(t)Bu-phenyl)pyridine] is also metallochromic with coordination of the cyanide lone pairs to two M(II) cations in MeCN (M = Ba, Zn) resulting in blue-shifts of the lowest-energy absorption and emission maxima. These effects are however modest because of (i) the presence of only two cyanide groups, and (ii) the fact that the lowest-energy excited state has a substantial (3)LC component and is therefore not purely charge-transfer in nature. Crystallisation of [Ir(ppy)(2)(CN)(2)](-) as its (PPN)(+) salt in the presence of excess of lanthanide(III) salts leads to formation of assemblies based on Ir-CN-Ln bonds, which generate in the solid state either Ir(2)Ln(2)(μ-CN)(4) square assemblies or linear trinuclear species with Ir-CN-Ln-NC-Ir cores. In the Ir(2)Eu(2)(μ-CN)(4) and Ir(2)Nd(2)(μ-CN)(4) complexes the Ir-based emission is substantially quenched due to energy-transfer to lower-lying f-f states of these lanthanide ions. In addition reaction of [Ir(F(2)ppy)(2)(CN)(2)](-) [F(2)ppy = cyclometallating anion of 2-(2,4-difluorophenyl)pyridine] with [Re(phen)(CO)(3)(MeCN)][PF(6)] in solution affords dinuclear IrRe and trinuclear IrRe(2) species in which {Re(phen)(CO)(3)} units are attached to the N-donor termini of one or both of the cyanide groups; these complexes have been structurally characterised and display quantitative Ir→Re energy-transfer, showing luminescence only from the Re(I) terminus on

  2. Low Power Polysilicon Sources for IR Applications

    NASA Technical Reports Server (NTRS)

    Das, N. C.; Jhabvala, M.; Shu, P.

    1998-01-01

    We have designed and fabricated polysilicon thin film infrared (IR) sources by micromachining technology. These sources are made with a lightly doped middle region for light emission and heavy doping of the supporting legs. The sources are fabricated on a 10 mm thick, low temperature process parameters in the fabrication of these silicon dioxide layer. Different doping levels were used to achieve various source resistances. From the power requirement to reach the required light emission versus source resistance curve it is seen that there exists a resistance value which minimizes the necessary input power.

  3. A deep look at the nuclear region of UGC 5101 through high angular resolution mid-IR data with GTC/CanariCam

    NASA Astrophysics Data System (ADS)

    Martínez-Paredes, M.; Alonso-Herrero, A.; Aretxaga, I.; Ramos Almeida, C.; Hernán-Caballero, A.; González-Martín, O.; Pereira-Santaella, M.; Packham, C.; Asensio Ramos, A.; Díaz-Santos, T.; Elitzur, M.; Esquej, P.; García-Bernete, I.; Imanishi, M.; Levenson, N. A.; Rodríguez Espinosa, J. M.

    2015-12-01

    We present an analysis of the nuclear infrared (IR, 1.6-18 μm) emission of the ultraluminous IR galaxy UGC 5101 to derive the properties of its active galactic nucleus (AGN) and its obscuring material. We use new mid-IR high angular resolution (0.3-0.5 arcsec) imaging using the Si-2 filter (λC = 8.7 μm) and 7.5-13 μm spectroscopy taken with CanariCam (CC) on the 10.4 m Gran Telescopio CANARIAS. We also use archival Hubble Space Telescope/NICMOS and Subaru/COMICS imaging and Spitzer/IRS spectroscopy. We estimate the near- and mid-IR unresolved nuclear emission by modelling the imaging data with GALFIT. We decompose the Spitzer/IRS and CC spectra using a power-law component, which represents the emission due to dust heated by the AGN, and a starburst component, both affected by foreground extinction. We model the resulting unresolved near- and mid-IR, and the starburst subtracted CC spectrum with the CLUMPY torus models of Nenkova et al. The derived geometrical properties of the torus, including the large covering factor and the high foreground extinction needed to reproduce the deep 9.7 μm silicate feature, are consistent with the lack of strong AGN signatures in the optical. We derive an AGN bolometric luminosity Lbol ˜ 1.9 × 1045 erg s-1 that is in good agreement with other estimates in the literature.

  4. Spitzer-IRS Spectroscopic Studies of Oxygen-Rich Asymptotic Giant Branch Star and Red Supergiant Star Dust Properties

    NASA Astrophysics Data System (ADS)

    Sargent, Benjamin A.; Srinivasan, Sundar; Speck, Angela; Volk, Kevin; Kemper, Ciska; Reach, William T.; Lagadec, Eric; Bernard, Jean-Philippe; McDonald, Iain; Meixner, Margaret

    2015-01-01

    We analyze the dust emission features seen in Spitzer Space Telescope Infrared Spectrograph (IRS) spectra of Oxygen-rich (O-rich) asymptotic giant branch (AGB) and red supergiant (RSG) stars. The spectra come from the Spitzer Legacy program SAGE-Spectroscopy (PI: F. Kemper) and other archival Spitzer-IRS programs. The broad 10 and 20 micron emission features attributed to amorphous dust of silicate composition seen in the spectra show evidence for systematic differences in the centroid of both emission features between O-rich AGB and RSG populations. Radiative transfer modeling using the GRAMS grid of models of AGB and RSG stars suggests that the centroid differences are due to differences in dust properties. We present an update of our investigation of differences in dust composition, size, shape, etc that might be responsible for these spectral differences. We explore how these differences may arise from the different circumstellar environments around RSG and O-rich AGB stars. BAS acknowledges funding from NASA ADAP grant NNX13AD54G.

  5. WATER ICE IN HIGH MASS-LOSS RATE OH/IR STARS

    SciTech Connect

    Suh, Kyung-Won; Kwon, Young-Joo

    2013-01-10

    We investigate water-ice features in spectral energy distributions (SEDs) of high mass-loss rate OH/IR stars. We use a radiative transfer code which can consider multiple components of dust shells to make model calculations for various dust species including water ice in the OH/IR stars. We find that the model SEDs are sensitively dependent on the location of the water-ice dust shell. For two sample stars (OH 127.8+0.0 and OH 26.5+0.6), we compare the detailed model results with the infrared observational data including the spectral data from the Infrared Space Observatory (ISO). For the two sample stars, we reproduce the crystalline water-ice features (absorption at 3.1 {mu}m and 11.5 {mu}m; emission at 44 and 62 {mu}m) observed by ISO using a separate component of the water-ice dust shell that condensed at about 84-87 K (r {approx} 1500-1800 AU) as well as the silicate dust shell that condensed at about 1000 K (r {approx} 19-25 AU). For a sample of 1533 OH/IR stars, we present infrared two-color diagrams (2CDs) using the Infrared Astronomical Satellite and AKARI data compared with theoretical model results. We find that the theoretical models clearly show the effects of the crystalline water-ice features (absorption at 11.5 {mu}m and emission at 62 {mu}m) on the 2CDs.

  6. Infrared absorption and emission characteristics of interstellar PAHs (Polycyclic Aromatic Hydrocarbon)

    SciTech Connect

    Allamandola, L.J.; Tielens, A.G.G.M.; Barker, J.R.

    1986-01-01

    The mid-infrared interstellar emission spectrum with features at 3050, 1610, 1300, 1150, and 885 cm/sup -1/ (3.28, 6.2, 7.7, 8.7 and 11.3 microns) is discussed in terms of the Polycyclic Aromatic Hydrocarbon (PAH) hypothesis. This hypothesis is based on the suggestive, but inconclusive comparison between the interstellar emission spectrum with the infrared absorption and Raman spectra of a few PAHs. The fundamental vibrations of PAHs and PAH-like species which determine the ir and Raman properties are discussed. Interstellar ir band emission is due to relaxation from highly vibrationally excited PAHs which have been excited by ultraviolet photons. The excitation/emission process is described in general and the ir fluorescence from one PAH, chrysene, is traced in detail. Generally, there is sufficient energy to populate several vibrational levels in each mode. Molecular vibrational potentials are anharmonic and emission from these higher levels will fall at lower frequencies and produce weak features to the red of the stronger fundamentals. This process is also described and can account for some spectroscopic details of the interstellar emission spectra previously unexplained. Analysis of the interstellar spectrum shows that PAHs containing between 20 and 30 carbon atoms are responsible for the emission. 43 refs., 11 figs.

  7. Nuclear IRS-1 and Cancer

    PubMed Central

    Reiss, Krzysztof; Valle, Luis Del; Lassak, Adam; Trojanek, Joanna

    2011-01-01

    The family of insulin receptor substrates (IRS) consists of four proteins (IRS-1 - IRS-4), which were initially characterized as typical cytosolic adaptor proteins involved in insulin receptor (IR) and insulin-like growth factor I receptor (IGF-IR) signaling. The first cloned and characterized member of the IRS family, IRS-1, has predicted molecular weight of 132 kDa, however, as a result of its extensive serine phosphorylation it separates on a SDS gel as a band of approximately 160–185 kDa. In addition to its metabolic and growth-promoting functions, IRS-1 is also suspected to play a role in malignant transformation. The mechanism by which IRS-1 supports tumor growth is not fully understood, and the argument that IRS-1 merely amplifies the signal from the IGF-1R and/or IR requires further investigation. Almost a decade ago, we reported the presence of nuclear IRS-1 in medulloblastoma clinical samples, which express viral oncoprotein, large T-antigen of human polyomavirus JC (JCV T-antigen). This first demonstration of nuclear IRS-1 was confirmed in several other laboratories. The nuclear IRS-1 was also detected by cells expressing the SV40 T-antigen, v-Src, in immortalized fibroblasts stimulated with IGF-I, in hepatocytes, 32D cells, and in an osteosarcoma cell line. More recently, nuclear IRS-1 was detected in breast cancer cells in association with estrogen receptor alpha (ERα), and in JC virus negative medulloblastoma cells expressing ERβ, further implicating nuclear IRS-1 in cellular transformation. Here, we discuss how nuclear IRS-1 acting on DNA repair fidelity, transcriptional activity, and cell growth can support tumor development and progression. PMID:22454254

  8. EXPLORATIONS BEYOND THE SNOW LINE: SPITZER/IRS SPECTRA OF DEBRIS DISKS AROUND SOLAR-TYPE STARS

    SciTech Connect

    Lawler, S. M.; Beichman, C. A.; Ciardi, D. R.; Bryden, G.; Tanner, A. M.; Stapelfeldt, K. R.; Su, K. Y. L.; Lisse, C. M.

    2009-11-01

    We have observed 152 nearby solar-type stars with the Infrared Spectrometer (IRS) on the Spitzer Space Telescope. Including stars that met our criteria but were observed in other surveys, we get an overall success rate for finding excesses in the long-wavelength IRS band (30-34 mum) of 11.8% +- 2.4%. The success rate for excesses in the short-wavelength band (8.5-12 mum) is approx1% including sources from other surveys. For stars with no excess at 8.5-12 mum, the IRS data set 3sigma limits of around 1000 times the level of zodiacal emission present in our solar system, while at 30-34 mum data set limits of around 100 times the level of our solar system. Two stars (HD 40136 and HD 10647) show weak evidence for spectral features; the excess emission in the other systems is featureless. If the emitting material consists of large (10 mum) grains as implied by the lack of spectral features, we find that these grains are typically located at or beyond the snow line, approx1-35 AU from the host stars, with an average distance of 14 +- 6 AU; however, smaller grains could be located at significantly greater distances from the host stars. These distances correspond to dust temperatures in the range approx50-450 K. Several of the disks are well modeled by a single dust temperature, possibly indicative of a ring-like structure. However, a single dust temperature does not match the data for other disks in the sample, implying a distribution of temperatures within these disks. For most stars with excesses, we detect an excess at both IRS and Multiband Imaging Photometer for Spitzer (MIPS) wavelengths. Only three stars in this sample show a MIPS 70 mum excess with no IRS excess, implying that very cold dust is rare around solar-type stars.

  9. HWIL IR imaging testing

    NASA Astrophysics Data System (ADS)

    Vinson, R. J.; Passwater, R. D.

    1981-03-01

    The Army simulator facilities are presently configured to conduct hardware-in-the-loop mission tasks on the HELLFIRE and COPPERHEAD missile systems. These systems presently use a LASER seeker. The facility is an ideal candidate to be converted to include infrared (IR) seekers used on the TGSM system. This study investigates the possibility and impact of a facility update. This report documents the feasibility of developing a hardware-in-the-loop (HWIL) hybrid simulation incorporating infrared IR seekers used for the Assault Breaker program. Other hardware to be considered are the autopilot, signal conditioning, signal processing, and actuators which may be integrated into the system simulation. Considerations are given to replacing all or elements of hardware while substituting math models in the system simulation.

  10. IRS Scan Mapping of IRAS16253-2429: A Textbook Example for Unlocking the Secrets of Protostellar Outflows

    NASA Astrophysics Data System (ADS)

    Barsony, Mary; Arce, Hector; Ciardi, David; Cole, David; Cotera, Angela; Forebrich, Dirk; Frank, Adam; Goodman, Alyssa; Haisch, Karl; Hurt, Robert; Moriarty-Schieven, Gerald; O'Linger, Joann; Phelps, Randy; Ressler, Michael; Sahai, Raghvendra; Simpson, Janet; Smith, Michael; Wolf-Chase, Grace; Ybarra, Jason

    2006-05-01

    IRAS 16253-2429 is a newly discovered Class 0 protostar in the nearby Rho Ophiuchi molecular clouds. Ground-based imaging tracing its 2.12 micron H2 emission and CO(3-2) molecular line maps reveal its bipolar, molecular outflow. The IRAC images from the Spitzer archive show a beautiful, bipolar hourglass structure, tracing the outflow cavities, in addition to shock features from the flow. The requested IRS scan mapping is necessary to separate the pure shocked molecular line emission associated with the flow, from the scattered dust continuum emission of the cavity, and from the PAH (polycyclic aromatic hydrocarbon) feature emission found throughout the Rho Oph clouds. Hydrodynamic jet models , including molecular chemistry and cooling, can then be quantitatively compared with the IRS scan maps to infer jet characteristics, such as the presence of an underlying pulsed, continuous, and/or precessing jet. The uniqueness of IRAS16253-2429 stems from the fact that its infall envelope is seen in absorption against the bright background PAH emission of its parent cloud, which is backlit by the FUV/UV light of the Sco OB2 association. This means we can derive the infallenvelope's density distribution (at multiple wavelengths, with IRS scan mapping), as well as the outflow cavities' density distributions at the highest spatial resolution ever achieved for a Class 0 protostar. The derived envelope density distribution will then serve as input for hydrodynamic models of jet-driven and wide-angled wind driven cavities. The predicted cavity density distributions from these models will then be quantitatively compared with the observations to infer the nature of the driving wind/jet at this very early protostellar stage.

  11. Spectral Emissivity (6 – 38 µm) of Jupiter's Trojan Asteroids

    NASA Astrophysics Data System (ADS)

    Martin, Audrey; Emery, Joshua P.; Lindsay, Sean S.

    2016-10-01

    Jovian Trojan asteroids, located in Jupiter's stable Lagrange points, are an extensive population of primitive bodies in the Solar System. Previous work in the visible and NIR shows Trojans have featureless, red-sloped spectra and low albedos, making mineralogical characterization difficult. However, it has been shown that three Trojans exhibit silicate emissivity features in the thermal IR (6 – 38 μm Emery et al. 2006, Icarus 182). The detected features indicate the presence of fine-grained (micron-sized) silicate dust on the surfaces, and closely resemble spectral features measured of cometary comae. We hypothesize that Trojan surface mineralogy is fairly uniform and is similar to comet dust. The principal goal of this work is, therefore, to derive primary surface mineralogy from thermal emission spectra. We present thermal IR spectra of 12 Trojans observed with NASA's Spitzer space telescope, using the InfraRed Spectrograph (IRS) in Staring Mode from June 2006 to June 2007. Eight objects were observed over the 5.2 – 38 µm spectral range, and four objects over the 7.5 – 38 µm range. Using the NEATM thermal model, we have computed size, albedo, and beaming parameter for the 12 Trojans. Results for these physical parameters are comparable to those derived from WISE data (Grav et al. 2011, ApJ 742 (1); Grav et al. 2012, ApJ 759 (49)). There are, however, some discrepancies, especially with 2797 Teucer. The emissivity spectra fall into groups that directly correlate with the red and less-red spectral slope groupings described in Emery et al. (2011, ApJ, 141(1)). Strong 10 µm emission features appear in each object, suggesting the presence of fine-grained silicates. Features found between 12-13 µm, and 18-19 µm are also observed in all spectra. We will present these new Trojan asteroid data with mineralogical estimates derived from the emissivity spectra.

  12. Thermal Emission from Structured Media

    NASA Astrophysics Data System (ADS)

    Zimmerman, Ian Andrew

    This dissertation covers a study of the use of macroscopic structure as a means of controlling thermal emission in the THz and mid-IR frequency regions. Chapter 1 presents a brief introduction to the THz frequency region and to the concept of the photonic crystal, the primary type of geometry used. Chapter 2 compares the two most common methods used to calculate the thermal emission of a structure whose components are all at the same temperature. These methods are compared in terms of the results they give and in terms of how computationally involved the methods are. The first method explored involves using Kirchhoff's law of thermal emission which equates the absorptivity and emissivity of a structure. The second method is to calculate the emission directly from the Green's function using the microscopic thermal currents given by the Fluctuation-Dissipation theorem. A derivation of the second method is given, and the equality between the two methods is proven in 1D. It is shown that the Kirchhoff's law method is much more computationally efficient, and it is therefore used for the parametric studies of the structures which make up the remainder of this document. Chapter 3 covers work done in the THz regime. In the THz frequency regime, where a historic lack of sources has in part impeded full exploration and utilization, a photonic crystal design is proposed to control the thermal emission. It is shown that using a 1D bi-layered photonic crystal, composed of alternating section of silicon wafers and vacuum sections, it is possible to tailor many narrowband emission features over a broadband frequency range. In simulation both spectral and directional thermal emission control is demonstrated, and a parametric study is performed to explore how changes in the geometry of the photonic crystal change its thermal emission signature. A description is then given of how the photonic crystal is constructed and how its thermal emission is measured using Fourier transform

  13. Spirobifluorene bridged Ir(III) and Os(II) polypyridyl arrays: synthesis, photophysical characterization, and energy transfer dynamics.

    PubMed

    Ventura, Barbara; Barbieri, Andrea; Degli Esposti, Alessandra; Seneclauze, Julie Batcha; Ziessel, Raymond

    2012-03-01

    The synthesis, characterization, photophysics, and time-dependent density functional theory (TD-DFT) calculations of spirobifluorene-bipyridine based iridium(III), osmium(II), and mixed Ir/Os complexes are presented. The preparation of the reference and mixed complexes proceeded step-by-step and microwave irradiation facilitated the complexation of osmium. The absorption of the target heterobimetallic derivative, Ir-L-Os, is described by linear combination of half of the absorption spectra of the homobimetallic analogues, Ir-L-Ir and Os-L-Os, due to the occurrence of mixed ligand and metal based transitions when the spirobifluorene-(bpy)(2) bridging ligand L is linked to the metal, confirming a negligible interaction between the substituted metallic chromophores. TD-DFT calculations on monometallic, homo- and hetero-bimetallic complexes fully disentangled the origin of the absorption features. Noticeably, in the mixed Ir-L-Os complex an almost quantitative energy transfer from the (3)Ir to the (3)Os MLCT state is occurring, with a rate constant of 4.1 × 10(8) s(-1) and nearly exclusively via a Dexter-type mechanism mediated by the orbitals of the spiroconjugated ligand. This result, together with the outcomes of the TD-DFT calculations, supports the existence of spiroconjugation and evidences the interesting role of this kind of bridge in the energy transfer dynamics of the arrays. In all the complexes, moreover, the ligand fluorescence is heavily quenched by energy transfer processes toward the metallic appended units; the rate constant is estimated in the order of 10(10) s(-1) for Ir-L-Os and higher than 10(12) s(-1) for the other complexes. In the heterometallic array, both at room temperature and at 77 K, all photons are thus funneled to the emissive Os (3)MLCT state, which acts as energy trap for the antenna cascade. PMID:22356478

  14. Characterizing the Dust-Correlated Anomalous Emission in LDN 1622

    NASA Astrophysics Data System (ADS)

    Cleary, Kieran; Casassus, Simon; Dickinson, Clive; Lawrence, Charles; Sakon, Itsuki

    2008-03-01

    The search for 'dust-correlated microwave emission' was started by the surprising excess correlation of COBE-DMR maps, at 31.5, 53 and 91GHz, with DIRBE dust emission at 140 microns. It was first thought to be Galactic free-free emission from the Warm Ionized Medium (WIM). However, Leitch et al. (1997) ruled out a link with free-free by comparing with Halpha templates and first confirmed the anomalous nature of this emission. Since then, this emission has been detected by a number of experiments in the frequency range 5-60 GHz. The most popular explanation is emission from ultra-small spinning dust grains (first postulated by Erickson, 1957), which is expected to have a spectrum that is highly peaked at about 20 GHz. Spinning dust models appear to be broadly consistent with microwave data at high latitudes, but the data have not been conclusive, mainly due to the difficulty of foreground separation in CMB data. LDN 1622 is a dark cloud that lies within the Orion East molecular cloud at a distance of 120 pc. Recent cm-wave observations, in combination with WMAP data, have verified the detection of anomalous dust-correlated emission in LDN 1622. This mid-IR-cm correlation in LDN 1622 is currently the only observational evidence that very small grains VSG emit at GHz frequencies. We propose a programme of spectroscopic observations of LDN 1622 with Spitzer IRS to address the following questions: (i) Are the IRAS 12 and 25 microns bands tracing VSG emission in LDN 1622? (ii) What Mid-IR features and continuum bands best correlate with the cm-wave emission? and (iii) How do the dust properties vary with the cm-wave emission? These questions have important implications for high-sensitivity CMB experiments.

  15. The IRS-1 signaling system.

    PubMed

    White, M F

    1994-02-01

    IRS-1 is a principal substrate of the insulin receptor tyrosine kinase. It undergoes multi-site tyrosine phosphorylation and mediates the insulin signal by associating with various signaling molecules containing Src homology 2 domains. Interleukin-4 also stimulates IRS-1 phosphorylation, and it is suspected that a few more growth factors or cytokines will be added to form a select group of receptors that utilize the IRS-1 signaling pathway. More IRS-1-like adapter molecules, such as 4PS (IRS-2), may remain to be found.

  16. IRS Spectral Maps of Photoevaporative Columns in M16, Carina, and the Galactic Center

    NASA Astrophysics Data System (ADS)

    Cotera, Angela; Healy, Kevin; Hester, Jeff; Sellgren, Kris; Simpson, Janet; Stolovy, Susan

    2008-03-01

    Photoevaporated columns of dust and gas - also called elephant trunks, pillars or fingers - are found in the periphery of H II regions, and have been observed within the Galaxy, the SMC and the LMC. These features are sites of current star formation, but the question remains whether the columns persist because stars formed in the denser regions prior to interactions with the UV radiation and stellar winds of nearby massive stars, or because of core collapse resulting from these interactions. Mapping the distribution of the physical states of the dust and gas in these columns is a necessary step towards understanding the possible star formation mechanisms within these dynamic objects. We propose to obtain IRS spectral maps of columns within M 16, the Carina nebula, and the Galactic center (GC) to understand the effects on these pillars from different stellar populations and initial conditions, and to better understand star formation in the GC. Within the spectral range of the high resolution IRS modes (9.9-37.2 micron) there are a wealth of molecular, atomic and PAH emission lines that will enable us to determine the excitation state, dust and gas temperatures, and probe the shock characteristics within the columns. Using the IRS spectral mapping mode, in conjunction with the CUBISM tool and the CLOUDY H II region model code, we will be able to construct detailed maps of the accessible emission lines and derived parameters for each column. IRS mapping of elephant trunks has not been done to date, yet provides a wealth of information unobtainable for the foreseeable future once Cycle 5 is completed.

  17. IR Spot Weld Inspect

    2014-01-01

    In automotive industry, destructive inspection of spot welds is still the mandatory quality assurance method due to the lack of efficient non-destructive evaluation (NDE) tools. However, it is costly and time-consuming. Recently at ORNL, a new NDE prototype system for spot weld inspection using infrared (IR) thermography has been developed to address this problem. This software contains all the key functions that ensure the NDE system to work properly: system input/output control, image acquisition, datamore » analysis, weld quality database generation and weld quality prediction, etc.« less

  18. IR Spot Weld Inspect

    SciTech Connect

    Chen, Jian; Feng, Zhili

    2014-01-01

    In automotive industry, destructive inspection of spot welds is still the mandatory quality assurance method due to the lack of efficient non-destructive evaluation (NDE) tools. However, it is costly and time-consuming. Recently at ORNL, a new NDE prototype system for spot weld inspection using infrared (IR) thermography has been developed to address this problem. This software contains all the key functions that ensure the NDE system to work properly: system input/output control, image acquisition, data analysis, weld quality database generation and weld quality prediction, etc.

  19. Mid-IR FORCAST/SOFIA Observations of M82

    NASA Astrophysics Data System (ADS)

    Nikola, T.; Herter, T. L.; Vacca, W. D.; Adams, J. D.; De Buizer, J. M.; Gull, G. E.; Henderson, C. P.; Keller, L. D.; Morris, M. R.; Schoenwald, J.; Stacey, G.; Tielens, A.

    2012-04-01

    We present 75'' × 75'' size maps of M82 at 6.4 μm, 6.6 μm, 7.7 μm, 31.5 μm, and 37.1 μm with a resolution of ~4'' that we have obtained with the mid-IR camera FORCAST on SOFIA. We find strong emission from the inner 60'' (~1 kpc) along the major axis, with the main peak 5'' west-southwest of the nucleus and a secondary peak 4'' east-northeast of the nucleus. The detailed morphology of the emission differs among the bands, which is likely due to different dust components dominating the continuum emission at short mid-IR wavelengths and long mid-IR wavelengths. We include Spitzer-IRS and Herschel/PACS 70 μm data to fit spectral energy distribution templates at both emission peaks. The best-fitting templates have extinctions of AV = 18 and AV = 9 toward the main and secondary emission peak and we estimated a color temperature of 68 K at both peaks from the 31 μm and 37 μm measurement. At the emission peaks the estimated dust masses are on the order of 104 M ⊙.

  20. Mineralogy of an OH/IR superwind

    NASA Astrophysics Data System (ADS)

    Lombaert, R.; de Vries, B. L.; Hillen, M.

    2016-07-01

    The mineralogy of the dense, dusty superwind of OH/IR stars can provide important constraints for understanding the dust formation process as well as the acceleration of the wind. We aim to model the ISO-SWS spectrum of the OH/IR star OH 30.1-0.7 in detail by reproducing the slope of the spectral energy distribution in the continuum regions between 3 and 8 μm and 12 and 15 μm. In addition to metallic Fe, we find that larger amorphous olivine grains of size on the order of 1 μm may also contribute to the continuum emission. We report here on the preliminary model results and discuss their validity given the important assumption of a 1D spherically symmetric stellar wind.

  1. Automated IR-weld seam control

    NASA Astrophysics Data System (ADS)

    Balle, Michel

    1990-03-01

    In 1975 the concept of visualizing, measuring and studying the thermal condition of welded seams was investigated by a laboratory of the French ministry of defense (at the request of a metal constructor). Gilbert Gaussorgues, the founding father of the company HGH was at the time in charge of the infrared laboratory in question, a department of the general administration of Armament in Toulon, France. His idea was to apply military IR-Technology to above mentioned welding application. Having developed a prototype, tests readily confirmed the validity of using IR-emission from the weld seam close to the actual moment of welding as an indicator of the quality of the fmal assembly. Nearly ten years later, in 1984, HGH decided, due to an increasing demand, to develop above preliminary tests to a complete product/application package designed specifically for welding process-control. The inspection oftubing and of the integrity welds of barrels with hazardous content, were the first applications.

  2. Theoretical IR spectra of ionized naphthalene

    NASA Technical Reports Server (NTRS)

    Pauzat, F.; Talbi, D.; Miller, M. D.; DeFrees, D. J.; Ellinger, Y.

    1992-01-01

    We report the results of a theoretical study of the effect of ionization on the IR spectrum of naphthalene, using ab initio molecular orbital theory. For that purpose we determined the structures, band frequencies, and intensities of neutral and positively ionized naphthalene. The calculated frequencies and intensities allowed an assignment of the most important bands appearing in the newly reported experimental spectrum of the positive ion. Agreement with the experimental spectrum is satisfactory enough to take into consideration the unexpected and important result that ionization significantly affects the intensities of most vibrations. A possible consequence on the interpretation of the IR interstellar emission, generally supposed to originate from polycyclic aromatic hydrocarbons (PAHs), is briefly presented.

  3. Controlling the red boundary of the tunneling photoeffect in nanodimensional carbon structures in a broad (UV-IR) wavelength range

    NASA Astrophysics Data System (ADS)

    Akchurin, G. G.; Yakunin, A. N.; Aban'shin, N. P.; Gorfinkel', B. I.; Akchurin, G. G.

    2013-06-01

    The tunneling photoeffect (PE) has been studied in a microdiode with an electrostatic field localized at an emitter based on a nanodimensional carbon structure. It is established that, when the carbon nanoemitter is exposed to laser and LED radiation photons of low energy (below work function) in the spectral range from near-UV (380 nm) to near-IR (1150 nm) at micro- and milliwatt optical power, a tunneling photocurrent can be initiated by controlling the electric field strength in the emitter-anode gap. The observed phenomenon can be adequately interpreted using a modified Fowler-Nordheim equation for non-equilibrium photoelectrons. Specific features of the construction and operation of photodetectors based on the tunneling PE with a controlled long-wavelength threshold (red boundary) of photoelectron emission are considered. The bandwidth of photoelectron emitters is evaluated, and the possibility of their operation in the wavelength range from UV up to far-IR is predicted.

  4. The IRS-1 signaling system.

    PubMed

    Myers, M G; Sun, X J; White, M F

    1994-07-01

    Insulin-receptor substrate 1 (IRS-1) is a principal substrate of the receptor tyrosine kinase for insulin and insulin-like growth factor 1, and a substrate for a tyrosine kinase activated by interleukin 4. IRS-1 undergoes multisite tyrosine phosphorylation and mediates downstream signals by 'docking' various proteins that contain Src homology 2 domains. IRS-1 appears to be a unique molecule; however, 4PS, a protein found mainly in hemopoietic cells, may represent another member of this family.

  5. The excess infrared emission of Herbig Ae/Be stars - Disks or envelopes?

    NASA Technical Reports Server (NTRS)

    Hartmann, Lee; Kenyon, Scott J.; Calvet, Nuria

    1993-01-01

    It is suggested that the near-IR emission in many Herbig Ae/Be stars arises in surrounding dusty envelopes, rather than circumstellar disks. It is shown that disks around Ae/Be stars are likely to remain optically thick at the required accretion rates. It is proposed that the IR excesses of many Ae/Be stars originate in surrounding dust nebulae instead of circumstellar disks. It is suggested that the near-IR emission of the envelope is enhanced by the same processes that produce anomalous strong continuum emission at temperatures of about 1000 K in reflection nebulae surrounding hot stars. This near-IR emission could be due to small grains transiently heated by UV photons. The dust envelopes could be associated with the primary star or a nearby companion star. Some Ae/Be stars show evidence for the 3.3-6.3-micron emission features seen in reflection nebulae around hot stars, which lends further support to this suggestion.

  6. Near-IR spectral evolution of dusty starburst galaxies

    NASA Astrophysics Data System (ADS)

    Lançon, Ariane; Rocca-Volmerange, Brigitte

    1996-11-01

    We propose a multicomponent analysis of starburst galaxies, based on a model that takes into account the young and evolved stellar components and the gas emission, with their respective extinction, in the frame of a coherent dust distribution pattern. Near-IR signatures are preferentially investigated, in order to penetrate as deep as possible into the dusty starburst cores. We computed the 1.4-2.5 μm spectra of synthetic stellar populations evolving through strong, short timescale bursts of star formation (continuum and lines, R ≃ 500). The evolution model is specifically sensitive to cool stellar populations (AGB and red supergiant stars). It takes advantage of the stellar library of Lançon & Rocca-Volmerange (1992) [A&ASS, 96, 593], observed with the same instrument (FTS/CFHT) as the analysed galaxy sample, so that the instrumental effects are minimised. The main near-IR observable constraints are the molecular signatures of CO and H2O and the slope of the continuum, observed over a range exceptionally broad for spectroscopic data. The H - K colour determined from the spectra measures the intrinsic stellar energy distribution but also differential extinction, which is further constrained by optical emission line ratios. Other observational constraints are the near-IR emission lines (Brγ, He I 2.06 μm, [Fe II] 1.64 μm, H2 2.12 μm) and the far-IR luminosity. The coherence of the results relies on the interpretation in terms of stellar populations from which all observable properties are derived, so that the link between the various wavelength ranges is secured. The luminosity LK is used for the absolute calibration. We apply this approach to the typical spectrum of the core of NGC 1614. Consistent solutions for the starburst characteristics (star-formation rate, IMF, burst age, morphology) are found and the role of each observational constraint in deriving satisfactory models is extensively discussed. The acceptable contamination of the K band light by the

  7. Multi-spectral IR reflectography

    NASA Astrophysics Data System (ADS)

    Fontana, Raffaella; Bencini, Davide; Carcagnì, Pierluigi; Greco, Marinella; Mastroianni, Maria; Materazzi, Marzia; Pampaloni, Enrico; Pezzati, Luca

    2007-07-01

    A variety of scientific investigation methods applied to paintings are, by now, an integral part of the repair process, both to plan the restoration intervention and to monitor its various phases. Optical techniques are widely diffused and extremely well received in the field of painting diagnostics because of their effectiveness and safety. Among them infrared reflectography is traditionally employed in non-destructive diagnostics of ancient paintings to reveal features underlying the pictorial layer thanks to transparency characteristics to NIR radiation of the materials composing the paints. High-resolution reflectography was introduced in the 90s at the Istituto Nazionale di Ottica Applicata, where a prototype of an innovative scanner was developed, working in the 900-1700 nm spectral range. This technique was recently improved with the introduction of an optical head, able to acquire simultaneously the reflectogram and the color image, perfectly superimposing. In this work we present a scanning device for multi-spectral IR reflectography, based on contact-less and single-point measurement of the reflectance of painted surfaces. The back-scattered radiation is focused on square-shaped fiber bundle that carries the light to an array of 14 photodiodes equipped with pass-band filters so to cover the NIR spectral range from 800 to 2500 nm

  8. Infrared molecular emissions from comets

    SciTech Connect

    Weaver, H.A.; Mumma, M.J.

    1983-07-01

    The possibility of detecting IR molecular line emission from cometary parent molecules is explored. Due to the non-LTE conditions in the inner coma and the large amount of near IR solar flux, IR fluorescence will be a significant source of cometary emission and, in fact, will dominate the grain radiation in a sufficiently high resolution instrument. The detection of this line emission will be difficult due to absorption in the terrestrial atmosphere, but it appears possible to measure cometary H2O emission from airplane altitudes. As IR molecular line emission represents one of the few promising methods of detecting cometary parent molecules directly, further research on this problem should be vigorously pursued.

  9. First observation of intra-5f fluorescence from an actinyl center: Np(VI) near-IR emission in Cs{sub 2}U(Np)O{sub 2}Cl{sub 4}

    SciTech Connect

    Wilkerson, Marianne P. . E-mail: mpw@lanl.gov; Berg, John M. . E-mail: jberg@lanl.gov; Hopkins, Todd A.; Dewey, Harry J. . E-mail: hd@lanl.gov

    2005-02-15

    Fluorescence from an excited 5f state of Np(VI) has been observed in the doped impurity system Cs{sub 2}U(Np)O{sub 2}Cl{sub 4}. This is the first intra-5f fluorescence transition that has been detected at room temperature in a condensed-phase system with an actinyl (An(VI)O{sub 2}{sup 2+}) core, and it is a rare example of fluorescence of any kind from non-uranyl ions of this type. The emission originates from an excited state approximately 6890cm{sup -1} above the ground state. Its emission spectrum and fluorescence lifetime at 295K will be discussed. Vibronic structure in the emission spectrum is assigned based on comparison with the detailed analysis of the absorption spectra published by Denning et al.

  10. The Infrared Spectra of Polycyclic Aromatic Hydrocarbons with Excess Peripheral H Atoms (Hn-PAHs) and their Relation to the 3.4 and 6.9 µm PAH Emission Features

    PubMed Central

    Sandford, Scott A.; Bernstein, Max P.; Materese, Christopher K.

    2015-01-01

    Polycyclic aromatic hydrocarbons (PAHs) are likely responsible for the family of infrared emission features seen in a wide variety of astrophysical environments. A potentially important subclass of these materials are PAHs whose edges contain excess H atoms (Hn-PAHs). This type of compound may be present in space, but it has been difficult to assess this possibility because of a lack of suitable laboratory spectra to assist with analysis of astronomical data. We present 4000-500 cm−1 (2.5–20 µm) infrared spectra of 23 Hn-PAHs and related molecules isolated in argon matrices under conditions suitable for interpretation of astronomical data. Spectra of molecules with mixed aromatic and aliphatic domains show characteristics that distinguish them from fully aromatic PAH equivalents. Two major changes occur as PAHs become more hydrogenated: (1) aromatic C-H stretching bands near 3.3 µm weaken and are replaced with stronger aliphatic bands near 3.4 µm, and (2) aromatic C-H out-of-plane bending mode bands in the 11–15 µm region shift and weaken concurrent with growth of a strong aliphatic -CH2-deformation mode near 6.9 µm. Implications for interpreting astronomical spectra are discussed with emphasis on the 3.4 and 6.9 µm features. Laboratory data is compared with emission spectra from IRAS 21282+5050, an object with normal PAH emission features, and IRAS 22272+5435 and IRAS 0496+3429, two protoplanetary nebulae with abnormally large 3.4 µm features. We show that ‘normal’ PAH emission objects contain relatively few Hn-PAHs in their emitter populations, but less evolved protoplanetary nebulae may contain significant abundances of these molecules. PMID:26435553

  11. THE INFRARED SPECTRA OF POLYCYCLIC AROMATIC HYDROCARBONS WITH EXCESS PERIPHERAL H ATOMS (H {sub n} -PAHs) AND THEIR RELATION TO THE 3.4 AND 6.9 {mu}m PAH EMISSION FEATURES

    SciTech Connect

    Sandford, Scott A.; Bernstein, Max P.; Materese, Christopher K.

    2013-03-01

    Polycyclic aromatic hydrocarbons (PAHs) are likely responsible for the family of infrared emission features seen in a wide variety of astrophysical environments. A potentially important subclass of these materials are PAHs whose edges contain excess H atoms (H {sub n} -PAHs). This type of compound may be present in space, but it has been difficult to assess this possibility because of a lack of suitable laboratory spectra to assist with analysis of astronomical data. We present 4000-500 cm{sup -1} (2.5-20 {mu}m) infrared spectra of 23 H {sub n} -PAHs and related molecules isolated in argon matrices under conditions suitable for interpretation of astronomical data. Spectra of molecules with mixed aromatic and aliphatic domains show characteristics that distinguish them from fully aromatic PAH equivalents. Two major changes occur as PAHs become more hydrogenated: (1) aromatic C-H stretching bands near 3.3 {mu}m weaken and are replaced with stronger aliphatic bands near 3.4 {mu}m, and (2) aromatic C-H out-of-plane bending mode bands in the 11-15 {mu}m region shift and weaken concurrent with growth of a strong aliphatic -CH{sub 2}- deformation mode near 6.9 {mu}m. Implications for interpreting astronomical spectra are discussed with emphasis on the 3.4 and 6.9 {mu}m features. Laboratory data is compared with emission spectra from IRAS 21282+5050, an object with normal PAH emission features, and IRAS 22272+5435 and IRAS 0496+3429, two protoplanetary nebulae with abnormally large 3.4 {mu}m features. We show that 'normal' PAH emission objects contain relatively few H {sub n} -PAHs in their emitter populations, but less evolved protoplanetary nebulae may contain significant abundances of these molecules.

  12. The Infrared Spectra of Polycyclic Aromatic Hydrocarbons with Excess Peripheral H Atoms (H(sub n)-PAHs) and their Relation to the 3.4 and 6.9 Micrometer PAH Emission Features

    NASA Technical Reports Server (NTRS)

    Sandford, Scott A.; Bernstein, Max P.; Materese, Christopher K.

    2013-01-01

    A population of polycyclic aromatic hydrocarbons (PAHs) and related materials are thought to be responsible for the family of infrared emission features that are seen towards a wide variety of astrophysical environments. A potentially important subclass of these materials are polycyclic aromatic hydrocarbons whose edges contain excess H atoms (H(sub n)-PAHs). While it has been suggested that this type of compound may be present in the interstellar population, it has been difficult to properly assess this possibility because of a lack of suitable infrared laboratory spectra to assist with analysis of the astronomical data. We present the 4000-500 cm(exp -1) (2.5-20 micrometers) infrared spectra of 23 H(sub n)-PAHs and related molecules isolated in argon matrices, under conditions suitable for use in the interpretation of astronomical data. The spectra of molecules with mixed aromatic and aliphatic domains show unique characteristics that distinguish them from their fully aromatic PAH equivalents. We discuss the changes to the spectra of these types of molecules as they transition from fully aromatic to fully aliphatic forms. The implications for the interpretation of astronomical spectra are discussed with specific emphasis on the 3.4 and 6.9 micrometer features. Laboratory data is compared with emission spectra from IRAS 21282+5050, an object with normal PAH emission features, in addition to IRAS 22272+5435 and IRAS 0496+3429, two protoplanetary nebulae with abnormally large 3.4 micrometer features. We show that 'normal' PAH emission objects contain relatively few H(sub n)-PAHs in their emitter populations, but less evolved protoplanetary nebulae may contain significant abundances of these molecules.

  13. Evaluation of the temporal profiles and the analytical features of a laser ablation - Pulsed glow discharge coupling for optical emission spectrometry

    NASA Astrophysics Data System (ADS)

    González de Vega, Claudia; Bordel, Nerea; Pereiro, Rosario; Sanz-Medel, Alfredo

    2016-07-01

    The coupling of a glow discharge (GD) in pulsed mode (PGD) as secondary source for excitation/ionization of the material provided by laser ablation (LA) has been investigated using optical emission spectrometry (OES). The variation of the laser pulse delay with respect to the GD pulse allows to producing the ablation process during prepeak, plateau or afterglow GD regions. Emission properties of the LA-PGD plasma in each temporal region of the GD pulse have been evaluated for analytical lines of different elements. Resonant atomic lines have shown higher emission intensity in the prepeak region compared to non-resonant lines. Non-resonant lines showed higher enhancement of the emission intensity in the afterglow region. Moreover, the coupled LA-PGD system offered better linear correlation coefficients using a set of glass standards for calibration as well as lower detection limits (by at least a factor of two) when compared to laser induced breakdown spectroscopy.

  14. Possible identifications of the 3.4 micrometer feature

    NASA Technical Reports Server (NTRS)

    Danks, Anthony C.; Lambert, D. L.

    1988-01-01

    A feature at 3.4 micrometer was first detected in Comet Halley by the IKS spectrometer on board the Vega 1 probe; and subsequently from the ground. The feature has since been reported in Comet Wilson. The presence of the feature is of considerable interest for a number of reasons. First, it may represent the detection of a new parent molecule, and when combined with data from Giotto and Vega yield new information on cometary chemistry and the early solar system composition. Secondly, it may represent a link to the interstellar medium, the feature corresponds in wavelength and shape with an interstellar feature seen in absorption in a luminous star, towards the Galactic center known as GC-IRS7. The feature in turn is thought to be related with a growing family of unidentified infrared emission features seen in stellar objects, planetary nebulae, reflection nebulae, HII regions and extra galactic sources. These features occur at wavelengths 3.3, 3.4, 3.5, 6.2, 7.7, 8.6, and 11.25 micrometers. Further identification theory is given.

  15. IR imaging simulation and analysis for aeroengine exhaust system based on reverse Monte Carlo method

    NASA Astrophysics Data System (ADS)

    Chen, Shiguo; Chen, Lihai; Mo, Dongla; Shi, Jingcheng

    2014-11-01

    The IR radiation characteristics of aeroengine are the important basis for IR stealth design and anti-stealth detection of aircraft. With the development of IR imaging sensor technology, the importance of aircraft IR stealth increases. An effort is presented to explore target IR radiation imaging simulation based on Reverse Monte Carlo Method (RMCM), which combined with the commercial CFD software. Flow and IR radiation characteristics of an aeroengine exhaust system are investigated, which developing a full size geometry model based on the actual parameters, using a flow-IR integration structured mesh, obtaining the engine performance parameters as the inlet boundary conditions of mixer section, and constructing a numerical simulation model of engine exhaust system of IR radiation characteristics based on RMCM. With the above models, IR radiation characteristics of aeroengine exhaust system is given, and focuses on the typical detecting band of IR spectral radiance imaging at azimuth 20°. The result shows that: (1) in small azimuth angle, the IR radiation is mainly from the center cone of all hot parts; near the azimuth 15°, mixer has the biggest radiation contribution, while center cone, turbine and flame stabilizer equivalent; (2) the main radiation components and space distribution in different spectrum is different, CO2 at 4.18, 4.33 and 4.45 micron absorption and emission obviously, H2O at 3.0 and 5.0 micron absorption and emission obviously.

  16. Kinematic structure of OH/IR stars

    NASA Astrophysics Data System (ADS)

    Sun, J.; Kwok, S.

    1987-10-01

    A kinematic model is constructed for 1612 MHz OH maser emssion in OH/IR stars. The spatial distributions of OH maser intensity are calculated from a model of spherically-symmetric uniformly-expanding circumstellar shell. By comparing VLA/VLBI maps of OH/IR stars with model results, the acceptable range of combination of physical parameters M/Ve, (nH2)max, (nH2)min, fOH = [nOH]/[nH2] are derived. The theoretical relations between OH shell radius R0 and mass loss rate Mand between OH maser luminosity LOH and Mare also obtained. These relations are in good agreement with empirical relations established by Bowers et al. (1983) and Baud et al. (1983). The ranges of (nH2)max and (nOH)min under different Mrequired for operating saturated 1612 MHz OH masers are also discussed. The authors find that the OH emission phase can last over 1000 years after the termination of the asymptotic giant branch and many protoplanetary nebulae may have the characteristics of OH/IR stars.

  17. IR DIAL performance modeling

    SciTech Connect

    Sharlemann, E.T.

    1994-07-01

    We are developing a DIAL performance model for CALIOPE at LLNL. The intent of the model is to provide quick and interactive parameter sensitivity calculations with immediate graphical output. A brief overview of the features of the performance model is given, along with an example of performance calculations for a non-CALIOPE application.

  18. Thermal Properties of Unusual Local-Scale Features on Vesta

    NASA Technical Reports Server (NTRS)

    Capria, M.; DeSanctis, M.; Palomba, E.; Grassi, D.; Capaccioni, F.; Ammannito, E.; Combe, J.; Sunshine, J. M.; Titus, T. N.; Mittlefehldt, D. W.; Li, J.; Russell, C. T.; Raymond, C. A.

    2012-01-01

    On Vesta, the thermal behavior of areas of unusual albedo seen at the local scale can be related to physical properties that can provide information about the origin of those materials. We used Dawn s Visible and Infrared Mapping Spectrometer (VIR) hyperspectral cubes to retrieve surface temperatures and emissivities, with high accuracy as long as temperatures are greater than 180 K. Data acquired in the Survey phase (23 July through 29 August 2011) show several unusual surface features: 1) high-albedo (bright) and low-albedo (dark) material deposits, 2) spectrally distinct ejecta and pitted materials, 3) regions suggesting finer-grained materials. Some of the unusual dark and bright features were reobserved by VIR in the subsequent High-Altitude Mapping Orbit (HAMO) and Low- Altitude Mapping Orbit (LAMO) phases at increased pixel resolution. In this work we present temperature maps and emissivities of several local-scale features that were observed by Dawn under different illumination conditions and different local solar times. Data from VIR's IR channel show that bright regions generally correspond to regions with lower thermal emission, i.e. lower temperature, while dark regions correspond to areas with higher thermal emission, i.e. higher temperature. This behavior confirms that many of the dark appearances in the VIS mainly reflect albedo variations, and not, for example, shadowing. During maximum daily insolation, dark features in the equatorial region may rise to temperatures greater than 270 K, while brightest features stop at roughly 258 K, local solar time being similar. However, pitted materials, showing relatively low reflectance, have significantly lower temperatures, as a result of differences in composition and/or structure (e.g, average grain size of the surface regolith, porosity, etc.). To complement this work, we provide preliminary values of thermal inertia for some bright and dark features.

  19. IDENTIFICATION OF THREE NEW PROTOPLANETARY NEBULAE EXHIBITING THE UNIDENTIFIED FEATURE AT 21 {mu}m

    SciTech Connect

    Cerrigone, Luciano; Hora, Joseph L.; Hart, Alexa; Fazio, Giovanni; Umana, Grazia; Trigilio, Corrado E-mail: jhora@cfa.harvard.edu E-mail: gfazio@cfa.harvard.edu E-mail: corrado.trigilio@oact.inaf.it

    2011-09-10

    Among its great findings, the Infrared Astronomical Satellite mission showed the existence of an unidentified mid-IR feature around 21 {mu}m. Since its discovery, this feature has been detected in all C-rich protoplanetary nebulae (PPNe) of intermediate spectral type (F-G) and-weakly-in a few PNe and asymptotic giant branch (AGB) stars, but the nature of its carriers remains unknown. In this paper, we show the detection of this feature in the spectra of three new stars transiting from the AGB to the PN stage obtained with the Spitzer Space Telescope. Following a recent suggestion, we try to model the spectral energy distributions of our targets with amorphous carbon and FeO, which might be responsible for the unidentified feature. The fit thus obtained is not completely satisfactory, since the shape of the feature is not well matched. In an attempt to relate the unidentified feature to other dust features, we retrieved mid-IR spectra of all 21 {mu}m sources currently known from Infrared Space Observatory and Spitzer online archives and noticed a correlation between the flux emitted in the 21 {mu}m feature and that emitted at 7 and 11 {mu}m (polycyclic aromatic hydrocarbon bands and hydrogenated amorphous carbon broad emission). Such a correlation may point to a common nature of the carriers.

  20. Spitzer-IRS Spectroscopic Studies of the Properties of Dust from Oxygen-Rich Asymptotic Giant Branch and Red Supergiant Stars

    NASA Astrophysics Data System (ADS)

    Sargent, Benjamin A.; Speck, A.; Volk, K.; Kemper, C.; Reach, W. T.; Lagadec, E.; Bernard, J.; McDonald, I.; Meixner, M.; Srinivasan, S.

    2014-01-01

    We analyze the dust emission features seen in Spitzer Space Telescope Infrared Spectrograph (IRS) spectra of Oxygen-rich (O-rich) asymptotic giant branch (AGB) and red supergiant (RSG) stars. The spectra come from the Spitzer Legacy program SAGE-Spectroscopy (PI: F. Kemper) and other archival Spitzer-IRS programs. The broad 10 and 20 micron emission features attributed to amorphous dust of silicate composition seen in the spectra show evidence for systematic differences in the centroid of both emission features between O-rich AGB and RSG populations. Radiative transfer modeling using the GRAMS grid of models of AGB and RSG stars suggests that the centroid differences are due to differences in dust properties. We investigate differences in dust composition, size, shape, etc that might be responsible for these spectral differences. We explore how these differences may arise from the different circumstellar environments around RSG and O-rich AGB stars. BAS acknowledges funding from NASA ADAP grant NNX13AD54G.

  1. Enhanced photophysics from self-assembled cyclometalated Ir(iii) complexes in water.

    PubMed

    McGoorty, Michelle M; Khnayzer, Rony S; Castellano, Felix N

    2016-06-14

    Two water-soluble anionic cyclometalated Ir(iii) complexes, Ir(ppy)2BPS [] and Ir(F-mppy)2BPS [] have been synthesized and display clear evidence of self-assembly in water. Concentration-induced aggregation enhances the excited-state properties of both complexes, blue-shifting the photoluminescence emission energies as well as increasing the corresponding excited state lifetimes and quantum yields up to a factor of 5. PMID:27240481

  2. The IR properties of ringed galaxies and the IRAS database

    NASA Technical Reports Server (NTRS)

    Buta, Ronald J.; Crocker, Deborah A.

    1993-01-01

    Our study of the Infrared Astronomy Satellite (IRAS) properties of ringed galaxies has been largely successful. We have identified what we think is the probable cause of the differences in the IRAS properties among non-interacting barred galaxies as the pattern speed of the bar. The key to identifying this parameter has been our focusing the study on outer-ringed galaxies where we know precisely what is present in the central regions (from available BVI CCD images in our library of images). The theory is that outer rings, through their morphology and other characteristics, can be identified with the outer Lindblad resonance, one of the major resonances in galaxy structure. Using a library of n-body simulations for comparison, we can reliably infer both low and high pattern speed galaxies from the appearance of outer rings and the existence of other ring features. It is clear that in some barred galaxies, the bar pattern speed is high enough to avoid an inner Lindblad resonance, hence such objects do not contain nuclear or circumnuclear star formation. The IRAS observations are most sensitive to nuclear star formation in early-type barred galaxies, and will thus select those barred galaxies where the pattern speed is low enough to allow an inner Lindblad resonance to exist. High pattern speed barred galaxies therefore weaken the correlation between bars and infrared excess. This finding helps to reconcile the inconsistent results found between different studies on the correlation between bars and far-IR emission.

  3. A three-field IR telescope

    NASA Astrophysics Data System (ADS)

    Barron, D. R.

    1986-01-01

    High performance confidence is now obtainable in thermal imaging telescopes with complex optomechanical layouts, in virtue of recent advancements in germanium surfaces' diamond turning and computer-aided mechanical design. Attention is presently given to the specifications, optical configuration and mechanical design features of a three-field IR telescope employing aspheric surfaces, which would be suitable for parent vehicle guidance, target acquisition, and target identification tasks. Dramatic weight and cost reductions are noted to be achievable through the use of mechanical modelling to ensure the most essential application of metalworking operations.

  4. Mid-IR Ultra-Deep Spectroscopy of the Cosmic Infrared Background

    NASA Astrophysics Data System (ADS)

    Yan, Lin; Bertoldi, Frank; Blain, Andrew; Caputi, Karina; Cesarsky, Catherine; Dole, Herve; Draine, Bruce; Fadda, Dario; Flores, Hector; Frayer, Dave; Genzel, Reinhard; Helou, George; Lagache, Guilaine; Le Floc'h, Emeric; Lutz, Dieter; Puget, Jean-Loup; Sajina, Anna; Sanders, Dave; Spoon, Henrik; Veilleux, Sylvain

    2006-05-01

    We propose to obtain low resolution, mid-IR spectra of a sample of 48 galaxies at z~1 and 2 with 24um flux densities between 0.15-0.5mJy in the CDFS. These sub-mJy 24um sources are shown to dominate the Cosmic Infrared Background (CIB) emission at 70 & 160um (Dole et al. 2006). Their redshift distribution peaks around 1, with a secondary peak at z~2. This implies these sources are LIRGs and ULIRGs at z=1 and 2, respectively. Measurements of IR luminosity functions support these findings and directly show these populations are responsible for more than 70% of the total (UV+IR) luminosity density at z=0.8-2.5. The proposed program is the natural extension of our previous studies of brighter, mJy 24um galaxies. Our primary goal is to characterize the mid-IR spectral properties of the galaxies producing the bulk of CIB. Specifically, we will disentangle the AGN/SB contribution to mid-IR emission, thus constrain the estimate of bolometric luminosities. The proposed spectra, in combination with brighter samples from previous IRS surveys, will allow us to trace the evolution of AGN/SB ratio, strength of PAH emission and mid-IR opacities as a function of L(ir) and z. The deep mid-IR spectra, together with the existing multi-wavelength dataset, will provide the lasting legacy for the astronomical communities for many years to come.

  5. Ultrafast 2D IR microscopy

    PubMed Central

    Baiz, Carlos R.; Schach, Denise; Tokmakoff, Andrei

    2014-01-01

    We describe a microscope for measuring two-dimensional infrared (2D IR) spectra of heterogeneous samples with μm-scale spatial resolution, sub-picosecond time resolution, and the molecular structure information of 2D IR, enabling the measurement of vibrational dynamics through correlations in frequency, time, and space. The setup is based on a fully collinear “one beam” geometry in which all pulses propagate along the same optics. Polarization, chopping, and phase cycling are used to isolate the 2D IR signals of interest. In addition, we demonstrate the use of vibrational lifetime as a contrast agent for imaging microscopic variations in molecular environments. PMID:25089490

  6. Inferring the evolutionary stages of the internal structures of NGC 7538 S and IRS1 from chemistry

    NASA Astrophysics Data System (ADS)

    Feng, S.; Beuther, H.; Semenov, D.; Henning, Th.; Linz, H.; Mills, E. A. C.; Teague, R.

    2016-09-01

    .g. NH2CHO, CH3OH, HCOOCH3, CH3OCH3), indicating that IRS1 is the most chemically evolved HMC presented here. We observe a continuum that is dominated by absorption features with at least three strong emission lines, potentially from CH3OH. The CH3OH lines which are purely in emission have higher excitation than the ones being purely in absorption. Potential reasons for this difference are discussed. Conclusions: This is the first comprehensive comparison of observations of the two high-mass cores NGC 7538 S and IRS1 and a chemical model. We have found that different chemical evolutionary stages can coexist in the same natal gas core. Our achievement illustrates the strength of chemical analysis for understanding HMSFRs.

  7. Qualification of security printing features

    NASA Astrophysics Data System (ADS)

    Simske, Steven J.; Aronoff, Jason S.; Arnabat, Jordi

    2006-02-01

    This paper describes the statistical and hardware processes involved in qualifying two related printing features for their deployment in product (e.g. document and package) security. The first is a multi-colored tiling feature that can also be combined with microtext to provide additional forms of security protection. The color information is authenticated automatically with a variety of handheld, desktop and production scanners. The microtext is authenticated either following magnification or manually by a field inspector. The second security feature can also be tile-based. It involves the use of two inks that provide the same visual color, but differ in their transparency to infrared (IR) wavelengths. One of the inks is effectively transparent to IR wavelengths, allowing emitted IR light to pass through. The other ink is effectively opaque to IR wavelengths. These inks allow the printing of a seemingly uniform, or spot, color over a (truly) uniform IR emitting ink layer. The combination converts a uniform covert ink and a spot color to a variable data region capable of encoding identification sequences with high density. Also, it allows the extension of variable data printing for security to ostensibly static printed regions, affording greater security protection while meeting branding and marketing specifications.

  8. Spitzer IRS Observations of Uranus and Neptune: Implications for Temperature Structure and Composition

    NASA Astrophysics Data System (ADS)

    Orton, Glenn; Fletcher, Leigh; Hines, Dean; Hammel, Heidi; Burgdorf, Martin; Merlet, Cecile; Line, Michael; Moses, Julianne

    We overview the results of the sensitive Spitzer Infrared Spectrometer (IRS) on the atmospheres of Uranus and Neptune, covering in some detail the observations of Uranus shortly after its equinox. IRS observations of Neptune in the Spitzer cycles 1 and 2 and Uranus in Cycle 1 and DD time near its equinox (2007 December 17) used the IRS in several modes. The low-resolution (R 90) spectral modes covered wavelengths between 5 and 21.5 microns, and its high-resolution (R 600) modes covered wavelengths between 10 and 36.5 microns. Spectral features arising from methane, ethane, acetylene, diacetylene and methylacetylene are easily detectable in both planets, and features of CH3 were detected for Neptune. For Uranus, sufficient coverage of the spectrum which is dominated by the opacity provided by the collision-induced absorption of molecular hydrogen allowed disk-averaged temperatures to be determined between 100 and 600 mbar pressure. An upward extension of this coverage to the lower stratosphere was facilitated by matching discrete hydrogen quadrupole S(1) and S(2) lines, which also provided constraints on the para-vs. ortho-hydrogen ratio. These constraints were merged with those at lower pressures derived from Voyager-2 occultation experiments. Regular and deuterated methane absorption and emission are consistent with vapor-pressure-limited mixing of methane in the stratosphere, an upper-tropospheric abundance which is 40 percent of its fully saturated value, and a D/H ratio consistent with one derived from earlier measurements by ISO. Observations of the disk-averaged spectrum over different longitudes imply substantial spatial variability of stratospheric temperatures at pressures below 1 mbar, but no variability above the 3 percent noise level of the spectra for deeper levels. These spectra are consistent with the somewhat noisier Cycle-1 observations taken on 6-7 July 2005.

  9. Evolution of Hot Dust Emission in z>6 Quasars

    NASA Astrophysics Data System (ADS)

    Fan, Xiaohui; Brandt, Niel; Carilli, Chris; Hines, Dean; Jiang, Linhua; Meisenheimer, Klaus; Richards, Gordon; Strauss, Michael; Walter, Fabian; Wang, Ran

    2007-05-01

    Strong hot dust emission from dust torus surrounding the central engine is an ubiquitous feature among Type-1 quasars at low redshift. In our previous GTO and GO-1 Spitzer programs, we observed a sample of quasars at 4emission at 24 micron, two objects at z~6 have extremely weak IR emission with SEDs consistent with power-law or pure disk emission without hot dust contribution. These two quasars also have the smallest black hole (BH) masses and highest Eddington ratios among z~6 quasars, indicative of short BH growth timescale. These observations suggest possible evolution in either dust torus structure or dust properties of quasars at the earliest epoch, constrained by both BH/AGN growth and timescale of dust formation in AGB envelops. In Cycle 4 we propose to carry out IRAC, IRS PUI 16 micron and MIPS 24 micron imaging of a sample of 9 new quasars at z>6 discovered in the last three years. The new observations will more than double the Spitzer sample size at z>6. All objects have excellent multiwavelength data, with BH mass estimates based on broad emission line width, and are GTO targets for Herschel at far-IR. With the combined Cycle 1/4 sample, we will (a) measure the fraction of quasars without hot dust emission at early epoch; (b) test the relation between hot dust properties and emission line properties, BH masses and accretion rates in quasars; (c) improve quasar IR SED measurements at z>6, and (d) probe the relation between hot and warm/cool dust traced by Herschel and sub/mm observations. In particular, three quasars in our new sample have similar emission line and BH properties to the two IR-weak quasars we found previously. We predict that they are likely candidates of new dust-deficient quasars at z>6.

  10. Light on the 3 μm Emission Band from Space with Molecular Beam Spectroscopy

    NASA Astrophysics Data System (ADS)

    Maltseva, Elena; Mackie, Cameron J.; Candian, Alessandra; Petrignani, Annemieke; Tielens, Xander; Oomens, Jos; Huang, Xinchuan; Lee, Timothy; Buma, Wybren Jan

    2016-06-01

    The majority of interstellar objects shows IR emission features also known as unidentified infrared (UIR) emission bands. These UIR bands are attributed to IR emission of highly-excited gaseous polycyclic aromatic hydrocarbons (PAHs). To understand the physical conditions and chemical evolution of the interstellar environment a precise identification of the emission carriers is desired. The 3 μm UIR feature is represented by a strong band at 3040 cm-1, a plateau from 3150 to 2700 cm-1 and a number of weak features within this plateau. The 3040 cm-1 component is assigned to fundamental CH-stretch vibrations of PAHs, but there still remain many questions on the origin of the other features. In this work we have studied experimentally the 3 μm region of regular, hydrogenated and methylated PAHs (up to 5 rings), combining molecular beam techniques with IR-UV ion dip spectroscopy, and theoretically by density functional theory (DFT) calculations within the harmonic and anharmonic approximation. We find that (a) the 3 μm region of PAHs is dominated by Fermi resonances and thereby cannot be treated within the harmonic approximation; (b) the periphery structure of the molecules strongly affects the shape of the 3 μm band. In particular, the two-component emission interpretation can be explained by the presence of molecules with and without bay-hydrogens; (c) due to strong Fermi resonances of fundamental modes with combination bands regular PAHs can significantly contribute to the 3 μm plateau in the 3150-2950 cm-1, while hydrogenated and methylated species are primarily responsible for features in the 2950-2750 cm-1 region.

  11. Comparison of Spitzer/IRAC Galactic Center Mid-IR Survey Results with X-ray and Radio Emission Due to High-Energy Processes in the Central 100 Parsecs

    NASA Technical Reports Server (NTRS)

    Gezari, D. Y.; Arendt, R. A.; Smith, R.; Yusef-Zadeh, F.; Stolovy, S.; Law, C.; Smith, H. A.; Moseley, Harvey; Ramirez, S.; Karr, J.

    2006-01-01

    We compare the results of a small region from our 3.6 - 8.0 micron Spitzer/IRAC imaging survey of 2 x 1.5 deg around the Galactic Center with x-ray and radio emission due to high energy processes. The region we studied covers 100 x 100 parsecs, and was chosen to include a rich collection of sources, including Sgr A* and the bright Sgr AWest infrared/radio source complex, the non-thermal radio filaments and the thermal: radio arches. In a 40 x 40 parsec subset of that region we also make a preliminary analysis of the correlation between approx.2300 x-ray sources identified by Muno et al. (2003) and 20,000 infrared sources from our survey. We also investigate the correlation between infrared and radio emission in the large-scale structures including the thermal radio arches and non-thermal radio filaments. We set constrictions on the synchrotron spectrum observed at radio and millimeter wavelengths extrapolated to 8 micons, and set limits on the midinfrared variability of Sgr A* during and after the coordinated multi-wavelength observing campaign in September 2004.

  12. Time-resolved UV-IR pump-stimulated emission pump spectroscopy to probe collisional relaxation of the 8p2P3/2 state of Cs I

    NASA Astrophysics Data System (ADS)

    Salahuddin, Mohammed; Arndt, Phill; McFarland, Jacob; Bayram, S. Burçin

    2015-12-01

    We describe and use a time-resolved pump-stimulated emission pump spectroscopic technique to measure collisional relaxation in a high-lying energy level of atomic cesium. Aligned 8p2P3/2 cesium atoms were produced by a pump laser. A second laser, the stimulated emission pump, promoted the population exclusively to the 5d2D5/2 level. The intensity of the 5 d 5/2 2 D → 6 s 1/2 2S cascade fluorescence at 852.12 nm was monitored. The linear polarization dependence of the 6 s 1/2 2S → 8 p 3/2 2P → 5 d 5/2 2S transition was measured in the presence of argon gas at various pressures. From the measurement, we obtained the disalignment cross sectional value for the 8p2P3/2 level due to collisions with ground-level argon atoms.

  13. Intensity of visible and IR emission of intracenter 4 f transitions of RE ions in Er- and Tm-doped ZnO films with additional Ag, Li, and N impurities

    NASA Astrophysics Data System (ADS)

    Mezdrogina, M. M.; Vinogradov, A. Ya.; Eremenko, M. V.; Levitskii, V. S.; Terukov, E. I.; Kozhanova, Yu. V.

    2016-08-01

    The use of Ag impurity in Er-doped ZnO films deposited by AC magnetron sputtering with a low growth rate has increased the emission intensity at λ = 1535-1540 nm. An increase in the deposition rate and in the temperature of substrates, as well as the use of Li and N+ impurities, led to a considerable increase in the intensity of the line with λ = 376-379 nm in the case of doping with rare-earth ions (Er, Tm), which makes it possible to use this semiconductor for creation of devices for the short-wavelength spectral region. Introduction of additional impurities in Er-doped ZnO films deposited on bulk ZnO crystals with increasing deposition rate and temperature caused an increase in the intensity of the line with λ = 1535-1540 nm. The photoluminescence spectra of ZnO films doped with Tm (ZnO) exhibited intense emission of lines with λmax = 377 nm.

  14. Optical/IR from ground

    NASA Technical Reports Server (NTRS)

    Strom, Stephen; Sargent, Wallace L. W.; Wolff, Sidney; Ahearn, Michael F.; Angel, J. Roger; Beckwith, Steven V. W.; Carney, Bruce W.; Conti, Peter S.; Edwards, Suzan; Grasdalen, Gary

    1991-01-01

    Optical/infrared (O/IR) astronomy in the 1990's is reviewed. The following subject areas are included: research environment; science opportunities; technical development of the 1980's and opportunities for the 1990's; and ground-based O/IR astronomy outside the U.S. Recommendations are presented for: (1) large scale programs (Priority 1: a coordinated program for large O/IR telescopes); (2) medium scale programs (Priority 1: a coordinated program for high angular resolution; Priority 2: a new generation of 4-m class telescopes); (3) small scale programs (Priority 1: near-IR and optical all-sky surveys; Priority 2: a National Astrometric Facility); and (4) infrastructure issues (develop, purchase, and distribute optical CCDs and infrared arrays; a program to support large optics technology; a new generation of large filled aperture telescopes; a program to archive and disseminate astronomical databases; and a program for training new instrumentalists)

  15. Results of IR working group

    SciTech Connect

    Ritson, D. |

    1992-03-01

    The IP luminosity at the Eloisatron will direct very large fluxes of hadronic debris into the IR quads. For instance at 1.10{sup 35} cm{sup 2}/sec the flux corresponds to 180 kilowatts. Already at the SSC fluxes in the neighborhood of 2 kilowatts are expected to require special handling. Scaling from SSC design experience we propose a configuration for the first IR quads at the Eloisatron capable of handling the heat load and radiation problems.

  16. WFC3 UVIS & IR photometry

    NASA Astrophysics Data System (ADS)

    Deustua, Susana

    2013-10-01

    This program's goals are : A} Monitor the photometric throughput in all WFC3 UVIS and IR filters during Cycle 21 GO programs, measure zeropoints and determine color term corrections. The data provide a monitor of the UVIS/IR flux stability as a function of time, wavelength and source brightness. This is a continuation of Program 13089.B} Monitor effects of contamination in all WFC3 IR filters. This is a continuation of Cy17-Cy20 contamination monitor programs. WFC3 UVIS:Observations of stars GD153 and P330E are obtained in subarrays at each of the four corners of the UVIS imager to monitor changes in the filter transmission in all the UV filters and to provide a monitor for the zeropoints, and color transformation terms2 stars, Amps B & CWFC3 IR: Observations of GD153 and P330E are obtained in subarray mode for all IR filters 2 stars, subarray mode, 1 orbit each, interleaved with observations of GRW+70Observations of GRW+70 are obtained in subarray mode for all IR filters1 star, subarray mode, 2 orbits separated by 6 months.Orbits required: 17 orbits for zeropoints, 2 orbits for contamination monitor.

  17. VLT near- to mid-IR imaging and spectroscopy of the M 17 UC1 - IRS5 region

    NASA Astrophysics Data System (ADS)

    Chen, Zhiwei; Nürnberger, Dieter E. A.; Chini, Rolf; Jiang, Zhibo; Fang, Min

    2015-06-01

    Aims: We investigate the surroundings of the hypercompact H ii region M 17 UC1 to probe the physical properties of the associated young stellar objects and the environment of massive star formation. Methods: We use diffraction-limited near-IR (VLT/NACO) and mid-IR (VLT/VISIR) images to reveal the different morphologies at various wavelengths. Likewise, we investigate the stellar and nebular content of the region with VLT/SINFONI integral field spectroscopy with a resolution R ˜ 1500 at H + K bands. Results: Five of the seven point sources in this region show L-band excess emission. A geometric match is found between the H2 emission and near-IR polarized light in the vicinity of IRS5A, and between the diffuse mid-IR emission and near-IR polarization north of UC1. The H2 emission is typical for dense photodissociation regions (PDRs), which are initially far-ultraviolet pumped and repopulated by collisional de-excitation. The spectral types of IRS5A and B273A are B3-B7 V/III and G4-G5 III, respectively. The observed infrared luminosity LIR in the range 1-20 μm is derived for three objects; we obtain 2.0 × 103 L⊙ for IRS5A, 13 L⊙ for IRS5C, and 10 L⊙ for B273A. Conclusions: IRS5 might be a young quadruple system. Its primary star IRS5A is confirmed to be a high-mass protostellar object (˜9 M⊙, ˜1 × 105 yrs); it might have terminated accretion due to the feedback from stellar activities (radiation pressure, outflow) and the expanding H ii region of M 17. The object UC1 might also have terminated accretion because of the expanding hypercompact H ii region, which it ionizes. The disk clearing process of the low-mass young stellar objects in this region might be accelerated by the expanding H ii region. The outflows driven by UC1 are running south-north with its northeastern side suppressed by the expanding ionization front of M 17; the blue-shifted outflow lobe of IRS5A is seen in two types of tracers along the same line of sight in the form of H2 emission

  18. Basaltic Crater in Color IR

    NASA Technical Reports Server (NTRS)

    2004-01-01

    [figure removed for brevity, see original site]

    Released August 6, 2004 This image shows two representations of the same infra-red image near Nili Fosse in the the Isidis region of Mars. On the left is a grayscale image showing surface temperature, and on the right is a false-color composite made from 3 individual THEMIS bands. The false-color image is colorized using a technique called decorrelation stretch (DCS), which emphasizes the spectral differences between the bands to highlight compositional variations. In many cases craters trap sand in their topographic depressions, interrupting the sand's migration across the Martian surface. This image is particularly interesting because there appears to be more than 1 type of sand in the bottom of this crater and in the hummocky terrain near the bottom of the image. The pink/magenta areas are characteristic of a basaltic composition, but there are also orange areas that are likely caused by the presence of andesite. These two compositions, basalt and andesite, are some of the most common found on Mars.

    Image information: IR instrument. Latitude 24, Longitude 80.7 East (297.3 West). 100 meter/pixel resolution.

    Note: this THEMIS visual image has not been radiometrically nor geometrically calibrated for this preliminary release. An empirical correction has been performed to remove instrumental effects. A linear shift has been applied in the cross-track and down-track direction to approximate spacecraft and planetary motion. Fully calibrated and geometrically projected images will be released through the Planetary Data System in accordance with Project policies at a later time.

    NASA's Jet Propulsion Laboratory manages the 2001 Mars Odyssey mission for NASA's Office of Space Science, Washington, D.C. The Thermal Emission Imaging System (THEMIS) was developed by Arizona State University, Tempe, in collaboration with Raytheon Santa Barbara Remote Sensing. The THEMIS investigation is led by Dr. Philip

  19. Atmospheric Effects in IR Color

    NASA Technical Reports Server (NTRS)

    2004-01-01

    [figure removed for brevity, see original site]

    Released August 3, 2004 This image shows two representations of the same infra-red image covering parts of Ius Chasma and Oudemans Crater. On the left is a grayscale image showing surface temperature, and on the right is a false-color composite made from 3 individual THEMIS bands. The false-color image is colorized using a technique called decorrelation stretch (DCS), which emphasizes the spectral differences between the bands to highlight compositional variations.

    This image is dominated by atmospheric effects. The pink/magenta colors inside the canyon show areas with a large amount of atmospheric dust. In the bottom half of the image, the patchy blue/cyan colors indicate the presence of water ice clouds out on the plains. Water ice clouds and high amounts of dust do not generally occur at the same place and time on Mars because the dust absorbs sunlight and heats the atmosphere. The more dust that is present, the warmer the atmosphere becomes, sublimating the water ice into water vapor and dissipating any clouds.

    Image information: IR instrument. Latitude -8.2, Longitude 267.9 East (92.1.West). 100 meter/pixel resolution.

    Note: this THEMIS visual image has not been radiometrically nor geometrically calibrated for this preliminary release. An empirical correction has been performed to remove instrumental effects. A linear shift has been applied in the cross-track and down-track direction to approximate spacecraft and planetary motion. Fully calibrated and geometrically projected images will be released through the Planetary Data System in accordance with Project policies at a later time.

    NASA's Jet Propulsion Laboratory manages the 2001 Mars Odyssey mission for NASA's Office of Space Science, Washington, D.C. The Thermal Emission Imaging System (THEMIS) was developed by Arizona State University, Tempe, in collaboration with Raytheon Santa Barbara Remote Sensing. The THEMIS investigation is

  20. External-Cavity Quantum Cascade Laser Spectroscopy for Mid-IR Transmission Measurements of Proteins in Aqueous Solution.

    PubMed

    Alcaráz, Mirta R; Schwaighofer, Andreas; Kristament, Christian; Ramer, Georg; Brandstetter, Markus; Goicoechea, Héctor; Lendl, Bernhard

    2015-07-01

    In this work, we report mid-IR transmission measurements of the protein amide I band in aqueous solution at large optical paths. A tunable external-cavity quantum cascade laser (EC-QCL) operated in pulsed mode at room temperature allowed one to apply a path length of up to 38 μm, which is four times larger than that applicable with conventional FT-IR spectrometers. To minimize temperature-induced variations caused by background absorption of the ν2-vibration of water (HOH-bending) overlapping with the amide I region, a highly stable temperature control unit with relative temperature stability within 0.005 °C was developed. An advanced data processing protocol was established to overcome fluctuations in the fine structure of the emission curve that are inherent to the employed EC-QCL due to its mechanical instabilities. To allow for wavenumber accuracy, a spectral calibration method has been elaborated to reference the acquired IR spectra to the absolute positions of the water vapor absorption bands. Employing this setup, characteristic spectral features of five well-studied proteins exhibiting different secondary structures could be measured at concentrations as low as 2.5 mg mL(-1). This concentration range could previously only be accessed by IR measurements in D2O. Mathematical evaluation of the spectral overlap and comparison of second derivative spectra confirm excellent agreement of the QCL transmission measurements with protein spectra acquired by FT-IR spectroscopy. This proves the potential of the applied setup to monitor secondary structure changes of proteins in aqueous solution at extended optical path lengths, which allow experiments in flow through configuration.

  1. THE 3-5 {mu}m SPECTRUM OF NGC 1068 AT HIGH ANGULAR RESOLUTION: DISTRIBUTION OF EMISSION AND ABSORPTION FEATURES ACROSS THE NUCLEAR CONTINUUM SOURCE

    SciTech Connect

    Geballe, T. R.; Mason, R. E.; Rodriguez-Ardila, A.; Axon, D. J.

    2009-08-20

    We report moderate resolution 3-5 {mu}m spectroscopy of the nucleus of NGC 1068 obtained at 0.''3 (20 pc) resolution with the spectrograph slit aligned approximately along the ionization cones of the active galactic nucleus. The deconvolved full width at half-maximum of the nuclear continuum source in this direction is 0.''3. Four coronal lines of widely different excitations were detected; the intensity of each peaks near radio knot C, approximately 0.''3 north of the infrared continuum peak, where the radio jet changes direction. Together with the broadened line profiles observed near that location, this suggests that shock ionization is the dominant excitation mechanism of the coronal lines. The depth of the 3.4 {mu}m hydrocarbon absorption is maximum at and just south of the continuum peak, similar to the 10 {mu}m silicate absorption. That and the similar and rapid variations of the optical depths of both features across the nucleus suggest that substantial portions of both arise in a dusty environment just in front of the continuum source(s). A new and tighter limit is set on the column density of CO. Although clumpy models of the dust screen might explain the shallowness of the silicate feature, the presence of the 3.4 {mu}m feature and the absence of CO are strongly reminiscent of Galactic diffuse cloud environments and a consistent explanation for them and the observed silicate feature is found if all three phenomena occur in such an environment, existing as close as 10 pc to the central engine.

  2. CO excitation in four IR luminous galaxies

    NASA Technical Reports Server (NTRS)

    Radford, Simon J. E.; Solomon, P. M.; Downes, Dennis

    1990-01-01

    The correlation between the CO and far infrared luminosities of spiral galaxies is well established. The luminosity ration, L sub FIR/L sub CO in IR luminous active galaxies is, however, systematically five to ten times higher than in ordinary spirals and molecular clouds in our Galaxy. Furthermore, the masses of molecular hydrogen in luminous galaxies are large, M (H2) approx. equals 10(exp 10) solar magnitude, which indicates the observed luminosity ratios are due to an excess of infrared output, rather than a deficiency of molecular gas. These large amounts of molecular gas may fuel luminous galaxies through either star formation or nuclear activity. This interpretation rests on applying the M (H2)/L sub CO ratio calibrated in our Galaxy to galaxies with strikingly different luminosity ratios. But are the physical conditions of the molecular gas different in galaxies with different luminosity ratios. And, if so, does the proportionality between CO and H2 also vary among galaxies. To investigate these questions researchers observed CO (2 to 1) and (1 to 0) emission from four luminous galaxies with the Institute for Radio Astronomy in the Millimeter range (IRAM) 30 m telescope. Researchers conclude that most of the CO emission from these Arp 193, Arp 220, and Mrk 231 arises in regions with moderate ambient densities similar to the clouds in the Milky Way molecular ring. The emission is neither from dense hot cloud cores nor from the cold low density gas characteristic of the envelopes of dark clouds.

  3. Optical emission, vibrational feature, and shear-thinning aspect of Tb3+-doped Gd2O3 nanoparticle-based novel ferrofluids irradiated by gamma photons

    NASA Astrophysics Data System (ADS)

    Paul, Nibedita; Hazarika, Samiran; Saha, Abhijit; Mohanta, Dambarudhar

    2013-10-01

    The present work reports on the spectroscopic and rheological properties of un-exposed and gamma (γ-) irradiated rare earth (RE) oxide nanoparticle-based ferrofluids (FFs). The FFs were produced by dispersing surfactant coated terbium (Tb3+)-doped gadolinium oxide (Gd2O3) nanoparticles in the ethanol medium and later on they were subjected to energetic γ-irradiation (1.25 MeV) at select doses (97 Gy and 2.635 kGy). The synthesized RE oxide nanoparticles were of ˜7 nm size and having a cubic crystal structure, as predicted from transmission electron microscopy and x-ray diffraction studies. Fourier transformed infra-red (FT-IR) spectra showed an adequate blue shift of the Gd-O vibrational stretching mode from a wavenumber value of ˜558 cm-1, for the un-irradiated sample to a value of ˜540 cm-1 corresponding to the irradiated sample (2.635 kGy). In contrast, photoluminescence spectra have revealed modification of defect states along with Tb3+ assisted radiative transitions. The rheology measurements have illustrated unusual shear thinning behavior of the FFs, with an apparently improved power index (s) value from 0.34 to 0.50, obtained for increasing γ-dose cases. The variation of the decay parameter with irradiation dose, as predicted from the nature of apparent viscosity curves, is attributed to the defect formation, role of impurity ions (Tb3+), and weakening of inter nanoparticle bonding. The unusual properties of the novel RE oxide based FFs may find scope in sealing and shielding elements in the radiation environment including accelerator and other related zones.

  4. Time features of delayed neutrons and partial emissive-fission cross sections for the neutron-induced fission of {sup 232}Th nuclei in the energy range 3.2-17.9 MeV

    SciTech Connect

    Roshchenko, V. A. Piksaikin, V. M. Korolev, G. G.; Egorov, A. S.

    2010-06-15

    The energy dependence of the relative abundances of delayed neutrons and the energy dependence of the half-lives of their precursors in the neutron-induced fission of {sup 232}Th nuclei in the energy range 3.2-17.9 MeV were measured for the first time. A systematics of the time features of delayed neutrons is developed. This systematics makes it possible to estimate the half-life of delayed-neutron precursors as a function of the nucleonic composition of fissile nuclei by using a single parameter set for all nuclides. The energy dependence of the partial cross sections for emissive fission in the reaction {sup 232}Th(n, f) was analyzed on the basis of data obtained for the relative abundances of delayed neutrons and the aforementioned half-lives and on the basis of the created systematics of the time features of delayed neutrons. It was shown experimentally for the first time that the decrease in the cross section after the reaction threshold in the fission of {sup 232}Th nuclei (it has a pronounced first-chance plateau) is not an exclusion among the already studied uranium, plutonium, and curium isotopes and complies with theoretical predictions obtained for the respective nuclei with allowance for shell, superfluid, and collective effects in the nuclear-level density and with allowance for preequilibrium neutron emission

  5. Gated IR Imaging of Shocked Surfaces

    NASA Astrophysics Data System (ADS)

    Lutz, Stephen; Turley, Dale; Rightley, Paul; Primas, Lori

    2001-06-01

    Gated IR images have been taken of a series of shocked surface geometries in tin and copper. Metal coupons machined with grooves, steps, and flats with various surface finishes, were mounted directly to high explosive. The HE was point initiated and 500 ns to 1 microsecond wide gated images of the target were taken immediately following shock breakout using a Santa Barbara Focalplane InSb CID camera (SB-134). Raw camera radiance data was temperature calibrated assuming plausible material emissivity. The spatial distribution of temperature was estimated from the images of the shocked flats and found not to be single valued. Several of the geometries were modeled using CTH, a two dimensional Eulerian hydrocode, and comparisons were made to observed results.

  6. Hybrid Single-Photon Emission Computed Tomography/Computed Tomography Imaging Features of Tumoral Calcinosis in Technetium-99m Methylene Diphosphonate Bone Scintigraphy

    PubMed Central

    Kamaleshwaran, Koramadai Karuppusamy; Asokumar, Premkumar; Malaikkal, Anjali; Mohanan, Vyshakh; Shinto, Ajit Sugunan

    2015-01-01

    Tumoral calcinosis (TC) is an uncommon ectopic calcification syndrome. TC is a benign condition characterized by the presence of large calcific soft tissue deposits occurring predominantly in a periarticular location. It generally occurs as a complication of renal dialysis or trauma, and is rarely seen in familial and sporadic cases. Bone scintigraphy is a sensitive method for diagnosing TC. We report a case of year old female with. She underwent bone scintigraphy to see the sites of involvement, which showed intense foci of tracer activity in soft tissue in bilateral thigh and gluteal region. Hybrid single-photon emission computed tomography/computed tomography of the pelvis and thigh localized tracer uptake to the calcification in the gluteal and thigh region. PMID:26097427

  7. Hybrid Single-Photon Emission Computed Tomography/Computed Tomography Imaging Features of Tumoral Calcinosis in Technetium-99m Methylene Diphosphonate Bone Scintigraphy.

    PubMed

    Kamaleshwaran, Koramadai Karuppusamy; Asokumar, Premkumar; Malaikkal, Anjali; Mohanan, Vyshakh; Shinto, Ajit Sugunan

    2015-01-01

    Tumoral calcinosis (TC) is an uncommon ectopic calcification syndrome. TC is a benign condition characterized by the presence of large calcific soft tissue deposits occurring predominantly in a periarticular location. It generally occurs as a complication of renal dialysis or trauma, and is rarely seen in familial and sporadic cases. Bone scintigraphy is a sensitive method for diagnosing TC. We report a case of year old female with. She underwent bone scintigraphy to see the sites of involvement, which showed intense foci of tracer activity in soft tissue in bilateral thigh and gluteal region. Hybrid single-photon emission computed tomography/computed tomography of the pelvis and thigh localized tracer uptake to the calcification in the gluteal and thigh region.

  8. Features of a micro-gas chromatograph equipped with enrichment device and microchip plasma emission detection (muPED) for air monitoring.

    PubMed

    Tienpont, Bart; David, Frank; Witdouck, Wim; Vermeersch, Dries; Stoeri, Herbert; Sandra, Pat

    2008-11-01

    A field portable gas chromatograph (GC) was constructed allowing the enrichment of organic solutes from air samples on a miniaturized chemical trap and the subsequent gas chromatographic analysis on a resistively heated capillary column. The heart of the system is an integrated chip-based plasma emission detector (muPED). As a non-selective detector, the sensitivity is similar to that of a flame ionization detector (FID). The detector shows good selectivity for phosphorus, sulfur and chlorine-containing compounds with relative selectivities of ca. 5 x 10(5) gP gC(-1), 50 gS gC(-1) and 10(2) gCl gC(-1). The lifetime of the plasma chip under air monitoring conditions exceeded 3000 analyses. PMID:18941680

  9. Magnetic polarization of Ir in underdoped nonsuperconducting Eu(Fe 0.94Ir0.06)2As2

    NASA Astrophysics Data System (ADS)

    Jin, W. T.; Xiao, Y.; Su, Y.; Nandi, S.; Jiao, W. H.; Nisbet, G.; Demirdis, S.; Cao, G. H.; Brückel, Th.

    2016-01-01

    Using polarized neutron diffraction and x-ray resonant magnetic scattering (XRMS) techniques, multiple phase transitions were revealed in an underdoped, nonsuperconducting Eu (Fe1 -xIrx )2As2 (x =0.06 ) single crystal. Compared with the parent compound EuFe2As2 , the tetragonal-to-orthorhombic structural phase transition and the antiferromagnetic order of the Fe+2 moments are significantly suppressed to TS=111 (2 ) K and TN,Fe=85 (2 ) K by 6% Ir doping, respectively. In addition, the Eu+2 spins order within the a b plane in the A-type antiferromagnetic structure similar to the parent compound. However, the order temperature is evidently suppressed to TN,Eu=16.0 (5 ) K by Ir doping. Most strikingly, the XRMS measurements at the Ir L3 edge demonstrates that the Ir 5 d states are also magnetically polarized, with the same propagation vector as the magnetic order of Fe. With TN,Ir=12.0 (5 ) K, they feature a much lower onset temperature compared with TN,Fe. Our observation suggests that the magnetism of the Eu sublattice has a considerable effect on the magnetic nature of the 5 d Ir dopant atoms and there exists a possible interplay between the localized Eu+2 moments and the conduction d electrons on the FeAs layers.

  10. The IRS 1 circumstellar disk, and the origin of the jet and CO outflow in B5.

    PubMed

    Langer, W D; Velusamy, T; Xie, T

    1996-09-01

    We report the discovery of the inner edge of the high velocity CO outflow associated with the bipolar jet originating from IRS 1 in Barnard 5 and the first ever resolution of its circumstellar disk in the 2.6 mm dust continuum and C18O. From high spatial resolution observations made with the Owens Valley Millimeter Array we are able to locate the origin of the outflow to within approximately 500 AU on either side of IRS 1 and apparently at the edge of, or possibly within, its circumstellar disk. The orientation of the continuum disk is perpendicular to the highly collimated jet outflow recently seen in optical emission at much farther distances. The disk has been detected in C18O giving a disk mass approximately 0.16 M (solar). Our HCO+ and HCN maps indicate significant chemical differentiation in the circumstellar region on small scales with HCO+ tracing an extended disk of material. The 12CO interferometer maps of the outflow show two conelike features originating at IRS 1, the blue one fanning open to the northeast and the red one to the southwest. The vertices of the cones are on either side of the circumstellar disk and have a projected opening angle of about 90 degrees. The intrinsic opening angle is in the range of 60 degrees-90 degrees which leads to significant interaction between outflow and infall.

  11. Dealing confidently with IRS, Part I: Preparing for IRS audits.

    PubMed

    Holub, S F; Walker, S R

    1978-10-01

    With the IRS apparently making health care institutions the focus of a nationwide audit emphasis, hospital administrators will want to prepare themselves for confident handling of audits. Four types of audit procedures are explained, suggestions are made for getting a hospital ready for an audit, and strategies are suggested for maintaining control over the audit's progress.

  12. Detection of IR target by fusing multispectral IR data

    NASA Astrophysics Data System (ADS)

    Li, Liya; Qi, Meng; Gao, Xuhui

    2011-08-01

    Detection of the small target in clutter, usually regarded as singular points in the infrared image, is an important issue in infrared searching and tracking (IRST) system. Because of the far range of the target to the sensor, the stealth technology, the effects of inherent sensor noise and the phenomena of nature, the target is more difficult to be detected. Multispectral sensor system has been proved it could greatly improve detection of the small, hard-to-find targets by multispectral processing techniques (such as sensor or image fusion). Aiming at the problem of multispectral IR Target Detection, a kind method of the multispectral IR target detection is proposed, based on the existed detection systems. In this method, the image registration is done firstly to make the different sensors have a same scene. Then, a fusion rule, named as adaptive weighted voting theory, is developed to combine the target detection results from the different spectral sensors. The adaptive weighted voting theory can give the different weights, based on the different spectral IR characteristics, and these weights decide the detected target is identified as real target or background. The experimental results show that the proposed method can reduce the detection uncertainty and improve the detection performance. Compared with the single spectral detection results and the others fusion detection methods, it can decrease the lost alarm rate and the false alarm rate effectively. The proposed method has been employed in our IR surveillance system, and it is easy to be used in the various circumstances.

  13. Nuclear obscuration in LINERs. Clues from Spitzer/IRS spectra on the Compton thickness and the existence of the dusty torus

    NASA Astrophysics Data System (ADS)

    González-Martín, O.; Masegosa, J.; Márquez, I.; Rodríguez-Espinosa, J. M.; Acosta-Pulido, J. A.; Ramos Almeida, C.; Dultzin, D.; Hernández-García, L.; Ruschel-Dutra, D.; Alonso-Herrero, A.

    2015-06-01

    Context. Most of the optically classified low-ionisation, narrow emission-line regions (LINERs) nuclei host an active galactic nucleus (AGN). However, how they fit into the unified model (UM) of AGN is still an open question. Aims: The aims of this work are to study at mid-infrared (mid-IR) (1) the Compton-thick nature of LINERs (i.e. hydrogen column densities of NH> 1.5 × 1024 cm-2) and (2) the disappearance of the dusty torus in LINERs predicted from theoretical arguments. Methods: We have compiled all the available low spectral-resolution, mid-IR spectra of LINERs from the InfraRed Spectrograph (IRS) onboard Spitzer. The sample contains 40 LINERs. We have complemented the LINER sample with Spitzer/IRS spectra of PG QSOs, Type-1 Seyferts (S1s), Type-2 Seyferts (S2s), and StarBurst (SB) nuclei. We studied the AGN compared to the starburst content in our sample using different indicators: the equivalent width of the polycyclic aromatic hydrocarbon at 6.2 μm, the strength of the silicate feature at 9.7 μm, and the steepness of the mid-IR spectra. We classified the spectra as SB-dominated and AGN-dominated, according to these diagnostics and compared the average mid-IR spectra of the various classes. Moreover, we studied the correlation between the 12 μm luminosity, νLν(12 μm), and the 2-10 keV energy band X-ray luminosity, LX(2-10 keV). Results: In 25 out of the 40 LINERs (i.e. 62.5%), the mid-IR spectra are not SB-dominated, similar to the comparison S2 sample (67.7%). The average spectra of both SB-dominated LINERs and S2s are very similar to the average spectrum of the SB class. The average spectrum of AGN-dominated LINERs is different from the average spectra of the other optical classes, showing a rather flat spectrum at 6-28 μm. We find that the average spectrum of AGN-dominated LINERs with X-ray luminosities LX(2-10 keV) > 1041 erg/s is similar to the average mid-IR spectrum of AGN-dominated S2s. However, faint LINERs (i.e. LX(2-10 keV) < 1041 erg

  14. A SPITZER IRS SURVEY OF NGC 1333: INSIGHTS INTO DISK EVOLUTION FROM A VERY YOUNG CLUSTER

    SciTech Connect

    Arnold, L. A.; Watson, Dan M.; Kim, K. H.; Manoj, P.; Remming, I.; Sheehan, P.; Forrest, W. J.; Mamajek, E.; Adame, L.; McClure, M.; Furlan, E.; Espaillat, C.; Ausfeld, K.; Rapson, V. A. E-mail: dmw@pas.rochester.edu

    2012-08-01

    We report on the {lambda} = 5-36 {mu}m Spitzer Infrared Spectrograph (IRS) spectra of 79 young stellar objects in the very young nearby cluster NGC 1333. NGC 1333's youth enables the study of early protoplanetary disk properties, such as the degree of settling and the formation of gaps and clearings. We construct spectral energy distributions (SEDs) using our IRS data as well as published photometry and classify our sample into SED classes. Using 'extinction-free' spectral indices, we determine whether the disk, envelope, or photosphere dominates the spectrum. We analyze the dereddened spectra of objects that show disk-dominated emission using spectral indices and properties of silicate features in order to study the vertical and radial structure of protoplanetary disks in NGC 1333. At least nine objects in our sample of NGC 1333 show signs of large (several AU) radial gaps or clearings in their inner disk. Disks with radial gaps in NGC 1333 show more nearly pristine silicate dust than their radially continuous counterparts. We compare properties of disks in NGC 1333 to those in three other well-studied regions, Taurus-Auriga, Ophiuchus, and Chamaeleon I, and find no difference in their degree of sedimentation and dust processing.

  15. Long-lived room temperature deep-red/near-IR emissive intraligand triplet excited state (3IL) of naphthalimide in cyclometalated platinum(II) complexes and its application in upconversion.

    PubMed

    Wu, Wenting; Guo, Huimin; Wu, Wanhua; Ji, Shaomin; Zhao, Jianzhang

    2011-11-21

    [C(^)NPt(acac)] (C(^)N = cyclometalating ligand; acac = acetylacetonato) complexes in which the naphthalimide (NI) moiety is directly cyclometalated (NI as the C donor of the C-Pt bond) were synthesized. With 4-pyrazolylnaphthalimide, isomers with five-membered (Pt-2) and six-membered (Pt-3) chelate rings were obtained. With 4-pyridinylnaphthalimide, only the complex with a five-membered chelate ring (Pt-4) was isolated. A model complex with 1-phenylpyrazole as the C(^)N ligand was prepared (Pt-1). Strong absorption of visible light (ε = 21,900 M(-1) cm(-1) at 443 nm for Pt-3) and room temperature (RT) phosphorescence at 630 nm (Pt-2 and Pt-3) or 674 nm (Pt-4) were observed. Long-lived phosphorescences were observed for Pt-2 (τ(P) = 12.8 μs) and Pt-3 (τ(P) = 61.9 μs). Pt-1 is nonphosphorescent at RT in solution because of the acac-localized T(1) excited state [based on density functional theory (DFT) calculations and spin density analysis], but a structured emission band centered at 415 nm was observed at 77 K. Time-resolved transient absorption spectra and spin density analysis indicated a NI-localized intraligand triplet excited state ((3)IL) for complexes Pt-2, Pt-3, and Pt-4. DFT calculations on the transient absorption spectra (T(1) → T(n) transitions, n > 1) also support the (3)IL assignment of the T(1) excited states of Pt-2, Pt-3, and Pt-4. The complexes were used as triplet sensitizers for triplet-triplet-annihilation (TTA) based upconversion, and the results show that Pt-3 is an efficient sensitizer with an upconversion quantum yield of up to 14.1%, despite its low phosphorescence quantum yield of 5.2%. Thus, we propose that the sensitizer molecules at the triplet excited state that are otherwise nonphosphorescent were involved in the TTA upconversion process, indicating that weakly phosphorescent or nonphosphorescent transition-metal complexes can be used as triplet sensitizers for TTA upconversion.

  16. PERIODIC ACCRETION INSTABILITIES IN THE PROTOSTAR L1634 IRS 7

    SciTech Connect

    Hodapp, Klaus W.; Chini, Rolf E-mail: rolf.chini@astro.ruhr-uni-bochum.de

    2015-11-10

    The small molecular cloud Lynds 1634 contains at least three outflow sources. We found one of these, IRS 7, to be variable with a period of 37.14 ± 0.04 days and an amplitude of approximately 2 mag in the K{sub s} band. The light curve consists of a quiescent phase with little or no variation, and a rapid outburst phase. During the outburst phase, the rapid variation in brightness generates light echoes that propagate into the surrounding molecular cloud, allowing a measurement of the distance to IRS 7 of 404 pc ± 35 pc. We observed only a marginally significant change in the H − K color during the outburst phase. The K-band spectrum of IRS 7 shows CO bandhead emission but its equivalent width does not change significantly with the phase of the light curve. The H{sub 2} 1–0 S(1) line emission does not follow the variability of the continuum flux. We also used the imaging data for a proper motion study of the outflows originating from the IRS 7 and the far-infrared source IRAS 05173-0555, and confirm that these are indeed distinct outflows.

  17. Using The Cornell Atlas of Spitzer/IRS Sources

    NASA Astrophysics Data System (ADS)

    Samsonyan, A. L.

    2016-06-01

    I summarize my research studying details of the emission line profiles of the mid infrared [NeII] 12.8 microns and [NeIII] 15.6 microns emission lines. Observations are from the Spitzer Infrared Spectrograph (IRS) (Houck et al. 2004), so I illustrate use of the archive of these spectra. The IRS team developed the Cornell Atlas of Spitzer IRS Sources (CASSIS) found at cassis.sirtf.com. At present, all low resolution (Lebouteiller et al. 2011) and high resolution (Lebouteiller et al. 2015) staring observations with the IRS are available (more than 20,000 spectra of about 15,000 distinct sources). Spectra are provided in various formats to enable easy viewing or measurements. Spectra cover 5 microns to 37 microns in low resolution (R ˜ 60 to 125) and 10 microns to 37 microns in high resolution (R ˜ 600) modes. CASSIS is intended as a long term resource for the astronomical community so that this fundamental data base of mid-infrared spectra will be easily usable perpetually, and I demonstrate some examples of its use.

  18. Periodic Accretion Instabilities in the Protostar L1634 IRS 7

    NASA Astrophysics Data System (ADS)

    Hodapp, Klaus W.; Chini, Rolf

    2015-11-01

    The small molecular cloud Lynds 1634 contains at least three outflow sources. We found one of these, IRS 7, to be variable with a period of 37.14 ± 0.04 days and an amplitude of approximately 2 mag in the Ks band. The light curve consists of a quiescent phase with little or no variation, and a rapid outburst phase. During the outburst phase, the rapid variation in brightness generates light echoes that propagate into the surrounding molecular cloud, allowing a measurement of the distance to IRS 7 of 404 pc ± 35 pc. We observed only a marginally significant change in the H - K color during the outburst phase. The K-band spectrum of IRS 7 shows CO bandhead emission but its equivalent width does not change significantly with the phase of the light curve. The H2 1-0 S(1) line emission does not follow the variability of the continuum flux. We also used the imaging data for a proper motion study of the outflows originating from the IRS 7 and the far-infrared source IRAS 05173-0555, and confirm that these are indeed distinct outflows.

  19. IRS View of a Planetary Collision in the Pleiades

    NASA Astrophysics Data System (ADS)

    Song, Inseok; Lisse, Carey; Rhee, Joseph; Zuckerman, Ben

    2008-03-01

    Recently, we identified a sun-like Pleiades member, HD 23514, hosting a huge quantity of warm dust grains. Next to BD+20 307 (a field sun-like star), HD 23514 is currently the second dustiest, adolescent-age, star known with warm excess IR emission. Very short removal timescales of warm dust grains and adolescent ages of these two stars (>~100 Myr) indicate that the very dusty, warm excess, phenomenon is a transient event. A catastrophic collision between planetary embryos or planets is the most plausible origin of so much warm dust and such a collision mimics the postulated Moon-creation event in our terrestrial system. But the N-band spectra of BD+20 307 and HD 23514 appear very different, with peculiar emission at HD 23514 peaking at ~9 microns, a peak wavelength hardly seen among young stars and other main sequence excess stars. The strange N-band spectrum may point to an extra-ordinary condition around HD 23514 such as a very thick crust of a planet, a freakish chemical composition, or shocked silicates from a planetary collision. An IRS spectrum covering the 5-35um spectral range, rather than the highly restricted ground-based N-band spectrum will provide much stronger and clearer constraints on the dusty environment of HD 23514. We propose IRS observations with all four low resolution modules to obtain a diagnostic mid-IR spectrum of this rare, fascinating star.

  20. IR spectral analysis for the diagnostics of crust earthquake precursors

    NASA Astrophysics Data System (ADS)

    Umarkhodgaev, R. M.; Liperovsky, V. A.; Mikhailin, V. V.; Meister, C.-V.; Naumov, D. Ju

    2012-04-01

    In regions of future earthquakes, a few days before the seismic shock, the emanation of radon and hydrogen is being observed, which causes clouds of increased ionisation in the atmosphere. In the present work the possible diagnostics of these clouds using infrared (IR) spectroscopy is considered, which may be important and useful for the general geophysical system of earthquake prediction and the observation of industrial emissions of radioactive materials into the atmosphere. Some possible physical processes are analysed, which cause, under the condition of additional ionisation in a pre-breakdown electrical field, emissions in the IR interval. In doing so, the transparency region of the IR spectrum at wavelengths of 7-15 μm is taken into account. This transparency region corresponds to spectral lines of small atmospheric constituents like CH4, CO2, N2O, NO2, NO, and O3. The possible intensities of the IR emissions observable in laboratories and in nature are estimated. The acceleration process of the electrons in the pre-breakdown electrical field before its adhesion to the molecules is analysed. The laboratory equipment for the investigation of the IR absorption spectrum is constructed for the cases of normal and decreased atmospheric pressures. The syntheses of ozone and nitrous oxides are performed in the barrier discharge. It is studied if the products of the syntheses may be used to model atmospheric processes where these components take part. Spectra of products of the syntheses in the wavelength region of 2-10 μm are observed and analysed. A device is created for the syntheses and accumulation of nitrous oxides. Experiments to observe the IR-spectra of ozone and nitrous oxides during the syntheses and during the further evolution of these molecules are performed. For the earthquake prediction, practically, the investigation of emission spectra is most important, but during the laboratory experiments, the radiation of the excited molecules is shifted by a

  1. Spectral variability of the IR source IRAS 01005+7910 optical component

    NASA Astrophysics Data System (ADS)

    Klochkova, V. G.; Chentsov, E. L.; Panchuk, V. E.; Sendzikas, E. G.; Yushkin, M. V.

    2014-10-01

    High-resolution optical spectra of the IR source IRAS01005+7910 are used to determine the spectral type of its central star, B1.5±0.3, identify the spectral features, and analyze their profile and radial-velocity variations. The systemic velocity V sys = -50.5 km s-1 is determined from the positions of the symmetric and stable profiles of the forbidden [NI], [N II], [OI], [S II], and [Fe II] emission lines. The presence of the [NII] and [SII] forbidden emissions indicates the onset of the ionization of the circumstellar envelope and the fact that the star is very close to undergoing the planetary nebula stage. The broad range of radial velocity V r estimates based on the line cores, which amounts to about 34 km s-1, is partly due to the deformations of the profiles caused by variable emissions. The variations of the V r in the line wings are smaller, about 23 km s-1, and may be due to pulsations and/or hidden binarity of the star. The deformations of the profiles of absorption-emission lines may result from variations of their absorption components caused by the variations of the geometry and kinematics in the wind base. The H α lines exhibit PCyg III type wind profiles. Deviations of the wind from spherical symmetry are shown to be small. The relatively low wind velocity (27-74 km s-1 from different observations) and the strong intensity of the red emission (it exceeds the continuum level by up to a factor of seven) are typical for hypergiants rather than the classical supergiants. IRAS01005 is an example of spectral mimicry of a low-mass post-AGB star masquerading as a massive hypergiant.

  2. Theoretical studies of Ir5Th and Ir5Ce nanoscale precipitates in Ir

    SciTech Connect

    Morris, James R; Averill, Frank; Cooper, Valentino R

    2014-01-01

    Experimentally, it is known that very small amounts of thorium and/or cerium added to iridium metal form a precipitate, Ir5Th / Ir5Ce, which improves the high temperature mechanical properties of the resulting alloys. We demonstrate that there are low-energy configurations for nano-scale precipitates of these phases in Ir, and that these coherent arrangements may assist in producing improved mechanical properties. One precipitate/matrix orientation gives a particularly low interfacial energy, and a low lattice misfit. Nanolayer precipitates with this orientation are found to be likely to form, with little driving force to coarsen. The predicted morphology of the precipitates and their orientation with the matrix phase provide a potential experiment that could be used to test these predictions.

  3. New Dust Features Observed with ISO

    NASA Technical Reports Server (NTRS)

    Tielens, Alexander G. G. M.; Young, Richard E. (Technical Monitor)

    1997-01-01

    This paper will review our current knowledge of circumstellar and interstellar dust with the emphasis on infrared spectroscopy with ISO. Objects embedded in or located behind molecular clouds show a wealth of absorption features due to simple molecules in an icy mantle. The SWS on ISO has provided us, for the first time, with complete 3-45 um spectra which allow an inventory of interstellar ice. Among the species identified are H2O, CH3OH, CH4, CO2, CO, and OCS. These species are formed through simple reactions among gas phase species accreted on grain surfaces, possibly modified by FUV photolysis and warm-up (ie., outgassing). The implications of the observations for our understanding of these processes will be reviewed. The IR spectra of many UV bright objects are dominated by strong emission features at 3.3, 6.2, 7.7, and 11.3 micrometers. These are generally attributed to Polycyclic Aromatic Hydrocarbons (PAHs) molecules. The observational evidence will be reviewed. The emphasis will be on recent data which show widespread spectral variations, particularly among protoplanetary and planetary nebulae, and their implications. One of the most exciting, recent discoveries on interstellar and circumstellar dust has been the detection of spectral structure due to crystalline olivine and enstatite in a variety of objects surrounded by circumstellar silicates. These spectra will be reviewed and circumstellar silicate mineralogy will be discussed.

  4. Divertor IR thermography on Alcator C-Moda)

    NASA Astrophysics Data System (ADS)

    Terry, J. L.; LaBombard, B.; Brunner, D.; Payne, J.; Wurden, G. A.

    2010-10-01

    Alcator C-Mod is a particularly challenging environment for thermography. It presents issues that will similarly face ITER, including low-emissivity metal targets, low-Z surface films, and closed divertor geometry. In order to make measurements of the incident divertor heat flux using IR thermography, the C-Mod divertor has been modified and instrumented. A 6° toroidal sector has been given a 2° toroidal ramp in order to eliminate magnetic field-line shadowing by imperfectly aligned divertor tiles. This sector is viewed from above by a toroidally displaced IR camera and is instrumented with thermocouples and calorimeters. The camera provides time histories of surface temperatures that are used to compute incident heat-flux profiles. The camera sensitivity is calibrated in situ using the embedded thermocouples, thus correcting for changes and nonuniformities in surface emissivity due to surface coatings.

  5. Concealing compensation from the IRS.

    PubMed

    Burda, D; Greene, J

    1991-01-28

    Tougher reporting requirements from the Internal Revenue Service are prompting some not-for-profit hospitals to seek ways to hide compensation arrangements from the public and the media. Critics believe those tactics could get hospitals in hot water with the law, especially now that the IRS has launched a new, aggressive auditing offensive.

  6. Pirmoji ir antroji kauno trianguliacijos

    NASA Astrophysics Data System (ADS)

    Girkus, Romualdas; Urbanavičius, Valdas

    2010-01-01

    Miesto planų sudarymo reikmėms atramos punktų tinklas tarpukariu Europos valstybėse buvo formuojamas trianguliacijos metodu. Kauno pirmą kartą 1924 m. jis buvo suprojektuotas iš 36 punktų, fiksuotas vietovėje ir išmatuotas inž. Z. Bačelio. Sudarytas trianguliacijos tinklas apėmė tuometinę Vilijampolės, Aleksoto, Žaliakalnio, Naujamiesčio ir Žemųjų Šančių teritoriją. Kaunas, tapęs laikinąja sostine, sparčiai augo, dėl to pirmoji trianguliacija netenkino poreikių: dauguma punktų vietovėje nebuvo išsaugoti, miestas dvigubai išsiplėtė, dėl naudotų geodezinių prietaisų nepakankamas buvo punktų tikslumas. Naujas tinklas buvo suprojektuotas taip, kad vienam punktui vidutini\\vskai tektų vienas kvadratinis kilometras miesto ploto ir būtų užtikrintas įtvirtintų punktų 10 cm ribinis tikslumas. Kauno antrosios trianguliacijos realizavimo nuopelnai priskirtini Kauno savivaldybės Matavimų dalies specialistams - vedėjui J. Deksniui ir jo pavaduotojui J. Ašmonui.

  7. The Orion Fingers: Near-IR Spectral Imaging of an Explosive Outflow

    NASA Astrophysics Data System (ADS)

    Youngblood, Allison; Ginsburg, Adam; Bally, John

    2016-06-01

    We present near-IR (1.1-2.4 μm) position-position-velocity cubes of the 500 year old Orion BN/KL explosive outflow with spatial resolution 1″ and spectral resolution 86 km s-1. We construct integrated intensity maps free of continuum sources of 15 H2 and [Fe ii] lines while preserving kinematic information of individual outflow features. Included in the detected H2 lines are the 1-0 S(1) and 1-0 Q(3) transitions, allowing extinction measurements across the outflow. Additionally, we present dereddened flux ratios for over two dozen outflow features to allow for the characterization of the true excitation conditions of the BN/KL outflow. All of the ratios show the dominance of the shock excitation of the H2 emission, although some features exhibit signs of fluorescent excitation from stellar radiation or J-type shocks. We also detect tracers of the PDR/ionization front north of the Trapezium stars in [O i] and [Fe ii] and analyze other observed outflows not associated with the BN/KL outflow.

  8. Measurement of the 1s2l3l’ Dielectronic Recombination Emission Line in Li-Like Ar and Its Contribution to the Faint X-Ray Feature Found in the Stacked Spectrum of Galaxy Clusters

    NASA Astrophysics Data System (ADS)

    Gall, Amy Christina; Silwal, Roshani; Dreiling, Joan; Borovik, Alexander; Ajello, Marco; Gillaspy, John; Kilgore, Ethan; Ralchenko, Yuri; Takacs, Endre

    2016-06-01

    Driven by the recent detection of an unidentified emission line previously reported at 3.55-3.57 keV in a stacked spectrum of galaxy clusters, we investigated the resonant DR process in Li-like Ar as a possible source of, or contributor to, the emission line. The Li-like transition 1s22l-1s2l3l’ was suggested to produce a 3.62 keV photon [1] near the unidentified line at 3.57 keV and was the primary focus of our investigation. Apart from the mentioned transitions, we have found other features that can be possible contributors to the emission in this region. The Electron Beam Ion Trap at NIST was used to produce and trap the highly-charged ions of argon. The energy of the quasi-monoenergetic electron beam was incremented in steps of 15 eV to scan over all of the Li-like Ar DR resonances. A Johann-type crystal spectrometer and a solid-state germanium detector were used to take x-ray measurements perpendicular to the electron beam. The DR cross sections were measured and normalized to the well-known photoionization cross sections using radiative recombination peaks in the measured spectra. Corrections for different instrument and method related effects such as charge state balance, electron beam space charge, and charge exchange have been considered. Our high-resolution crystal spectra allowed the experimental separation of features that are less than 2 eV apart. We have used a collisional radiative model NOMAD [2] aided by atomic data calculations by FAC [3] to interpret our observations and account for the corrections and uncertainties. Experimental results were compared to the AtomDB theoretical emission lines used to fit the galaxy cluster spectra containing the unidentified 3.57 keV line. These data points can be added benchmarks in the database and used to accurately interpret spectra from current x-ray satellites, including Hitomi, Chandra, and XMM-Newton x-ray observatories.[1] Bulbul E. et al., 2014, ApJ, 789, 13[2] Ralchenko Yu. et al., 2014, JQSRT, 71

  9. Properties of Discrete and Axisymmetric Features in Jupiter's Atmosphere from Observations of Thermal Emission: Recent Updates on the Eve of the Juno Mission Arrival at Jupiter

    NASA Astrophysics Data System (ADS)

    Orton, G. S.; Fletcher, L. N.; Giles, R.; Sinclair, J.; Greathouse, T. K.; Momary, T.; Yanamandra-Fisher, P. A.; Fujiyoshi, T.; Fisher, B.; Payne, A.; Seede, R.; Simon, J.; Lai, M.; Nguyen, M.; Fernandez, J.; Baines, K. H.

    2015-12-01

    We have derived the spatial distribution and evolution of key properties of Jupiter's atmosphere through the analysis of imaging and spatially resolved spectroscopy of its thermal emission. These observations and their analysis represent a source of data we plan to acquire as a key component of support for the Juno mission's atmospheric investigation. From thermal imaging and spectroscopy in the 7-25 µm region, we can derive temperatures between 10 and 500 mbar atmospheric pressure, cloud opacities between 500 mbar and 5 bars, the para-H2 fraction near 300 mbar, the 100-400 mbar distributions of ammonia and phosphine, and the distribution of hydrocarbons in the stratosphere (~1 µbar - 10 mbar). Earlier work determined atmospheric properties of Jupiter's Great Red Spot (Fletcher et al. 2010, Icarus 208, 306) and the evolution of the South Equatorial Belt (SEB) fade (whitening) in 2009-2010 (Fletcher et al. 2011 Icarus, 213, 564). We will illustrate recent results from an examination of (1) the revival (re-darkening) of the SEB in 2010-2011, (2) discovery of uniquely dry regions of the atmosphere that are identified with visible "brown barges" typically located at the northern edge of Jupiter's North Equatorial Belt (NEB), (3) vertical structure of stratospheric waves constituting Jupiter's Quadrennial Oscillation (QQO) (Leovy et al. 1991, Nature 354, 380), and (4) previously unsuspected long-term tropospheric thermal waves uncovered in our multi-year program covering well over a Jovian year. Efforts are underway to provide mission-supporting observations using mid-infrared facility and guest instruments at several observatories during the 14-day orbits of the Juno mission, particularly - but not exclusively - the early orbits dedicated to remote sensing observations.

  10. Conjugated Polymer-Based Hybrid Nanoparticles with Two-Photon Excitation and Near-Infrared Emission Features for Fluorescence Bioimaging within the Biological Window.

    PubMed

    Lv, Yanlin; Liu, Peng; Ding, Hui; Wu, Yishi; Yan, Yongli; Liu, Heng; Wang, Xuefei; Huang, Fei; Zhao, Yongsheng; Tian, Zhiyuan

    2015-09-23

    Hybrid fluorescent nanoparticles (NPs) capable of fluorescing near-infrared (NIR) light (centered ∼730 nm) upon excitation of 800 nm laser light were constructed. A new type of conjugated polymer with two-photon excited fluorescence (TPEF) feature, P-F8-DPSB, was used as the NIR-light harvesting component and the energy donor while a NIR fluorescent dye, DPA-PR-PDI, was used as the energy acceptor and the NIR-light emitting component for the construction of the fluorescent NPs. The hybrid NPs possess δ value up to 2.3 × 10(6) GM per particle upon excitation of 800 nm pulse laser. The excellent two-photon absorption (TPA) property of the conjugated polymer component, together with its high fluorescence quantum yield (ϕ) up to 45% and the efficient energy transfer from the conjugated polymer to NIR-emitting fluorophore with efficiency up to 90%, imparted the hybrid NPs with TPEF-based NIR-input-NIR-output fluorescence imaging ability with penetration depth up to 1200 μm. The practicability of the hybrid NPs for fluorescence imaging in Hela cells was validated. PMID:26340609

  11. Dust Emission from a Large Scale Shock Near the Galactic Center

    NASA Astrophysics Data System (ADS)

    Staguhn, J.; Morris, M.; Uchida, K.; Benford, D.; Bertoldi, F.

    2008-03-01

    AFGL5376 is a prominent 25 μm source near the Galactic Center produced by a large scale (˜100 pc) shock that extends well above the Galactic plane. This shock region coincides with the edge of a vertical radio continuum feature, which appears to be at the surface of a 150-pc lobe that encompasses the Galactic center. There is no evidence for nearby star formation. The unusually warm (T˜100 K) dust emission peak, traced by the 25 μm emission, is clearly surrounded by high velocity ^{12}CO(2-1) emission. We are currently conducting a comprehensive observing study of the region including Spitzer IRS and MIPS observations. Our continuum observations are aimed at allowing the derivation of mass and temperature distribution at sub-parsec resolution. Here we present MIPS 24 μm observations in combination with MAMBO observations at 1.2 mm wavelength. The latter reveal the presence of strong millimeter continuum emission in the vicinity of AFGL5376. We present a first estimate of the masses of the cold molecular clouds that are associated with this region. Our complete set of continuum Spitzer and (sub-)millimeter emission measurements together with our IRS spectroscopy will be used later to constrain magnetohydrodynamic models for the production of this highly energetic feature.

  12. Evaluating uniformity of IR reference sources

    NASA Astrophysics Data System (ADS)

    Barrat, Catherine; Violleau, Sébastien

    2015-10-01

    Infrared reference sources such as blackbodies are used to calibrate and test IR sensors and cameras.. Applications requiring a high thermal uniformity over the emissive surface become more and more frequent compared to the past applications. Among these applications are non uniformity correction of infrared cameras focused at short distance and simultaneous calibration of a set of sensor facing a large area blackbody. Facing these demanding applications requires to accurately measuring thee thermal radiation of each point of the emissive surface of the reference source. The use of an infrared camera for this purpose turns out to be absolutely inefficient since the uniformity off response of this camera is usually worse than the uniformity of thee source to bee measured. Consequently, HGH has developed a testing bench for accurate measurement of uniformity of infrared sources based on a low noise radiometer mounted of translating stages and using an exclusive drift correction method. This bench delivers a reliable thermal map of any kind of infrared reference source.

  13. Shaped Ir-Ni bimetallic nanoparticles for minimizing Ir utilization in oxygen evolution reaction.

    PubMed

    Lim, Jinkyu; Yang, Sungeun; Kim, Chanyeon; Roh, Chi-Woo; Kwon, Yongwoo; Kim, Yong-Tae; Lee, Hyunjoo

    2016-04-25

    Shaped Ir-Ni bimetallic nanoparticles were synthesized and used for electrocatalytic oxygen evolution reaction (OER). The obtained bimetallic nanoparticles showed significantly enhanced Ir mass activity and durability compared with Ir nanoparticles. PMID:27034092

  14. Olivine Composition of the Mars Trojan 5261 Eureka: Spitzer IRS Data

    NASA Technical Reports Server (NTRS)

    Lim, L. F.; Burt, B. J.; Emery, J. P.; Mueller, M.; Rivkin, A. S.; Trilling, D.

    2011-01-01

    The largest Mars trojan, 5261 Eureka, is one of two prototype "Sa" asteroids in the Bus-Demeo taxonomy. Analysis of its visible/near-IR spectrum led to the conclusion that it might represent either an angritic analog or an olivine-rich composition such as an R chondrite. Spitzer IRS data (5-30 micrometers) have enabled us to resolve this ambiguity. The thermal-IR spectrum exhibits strong olivine reststrahlen features consistent with a composition of approximately equals Fo60-70. Laboratory spectra of R chondrites, brachinites, and chassignites are dominated by similar features.

  15. Surface emissivity and temperature retrieval for a hyperspectral sensor

    SciTech Connect

    Borel, C.C.

    1998-12-01

    With the growing use of hyper-spectral imagers, e.g., AVIRIS in the visible and short-wave infrared there is hope of using such instruments in the mid-wave and thermal IR (TIR) some day. The author believes that this will enable him to get around using the present temperature-emissivity separation algorithms using methods which take advantage of the many channels available in hyper-spectral imagers. A simple fact used in coming up with a novel algorithm is that a typical surface emissivity spectrum are rather smooth compared to spectral features introduced by the atmosphere. Thus, a iterative solution technique can be devised which retrieves emissivity spectra based on spectral smoothness. To make the emissivities realistic, atmospheric parameters are varied using approximations, look-up tables derived from a radiative transfer code and spectral libraries. One such iterative algorithm solves the radiative transfer equation for the radiance at the sensor for the unknown emissivity and uses the blackbody temperature computed in an atmospheric window to get a guess for the unknown surface temperature. By varying the surface temperature over a small range a series of emissivity spectra are calculated. The one with the smoothest characteristic is chosen. The algorithm was tested on synthetic data using MODTRAN and the Salisbury emissivity database.

  16. ALLFlight: detection of moving objects in IR and ladar images

    NASA Astrophysics Data System (ADS)

    Doehler, H.-U.; Peinecke, Niklas; Lueken, Thomas; Schmerwitz, Sven

    2013-05-01

    Supporting a helicopter pilot during landing and takeoff in degraded visual environment (DVE) is one of the challenges within DLR's project ALLFlight (Assisted Low Level Flight and Landing on Unprepared Landing Sites). Different types of sensors (TV, Infrared, mmW radar and laser radar) are mounted onto DLR's research helicopter FHS (flying helicopter simulator) for gathering different sensor data of the surrounding world. A high performance computer cluster architecture acquires and fuses all the information to get one single comprehensive description of the outside situation. While both TV and IR cameras deliver images with frame rates of 25 Hz or 30 Hz, Ladar and mmW radar provide georeferenced sensor data with only 2 Hz or even less. Therefore, it takes several seconds to detect or even track potential moving obstacle candidates in mmW or Ladar sequences. Especially if the helicopter is flying with higher speed, it is very important to minimize the detection time of obstacles in order to initiate a re-planning of the helicopter's mission timely. Applying feature extraction algorithms on IR images in combination with data fusion algorithms of extracted features and Ladar data can decrease the detection time appreciably. Based on real data from flight tests, the paper describes applied feature extraction methods for moving object detection, as well as data fusion techniques for combining features from TV/IR and Ladar data.

  17. Spitzer IRS (8-30 micron) Spectra of Basaltic Asteroids 1459 Magnya and 956 Elisa: Mineralogy and Thermal Properties

    NASA Technical Reports Server (NTRS)

    Lim, Lucy F.; Emery, J. P.; Moskovitz, N. A.

    2009-01-01

    We report preliminary results from Spitzer IRS (Infrared Spectrograph) spectroscopy of 956 Elisa, 1459 Magnya, and other small basaltic asteroids with the Spitzer IRS. Program targets include members of the dynamical family of the unique large differentiated asteroid 4 Vesta ("Vestoids"), several outer-main-belt basaltic asteroids whose orbits exclude them from originating on 4 Vesta, and the basaltic near-Earth asteroid 4055 Magellan. The preliminary thermal model (STM) fit to the 5--35 micron spectrum of 956 Elisa gives a radius of 5.4 +/- 0.3 km and a subsolar- point temperature of 282.2 +/- 0.5 K. This temperature corresponds to eta approximately equals 1.06 +/- 0.02, which is substantially higher than the eta approximately equals 0.756 characteristic of large main-belt asteroids. Unlike 4 Vesta and other large asteroids, therefore, 956 Elisa has significant thermal inertia in its surface layer. The wavelength of the Christiansen feature (emissivity maximum near 9 micron), the positions and shapes of the narrow maxima (10 micron, 11 micron) within the broad 9--14 micron silicate band, and the 19--20 micron minimum are consistent with features found in the laboratory spectra of diogenites and of low-Ca pyroxenes of similar composition (Wo<5, En50-En75).

  18. MEASURING ORGANIC MOLECULAR EMISSION IN DISKS WITH LOW-RESOLUTION SPITZER SPECTROSCOPY

    SciTech Connect

    Teske, Johanna K.; Najita, Joan R.; Carr, John S.; Pascucci, Ilaria; Apai, Daniel; Henning, Thomas E-mail: najita@noao.edu E-mail: pascucci@stsci.edu E-mail: henning@mpia.de

    2011-06-10

    We explore the extent to which Spitzer Infrared Spectrograph (IRS) spectra taken at low spectral resolution can be used in quantitative studies of organic molecular emission from disks surrounding low-mass young stars. We use Spitzer IRS spectra taken in both the high- and low-resolution modules for the same sources to investigate whether it is possible to define line indices that can measure trends in the strength of the molecular features in low-resolution data. We find that trends in the HCN emission strength seen in the high-resolution data can be recovered in low-resolution data. In examining the factors that influence the HCN emission strength, we find that the low-resolution HCN flux is modestly correlated with stellar accretion rate and X-ray luminosity. Correlations of this kind are perhaps expected based on recent observational and theoretical studies of inner disk atmospheres. Our results demonstrate the potential of using the large number of low-resolution disk spectra that reside in the Spitzer archive to study the factors that influence the strength of molecular emission from disks. Such studies would complement results for the much smaller number of circumstellar disks that have been observed at high resolution with IRS.

  19. Titan's Aerosol and Condensation Cloud Properties in the Far-IR Between 2005 and 2010

    NASA Technical Reports Server (NTRS)

    Anderson, Carrie; Samuelson, Robert

    2011-01-01

    Analyses of far-IR spectra between 20 and 560 cm(exp -1) (500 to 18 micron) recorded by the Cassini Composite Infrared Spectrometer (CIRS) yield the spectral dependence and the vertical distribution of Titan's photochemical aerosol and ice clouds. Titan's aerosol appears to be well mixed between the surface and an altitude of 300 km, with a spectral shape that does not change with latitude or time. The aerosol exhibits an extremely broad emission feature with a spectral peak at 140 cm(exp -1) (71 micron), which is not evident in laboratory simulated Titan aerosols (tholin). This low- energy aerosol emission feature may arise from low-energy molecules such as polycyclic aromatic hydrocarbons and/or nitrogenated aromatics. Unlike the vertically well-mixed aerosol, Titan's condensate clouds are located in highly restricted altitudes in the lower stratosphere, ranging between 60 and 100 km at low and moderate latitudes, to between 150 and 165 km at high northern latitudes during northern winter. Such clouds are located at altitudes where nitrile vapors are expected to condense and appear to be dominated by HCN and HC3N, which are the two most abundant nitriles in Titan's atmosphere. Associated with this ice cloud is a broad emission feature that spectrally peaks near 160 cm(exp -1) (62.5 micron). This ice composite appears to chemically change with altitude and latitude, probably as a result of differences in vapor abundance and condensation temperature, and the ice cloud appears to be global in extent. Both CIRS and the Huygens Descent Imager and Spectral Radiometer (DISR) show evidence of cloud layering in Titan's lower stratosphere. The 15 km difference in cloud altitude indicated by the two instruments suggests a difference in ice composition. CIRS also indicates a second ice cloud that exists at isolated latitudes and is consistent with hydrocarbon condensation above the tropopause. This cloud exhibits an emission feature that spectrally peaks near 80 cm(exp -1

  20. Ir/IrSi3/Si Schottky-Barrier Infrared Detector

    NASA Technical Reports Server (NTRS)

    Lin, True-Lon

    1991-01-01

    Quantum efficiency increased. Proposed Schottky-barrier infrared detector has double metallic layer of Ir and IrSi3 instead of single metallic layer of Ir, IrSi, or IrSi3. Offers advantages of both relatively high infrared absorption in thin film of Ir and stability and reproducibility of layer of IrSi3 in contact with Si. Also serves as barrier to chemical reactions between Ir overlayer and Si substrate. Detectors used to form focal-plane array integrated with charge-coupled-device-addressing and image-processing circuitry.

  1. Infrared applications for portable devices using IrDA transceivers

    NASA Astrophysics Data System (ADS)

    Krishnan, Sanjay M.; Pamidighantam, Ramana V.; Tan, Wee S.

    2001-11-01

    The internet has been the mantra in last decade and digital convergence is the latest talk on the tech streets. Features that once clearly discerned a mobile phone from a PDA or a PDA from a laptop are being replaced with multi-functional overlapping features and there is a growing need for wireless access and interoperability. Infrared communications has been addressing these needs for quite some time. The technology has matured through standardization efforts of IrDA (Infrared Data Association) and is widely used in PDAs, mobile phones, laptops, printers and digital cameras to name a few. This paper explores some new application scenarios for an IrDA transceiver. The first part of the paper describes a reference architecture for using infrared wireless communication for MP3 file exchange and the various possible user models. The second part of the paper discusses various configurations for implementing an ambient light detection scheme using IrDA transceivers, to turn off the backlighting of a LCD panel of a PDA or mobile phone in the presence of ambient light. The third part of the paper discusses various techniques of enabling extended link distance operation of IrDA transceivers for toy and remote control applications.

  2. Thermal emissivity analysis of a GEMINI 8-meter telescopes design

    NASA Technical Reports Server (NTRS)

    St. Clair Dinger, Ann

    1993-01-01

    The GEMINI 8-meter Telescopes Project is designing twin 8-meter telescopes to be located in Hawaii and Chile. The GEMINI telescopes will have interchangeable secondary mirrors for use in the visible and IR. The APART/PADE program is being used to evaluate the effective IR emissivity of the IR configuration plus enclosure as a function of mirror contamination at three IR wavelengths. The goal is to design a telescope whose effective IR emissivity is no more than 2 percent when the mirrors are clean.

  3. IRS memorandum limits joint ventures.

    PubMed

    Herman, A W

    1992-08-01

    Based on a new memorandum, the Internal Revenue Service (IRS) will be looking at joint hospital/physician activities with greater attention to the nuances of public versus private benefit. As a result, hospitals face greater risk of losing their tax-exempt status in the maze of joint ventures, physician recruitment, and practice acquisition. To be successful, ventures will have to be backed by sound reasoning and thorough documentation.

  4. A Small, Rapid Optical-IR Response Gamma-Ray Burst Space Observatory Concept: The NGRG

    NASA Astrophysics Data System (ADS)

    Grossan, B.; Kumar, P.; Perley, D.; Smoot, G. F.

    2014-10-01

    After Swift, there is no sure plan to furnish a replacement for the rapidly disseminated, high-precision GRB positions it provides, nor a new type of observatory to probe new GRB parameter space. We propose a new GRB mission concept, the Next Generation Rapid Optical-NIR (near infrared) Response GRB Observatory (NGRG) concept, and demonstrate, through analysis of Swift BAT data, studies of new GRB samples, and extinction predictions, that a relatively modest size observatory will produce valuable new measurements and good GRB detection rates. As with Swift, GRBs are initially located with a coded-mask X-ray camera. However, the NGRG has two distinguishing features: first, a beam-steering system to begin optical observations within ~1 s after location; second, in addition to the optical camera, a separate near-IR (NIR) camera viewing the same field, greatly increasing sensitivity to extinguished bursts. These features yield the unique capability of exploring the rise phase of GRB optical-NIR emission. Thus far, among GRBs with optical afterglow detections, a peak is measured in only ~26-40% of the light curves. The rise time for prompt, or pre-afterglow, optical emission is rarely measured, as is the transition to afterglow emission. Prompt or pre-afterglow NIR emission is even less frequently measured. Rapid-response measurements give new tools for exploration of many science topics, including optical emission mechanisms (synchrotron vs. SSC, photospheric emission) and jet characteristics (reverse vs. forward shock emission, baryon-dominated vs. magnetic dominated). The rapid-response capability also allows measurement of dynamic evolution of extinction due to vaporization of progenitor system dust. This dynamic dust measurement is the only tool we know of to separate the effects of star-system-scale dust and galactic-structure-scale dust; it is remarkable that this probe of small-scale phenomena can be used at the high redshifts where GRBs are observed. In this

  5. Spatially resolved Spitzer-IRS spectral maps of the superwind in M82

    NASA Astrophysics Data System (ADS)

    Beirão, P.; Armus, L.; Lehnert, M. D.; Guillard, P.; Heckman, T.; Draine, B.; Hollenbach, D.; Walter, F.; Sheth, K.; Smith, J. D.; Shopbell, P.; Boulanger, F.; Surace, J.; Hoopes, C.; Engelbracht, C.

    2015-08-01

    We have mapped the superwind/halo region of the nearby starburst galaxy M82 in the mid-infrared with Spitzer - IRS. The spectral regions covered include the H2 S(1)-S(3), [Ne II], [Ne III] emission lines and polycyclic aromatic hydrocarbon (PAH) features. We estimate the total warm H2 mass and the kinetic energy of the outflowing warm molecular gas to be between Mwarm ˜ 5 and 17 × 106 M⊙ and EK ˜ 6 and 20 × 1053 erg. Using the ratios of the 6.2, 7.7 and 11.3 μm PAH features in the IRS spectra, we are able to estimate the average size and ionization state of the small grains in the superwind. There are large variations in the PAH flux ratios throughout the outflow. The 11.3/7.7 and the 6.2/7.7 PAH ratios both vary by more than a factor of 5 across the wind region. The northern part of the wind has a significant population of PAH's with smaller 6.2/7.7 ratios than either the starburst disc or the southern wind, indicating that on average, PAH emitters are larger and more ionized. The warm molecular gas to PAH flux ratios (H2/PAH) are enhanced in the outflow by factors of 10-100 as compared to the starburst disc. This enhancement in the H2/PAH ratio does not seem to follow the ionization of the atomic gas (as measured with the [Ne III]/[Ne II] line flux ratio) in the outflow. This suggests that much of the warm H2 in the outflow is excited by shocks. The observed H2 line intensities can be reproduced with low-velocity shocks (v < 40 km s-1) driven into moderately dense molecular gas (102 < nH < 104 cm-3) entrained in the outflow.

  6. High temperature Ir segregation in Ir-B ceramics: Effect of oxygen presence on stability of IrB2 and other Ir-B phases

    DOE PAGESBeta

    Xie, Zhilin; Terracciano, Anthony C.; Cullen, David A.; Blair, Richard G.; Orlovskaya, Nina

    2015-05-13

    The formation of IrB2, IrB1.35, IrB1.1 and IrB monoboride phases in the Ir–B ceramic nanopowder was confirmed during mechanochemical reaction between metallic Ir and elemental B powders. The Ir–B phases were analysed after 90 h of high energy ball milling and after annealing of the powder for 72 h at 1050°C in vacuo. The iridium monoboride (IrB) orthorhombic phase was synthesised experimentally for the first time and identified by powder X-ray diffraction. Additionally, the ReB2 type IrB2 hexagonal phase was also produced for the first time and identified by high resolution transmission electron microscope. Ir segregation along disordered domains ofmore » the boron lattice was found to occur during high temperature annealing. Furthermore, these nanodomains may have useful catalytic properties.« less

  7. The Value of 5-Aminolevulinic Acid in Low-grade Gliomas and High-grade Gliomas Lacking Glioblastoma Imaging Features: An Analysis Based on Fluorescence, Magnetic Resonance Imaging, 18F-Fluoroethyl Tyrosine Positron Emission Tomography, and Tumor Molecular Factors

    PubMed Central

    Jaber, Mohammed; Wölfer, Johannes; Ewelt, Christian; Holling, Markus; Hasselblatt, Martin; Niederstadt, Thomas; Zoubi, Tarek; Weckesser, Matthias

    2015-01-01

    BACKGROUND: Approximately 20% of grade II and most grade III gliomas fluoresce after 5-aminolevulinic acid (5-ALA) application. Conversely, approximately 30% of nonenhancing gliomas are actually high grade. OBJECTIVE: The aim of this study was to identify preoperative factors (ie, age, enhancement, 18F-fluoroethyl tyrosine positron emission tomography [18F-FET PET] uptake ratios) for predicting fluorescence in gliomas without typical glioblastomas imaging features and to determine whether fluorescence will allow prediction of tumor grade or molecular characteristics. METHODS: Patients harboring gliomas without typical glioblastoma imaging features were given 5-ALA. Fluorescence was recorded intraoperatively, and biopsy specimens collected from fluorescing tissue. World Health Organization (WHO) grade, Ki-67/MIB-1 index, IDH1 (R132H) mutation status, O6-methylguanine DNA methyltransferase (MGMT) promoter methylation status, and 1p/19q co-deletion status were assessed. Predictive factors for fluorescence were derived from preoperative magnetic resonance imaging and 18F-FET PET. Classification and regression tree analysis and receiver-operating-characteristic curves were generated for defining predictors. RESULTS: Of 166 tumors, 82 were diagnosed as WHO grade II, 76 as grade III, and 8 as glioblastomas grade IV. Contrast enhancement, tumor volume, and 18F-FET PET uptake ratio >1.85 predicted fluorescence. Fluorescence correlated with WHO grade (P < .001) and Ki-67/MIB-1 index (P < .001), but not with MGMT promoter methylation status, IDH1 mutation status, or 1p19q co-deletion status. The Ki-67/MIB-1 index in fluorescing grade III gliomas was higher than in nonfluorescing tumors, whereas in fluorescing and nonfluorescing grade II tumors, no differences were noted. CONCLUSION: Age, tumor volume, and 18F-FET PET uptake are factors predicting 5-ALA-induced fluorescence in gliomas without typical glioblastoma imaging features. Fluorescence was associated with an increased

  8. UV extinction and IR emission in diffuse H2 regions

    NASA Technical Reports Server (NTRS)

    Aannestad, Per A.

    1994-01-01

    During this period, much work was spent in an attempt to use theoretical UV line indices as a basis for spectral calibration of the program stars. Five line indices are shown as functions of effective temperature and log g, calculated with the spectral synthesis programs of Kurucz. Open stars and circles are observed values from Fanelli et al., using the spectral class-effective temperature calibration of Schmidt-Kaler. We conclude that these line indices may be used to determine an effective stellar temperature, but with uncertainties of approximately a few thousand degrees. Also, for the hotter stars, theoretical line opacities are systematically low compared to observations. We have also found that Kurucz's new models appear to represent hot stars very well, even at far-UV wavelengths. This is shown in an example where two spectra of mu Col (spectral class 09.5 V) are compared to a synthetic spectrum for T(sub eff) = 33,000 K, log g = 4.0. Also shown (uppermost curve) is an empirical estimate of the intrinsic flux distribution for 09.5 V stars from Papaj, Wegner, and Krelowski.

  9. The development of in-situ calibration method for divertor IR thermography in ITER

    SciTech Connect

    Takeuchi, M.; Sugie, T.; Ogawa, H.; Takeyama, S.; Itami, K.

    2014-08-21

    For the development of the calibration method of the emissivity in IR light on the divertor plate in ITER divertor IR thermography system, the laboratory experiments have been performed by using IR instruments. The calibration of the IR camera was performed by the plane black body in the temperature of 100–600 degC. The radiances of the tungsten heated by 280 degC were measured by the IR camera without filter (2.5–5.1 μm) and with filter (2.95 μm, 4.67 μm). The preliminary data of the scattered light of the laser of 3.34 μm that injected into the tungsten were acquired.

  10. IR Variability During a Shell Ejection of Eta Carinae

    NASA Astrophysics Data System (ADS)

    Smith, Nathan

    2006-02-01

    Every 5.5 years, η Carinae experiences a dramatic ``spectroscopic event'' when high-excitation lines in its UV, optical, and IR spectrum disappear, and its hard X-ray and radio continuum flux crash. This periodicity has been attributed to a very eccentric binary system with a shell ejection occurring at periastron. Mid-IR images and spectra with T-ReCS are needed to measure changes in the current bolometric luminosity and to trace dust formation episodes. This will provide a direct estimate of the mass ejected. Near-IR emission lines trace related changes in the post-event wind and ionization changes in the circumstellar environment needed to test specific models for the cause of η Car's variability as it recovers from its recent ``event''. High resolution near-IR spectra with GNIRS will continue the important work of HST/STIS, investigating changes in the direct and reflected spectrum of the stellar wind, and ionization changes in the nebula. The complex kinematic structure of η Car's ejecta also holds important clues to its mass ejection history, and is essential for interpreting other data. Phoenix can provide a unique kinematic map of the complex density and time-variable ionization structure of η Car's nebula, which is our best example of the pre-explosion environment of very massive stars.

  11. AGN content of X-ray, IR and radio sources

    NASA Astrophysics Data System (ADS)

    Mickaelian, A. M.; Paronyan, G. M.; Abrahamyan, H. V.; Gyulzadyan, M. V.; Mikayelyan, G. A.

    2016-09-01

    We have carried out a number of surveys and identification works related to X-ray, IR and radio sources and searched for extragalactic ones. Among them, most interesting are Active Galactic Nuclei (AGN) and Starburst (SB) Galaxies. Some 4500 AGN have been revealed from ROSAT BSC and FSC sources, and many more are hidden ones; those showing evidence of activity but with no emission lines in optical wavelengths. We estimated AGN content of X-ray sources as 52.9%. IR sources contain thousands of SBs, and most important are those having signs of interaction and/or merging. We have carried out optical identifications of IRAS point sources, and 1278 IR galaxies have been revealed, including LIRGs and ULIRGs. We have also combined IRAS PSC and FSC catalogs and compiled its extragalactic sample, which allowed to estimate AGN content among IR sources as 23.7%. Extragalactic radio sources contain bright galaxies, AGN and SBs. We have studied the border between AGN and normal galaxies by radio/optical flux ratios to establish which objects may be attributed to AGN based on radio properties. Interestingly, absolute majority of objects associated with both X-ray and radio sources are AGN.

  12. IR susceptibility of naval ships using ShipIR/NTCS

    NASA Astrophysics Data System (ADS)

    Vaitekunas, David A.

    2010-04-01

    Methods of analysing the signature and susceptibility of naval platforms to infrared detection are described. An unclassified ShipIR destroyer model is used to illustrate the primary sources of infrared signature and detection: the exhaust system, solar-heating, and operating climate. The basic detection algorithm used by the Naval Threat Countermeasure Simulator (NTCS) component of ShipIR is described and used to analyse the effectiveness of various stealth technologies: stack suppression, low solar absorptive (LSA) paints, and Active Hull Cooling (AHC). Standard marine climate statistics are used to determine a minimum (5%), average (50%) and maximum (95%) signature condition for each operating region. The change in detection range of two wave-band sensors (3-5μm, 8-12 μm) operating at different altitudes (10m, 270m) in each of four climatic conditions is used to assess the effectiveness of each stealth solution, providing a more integral approach to infrared stealth design. These tools and methods form the basis on which future platform designs are being evaluated.

  13. Carbon nanotube IR detectors (SV)

    SciTech Connect

    Leonard, F. L.

    2012-03-01

    Sandia National Laboratories (Sandia) and Lockheed Martin Corporation (LMC) collaborated to (1) evaluate the potential of carbon nanotubes as channels in infrared (IR) photodetectors; (2) assemble and characterize carbon nanotube electronic devices and measure the photocurrent generated when exposed to infrared light;(3) compare the performance of the carbon nanotube devices with that of traditional devices; and (4) develop and numerically implement models of electronic transport and opto-electronic behavior of carbon nanotube infrared detectors. This work established a new paradigm for photodetectors.

  14. Formation of a Keplerian Disk in the Infalling Envelope around L1527 IRS: Transformation from Infalling Motions to Kepler Motions

    NASA Astrophysics Data System (ADS)

    Ohashi, Nagayoshi; Saigo, Kazuya; Aso, Yusuke; Aikawa, Yuri; Koyamatsu, Shin; Machida, Masahiro N.; Saito, Masao; Takahashi, Sanemichi Z.; Takakuwa, Shigehisa; Tomida, Kengo; Tomisaka, Kohji; Yen, Hsi-Wei

    2014-12-01

    We report Atacama Large Millimeter/submillimeter Array (ALMA) cycle 0 observations of the C18O (J = 2-1), SO (JN = 65-54), and the 1.3 mm dust continuum toward L1527 IRS, a class 0 solar-type protostar surrounded by an infalling and rotating envelope. C18O emission shows strong redshifted absorption against the bright continuum emission associated with L1527 IRS, strongly suggesting infall motions in the C18O envelope. The C18O envelope also rotates with a velocity mostly proportional to r -1, where r is the radius, whereas the rotation profile at the innermost radius (~54 AU) may be shallower than r -1, suggestive of formation of a Keplerian disk around the central protostar of ~0.3 M ⊙ in dynamical mass. SO emission arising from the inner part of the C18O envelope also shows rotation in the same direction as the C18O envelope. The rotation is, however, rigid-body-like, which is very different from the differential rotation shown by C18O. In order to explain the line profiles and the position-velocity (PV) diagrams of C18O and SO observed, simple models composed of an infalling envelope surrounding a Keplerian disk of 54 AU in radius orbiting a star of 0.3 M ⊙ are examined. It is found that in order to reproduce characteristic features of the observed line profiles and PV diagrams, the infall velocity in the model has to be smaller than the free-fall velocity yielded by a star of 0.3 M ⊙. Possible reasons for the reduced infall velocities are discussed.

  15. Formation of a Keplerian disk in the infalling envelope around L1527 IRS: transformation from infalling motions to Kepler motions

    SciTech Connect

    Ohashi, Nagayoshi; Saigo, Kazuya; Aso, Yusuke; Koyamatsu, Shin; Aikawa, Yuri; Machida, Masahiro N.; Saito, Masao; Takahashi, Sanemichi Z.; Takakuwa, Shigehisa; Yen, Hsi-Wei; Tomida, Kengo; Tomisaka, Kohji

    2014-12-01

    We report Atacama Large Millimeter/submillimeter Array (ALMA) cycle 0 observations of the C{sup 18}O (J = 2-1), SO (J{sub N} = 6{sub 5}-5{sub 4}), and the 1.3 mm dust continuum toward L1527 IRS, a class 0 solar-type protostar surrounded by an infalling and rotating envelope. C{sup 18}O emission shows strong redshifted absorption against the bright continuum emission associated with L1527 IRS, strongly suggesting infall motions in the C{sup 18}O envelope. The C{sup 18}O envelope also rotates with a velocity mostly proportional to r {sup –1}, where r is the radius, whereas the rotation profile at the innermost radius (∼54 AU) may be shallower than r {sup –1}, suggestive of formation of a Keplerian disk around the central protostar of ∼0.3 M {sub ☉} in dynamical mass. SO emission arising from the inner part of the C{sup 18}O envelope also shows rotation in the same direction as the C{sup 18}O envelope. The rotation is, however, rigid-body-like, which is very different from the differential rotation shown by C{sup 18}O. In order to explain the line profiles and the position-velocity (PV) diagrams of C{sup 18}O and SO observed, simple models composed of an infalling envelope surrounding a Keplerian disk of 54 AU in radius orbiting a star of 0.3 M {sub ☉} are examined. It is found that in order to reproduce characteristic features of the observed line profiles and PV diagrams, the infall velocity in the model has to be smaller than the free-fall velocity yielded by a star of 0.3 M {sub ☉}. Possible reasons for the reduced infall velocities are discussed.

  16. CRISTA, a cryogenic IR telescope with high spatial resolution

    SciTech Connect

    Barthol, P.; Grossmann, K.U.; Offermann, D.

    1994-12-31

    A limb sounding cryogenic IR telescope named CRISTA (CRyogenic Infrared Spectrometers and Telescopes for the Atmosphere) has been developed to study dynamic disturbances in the middle atmosphere with high spatial (horizontal and vertical) resolution. For this purpose, it measures mid and far IR emissions of several trace constituents at earth`s limb using three independent telescopes with high off-axis rejection performance. Height profiles are derived from simultaneous scans of the three telescope LOS. The radiation received is spectrally analyzed by gating spectrometers followed by Si:Ga and Ge:Ga detectors. High sensitivity together with improved spatial resolution leads to a spacing of only 500 km to 600 km between two adjacent measurement points and thus to a far more detailed picture of the atmosphere compared to present day satellite experiments. CRISTA, integrated in the free-flyer ASTROSPAS, will be launched 1994 by the Space Shuttle for a short duration mission and will be part of ATLAS 3.

  17. PAH and H2 emission in the Ring Nebula

    NASA Astrophysics Data System (ADS)

    Cox, N. L. J.; Pilleri, P.; Berné, O.; Cernicharo, J.; Joblin, C.

    2016-07-01

    This paper presents the Spitzer IRS (Infra Red Spectrograph) detection of mid-infrared polycyclic aromatic hydrocarbon (PAH) emission features and H2 associated with dense knots in the ring of the “oxygen-rich” (C/O∼⃒0.6-0.8) planetary nebula (PN) NGC6720 (Ring Nebula). We explored a further three oxygen-rich extended PNe with similar dataset available. These turned out to be non-detection of PAHs, although two of these do contain H2 emission knots. The presence of PAHs is discussed in the context of a bottom-up formation mechanism, in which first small hydrocarbons, and later PAHs, are formed in warm dense knots inside the ionised regions of PNe.

  18. Detection of Soluble and Fixed NH4+ in Clay Minerals by DTA and IR Reflectance Spectroscopy : A Potential Tool for Planetary Surface Exploration

    NASA Technical Reports Server (NTRS)

    Janice, Bishop; Banin, A.; Mancinelli, R. L.; Klovstad, M. R.; DeVincenzi, Donald L. (Technical Monitor)

    2001-01-01

    Nitrogen is an essential element for life. It is the only element among the six major biogenic elements, C, O, S, O, P, H, whose presence in the Martian soil has not been positively and directly established. We describe here a study assessing the ability to detect NH4 in soils by two methods: differential thermal analysis (DTA) and infrared (IR) reflectance spectroscopy. Four standard clay minerals (kaolinite, montmorillonite, illite and attapulgite) and an altered tephra sample from Mauna Kea were treated with NH4 in this study. Samples of the NH4-treated and leached clays were analyzed by DTA and infrared (IR) reflectance spectroscopy to quantify the delectability of soluble and sorbed/fixed NH4. An exotherm at 270-280 C was clearly detected in the DTA curves of NH4-treated (non-leached) samples. This feature is assigned to the thermal decomposition reaction of NH4. Spectral bands observed at 1.56, 2.05, 2.12, 3.06, 3.3, 3.5, 5.7 and 7.0 microns in the reflectance spectra of NH4-treated and leached samples are assigned to the sorbed/fixed ammonium in the clays. The montmorillonite has shown the most intense absorbance due to fixed ammonium among the leached samples in this study, as a result of its high cation sorption capacity. It is concluded that the presence of sorbed or fixed NH4 in clays may be detected by infrared (IR) reflectance or emission spectroscopy. Distinction between soluble and sorbed NH4 may be achieved through the presence or absence of several spectral features assigned to the sorbed NH4 moietyi and, specifically, by use of the 4.2 micrometer feature assigned to solution NH4. Thermal analyses furnish supporting evidence of ammonia in our study through detection of N released at temperatures of 270-330 C. Based on these results it is estimated that IR spectra measured from a rover should be able to detect ammonia if present above 20 mg NH4/g sample in the surface layers. Orbital IR spectra and thermal analyses measured on a rover may be able to

  19. Photonic crystals and Bragg gratings for the mid-IR and terahertz spectral ranges

    SciTech Connect

    Usikova, A. A. Il’inskaya, N. D.; Matveev, B. A.; Shubina, T. V.; Kop’ev, P. S.

    2013-12-15

    A method for the fabrication of 2D periodic structures by contact optical photolithography with image inversion is reported. The optical properties of photonic crystals and Bragg gratings for mid-IR and terahertz emitters are considered. The possibility of raising the integral emission intensity of light-emitting diodes for the mid-IR spectral range is demonstrated. The requirements to gratings for the output of terahertz emission generated by surface plasmons excited in layers of narrow-gap degenerate semiconductors with an accumulation layer are determined.

  20. High-resolution IR Absorption Spectroscopy of Polycyclic Aromatic Hydrocarbons in the 3 μm Region: Role of Periphery

    NASA Astrophysics Data System (ADS)

    Maltseva, Elena; Petrignani, Annemieke; Candian, Alessandra; Mackie, Cameron J.; Huang, Xinchuan; Lee, Timothy J.; Tielens, Alexander G. G. M.; Oomens, Jos; Buma, Wybren Jan

    2016-11-01

    In this work we report on high-resolution IR absorption studies that provide a detailed view on how the peripheral structure of irregular polycyclic aromatic hydrocarbons (PAHs) affects the shape and position of their 3 μm absorption band. For this purpose, we present mass-selected, high-resolution absorption spectra of cold and isolated phenanthrene, pyrene, benz[a]antracene, chrysene, triphenylene, and perylene molecules in the 2950–3150 cm‑1 range. The experimental spectra are compared with standard harmonic calculations and anharmonic calculations using a modified version of the SPECTRO program that incorporates a Fermi resonance treatment utilizing intensity redistribution. We show that the 3 μm region is dominated by the effects of anharmonicity, resulting in many more bands than would have been expected in a purely harmonic approximation. Importantly, we find that anharmonic spectra as calculated by SPECTRO are in good agreement with the experimental spectra. Together with previously reported high-resolution spectra of linear acenes, the present spectra provide us with an extensive data set of spectra of PAHs with a varying number of aromatic rings, with geometries that range from open to highly condensed structures, and featuring CH groups in all possible edge configurations. We discuss the astrophysical implications of the comparison of these spectra on the interpretation of the appearance of the aromatic infrared 3 μm band, and on features such as the two-component emission character of this band and the 3 μm emission plateau.

  1. Study of a V-shape flame based on IR spectroscopy and IR imaging

    NASA Astrophysics Data System (ADS)

    Pouplin, J.; Collin, A.; Acem, Z.; Parent, G.; Boulet, P.; Vena, P.; Galizzi, C.; Kühni, M.; André, F.; Escudié, D.

    2016-01-01

    Applicability of an IR imaging/spectroscopy diagnostic was tested on a laboratory- scale flame. For this purpose, measurements were carried out on a V-shape flame developed along a wall, with the aim of evaluating the wall temperature and of identifying the flame properties (temperature and species concentrations). Infrared measurements with a multiband camera and a spectrometer were post-processed and compared, in particular, with thermocouple measurements carried out for the wall temperature. Simple evaluation involving a correction for the emissivity showed a quite good agreement when assessed against experimental data. An attempt to reconstruct a flame emission spectrum was also carried out, expecting a possible inverse identification of the flame properties. The method showed a promising behaviour on synthetic data built with a radiative transfer model for gas and wall radiation. However, the spectrum reconstruction method is not yet accurate enough to allow an identification of the flame properties in full confidence when applied to actual experimental data. First tests showed a correct qualitative behaviour, but model refinements are required at least for the flame radiation, before getting accurate flame properties.

  2. Oxyfunctionalization with Cp*Ir(III)(NHC)(Me)(Cl) with O₂: identification of a rare bimetallic Ir(IV) μ-oxo intermediate.

    PubMed

    Lehman, Matthew C; Pahls, Dale R; Meredith, Joseph M; Sommer, Roger D; Heinekey, D Michael; Cundari, Thomas R; Ison, Elon A

    2015-03-18

    Methanol formation from [Cp*Ir(III)(NHC)Me(CD2Cl2)](+) occurs quantitatively at room temperature with air (O2) as the oxidant and ethanol as a proton source. A rare example of a diiridium bimetallic complex, [(Cp*Ir(NHC)Me)2(μ-O)][(BAr(F)4)2], 3, was isolated and shown to be an intermediate in this reaction. The electronic absorption spectrum of 3 features a broad observation at ∼660 nm, which is primarily responsible for its blue color. In addition, 3 is diamagnetic and can be characterized by NMR spectroscopy. Complex 3 was also characterized by X-ray crystallography and contains an Ir(IV)-O-Ir(IV) core in which two d(5) Ir(IV) centers are bridged by an oxo ligand. DFT and MCSCF calculations reveal several important features of the electronic structure of 3, most notably, that the μ-oxo bridge facilitates communication between the two Ir centers, and σ/π mixing yields a nonlinear arrangement of the μ-oxo core (Ir-O-Ir ∼ 150°) to facilitate oxygen atom transfer. The formation of 3 results from an Ir oxo/oxyl intermediate that may be described by two competing bonding models, which are close in energy and have formal Ir-O bond orders of 2 but differ markedly in their electronic structures. The radical traps TEMPO and 1,4-cyclohexadiene do not inhibit the formation of 3; however, methanol formation from 3 is inhibited by TEMPO. Isotope labeling studies confirmed the origin of the methyl group in the methanol product is the iridium-methyl bond in the [Cp*Ir(NHC)Me(CD2Cl2)][BAr(F)4] starting material. Isolation of the diiridium-containing product [(Cp*Ir(NHC)Cl)2][(BAr(F)4)2], 4, in high yields at the end of the reaction suggests that the Cp* and NHC ligands remain bound to the iridium and are not significantly degraded under reaction conditions.

  3. Oxyfunctionalization with Cp*Ir(III)(NHC)(Me)(Cl) with O₂: identification of a rare bimetallic Ir(IV) μ-oxo intermediate.

    PubMed

    Lehman, Matthew C; Pahls, Dale R; Meredith, Joseph M; Sommer, Roger D; Heinekey, D Michael; Cundari, Thomas R; Ison, Elon A

    2015-03-18

    Methanol formation from [Cp*Ir(III)(NHC)Me(CD2Cl2)](+) occurs quantitatively at room temperature with air (O2) as the oxidant and ethanol as a proton source. A rare example of a diiridium bimetallic complex, [(Cp*Ir(NHC)Me)2(μ-O)][(BAr(F)4)2], 3, was isolated and shown to be an intermediate in this reaction. The electronic absorption spectrum of 3 features a broad observation at ∼660 nm, which is primarily responsible for its blue color. In addition, 3 is diamagnetic and can be characterized by NMR spectroscopy. Complex 3 was also characterized by X-ray crystallography and contains an Ir(IV)-O-Ir(IV) core in which two d(5) Ir(IV) centers are bridged by an oxo ligand. DFT and MCSCF calculations reveal several important features of the electronic structure of 3, most notably, that the μ-oxo bridge facilitates communication between the two Ir centers, and σ/π mixing yields a nonlinear arrangement of the μ-oxo core (Ir-O-Ir ∼ 150°) to facilitate oxygen atom transfer. The formation of 3 results from an Ir oxo/oxyl intermediate that may be described by two competing bonding models, which are close in energy and have formal Ir-O bond orders of 2 but differ markedly in their electronic structures. The radical traps TEMPO and 1,4-cyclohexadiene do not inhibit the formation of 3; however, methanol formation from 3 is inhibited by TEMPO. Isotope labeling studies confirmed the origin of the methyl group in the methanol product is the iridium-methyl bond in the [Cp*Ir(NHC)Me(CD2Cl2)][BAr(F)4] starting material. Isolation of the diiridium-containing product [(Cp*Ir(NHC)Cl)2][(BAr(F)4)2], 4, in high yields at the end of the reaction suggests that the Cp* and NHC ligands remain bound to the iridium and are not significantly degraded under reaction conditions. PMID:25700811

  4. IR properties of AGN and SB

    NASA Astrophysics Data System (ADS)

    Talezade Lari, M. H.; Davoudifar, P.; Mickaelian, A. M.

    2016-09-01

    Through multi-wavelength flux ratios it is possible to detect AGN and Star-burst Galaxies. Techniques of detecting extragalactic objects as well as AGN are studied in different wavelengths (X-Ray, Radio and IR). Specification of AGN as IR and radio sources is discussed. IR catalogues of 2MASS and WISE were used to study the interrelationship between interactions/merging, starburst and AGN phenomena.

  5. Spatial Resolution of the Silicate Feature in T Tauri Binary Stars

    NASA Astrophysics Data System (ADS)

    Van Cleve, J. E.; Hayward, T. L.; Houck, J. R.; Miles, J.

    1994-05-01

    We took low resolution spectra from 7.9 to 13.0 microns of the T Tauri binary systems T Tau and Haro 6-10, as well as images of these systems and UY Aur, FV Tau, and FX Tau at 7.9 or 8.8, 10.3, and 12.5 microns, using the Cornell SpectroCam-10 imaging spectrometer on the 5-m Hale telescope. These binaries resemble planetary systems in that the projected separation of the components (100 to 180 AU) is roughly the diameter of our Solar System. For the images, the observed flux distribution along the axis of the binary was deconvolved by the flux distribution perpendicular to that axis. The resulting visibility function was then fitted to a two point-source model to obtain the relative flux of the components. The spectra were deconvolved by calibrator star spectra, and the model was fit to each wavelength of the visibility function spectrum to obtain the relative flux. Images and spectra agree and show that in binaries which contain an infrared companion -- such as T Tau and Haro 6-10 -- the IR companion has a deep silicate absorption feature, while the other component is featureless or shows a weak emission feature. In Haro 6-10, for example, the optical depth of the silicate absorption in the IR companion (Haro 6-10 N) is ~ 1 near its maximum at 9.7 microns. These results suggest that the components (including dust shells or disks around each star) of an IR companion system are not both coplanar and coeval. For a giant planet and a single star, however, we'd expect a circumplanetary disk to lie in the plane of the circumstellar disk, and be about the same age. At least for the IR companion systems, the analogy of binary stars and planetary systems is not a good one in this respect.

  6. Nearby early-type galaxies with ionized gas. VI. The Spitzer-IRS view. Basic data set analysis and empirical spectral classification

    NASA Astrophysics Data System (ADS)

    Panuzzo, P.; Rampazzo, R.; Bressan, A.; Vega, O.; Annibali, F.; Buson, L. M.; Clemens, M. S.; Zeilinger, W. W.

    2011-04-01

    Context. A large fraction of early-type galaxies (ETGs) shows emission lines in their optical spectra, mostly with LINER characteristics. Despite the number of studies, the nature of the ionization mechanisms is still debated. Many ETGs also show several signs of rejuvenation episodes. Aims: We aim to investigate the ionization mechanisms and the physical processes of a sample of ETGs using mid-infrared spectra. Methods: We present here low resolution Spitzer-IRS spectra of 40 ETGs, 18 of which from our proposed Cycle 3 observations, selected from a sample of 65 ETGs showing emission lines in their optical spectra. We homogeneously extract the mid-infrared (MIR) spectra, and after the proper subtraction of a "passive" ETG template, we derive the intensity of the ionic and molecular lines and of the polycyclic aromatic hydrocarbon (PAH) emission features. We use MIR diagnostic diagrams to investigate the powering mechanisms of the ionized gas. Results: The mid-infrared spectra of early-type galaxies show a variety of spectral characteristics. We empirically sub-divide the sample into five classes of spectra with common characteristics. Class-0, accounting for 20% of the sample, are purely passive ETGs with neither emission lines nor PAH features. Class-1 show emission lines but no PAH features, and account for 17.5% of the sample. Class-2, in which 50% of the ETGs are found, as well as having emission lines, show PAH features with unusual ratios, e.g. 7.7 μm/11.3 μm ≤ 2.3. Class-3 objects (7.5% of the sample) have emission lines and PAH features with ratios typical of star-forming galaxies. Class-4, containing only 5% of the ETGs, is dominated by a hot dust continuum. The diagnostic diagram [Ne iii]15.55 μm/[Ne ii]12.8 μm vs. [S iii]33.48 μm/[Si ii]34.82 μm, is used to investigate the different mechanisms ionizing the gas. According to the above diagram most of our ETGs contain gas ionized via either AGN-like or shock phenomena, or both. Conclusions: Most of

  7. The Ionotropic Receptors IR21a and IR25a mediate cool sensing in Drosophila

    PubMed Central

    Ni, Lina; Klein, Mason; Svec, Kathryn V; Budelli, Gonzalo; Chang, Elaine C; Ferrer, Anggie J; Benton, Richard; Samuel, Aravinthan DT; Garrity, Paul A

    2016-01-01

    Animals rely on highly sensitive thermoreceptors to seek out optimal temperatures, but the molecular mechanisms of thermosensing are not well understood. The Dorsal Organ Cool Cells (DOCCs) of the Drosophila larva are a set of exceptionally thermosensitive neurons critical for larval cool avoidance. Here, we show that DOCC cool-sensing is mediated by Ionotropic Receptors (IRs), a family of sensory receptors widely studied in invertebrate chemical sensing. We find that two IRs, IR21a and IR25a, are required to mediate DOCC responses to cooling and are required for cool avoidance behavior. Furthermore, we find that ectopic expression of IR21a can confer cool-responsiveness in an Ir25a-dependent manner, suggesting an instructive role for IR21a in thermosensing. Together, these data show that IR family receptors can function together to mediate thermosensation of exquisite sensitivity. DOI: http://dx.doi.org/10.7554/eLife.13254.001 PMID:27126188

  8. General features

    SciTech Connect

    Wallace, R.E.

    1990-01-01

    The San Andreas fault system, a complex of faults that display predominantly large-scale strike slip, is part of an even more complex system of faults, isolated segments of the East Pacific Rise, and scraps of plates lying east of the East Pacific Rise that collectively separate the North American plate from the Pacific plate. This chapter briefly describes the San Andreas fault system, its setting along the Pacific Ocean margin of North America, its extent, and the patterns of faulting. Only selected characteristics are described, and many features are left for depictions on maps and figures.

  9. Improved Correction of IR Loss in Diffuse Shortwave Measurements: An ARM Value-Added Product

    SciTech Connect

    Younkin, K; Long, CN

    2003-11-01

    Simple single black detector pyranometers, such as the Eppley Precision Spectral Pyranometer (PSP) used by the Atmospheric Radiation Measurement (ARM) Program, are known to lose energy via infrared (IR) emission to the sky. This is especially a problem when making clear-sky diffuse shortwave (SW) measurements, which are inherently of low magnitude and suffer the greatest IR loss. Dutton et al. (2001) proposed a technique using information from collocated pyrgeometers to help compensate for this IR loss. The technique uses an empirically derived relationship between the pyrgeometer detector data (and alternatively the detector data plus the difference between the pyrgeometer case and dome temperatures) and the nighttime pyranometer IR loss data. This relationship is then used to apply a correction to the diffuse SW data during daylight hours. We developed an ARM value-added product (VAP) called the SW DIFF CORR 1DUTT VAP to apply the Dutton et al. correction technique to ARM PSP diffuse SW measurements.

  10. Develop algorithms to improve detectability of defects in Sonic IR imaging NDE

    NASA Astrophysics Data System (ADS)

    Obeidat, Omar; Yu, Qiuye; Han, Xiaoyan

    2016-02-01

    Sonic Infrared (IR) technology is relative new in the NDE family. It is a fast, wide area imaging method. It combines ultrasound excitation and infrared imaging while the former to apply ultrasound energy thus induce friction heating in defects and the latter to capture the IR emission from the target. This technology can detect both surface and subsurface defects such as cracks and disbands/delaminations in various materials, metal/metal alloy or composites. However, certain defects may results in only very small IR signature be buried in noise or heating patterns. In such cases, to effectively extract the defect signals becomes critical in identifying the defects. In this paper, we will present algorithms which are developed to improve the detectability of defects in Sonic IR.

  11. IR Variability of Eta Carinae: The 2009 Event

    NASA Astrophysics Data System (ADS)

    Smith, Nathan

    2008-08-01

    Every 5.5 years, η Carinae experiences a dramatic ``spectroscopic event'' when high-excitation lines in its UV, optical, and IR spectrum disappear, and its hard X-ray and radio continuum flux crash. This periodicity has been attributed to an eccentric binary system with a shell ejection occurring at periastron, and the next periastron event will occur in January 2009. The last event in June/July 2003 was poorly observed because the star was very low in the sky, but this next event is perfectly suited for an intense ground-based monitoring campaign. Mid-IR images and spectra with T-ReCS provide a direct measure of changes in the current bolometric luminosity and a direct measure of the mass in dust formation episodes that may occur at periastron in the colliding wind shock. Near-IR emission lines trace related changes in the post-event wind and ionization changes in the circumstellar environment needed to test specific models for the cause of η Car's variability as it recovers from its recent ``event''. Because the nebular geometry is known very well from previous observations in this program, monitoring the changes in nebular ionization will yield a 3-D map of the changing asymmetric UV radiation field geometry in the binary system, and the first estimate of the orientation of its orbit.

  12. Gold-black as IR Absorber and Solar Cell Enhancer

    SciTech Connect

    Peale, Robert E.; Cleary, Justin W.; Ishimaru, Manabu; Smith, C. W.; Baillie, K.; Colwell, J. E.; Beck, Kenneth M.; Joly, Alan G.; Edwards, Oliver; Fredricksen, C. J.

    2010-03-01

    Infrared absorbance and visible/near-IR excited plasmon resonances are investigated in gold-black, a porous nano-structured conducting film. A two level full factorial optimization study with evaporation-chamber pressure, boat current, substrate temperature, and degree of polymer infusion (for hardening) was performed. Polymer infusion was found generally to reduce absorbance in the long wave IR but has little effect at THz wavelengths, although for samples with the highest absorbance there is a slight improvement in the absorbance figure of merit (FOM) in both wavelength regimes. The characteristic length scales of the structured films vary considerably as a function of deposition parameters, but the IR FOM is found to be only weakly correlated with these distributions, which are determined by wavelet analysis of scanning electron micrographs images. Initial investigations of gold-black by photoelectron emission microscopy (PEEM) reveal plasmon resonances, which have potential to enhance the efficiency of thin film solar cells. For films with different characteristic length scales, the plasmon resonances appear in portions of the film with similar length scales.

  13. Blackbody radiation sources for the IR spectral range

    SciTech Connect

    Ogarev, S. A.; Morozova, S. P.; Katysheva, A. A.; Lisiansky, B. E.; Samoylov, M. L.

    2013-09-11

    Metrological radiometric facilities for optoelectronic instruments calibration utilize in terms of standards as radiation detectors in a form of cryogenic radiometers (CR), so as radiation sources. However in practice, there are no CR working within IR spectral range. An alternative way of radiometric calibration in middle and far IR ranges is to develop a parametric series of standard radiation sources - blackbody (BB) models. The paper describes some of BBs developed at VNIIOFI for the last time [1] from cryogenic (80 K to 200 K), to low (about 200 K to 400 K) and medium (400 K to 700 K) temperature regions for calibration of the IR instruments under cryogenic-vacuum conditions. These BBs are presented by models of both types: variable-temperature and based on fixed points of Ga or In. BBs are characterized with high temperature uniformity and stability. Copper and aluminum alloys are used as the radiation cavity materials. The required value of emissivity ε{sub λ} is achieved by using different black coatings. Low-temperature and cryogenic BBs are based on the principles of indirect multi-zone electric heating (with heat isolation from LN2 cooling loop, or by using an external liquid thermostat with circulating heat-transfer agent. The principles of operation, design and test results of BBs are described.

  14. The circumstellar envelope of S 106 - IRS 4

    NASA Astrophysics Data System (ADS)

    Felli, M.; Simon, M.; Fischer, J.; Hamann, F.

    1985-04-01

    The authors present new observations that help set the parameters of the ionized circumstellar envelope of S 106-IRS 4. The part of the envelope that is optically thick at 1.35 cm wavelength is smaller than 0arcsec.15 diameter which corresponds to 90 AU at 600 pc distance. The profiles of the Brackett-α and -γ lines are somewhat different with half power widths of 121±10 and 181±15 km s-1, respectively. The He I (21P-21S) line is detected at the S 106 nebula but not at IRS 4. The He I line emission of the nebula indicates that the central star of IRS 4 must have an effective temperature of about 35,000K. Comparison of the wind model scenario presented by Felli et al. (1984) with the present data and the Paschen line and Paschen edge data of McGregor et al. (1984) shows that the model encounters difficulties when observables that require details of the velocity field and of the innermost regions of the flow are considered.

  15. Morphological Typology of Languages for IR.

    ERIC Educational Resources Information Center

    Pirkola, Ari

    2001-01-01

    Presents a morphological classification of languages from the information retrieval (IR) perspective. Discusses differences in inflection, derivation, and compounding; index of synthesis and index of fusion; cross-language retrieval research; the need for semantic and syntactic typologies; and the effects of morphology and stemming in IR.…

  16. Status Of Sofradir IR-CCD Detectors

    NASA Astrophysics Data System (ADS)

    Tribolet, Philippe; Radisson, Patrick

    1988-05-01

    The topics of this paper deal with the IR-CCD detectors manufactured by SOFRADIR the new French joint venture. Description of the IRCCD technology and the advantages of this approach are given. In conclusion, some IR-CCD typical results are given.

  17. High temperature Ir segregation in Ir-B ceramics: Effect of oxygen presence on stability of IrB2 and other Ir-B phases

    SciTech Connect

    Xie, Zhilin; Terracciano, Anthony C.; Cullen, David A.; Blair, Richard G.; Orlovskaya, Nina

    2015-05-13

    The formation of IrB2, IrB1.35, IrB1.1 and IrB monoboride phases in the Ir–B ceramic nanopowder was confirmed during mechanochemical reaction between metallic Ir and elemental B powders. The Ir–B phases were analysed after 90 h of high energy ball milling and after annealing of the powder for 72 h at 1050°C in vacuo. The iridium monoboride (IrB) orthorhombic phase was synthesised experimentally for the first time and identified by powder X-ray diffraction. Additionally, the ReB2 type IrB2 hexagonal phase was also produced for the first time and identified by high resolution transmission electron microscope. Ir segregation along disordered domains of the boron lattice was found to occur during high temperature annealing. Furthermore, these nanodomains may have useful catalytic properties.

  18. Hydrogen intercalation under graphene on Ir(111)

    NASA Astrophysics Data System (ADS)

    Grånäs, Elin; Gerber, Timm; Schröder, Ulrike A.; Schulte, Karina; Andersen, Jesper N.; Michely, Thomas; Knudsen, Jan

    2016-09-01

    Using high resolution X-ray photoelectron spectroscopy and scanning tunneling microscopy we study the intercalation of hydrogen under graphene/Ir(111). The hydrogen intercalated graphene is characterized by a component in C 1s that is shifted -0.10 to -0.18 eV with respect to pristine graphene and a component in Ir 4f at 60.54 eV. The position of this Ir 4f component is identical to that of the Ir(111) surface layer with hydrogen atoms adsorbed, indicating that the atomic hydrogen adsorption site on bare Ir(111) and beneath graphene is the same. Based on co-existence of fully- and non-intercalated graphene, and the inability to intercalate a closed graphene film covering the entire Ir(111) surface, we conclude that hydrogen dissociatively adsorbs at bare Ir(111) patches, and subsequently diffuses rapidly under graphene. A likely entry point for the intercalating hydrogen atoms is identified to be where graphene crosses an underlying Ir(111) step.

  19. The composition of Martian aeolian sands: Thermal emissivity from Viking IRTM observations

    NASA Technical Reports Server (NTRS)

    Edgett, Kenneth S.; Christensen, Philip R.

    1992-01-01

    Aeolian sands provide excellent surfaces for the remote determination of the mineralogic composition of Martian materials, because such deposits consist of relatively well-sorted, uniform particle sizes and might consist of chemically unaltered, primary mineral grains derived from bedrock. Dark features on the floors of Martian craters are controlled by aeolian processes and many consist largely of unconsolidated, windblown sand. Measurement of the thermal emissivity of geologic materials provides a way to identify mid-infrared absorption bands, the strength and positions of which vary with mineral structure and composition. The Viking Infrared Thermal Mapper (IRTM) had four surface-sensing mid-IR bands, three of which, the 7, 9, and 11 micron channels, correspond to absorption features characteristic of carbonates, sialic, and mafic minerals, respectively. In this study, the highest quality IRTM data were constrained so as to avoid the effects of atmospheric dust, clouds, surface frosts, and particle size variations (the latter using data obtained between 7 and 9 H, and they were selected for dark intracrater features such that only data taken directly from the dark feature were used, so as to avoid thermal contributions from adjacent but unrelated materials. Three-point emissivity spectra of Martian dart intracrater features were compared with laboratory emission spectra of minerals and terrestrial aeolian sands convolved using the IRTM response function to the four IRTM spectral channels.

  20. Automatic temperature computation for realistic IR simulation

    NASA Astrophysics Data System (ADS)

    Le Goff, Alain; Kersaudy, Philippe; Latger, Jean; Cathala, Thierry; Stolte, Nilo; Barillot, Philippe

    2000-07-01

    Polygon temperature computation in 3D virtual scenes is fundamental for IR image simulation. This article describes in detail the temperature calculation software and its current extensions, briefly presented in [1]. This software, called MURET, is used by the simulation workshop CHORALE of the French DGA. MURET is a one-dimensional thermal software, which accurately takes into account the material thermal attributes of three-dimensional scene and the variation of the environment characteristics (atmosphere) as a function of the time. Concerning the environment, absorbed incident fluxes are computed wavelength by wavelength, for each half an hour, druing 24 hours before the time of the simulation. For each polygon, incident fluxes are compsed of: direct solar fluxes, sky illumination (including diffuse solar fluxes). Concerning the materials, classical thermal attributes are associated to several layers, such as conductivity, absorption, spectral emissivity, density, specific heat, thickness and convection coefficients are taken into account. In the future, MURET will be able to simulate permeable natural materials (water influence) and vegetation natural materials (woods). This model of thermal attributes induces a very accurate polygon temperature computation for the complex 3D databases often found in CHORALE simulations. The kernel of MUET consists of an efficient ray tracer allowing to compute the history (over 24 hours) of the shadowed parts of the 3D scene and a library, responsible for the thermal computations. The great originality concerns the way the heating fluxes are computed. Using ray tracing, the flux received in each 3D point of the scene accurately takes into account the masking (hidden surfaces) between objects. By the way, this library supplies other thermal modules such as a thermal shows computation tool.

  1. The Venus Emissivity Mapper

    NASA Astrophysics Data System (ADS)

    Helbert, Joern; Marcq, Emmanuel; Widemann, Thomas; Mueller, Nils; Kappel, David; Tsang, Constantine; Maturilli, Alessandro; Ferrari, Sabrina; D'Amore, Mario; Dyar, Melinda; Smrekar, Suzanne

    2016-10-01

    The permanent cloud cover of Venus prohibits observations of the surface with traditional imaging techniques over the entire visible spectral range. Fortunately, Venus' atmospheric gases are largely transparent in narrow spectral windows near 1 mm. Ground observers were the first to successfully use these windows, followed by spacecraft observations during the flyby of the Galileo mission on its way to Jupiter and most recently from Venus orbit by ESA's Venus Express with the VMC and VIRTIS instruments. Analyses of VIRTIS measurements have successfully demonstrated that surface information can be extracted from these windows, but the design of the instrument limited its use for more in-depth surface investigations.Based on experience gained from using VIRTIS to observe the surface of Venus and new high temperature laboratory experiments currently performed at the Planetary Spectroscopy Laboratory of DLR, we have designed the multi-spectral Venus Emissivity Mapper (VEM). Observations from VIRTIS have revealed surface emissivity variations correlated with geological features, but existing data sets contain only three spectral channels. VEM is optimized to map the surface composition and texture, and to search for active volcanism using the narrow atmospheric windows, building on lessons from prior instrumentation and methodology. It offers an opportunity to gain important information about surface mineralogy and texture by virtue of having six different channels for surface mapping.VEM is focused mainly on observing the surface, mapping in all near-IR atmospheric windows using filters with spectral characteristics optimized for the wavelengths and widths of those windows. It also observes bands necessary for correcting atmospheric effects; these bands also provide valuable scientific data on composition as well as altitude and size distribution of the cloud particles, and on H2O vapor abundance variations in the lowest 15 km of the atmosphere.In combination with a

  2. Mineralogy and Thermal Properties of V-Type Asteroid 956 Elisa: Evidence for Diogenitic Material from the Spitzer IRS (5-35 Micrometers) Spectrum

    NASA Technical Reports Server (NTRS)

    Lim, Lucy F.; Emery, Joshua P.; Moskovitz, Nicholas A.

    2010-01-01

    We present the thermal infrared (5-35 micrometer) spectrum of 956 Elisa as measured by the Spitzer Infrared Spectrograph ("IRS"; Houck,1.R. et .11. [20041. Astrophys, 1. SuppL 154, 18-24) together with new ground-based lightcurve data and near-IR spectra. From the visible lightcurve photometry, we determine a rotation period of 16.494 +/- 0.001 h, identify the rotational phase of the Spitzer observations, and estimate the visible absolute magnitude (Hv) at that rotational phase to be 12.58 +/- 0.04. From radiometric analysis of the thermal flux spectrum, we find that at the time of observation 956 Elisa had a projected radius of 5.3 +/- 0.4 km with a visible albedo pv = 0.142+/- 0.022, significantly lower than that of the prototype V-type asteroid, 4 Vesta. (This corresponds to a radius of 5.2 +/- 0.4 km at lightcurve mean.) Analysis with the standard thermal model (STM) results in a sub-solar temperature of 292.3 +/- 2.8 K and beaming parameter eta = 1.16 +/- 0.05. Thermophysical modeling places a lower limit of 20 J m(exp -2)K(exp -1)s(exp -1/2) on the thermal inertia of the asteroid's surface layer (if the surface is very smooth) but more likely values fall between 30 and 150 J m(exp -2)K(exp -1)s(exp -1/2) depending on the sense of rotation. The emissivity spectrum, calculated by dividing the measured thermal flux spectrum by the modeled thermal continuum, exhibits mineralogically interpretable spectral features within the 9-12 micrometer reststrahlen band, the 15-16.5 micrometer Si-O-Si stretching region, and the 16-25 micrometer reststrahlen region that are consistent with pyroxene of diogenitic composition: extant diogenitic pyroxenes fall within the narrow compositional range W0(sub 2+/-1)En(sub 74+/-2)Fs(sub 24+/-1). Spectral deconvolution of the 9-12 micrometer reststrahlen features indicates that up to approximately 20% olivine may also be present, suggesting an olivine-diogenite-like mineralogy. The mid-IR spectrum is inconsistent with non

  3. Mineralogy and thermal properties of V-type Asteroid 956 Elisa: Evidence for diogenitic material from the Spitzer IRS (5-35 μm) spectrum

    NASA Astrophysics Data System (ADS)

    Lim, Lucy F.; Emery, Joshua P.; Moskovitz, Nicholas A.

    2011-06-01

    We present the thermal infrared (5-35 μm) spectrum of 956 Elisa as measured by the Spitzer Infrared Spectrograph ("IRS"; Houck, J.R. et al. [2004]. Astrophys. J. Suppl. 154, 18-24) together with new groundbased lightcurve data and near-IR spectra. From the visible lightcurve photometry, we determine a rotation period of 16.494 ± 0.001 h, identify the rotational phase of the Spitzer observations, and estimate the visible absolute magnitude ( HV) at that rotational phase to be 12.58 ± 0.04. From radiometric analysis of the thermal flux spectrum, we find that at the time of observation 956 Elisa had a projected radius of 5.3 ± 0.4 km with a visible albedo p V = 0.142 ± 0.022, significantly lower than that of the prototype V-type asteroid, 4 Vesta. (This corresponds to a radius of 5.2 ± 0.4 km at lightcurve mean.) Analysis with the standard thermal model (STM) results in a sub-solar temperature of 292.3 ± 2.8 K and beaming parameter η = 1.16 ± 0.05. Thermophysical modeling places a lower limit of 20Jm-2K-1s on the thermal inertia of the asteroid's surface layer (if the surface is very smooth) but more likely values fall between 30 and 150Jm-2K-1s depending on the sense of rotation. The emissivity spectrum, calculated by dividing the measured thermal flux spectrum by the modeled thermal continuum, exhibits mineralogically interpretable spectral features within the 9-12 μm reststrahlen band, the 15-16.5 μm Si-O-Si stretching region, and the 16-25 μm reststrahlen region that are consistent with pyroxene of diogenitic composition: extant diogenitic pyroxenes fall within the narrow compositional range Wo 2±1En 74±2Fs 24±1. Spectral deconvolution of the 9-12 μm reststrahlen features indicates that up to ≈20% olivine may also be present, suggesting an olivine-diogenite-like mineralogy. The mid-IR spectrum is inconsistent with non-cumulate eucrite as the major component on the surface of 956 Elisa, although cumulate eucrite material may be present at

  4. ISO-SWS spectra of galaxies: Continuum and features

    NASA Astrophysics Data System (ADS)

    Sturm, E.; Lutz, D.; Tran, D.; Feuchtgruber, H.; Genzel, R.; Kunze, D.; Moorwood, A. F. M.; Thornley, M. D.

    2000-06-01

    We present an inventory of mid-infrared spectral features detected in high resolution (R ~ 1500) ISO-SWS 2.4-45mu m spectra of the galaxies M 82, NGC 253, Circinus, NGC 1068, and a position in the 30 Doradus region of the Large Magellanic Cloud. We discuss their identifications and highlight possible relations between these features and the physical state of the interstellar medium in galaxies. The spectral features vary considerably from source to source in presence and relative strength. Emission features are largely absent in the intense radiation field close to an AGN. Compared to normal infrared-selected starbursts, they also seem to be weaker in a low metallicity, intensely star forming environment. The large number of features beyond 13mu m is remarkable. Some of the features have - to our knowledge - not been reported before in astronomical objects. In the 5-13mu m region, emission from unidentified infrared bands (UIBs), usually ascribed to aromatic molecules, and apparent silicate absorption dominate the spectrum. The density of features makes it difficult to determine the continuum, particularly in ground-based data of limited wavelength coverage. In fact the apparent depth of the 9.7mu m silicate absorption may be overestimated in the presence of UIB emission, as we demonstrate by comparing the spectrum of M 82 to the (absorption free) spectrum of the reflection nebula NGC 7023. No strong silicate absorption is present in M 82. The (very small grain) dust continuum under the UIB emission in our starburst templates can be modeled by a simple power law, starting at wavelengths between 8 and 9mu m. We find broad H_2O-ice absorption features at 3.0mu m in M 82 and NGC 253. Their optical depths (relative to the visual extinction) indicate that the lines of sight towards these galaxies have similar properties as the line of sight towards the Galactic Center. The active galaxy NGC 1068 exhibits a clearly different spectrum of absorption features, indicating

  5. Probability of detection using ShipIR/NV-IPM

    NASA Astrophysics Data System (ADS)

    Vaitekunas, David A.; Holst, Gerald C.; Ramaswamy, Srinivasan

    2015-05-01

    Existing FLIR detection models such as NVThermIP and NV-IPM, from the U.S. Army Night Vision and Electronic Sensors Directorate (NVESD), use only basic inputs to describe the target and background (area of the target, average and RMS temperatures of both the target and background). The objective of this work is to try and bridge the gap between more sophisticated FLIR detection models (of the sensor) and high-fidelity signature models, such as the NATO-Standard ShipIR model. A custom API is developed to load an existing ShipIR scenario model and perform the analysis from any user-specified range, altitude, and attack angle. The analysis consists of computing the total area of the target (m2), the average and RMS variation in target source temperature, and the average and RMS variation in the apparent temperature of the background. These results are then fed into the associated sensor model in NV-IPM to determine its probability of detection (versus range). Since ShipIR computes and attenuates the spectral source radiance at every pixel, the black body source and apparent temperatures are easily obtained for each point using numerical iteration (on temperature), using the spectral attenuation and path emissions from MODTRAN (already used by ShipIR to predict the apparent target and background radiance). In addition to performing the above calculations on the whole target area, a variable threshold and clustering algorithm is used to analyse whether a sub-area of the target, with a higher contrast signature but smaller size, is more likely to be detected. The methods and results from this analysis should provide the basis for a more formal interface between the two models.

  6. IRS1 deficiency protects β-cells against ER stress-induced apoptosis by modulating sXBP-1 stability and protein translation

    PubMed Central

    Takatani, Tomozumi; Shirakawa, Jun; Roe, Michael W.; Leech, Colin A.; Maier, Bernhard F.; Mirmira, Raghavendra G.; Kulkarni, Rohit N.

    2016-01-01

    Endoplasmic reticulum (ER) stress is among several pathological features that underlie β-cell failure in the development of type 1 and type 2 diabetes. Adaptor proteins in the insulin/insulin-like-growth factor-1 signaling pathways, such as insulin receptor substrate-1 (IRS1) and IRS2, differentially impact β-cell survival but the underlying mechanisms remain unclear. Here we report that β-cells deficient in IRS1 (IRS1KO) are resistant, while IRS2 deficiency (IRS2KO) makes them susceptible to ER stress-mediated apoptosis. IRS1KOs exhibited low nuclear accumulation of spliced XBP-1 due to its poor stability, in contrast to elevated accumulation in IRS2KO. The reduced nuclear accumulation in IRS1KO was due to protein instability of Xbp1 secondary to proteasomal degradation. IRS1KO also demonstrated an attenuation in their general translation status in response to ER stress revealed by polyribosomal profiling. Phosphorylation of eEF2 was dramatically increased in IRS1KO enabling the β-cells to adapt to ER stress by blocking translation. Furthermore, significantly high ER calcium (Ca2+) was detected in IRS1KO β-cells even upon induction of ER stress. These observations suggest that IRS1 could be a therapeutic target for β-cell protection against ER stress-mediated cell death by modulating XBP-1 stability, protein synthesis, and Ca2+ storage in the ER. PMID:27378176

  7. Vertical Feature Mask Feature Classification Flag Extraction

    Atmospheric Science Data Center

    2013-03-28

      Vertical Feature Mask Feature Classification Flag Extraction This routine demonstrates extraction of the ... in a CALIPSO Lidar Level 2 Vertical Feature Mask feature classification flag value. It is written in Interactive Data Language (IDL) ...

  8. IR-based spot weld NDT in automotive applications

    NASA Astrophysics Data System (ADS)

    Chen, Jian; Feng, Zhili

    2015-05-01

    Today's auto industry primarily relies on destructive teardown evaluation to ensure the quality of the resistance spot welds (RSWs) due to their criticality in crash resistance and performance of vehicles. The destructive teardown evaluation is labor intensive and costly. The very nature of the destructive test means only a few selected welds will be sampled for quality. Most of the welds in a car are never checked. There are significant costs and risks associated with reworking and scrapping the defective welded parts made between the teardown tests. IR thermography as a non-destructive testing (NDT) tool has its distinct advantage — its non-intrusive and non-contact nature. This makes the IR based NDT especially attractive for the highly automated assembly lines. IR for weld quality inspection has been explored in the past, mostly limited to the offline post-processing manner in a laboratory environment. No online real-time RSW inspection using IR thermography has been reported. Typically for postprocessing inspection, a short-pulse heating via xenon flash lamp light (in a few milliseconds) is applied to the surface of a spot weld. However, applications in the auto industry have been unsuccessful, largely due to a critical drawback that cannot be implemented in the high-volume production line - the prerequisite of painting the weld surface to eliminate surface reflection and other environmental interference. This is due to the low signal-to-noise ratio resulting from the low/unknown surface emissivity and the very small temperature changes (typically on the order of 0.1°C) induced by the flash lamp method. An integrated approach consisting of innovations in both data analysis algorithms and hardware apparatus that effectively solved the key technical barriers for IR NDT. The system can be used for both real-time (during welding) and post-processing inspections (after welds have been made). First, we developed a special IR thermal image processing method that

  9. Quantifying Flaw Characteristics from IR NDE Data

    SciTech Connect

    Miller, W; Philips, N R; Burke, M W; Robbins, C L

    2003-02-14

    Work is presented which allows flaw characteristics to be quantified from the transient IR NDE signature. The goal of this effort was to accurately determine the type, size and depth of flaws revealed with IR NDE, using sonic IR as the example IR NDE technique. Typically an IR NDE experiment will result in a positive qualitative indication of a flaw such as a cold or hot spot in the image, but will not provide quantitative data thereby leaving the practitioner to make educated guesses as to the source of the signal. The technique presented here relies on comparing the transient IR signature to exact heat transfer analytical results for prototypical flaws, using the flaw characteristics as unknown fitting parameters. A nonlinear least squares algorithm is used to evaluate the fitting parameters, which then provide a direct measure of the flaw characteristics that can be mapped to the imaged surface for visual reference. The method uses temperature data for the heat transfer analysis, so radiometric calibration of the IR signal is required. The method provides quantitative data with a single thermal event (e.g. acoustic pulse or flash), as compared to phase-lock techniques that require many events. The work has been tested with numerical data but remains to be validated by experimental data, and that effort is underway.

  10. Looking for event horizons using UV-IR relations

    NASA Astrophysics Data System (ADS)

    Gregory, James P.; Ross, Simon F.

    2001-05-01

    A primary goal in holographic theories of gravity is to study the causal structure of spacetime from the field theory point of view. This is a particularly difficult problem when the spacetime has a nontrivial causal structure, such as a black hole. We attempt to study causality through the UV-IR relation between field theory and spacetime quantities, which encodes information about bulk position. We study the UV-IR relations for charged black hole spacetimes in the AdS-CFT correspondence. We find that the UV-IR relations have a number of interesting features, but find little information about the presence of a horizon in the bulk. The scale of Wilson loops is simply related to radial position, whether or not there is a horizon. For time-dependent probes, the part of the history near the horizon only affects the late-time behavior of field theory observables. Static supergravity probes have a finite scale size related to radial position in generic black holes, but there is an interesting logarithmic divergence as the temperature approaches zero.

  11. The Spectacular Radio-Near-IR-X-Ray Jet of 3C 111

    NASA Astrophysics Data System (ADS)

    Clautice, Devon; Perlman, Eric S.; Georganopoulos, Markos; Lister, Matthew L.; Tombesi, Francesco; Cara, Mihai; Marshall, Herman L.; Hogan, Brandon Scott; Kazanas, Demos

    2016-01-01

    Relativistic jets from active galactic nuclei (AGN) are powerful phenomena that transport prodigious amounts of energy and mass from the core of a galaxy out to kiloparsec or even megaparsec distances. While most spatially-resolved jets are seen in the radio, an increasing number have been discovered to emit in the optical/near-IR and/or X-ray bands. Here we discuss a spectacular example of this class, the 3C 111 jet, housed in one of the nearest, double-lobed FR II radio galaxies known. The jet itself extends over 100 kpc on each side, making it one of the longest to be seen in the radio, near-IR/optical and X-ray bands; its length and straight nature makes it ideal for studying jet physics over many kiloparsecs. We discuss new, deep Chandra and HST observations that reveal both near-IR and X-ray emission from several components of the 3C 111 jet, as well as both the approaching and receding hotspots. We also discuss new VLA observations of the jet. The near-IR and X-ray emission in the jet is restricted to several knots, and there are important differences between the morphologies seen in the radio, near-IR bands, and X-ray bands. We analyze the broad-band spectral energy distributions of the jet components. We compare competing models of emission as they relate to frequency-dependent relativistic beaming. Synchrotron emission seems to fit adequately the observed emissions of all knots and hotspots.

  12. Experimental bandstructure of the 5 d transition metal oxide IrO2

    NASA Astrophysics Data System (ADS)

    Kawasaki, Jason; Nie, Yuefeng; Uchida, Masaki; Schlom, Darrell; Shen, Kyle

    2015-03-01

    In the 5 d iridium oxides the close energy scales of spin-orbit coupling and electron-electron correlations lead to emergent quantum phenomena. Much research has focused on the ternary iridium oxides, e.g. the Ruddlesden-Poppers An + 1BnO3 n + 1 , which exhibit behavior from metal to antiferromagnetic insulator ground states, share common features with the cuprates, and may host a number of topological phases. The binary rutile IrO2 is another important 5 d oxide, which has technological importance for spintronics due to its large spin Hall effect and also applications in catalysis. IrO2 is expected to share similar physics as its perovskite-based cousins; however, due to bond-length distortions of the IrO6 octahedra in the rutile structure, the extent of similarities remains an open question. Here we use angle-resolved photoemission spectroscopy to perform momentum-resolved measurements of the electronic structure of IrO2 . IrO2 thin films were grown by molecular beam epitaxy on TiO2 (110) substrates using an Ir e-beam source and distilled ozone. Films were subsequently transferred through ultrahigh vacuum to a connected ARPES system. Combined with first-principles calculations we explore the interplay of spin-orbit coupling and correlations in IrO2 .

  13. Spitzer/IRS Observations of Seyfert 1.8 and 1.9 Galaxies: Probing the Dusty Torus at Intermediate Viewing Angles

    NASA Astrophysics Data System (ADS)

    Kraemer, Steven; Crenshaw, Michael; Dietrich, Matthias; Elitzur, Moshe; Gull, Theodore; Teplitz, Harry; Turner, Jane

    2004-09-01

    According to the unified model for AGN, Seyfert 1.8 and 1.9 galaxies are viewed at inclinations between those of Seyfert 1s (face-on) and Seyfert 2s (edge-on) with respect to the source of obscuration, typically envisioned as a dusty torus. This view is supported by the weak broad emission-line components of the Balmer lines, with ratios that are consistent with significant (E(B-V} ~ 1 mag) reddening of the broad-line region. Mid-IR spectra are the only means with which to probe the circumnuclear gas in these intermediate Seyferts and constrain the physical structure of the torus, such as its size, scale height, and clumpiness. Seyfert 1.8s and 1.9s also tend to possess relatively weak high ionization narrow lines (e.g. [Fe~VII] 6087 A) compared to Seyfert 1s, suggesting that the dusty circumnuclear gas may also obscure the inner narrow line region. We request Spitzer IRS spectra of 12 Seyfert 1.8s and 1.9s in order to 1) determine the temperature of the dust, and hence its radial distance from the central engine, to test for a torus origin, 2) determine the scale height and clumpiness of the torus atmosphere via the silicate 10 feature and comparisons with clumpy torus models, and 3) penetrate the obscuring gas via mid-IR emission lines, such as [Ne~V] 14.3 microns and [O~IV] 25.9 microns, to reveal the hidden high-ionization inner narrow line region. We have selected targets with host galaxies that are close to face-on, to minimize contamination of the mid-IR spectra by dust in their galactic planes. Among the more than 60 Seyferts in the Spitzer/IRS reserved target catalog, there are only a handful of true Seyfert 1.8s and 1.9s, and all of these have inclined (b/a < 0.5 ) host galaxies.

  14. C2D Spitzer-IRS spectra of disks around T Tauri stars. V. Spectral decomposition

    NASA Astrophysics Data System (ADS)

    Olofsson, J.; Augereau, J.-C.; van Dishoeck, E. F.; Merín, B.; Grosso, N.; Ménard, F.; Blake, G. A.; Monin, J.-L.

    2010-09-01

    Context. Dust particles evolve in size and lattice structure in protoplanetary disks, due to coagulation, fragmentation and crystallization, and are radially and vertically mixed in disks due to turbulent diffusion and wind/radiation pressure forces. Aims: This paper aims at determining the mineralogical composition and size distribution of the dust grains in planet forming regions of disks around a statistical sample of 58 T Tauri stars observed with Spitzer/IRS as part of the Cores to Disks (c2d) Legacy Program. Methods: We present a spectral decomposition model, named “B2C”, that reproduces the IRS spectra over the full spectral range (5-35 μm). The model assumes two dust populations: a warm component responsible for the 10 μm emission arising from the disk inner regions (≲1 AU) and a colder component responsible for the 20-30 μm emission, arising from more distant regions (≲10 AU). The fitting strategy relies on a random exploration of parameter space coupled with a Bayesian inference method. Results: We show evidence for a significant size distribution flattening in the atmospheres of disks compared to the typical MRN distribution, providing an explanation for the usual flat, boxy 10 μm feature profile generally observed in T Tauri star spectra. We reexamine the crystallinity paradox, observationally identified by Olofsson et al. (2009 , A&A, 507, 327), and we find a simultaneous enrichment of the crystallinity in both the warm and cold regions, while grain sizes in both components are uncorrelated. We show that flat disks tend to have larger grains than flared disk. Finally our modeling results do not show evidence for any correlations between the crystallinity and either the star spectral type, or the X-ray luminosity (for a subset of the sample). Conclusions: The size distribution flattening may suggests that grain coagulation is a slightly more effective process than fragmentation (helped by turbulent diffusion) in disk atmospheres, and that

  15. Fatty Liver, Insulin Resistance, and Features of Metabolic Syndrome

    PubMed Central

    Sung, Ki-Chul; Wild, Sarah H.; Kwag, Hyon Joo; Byrne, Christopher D.

    2012-01-01

    OBJECTIVE Nonalcoholic fatty liver disease (NAFLD) coexists with insulin resistance (IR), but it is uncertain whether NAFLD and IR contribute independently to atherosclerosis. We tested whether fatty liver, IR, and metabolic syndrome (MetS) features (waist, glucose, triglyceride, HDL cholesterol [HDL-C], and blood pressure) were associated with a marker of atherosclerosis (coronary artery calcium [CAC] score >0), independently of cardiovascular risk factors and cardiovascular disease (CVD). RESEARCH DESIGN AND METHODS Data were analyzed from a South Korean occupational cohort of 10,153 people who all received ultrasound measurements of fatty liver and a cardiac computed tomography CAC score. IR was defined by homeostasis model assessment of IR (HOMA-IR) ≥75th percentile. Odds ratios (ORs) (95% CIs) for the presence of a CAC score >0 were estimated using logistic regression. RESULTS There were 915 people with a CAC score >0. MetS features were increased (glucose, blood pressure, triglyceride, and waist) or decreased (HDL-C) among people with a CAC score >0 (all comparisons against CAC score ≤0; P < 0.0001). Of subjects with a CAC score >0, 55% had fatty liver and 33.7% were insulin resistant. Fatty liver (OR 1.21 [95% CI 1.01–1.45]; P = 0.04) and HOMA-IR (1.10 [1.02–1.18]; P = 0.02) were associated with CAC score >0, independently of all MetS features, conventional cardiovascular risk factors, and prior evidence of CVD. The presence of IR and fatty liver combined was associated with CAC score >0 (1.53 [1.20–1.95]; P = 0.001). CONCLUSIONS Fatty liver and HOMA-IR are both associated with a CAC score >0 (independently of each other), features of MetS, conventional cardiovascular risk factors, and existing CVD. PMID:22829522

  16. Near-IR spectroscopic monitoring of CLASS I protostars: Variability of accretion and wind indicators

    SciTech Connect

    Connelley, Michael S.; Greene, Thomas P.

    2014-06-01

    We present the results of a program that monitored the near-IR spectroscopic variability of a sample of 19 embedded protostars. Spectra were taken on time intervals from 2 days to 3 yr, over a wavelength range from 0.85 μm to 2.45 μm, for 4-9 epochs of observations per target. We found that the spectra of all targets are variable and that every emission feature observed is also variable (although not for all targets). With one exception, there were no drastic changes in the continua of the spectra, nor did any line completely disappear, nor did any line appear that was not previously apparent. This analysis focuses on understanding the connection between accretion (traced by H Br γ and CO) and the wind (traced by He I, [Fe II], and sometimes H{sub 2}). For both accretion and wind tracers, the median variability was constant versus the time interval between observations; however, the maximum variability that we observed increased with the time interval between observations. Extinction is observed to vary within the minimum sampling time of 2 days, suggesting extinguishing material within a few stellar radii at high disk latitudes. The variability of [Fe II] and H{sub 2} were correlated for most (but not all) of the 7 young stellar objects showing both features, and the amplitude of the variability depends on the veiling. Although the occurrence of CO and Br γ emission are connected, their variability is uncorrelated, suggesting that these emissions originate in separate regions near the protostar (e.g., disk and wind). The variability of Br γ and wind tracers were found to be positively correlated, negatively correlated, or uncorrelated, depending on the target. The variability of Br γ, [Fe II], and H{sub 2} always lies on a plane, although the orientation of the plane in three dimensions depends on the target. While we do not understand all interactions behind the variability that we observed, we have shown that spectroscopic variability is a powerful tool

  17. Transient 2D IR spectroscopy of charge injection in dye-sensitized nanocrystalline thin films.

    PubMed

    Xiong, Wei; Laaser, Jennifer E; Paoprasert, Peerasak; Franking, Ryan A; Hamers, Robert J; Gopalan, Padma; Zanni, Martin T

    2009-12-23

    We use nonlinear 2D IR spectroscopy to study TiO(2) nanocrystalline thin films sensitized with a Re dye. We find that the free electron signal, which often obscures the vibrational features in the transient absorption spectrum, is not observed in the 2D IR spectra. Its absence allows the vibrational features of the dye to be much better resolved than with the typical IR absorption probe. We observe multiple absorption bands but no cross peaks in the 2D IR spectra, which indicates that the dyes have at least three conformations. Furthermore, by using a pulse sequence in which we initiate electron transfer in the middle of the infrared pulse train, we are able to assign the excited state features by correlating them to the ground state vibrational modes and determine that the three conformations have different time scales and cross sections for electron injection. 2D IR spectroscopy is proving to be very useful in disentangling overlapping structural distributions in biological and chemical physics processes. These experiments demonstrate that nonlinear infrared probes are also a powerful new tool for studying charge transfer at interfaces.

  18. Venus O2 visible and IR nightglow: Implications for lower thermosphere dynamics and chemistry

    NASA Astrophysics Data System (ADS)

    Bougher, S. W.; Borucki, W. J.

    1994-02-01

    The National Center for Atmospheric Research thermospheric general circulation model for the Venus thermosphere is modified to examine two observed night airglow features, both of which serve as sensitive tracers of the thermospheric circulation. New O2 nightglow data from the Pioneer Venus Orbiter (PVO) star tracker (O2 Herzberg II at 400-800 nm) and ground-based telescopes (O2 IR at 1.27 microns) yield additional model constraints for estimating Venus winds over 100-130 km. Atomic oxygen, produced by dayside CO2 photolysis peaking near 110 km, and transported to the nightside by the global wind system, is partially destroyed through three-body recombination, yielding the O2 Herzberg II visible nightglow. This emission is very sensitive to horizontal winds at altitudes between 100 and 130 km. Other trace species catalytic reactions also contribute to the production of the very strong nightside infrared (1.27 microns) emission. This paper examines the dynamical and chemical implications of these new data using the Venus thermospheric general circulation model (VTGCM) as an analysis tool. Three-dimensional calculations are presented for both solar maximum and solar medium conditions, corresponding to early PVO (1979-1981) and PVO entry (mid-1992) time periods. Very distinct periods are identified in which zonal winds are alternately weak and strong in the Venus lower thermosphere. VTGCM sensitivity studies are conducted to assess the impacts of potential changes in thermospheric zonal and day-to-night winds, and eddy diffusion on the corresponding nightglow intensities. It appears that cyclostrophic balance extends above 80 km periodically, owing to a reversal of the upper mesosphere latitudinal temperature gradient, and thereby producing strong zonal winds and correspondingly modified O2 nightglow distributions that are observed.

  19. Microscopic Disease Extension in Three Dimensions for Non-Small-Cell Lung Cancer: Development of a Prediction Model Using Pathology-Validated Positron Emission Tomography and Computed Tomography Features

    SciTech Connect

    Loon, Judith van; Siedschlag, Christian; Stroom, Joep; Blauwgeers, Hans; Suylen, Robert-Jan van; Knegjens, Joost; Rossi, Maddalena; Baardwijk, Angela van; Boersma, Liesbeth; Klomp, Houke; Vogel, Wouter; Burgers, Sjaak; Gilhuijs, Kenneth

    2012-01-01

    Purpose: One major uncertainty in radiotherapy planning of non-small-cell lung cancer concerns the definition of the clinical target volume (CTV), meant to cover potential microscopic disease extension (MDE) around the macroscopically visible tumor. The primary aim of this study was to establish pretreatment risk factors for the presence of MDE. The secondary aim was to establish the impact of these factors on the accuracy of positron emission tomography (PET) and computed tomography (CT) to assess the total tumor-bearing region at pathologic examination (CTV{sub path}). Methods and Materials: 34 patients with non-small-cell lung cancer who underwent CT and PET before lobectomy were included. Specimens were examined microscopically for MDE. The gross tumor volume (GTV) on CT and PET (GTV{sub CT} and GTV{sub PET}, respectively) was compared with the GTV and the CTV at pathologic examination, tissue deformations being taken into account. Using multivariate logistic regression, image-based risk factors for the presence of MDE were identified, and a prediction model was developed based on these factors. Results: MDE was found in 17 of 34 patients (50%). The MDE did not exceed 26 mm in 90% of patients. In multivariate analysis, two parameters (mean CT tumor density and GTV{sub CT}) were significantly associated with MDE. The area under the curve of the two-parameter prediction model was 0.86. Thirteen tumors (38%, 95% CI: 24-55%) were identified as low risk for MDE, being potential candidates for reduced-intensity therapy around the GTV. In the low-risk group, the effective diameter of the GTV{sub CT/PET} accurately represented the CTV{sub path}. In the high-risk group, GTV{sub CT/PET} underestimated the CTV{sub path} with, on average, 19.2 and 26.7 mm, respectively. Conclusions: CT features have potential to predict the presence of MDE. Tumors identified as low risk of MDE show lower rates of disease around the GTV than do high-risk tumors. Both CT and PET accurately

  20. Irs2 and Irs4 synergize in non-LepRb neurons to control energy balance and glucose homeostasis.

    PubMed

    Sadagurski, Marianna; Dong, X Charlie; Myers, Martin G; White, Morris F

    2014-02-01

    Insulin receptor substrates (Irs1, 2, 3 and Irs4) mediate the actions of insulin/IGF1 signaling. They have similar structure, but distinctly regulate development, growth, and metabolic homeostasis. Irs2 contributes to central metabolic sensing, partially by acting in leptin receptor (LepRb)-expressing neurons. Although Irs4 is largely restricted to the hypothalamus, its contribution to metabolic regulation is unclear because Irs4-null mice barely distinguishable from controls. We postulated that Irs2 and Irs4 synergize and complement each other in the brain. To examine this possibility, we investigated the metabolism of whole body Irs4(-/y) mice that lacked Irs2 in the CNS (bIrs2(-/-)·Irs4(-/y)) or only in LepRb-neurons (Lepr (∆Irs2) ·Irs4 (-/y) ). bIrs2(-/-)·Irs4(-/y) mice developed severe obesity and decreased energy expenditure, along with hyperglycemia and insulin resistance. Unexpectedly, the body weight and fed blood glucose levels of Lepr (∆Irs2) ·Irs4 (-/y) mice were not different from Lepr (∆Irs2) mice, suggesting that the functions of Irs2 and Irs4 converge upon neurons that are distinct from those expressing LepRb.

  1. Irs2 and Irs4 synergize in non-LepRb neurons to control energy balance and glucose homeostasis★

    PubMed Central

    Sadagurski, Marianna; Dong, X. Charlie; Myers, Martin G.; White, Morris F.

    2013-01-01

    Insulin receptor substrates (Irs1, 2, 3 and Irs4) mediate the actions of insulin/IGF1 signaling. They have similar structure, but distinctly regulate development, growth, and metabolic homeostasis. Irs2 contributes to central metabolic sensing, partially by acting in leptin receptor (LepRb)-expressing neurons. Although Irs4 is largely restricted to the hypothalamus, its contribution to metabolic regulation is unclear because Irs4-null mice barely distinguishable from controls. We postulated that Irs2 and Irs4 synergize and complement each other in the brain. To examine this possibility, we investigated the metabolism of whole body Irs4−/y mice that lacked Irs2 in the CNS (bIrs2−/−·Irs4−/y) or only in LepRb-neurons (Lepr∆IrsIrs4−/y). bIrs2−/−·Irs4−/y mice developed severe obesity and decreased energy expenditure, along with hyperglycemia and insulin resistance. Unexpectedly, the body weight and fed blood glucose levels of Lepr∆IrsIrs4−/y mice were not different from Lepr∆Irs2 mice, suggesting that the functions of Irs2 and Irs4 converge upon neurons that are distinct from those expressing LepRb. PMID:24567904

  2. The infra-red (IR) landscape of Triatoma infestans. An hypothesis about the role of IR radiation as a cue for Triatominae dispersal.

    PubMed

    Catalá, Silvia S

    2011-12-01

    This paper presents the infrared (IR) emission spectrum of hosts and habitats of Triatoma infestans in the chaco region of NW Argentina, representing the first attempt to correlate the natural infrared stimulus with the known behaviour of these blood-sucking insect, vectors of Trypanosoma cruzi--causative agent of Chagas disease. The study was carried out in two rural villages of La Rioja Province (Argentina). A FLYR i40 camera was used to obtain IR pictures which were analyzed to determine the thermal range for humans, domestic animals, building materials, and general background emissions. From sunset to the first hours of night, the thermal contrast between hosts and their landscape rises, increasing the likelihood that hosts could be differentiated by the vector. However, some building materials, can retain high temperatures during the night, which might add attractiveness to the presence of hosts. The results suggest that the most attractive habitats for dispersing bugs would be those at short distance, with high CO2 emission and strong IR radiation indicative of host presence. Goats corrals may be the most attractive habitat to disperse, within the domestic habitat. Dispersal would be favoured in periods of low atmospheric water saturation when IR perception is highest. In the IR band, the potential host and habitat discrimination available for the insects fits well with their known sensory capacities and observed dispersive behavior. Research in this area could be of considerable interest in relation to vector surveillance, epidemiology of Chagas disease transmission, and to develop new methods to minimise triatomine colonisation of new habitats. PMID:21856443

  3. PKC{delta}-mediated IRS-1 Ser24 phosphorylation negatively regulates IRS-1 function

    SciTech Connect

    Greene, Michael W. . E-mail: michael.greene@bassett.org; Ruhoff, Mary S.; Roth, Richard A.; Kim, Jeong-a; Quon, Michael J.; Krause, Jean A.

    2006-10-27

    The IRS-1 PH and PTB domains are essential for insulin-stimulated IRS-1 Tyr phosphorylation and insulin signaling, while Ser/Thr phosphorylation of IRS-1 disrupts these signaling events. To investigate consensus PKC phosphorylation sites in the PH-PTB domains of human IRS-1, we changed Ser24, Ser58, and Thr191 to Ala (3A) or Glu (3E), to block or mimic phosphorylation, respectively. The 3A mutant abrogated the inhibitory effect of PKC{delta} on insulin-stimulated IRS-1 Tyr phosphorylation, while reductions in insulin-stimulated IRS-1 Tyr phosphorylation, cellular proliferation, and Akt activation were observed with the 3E mutant. When single Glu mutants were tested, the Ser24 to Glu mutant had the greatest inhibitory effect on insulin-stimulated IRS-1 Tyr phosphorylation. PKC{delta}-mediated IRS-1 Ser24 phosphorylation was confirmed in cells with PKC{delta} catalytic domain mutants and by an RNAi method. Mechanistic studies revealed that IRS-1 with Ala and Glu point mutations at Ser24 impaired phosphatidylinositol-4,5-bisphosphate binding. In summary, our data are consistent with the hypothesis that Ser24 is a negative regulatory phosphorylation site in IRS-1.

  4. Detection of Extended Thermal Infrared Emission around the Vega-like Source HD 141569.

    PubMed

    Fisher; Telesco; Piña; Knacke; Wyatt

    2000-04-01

    We report the detection of extended IR emission at 10.8 and 18.2 µm around the Vega-like source HD 141569. Mid-IR imaging with OSCIR on Keck II shows emission from dust extending out to 100 AU from the B9.5 Ve star. Our modeling of the dust places an upper limit of approximately 2 µm on the diameter of the mid-IR-emitting particles if they are Mie spheres of astronomical silicates. Comparison of our mid-IR images to the near-IR (1.1 µm) NICMOS images of HD 141569 (Weinberger et al. 1999) shows that the mid-IR emission originates at smaller distances from the star than the scattered near-IR light, as also previously observed for the archetype Vega-like source beta Pictoris. PMID:10715244

  5. Near-IR Spectral Variability of Young Stars

    NASA Astrophysics Data System (ADS)

    Zajac, Stephanie; Eisner, J. A.; Rudolph, A.

    2011-01-01

    Young stars (such as T Tauri and Herbig Ae/Be sources) exhibit photometric variability across the electromagnetic spectrum, including in the visible and infrared regions. Time-variable mass accretion rates may cause some of the observed variability, although other mechanisms such as starspots or structural changes in the circumstellar disks, provide alternative explanations. Spectroscopic observations provide a means to probe accretion via diagnostic emission lines, and to probe the ratio of stellar-to-circumstellar flux via veiling of stellar absorption lines. While spectroscopic variability in the optical range has been previously investigated, variability in the near-IR has not been explored as thoroughly. We have undertaken a project to track the spectral variability of young stars in the near-IR. Using the 90-inch Bok telescope on Kitt Peak, we observed about 40 young stars with FSPEC during two five-night runs separated by one month. As this project continues, in order to extend the timescales covered by our data, we will survey the same targets under similar circumstances in the summer of 2011. Ultimately, we hope to follow a sample of about 100 young stars with five-night observing runs every month of the year. Here we present initial results showing Brackett gamma Hydrogen line emission for several sources. We show that the emission line luminosity varies, and we use this variability to constrain the mass accretion rate with time for the observed objects. We acknowledge the NSF for funding under Award No. AST-0847170, a PAARE Grant for the Calfornia-Arizona Minority Partnership for Astronomy Research and Education (CAMPARE).

  6. Insights into Epoxy Network Nanostructural Heterogeneity Using AFM-IR.

    PubMed

    Morsch, Suzanne; Liu, Yanwen; Lyon, Stuart B; Gibbon, Simon R

    2016-01-13

    The first direct observation of a chemically heterogeneous nanostructure within an epoxy resin is reported. Epoxy resins comprise the matrix component of many high performance composites, coatings and adhesives, yet the molecular network structure that underpins the performance of these industrially essential materials is not well understood. Internal nodular morphologies have repeatedly been reported for epoxy resins analyzed using SEM or AFM, yet the origin of these features remains a contentious subject, and epoxies are still commonly assumed to be chemically homogeneous. Uniquely, in this contribution we use the recently developed AFM-IR technique to eliminate previous differences in interpretation, and establish that nodule features correspond to heterogeneous network connectivity within an epoxy phenolic formulation.

  7. WFC3 IR Image Quality

    NASA Astrophysics Data System (ADS)

    Dressel, Linda

    2009-07-01

    The IR imaging performance over the detector will be assessed periodically {every 4 months} in two passbands to check for image stability. The field around star 58 in the open cluster NGC188 is the chosen target because it is sufficiently dense to provide good sampling over the FOV while providing enough isolated stars to permit accurate PSF {point spread function} measurement. It is available year-round and used previously for ACS image quality assessment. The field is astrometric, and astrometric guide stars will be used, so that the plate scale and image orientation may also be determined if necessary {as in SMOV proposals 11437 and 11443}. Full frame images will be obtained at each of 4 POSTARG offset positions designed to improve sampling over the detector in F098M, F105W, and F160W. The PSFs will be sampled at 4 positions with subpixel shifts in filters F164N and F127M.This proposal is a periodic repeat {once every 4 months} of the visits in SMOV proposal 11437 {activity ID WFC3-24}. The data will be analyzed using the code and techniques described in ISR WFC3 2008-41 {Hartig}. Profiles of encircled energy will be monitored and presented in an ISR. If an update to the SIAF is needed, {V2,V3} locations of stars will be obtained from the Flight Ops Sensors and Calibrations group at GSFC, the {V2,V3} of the reference pixel and the orientation of the detector will be determined by the WFC3 group, and the Telescopes group will update and deliver the SIAF to the PRDB branch.The specific PSF metrics to be examined are encircled energy for aperture diameter 0.25, 0.37, and 0.60 arcsec, FWHM, and sharpness. {See ISR WFC3 2008-41 tables 2 and 3 and preceding text.} 20 stars distributed over the detector will be measured in each exposure for each filter. The mean, rms, and rms of the mean will be determined for each metric. The values determined from each of the 4 exposures per filter within a visit will be compared to each other to see to what extent they are affected

  8. GPU-accelerated real-time IR smoke screen simulation and assessment of its obscuration

    NASA Astrophysics Data System (ADS)

    Wu, Xin; Zhang, Jian-qi; Huang, Xi; Liu, De-lian

    2012-01-01

    With the growing demand for the Battlefield Environment Simulation (BES), IR smoke screen, which is computationally expensive and absolutely indispensable, should be modeled true to life and correct in its thermal radiation characteristics. This paper analyzes the features of an IR smoke screen, and represents an IR smoke screen model based on light extinction, particle dispersion and temperature attenuation, which is calculated by GPU and rendered to screen in real time. Thus a method considering both the real-life in profile and the real-time in efficiency is presented. Additionally, the comparison between the simulated results and the measured data is made to verify the correctness of the smoke screen's obscuration, which illustrates the effect of its interference feature in an infrared scene.

  9. LENS MODELS OF HERSCHEL-SELECTED GALAXIES FROM HIGH-RESOLUTION NEAR-IR OBSERVATIONS

    SciTech Connect

    Calanog, J. A.; Cooray, A.; Ma, B.; Casey, C. M.; Fu, Hai; Wardlow, J.; Amber, S.; Baker, A. J.; Baes, M.; Bock, J.; Bourne, N.; Dye, S.; Bussmann, R. S.; Chapman, S. C.; Clements, D. L.; Conley, A.; Dannerbauer, H.; Dunne, L.; Eales, S.; and others

    2014-12-20

    We present Keck-Adaptive Optics and Hubble Space Telescope high resolution near-infrared (IR) imaging for 500 μm bright candidate lensing systems identified by the Herschel Multi-tiered Extragalactic Survey and Herschel Astrophysical Terahertz Large Area Survey. Out of 87 candidates with near-IR imaging, 15 (∼17%) display clear near-IR lensing morphologies. We present near-IR lens models to reconstruct and recover basic rest-frame optical morphological properties of the background galaxies from 12 new systems. Sources with the largest near-IR magnification factors also tend to be the most compact, consistent with the size bias predicted from simulations and previous lensing models for submillimeter galaxies (SMGs). For four new sources that also have high-resolution submillimeter maps, we test for differential lensing between the stellar and dust components and find that the 880 μm magnification factor (μ{sub 880}) is ∼1.5 times higher than the near-IR magnification factor (μ{sub NIR}), on average. We also find that the stellar emission is ∼2 times more extended in size than dust. The rest-frame optical properties of our sample of Herschel-selected lensed SMGs are consistent with those of unlensed SMGs, which suggests that the two populations are similar.

  10. Low cost molded optics for IR imaging

    NASA Astrophysics Data System (ADS)

    Zhao, Jing; DiFilippo, Vincent; Li, Michael

    2009-05-01

    Infrared sensors play a critical role in detection, guidance, and targeting in today's military systems and warfighter equipment, ranging from man-portable to space-borne. Although significant progress is being made in the development of IR imagers, another important component of IR sensors has not evolved significantly-the optics. Current IR lenses are primarily made of expensive single-crystal germanium with tedious mechanical fabrication operations that include grinding, polishing, and edging. There is an industry wide need for lower cost and higher performance IR lenses. Agiltron has developed a technology to directly mold IR lenses to net-shape without additional finishing operations. This manufacturing technology produces optics with many-fold reductions in cost, size, weight, and fabrication time. The ability to reproducibly manufacture aspheric optics with complex net-shapes reduces the number of lenses traditionally required for imaging systems, providing aberration correction as well as system weight and size reductions. Additionally, anti-reflective surfaces can be molded into the glass, eliminating the need for expensive AR coatings. This technology utilizes a new chalcogenide glass material that reduces temperature induced index of refraction changes to near zero, and has a thermal expansion coefficient similar to aluminum. The result is a new generation of low cost, high performance and thermally robust IR lens systems.

  11. Isolated gramicidin peptides probed by IR spectroscopy.

    PubMed

    Rijs, Anouk M; Kabeláč, Martin; Abo-Riziq, Ali; Hobza, Pavel; de Vries, Mattanjah S

    2011-07-11

    We report double-resonant IR/UV ion-dip spectroscopy of neutral gramicidin peptides in the gas phase. The IR spectra of gramicidin A and C, recorded in both the 1000 cm(-1) to 1800 cm(-1) and the 2700 to 3750 cm(-1) region, allow structural analysis. By studying this broad IR range, various local intramolecular interactions are probed, and complementary IR modes can be accessed. Ab initio quantum chemical calculations are used to support the interpretation of the experimental IR spectra. The comparison of the calculated frequencies with the experimental IR spectrum probed via the strong infrared absorptions of all the amide groups (NH stretch, C=O stretch and NH bend), shows evidence for a helical structure in the gas phase, which is similar to that in the condensed phase. Additionally, we show that to improve the spectral resolution when studying large neutral molecular structures of the size of gramicidin, the use of heavier carrier gas could be advantageous.

  12. Broadband high-power mid-IR femtosecond pulse generation from an ytterbium-doped fiber laser pumped optical parametric amplifier.

    PubMed

    Hu, Chengzhi; Chen, Tao; Jiang, PeiPei; Wu, Bo; Su, Jianjia; Shen, Yonghang

    2015-12-15

    We report on a high-power periodically poled MgO-doped lithium niobate (MgO:PPLN)-based femtosecond optical parametric amplifier (OPA), featuring a spectral seamless broadband mid-infrared (MIR) output. By modifying the initial chirp and spectrum of the mode-locked seed laser, the Yb fiber pump laser exhibits a final output power of 14 W with sub-200-fs pulse duration after power amplification and compression. When the OPA was seeded with a broadband amplified spontaneous emission (ASE) source, a damage-limited 0.6 W broadband MIR radiation was experimentally obtained under the pump power of 10.15 W at 82 MHz repetition rate, corresponding to an overall OPA conversion efficiency of 32.7%. The 3 dB bandwidth of the mid-IR idler was 291.9 nm, centering at 3.34 μm. PMID:26670509

  13. Spitzer IRAC Observations of IR Excess in Holmberg IX X-1: A Circumbinary Disk or a Variable Jet?

    NASA Astrophysics Data System (ADS)

    Dudik, R. P.; Berghea, C. T.; Roberts, T. P.; Grisé, F.; Singh, A.; Pagano, R.; Winter, L. M.

    2016-11-01

    We present Spitzer Infrared Array Camera photometric observations of the ultraluminous X-ray source (ULX, X-1) in Holmberg IX. We construct a spectral energy distribution (SED) for Holmberg IX X-1 based on published optical, UV, and X-ray data combined with the IR data from this analysis. We modeled the X-ray and optical data with disk and stellar models; however, we find a clear IR excess in the ULX SED that cannot be explained by fits or extrapolations of any of these models. Instead, further analysis suggests that the IR excess results from dust emission, possibly a circumbinary disk, or a variable jet.

  14. Work function measurements by the field emission retarding potential method

    NASA Technical Reports Server (NTRS)

    Swanson, L. W.; Strayer, R. W.; Mackie, W. A.

    1971-01-01

    Using the field emission retarding potential method true work functions have been measured for the following monocrystalline substrates: W(110), W(111), W(100), Nb(100), Ni(100), Cu(100), Ir(110) and Ir(111). The electron elastic and inelastic reflection coefficients from several of these surfaces have also been examined near zero primary beam energy.

  15. The infrared emission from the elliptical galaxy NGC 1052

    NASA Technical Reports Server (NTRS)

    Becklin, E. E.; Tokunaga, A. T.; Wynn-Williams, C. G.

    1982-01-01

    Multi-aperture IR photometry of the elliptical galaxy NGC 1052 shows that its IR excess is confined to a region smaller than 2 arc sec (300 pc) in diameter coincident with the visible nucleus. It is suggested that the emission in the 5-20 micron range arises from dust heated by the nonthermal source seen at other wavelengths.

  16. The Near-IR Band Strengths of Molecules in N2 and H2O Ices

    NASA Astrophysics Data System (ADS)

    Richey, Christina; Gerakines, P. A.

    2008-09-01

    In order to determine the column density of an ice component, the band strength of an absorption feature must be known. The sizes of near-IR features can be correlated with a previously studied mid-IR feature whose band strength is already known. Molecules in mixtures may affect position, FWHM, shapes and intensities of absorption peaks, as well as band strength. Many satellites within the solar system have surfaces are dominated by either N2 or H2O (Review by Roush 2001). It has already been shown that for CH4 and CO isolated in N2 the peak positions will be shifted, and width and peak intensities will be altered in comparison to pure ice spectra (Quirico et al. 1999). The experiments here focus on changes in band strength, intensity, FWHM, and positioning for N2 mixed with CO, CO2, CH4, NH3, and H2O in 5:1 ratios and H2O mixed with CO, CO2, CH4, NH3, and N2 in 5:1 ratios and is a continuation of previous results published by the Astro- and Solar-System Program at UAB (Gerakines et. al. 2005). These data may be used to determine ice abundances from observed near-IR spectra or to predict the sizes of near-IR features in astrophysical environments.

  17. Calibrating Historical IR Sensors Using GEO, and AVHRR Infrared Tropical Mean Calibration Models

    NASA Technical Reports Server (NTRS)

    Scarino, Benjamin; Doelling, David R.; Minnis, Patrick; Gopalan, Arun; Haney, Conor; Bhatt, Rajendra

    2014-01-01

    Long-term, remote-sensing-based climate data records (CDRs) are highly dependent on having consistent, wellcalibrated satellite instrument measurements of the Earth's radiant energy. Therefore, by making historical satellite calibrations consistent with those of today's imagers, the Earth-observing community can benefit from a CDR that spans a minimum of 30 years. Most operational meteorological satellites rely on an onboard blackbody and space looks to provide on-orbit IR calibration, but neither target is traceable to absolute standards. The IR channels can also be affected by ice on the detector window, angle dependency of the scan mirror emissivity, stray-light, and detector-to-detector striping. Being able to quantify and correct such degradations would mean IR data from any satellite imager could contribute to a CDR. Recent efforts have focused on utilizing well-calibrated modern hyper-spectral sensors to intercalibrate concurrent operational IR imagers to a single reference. In order to consistently calibrate both historical and current IR imagers to the same reference, however, another strategy is needed. Large, well-characterized tropical-domain Earth targets have the potential of providing an Earth-view reference accuracy of within 0.5 K. To that effort, NASA Langley is developing an IR tropical mean calibration model in order to calibrate historical Advanced Very High Resolution Radiometer (AVHRR) instruments. Using Meteosat-9 (Met-9) as a reference, empirical models are built based on spatially/temporally binned Met-9 and AVHRR tropical IR brightness temperatures. By demonstrating the stability of the Met-9 tropical models, NOAA-18 AVHRR can be calibrated to Met-9 by matching the AVHRR monthly histogram averages with the Met-9 model. This method is validated with ray-matched AVHRR and Met-9 biasdifference time series. Establishing the validity of this empirical model will allow for the calibration of historical AVHRR sensors to within 0.5 K, and thereby

  18. IR spectroscopic characteristics of cell cycle and cell death probed by synchrotron radiation based Fourier transform IR spectromicroscopy

    NASA Technical Reports Server (NTRS)

    Holman, H. Y.; Martin, M. C.; Blakely, E. A.; Bjornstad, K.; McKinney, W. R.

    2000-01-01

    Synchrotron radiation based Fourier transform IR (SR-FTIR) spectromicroscopy allows the study of individual living cells with a high signal to noise ratio. Here we report the use of the SR-FTIR technique to investigate changes in IR spectral features from individual human lung fibroblast (IMR-90) cells in vitro at different points in their cell cycle. Clear changes are observed in the spectral regions corresponding to proteins, DNA, and RNA as a cell changes from the G(1)-phase to the S-phase and finally into mitosis. These spectral changes include markers for the changing secondary structure of proteins in the cell, as well as variations in DNA/RNA content and packing as the cell cycle progresses. We also observe spectral features that indicate that occasional cells are undergoing various steps in the process of cell death. The dying or dead cell has a shift in the protein amide I and II bands corresponding to changing protein morphologies, and a significant increase in the intensity of an ester carbonyl C===O peak at 1743 cm(-1) is observed. Copyright John Wiley & Sons, Inc. Biopolymers (Biospectroscopy) 57: 329-335, 2000.

  19. Late emission from SN 1987A

    NASA Technical Reports Server (NTRS)

    Fransson, C.; Chevalier, R. A.

    1987-01-01

    Multiwavelength observations of SN 1987A are examined, and the late emission from the mantle gas is modeled under the assumption of energy input by gamma rays from Co-56 decay. An emission line spectrum of low-ionization species has been produced at optical through IR wavelengths. At an age of about 700 days, an IR catastrophe occurs, and most of the radiation is then emitted in IR fine-structure lines. The gamma-ray intensity is found to peak in the 15-solar-mass model at an age of 270 days. Very little production of X-rays below 50 keV is expected if the photon interaction with the hydrogen envelope can be neglected. It is suggested that the radio emission from the pulsar may be absorbed by the ejecta for several years.

  20. UNUSUAL PAH EMISSION IN NEARBY EARLY-TYPE GALAXIES: A SIGNATURE OF AN INTERMEDIATE-AGE STELLAR POPULATION?

    SciTech Connect

    Vega, O.; Bressan, A.; Panuzzo, P.; Granato, G. L.; Silva, L.; Zeilinger, W. W.

    2010-10-01

    We present the analysis of Spitzer-IRS spectra of four early-type galaxies (ETGs), NGC 1297, NGC 5044, NGC 6868, and NGC 7079, all classified as LINERs in the optical bands. Their IRS spectra present the full series of H{sub 2} rotational emission lines in the range 5-38 {mu}m, atomic lines, and prominent polycyclic aromatic hydrocarbon (PAH) features. We investigate the nature and origin of the PAH emission, characterized by unusually low 6-9/11.3 {mu}m interband ratios. After the subtraction of a passive ETG template, we find that the 7-9 {mu}m spectral region requires dust features not normally present in star-forming galaxies. Each spectrum is then analyzed with the aim of identifying their components and origin. In contrast to normal star-forming galaxies, where cationic PAH emission prevails, our 6-14 {mu}m spectra seem to be dominated by large and neutral PAH emission, responsible for the low 6-9/11.3 {mu}m ratios, plus two broad dust emission features peaking at 8.2 {mu}m and 12 {mu}m. These broad components, observed until now mainly in evolved carbon stars and usually attributed to pristine material, contribute approximately 30%-50% of the total PAH flux in the 6-14 {mu}m region. We propose that the PAH molecules in our ETGs arise from fresh carbonaceous material that is continuously released by a population of carbon stars, formed in a rejuvenation episode that occurred within the last few Gyr. The analysis of the MIR spectra allows us to infer that, in order to maintain the peculiar size and charge distributions biased to large and neutral PAHs, this material must be shocked and excited by the weak UV interstellar radiation field of our ETGs.

  1. Efficient enhancement of the visible-light absorption of cyclometalated Ir(III) complexes triplet photosensitizers with Bodipy and applications in photooxidation and triplet-triplet annihilation upconversion.

    PubMed

    Sun, Jifu; Zhong, Fangfang; Yi, Xiuyu; Zhao, Jianzhang

    2013-06-01

    We report molecular designing strategies to enhance the effective visible-light absorption of cyclometalated Ir(III) complexes. Cationic cyclometalated Ir(III) complexes were prepared in which boron-dipyrromethene (Bodipy) units were attached to the 2,2'-bipyridine (bpy) ligand via -C≡C- bonds at either the meso-phenyl (Ir-2) or 2 position of the π core of Bodipy (Ir-3). For the first time the effect of π conjugating (Ir-3) or tethering (Ir-2) of a light-harvesting chromophore to the coordination center on the photophysical properties was compared in detail. Ir(ppy)2(bpy) (Ir-1; ppy = 2-phenylpyridine) was used as model complex, which gives the typical weak absorption in visible range (ε < 4790 M(-1) cm(-1) in region > 400 nm). Ir-2 and Ir-3 showed much stronger absorption in the visible range (ε = 71,400 M(-1) cm(-1) at 499 nm and 83,000 M(-1) cm(-1) at 527 nm, respectively). Room-temperature phosphorescence was only observed for Ir-1 (λ(em) = 590 nm) and Ir-3 (λ(em) = 742 nm). Ir-3 gives RT phosphorescence of the Bodipy unit. On the basis of the 77 K emission spectra, nanosecond transient absorption spectra, and spin density analysis, we proposed that Bodipy-localized long-lived triplet excited states were populated for Ir-2 (τT = 23.7 μs) and Ir-3 (87.2 μs). Ir-1 gives a much shorter triplet-state lifetime (0.35 μs). Complexes were used as singlet oxygen ((1)O2) photosensitizers in photooxidation. The (1)O2 quantum yield of Ir-3 (ΦΔ = 0.97) is ca. 2-fold of Ir-2 (ΦΔ = 0.52). Complexes were also used as triplet photosensitizer for TTA upconversion; upconversion quantum yields of 1.2% and 2.8% were observed for Ir-2 and Ir-3, respectively. Our results proved that the strong absorption of visible light of Ir-2 failed to enhance production of a triplet excited state. These results are useful for designing transition metal complexes that show effective strong visible-light absorption and long-lived triplet excited states, which can be used as ideal

  2. Mid-IR enhanced laser ablation molecular isotopic spectrometry

    NASA Astrophysics Data System (ADS)

    Brown, Staci; Ford, Alan; Akpovo, Codjo A.; Johnson, Lewis

    2016-08-01

    A double-pulsed laser-induced breakdown spectroscopy (DP-LIBS) technique utilizing wavelengths in the mid-infrared (MIR) for the second pulse, referred to as double-pulse LAMIS (DP-LAMIS), was examined for its effect on detection limits compared to single-pulse laser ablation molecular isotopic spectrometry (LAMIS). A MIR carbon dioxide (CO2) laser pulse at 10.6 μm was employed to enhance spectral emissions from nanosecond-laser-induced plasma via mid-IR reheating and in turn, improve the determination of the relative abundance of isotopes in a sample. This technique was demonstrated on a collection of 10BO and 11BO molecular spectra created from enriched boric acid (H3BO3) isotopologues in varying concentrations. Effects on the overall ability of both LAMIS and DP-LAMIS to detect the relative abundance of boron isotopes in a starting sample were considered. Least-squares fitting to theoretical models was used to deduce plasma parameters and understand reproducibility of results. Furthermore, some optimization for conditions of the enhanced emission was achieved, along with a comparison of the overall emission intensity, plasma density, and plasma temperature generated by the two techniques.

  3. Power-Law Template for IR Point Source Clustering

    NASA Technical Reports Server (NTRS)

    Addison, Graeme E.; Dunkley, Joanna; Hajian, Amir; Viero, Marco; Bond, J. Richard; Das, Sudeep; Devlin, Mark; Halpern, Mark; Hincks, Adam; Hlozek, Renee; Marriage, Tobias A.; Moodley, Kavilan; Page, Lyman A.; Reese, Erik D.; Scott, Douglass; Spergel, David N.; Staggs,Suzanne T.; Wollack, Edward

    2011-01-01

    We perform a combined fit to angular power spectra of unresolved infrared (IR) point sources from the Planck satellite (at 217,353,545 and 857 GHz, over angular scales 100 < I < 2200), the Balloonborne Large-Aperture Submillimeter Telescope (BLAST; 250, 350 and 500 microns; 1000 < I < 9000), and from correlating BLAST and Atacama Cosmology Telescope (ACT; 148 and 218 GHz) maps. We find that the clustered power over the range of angular scales and frequencies considered is well fit by a simple power law of the form C_l\\propto I(sup -n) with n = 1.25 +/- 0.06. While the IR sources are understood to lie at a range of redshifts, with a variety of dust properties, we find that the frequency dependence of the clustering power can be described by the square of a modified blackbody, nu(sup beta) B(nu,T_eff), with a single emissivity index beta = 2.20 +/- 0.07 and effective temperature T_eff= 9.7 K. Our predictions for the clustering amplitude are consistent with existing ACT and South Pole Telescope results at around 150 and 220 GHz, as is our prediction for the effective dust spectral index, which we find to be alpha_150-220 = 3.68 +/- 0.07 between 150 and 220 GHz. Our constraints on the clustering shape and frequency dependence can be used to model the IR clustering as a contaminant in Cosmic Microwave Background anisotropy measurements. The combined Planck and BLAST data also rule out a linear bias clustering model.

  4. Far-infrared surface emissivity and climate.

    PubMed

    Feldman, Daniel R; Collins, William D; Pincus, Robert; Huang, Xianglei; Chen, Xiuhong

    2014-11-18

    Presently, there are no global measurement constraints on the surface emissivity at wavelengths longer than 15 μm, even though this surface property in this far-IR region has a direct impact on the outgoing longwave radiation (OLR) and infrared cooling rates where the column precipitable water vapor (PWV) is less than 1 mm. Such dry conditions are common for high-altitude and high-latitude locations, with the potential for modeled climate to be impacted by uncertain surface characteristics. This paper explores the sensitivity of instantaneous OLR and cooling rates to changes in far-IR surface emissivity and how this unconstrained property impacts climate model projections. At high latitudes and altitudes, a 0.05 change in emissivity due to mineralogy and snow grain size can cause a 1.8-2.0 W m(-2) difference in the instantaneous clear-sky OLR. A variety of radiative transfer techniques have been used to model the far-IR spectral emissivities of surface types defined by the International Geosphere-Biosphere Program. Incorporating these far-IR surface emissivities into the Representative Concentration Pathway (RCP) 8.5 scenario of the Community Earth System Model leads to discernible changes in the spatial patterns of surface temperature, OLR, and frozen surface extent. The model results differ at high latitudes by as much as 2°K, 10 W m(-2), and 15%, respectively, after only 25 y of integration. Additionally, the calculated difference in far-IR emissivity between ocean and sea ice of between 0.1 and 0.2, suggests the potential for a far-IR positive feedback for polar climate change. PMID:25368189

  5. Far-infrared surface emissivity and climate

    PubMed Central

    Feldman, Daniel R.; Collins, William D.; Pincus, Robert; Huang, Xianglei; Chen, Xiuhong

    2014-01-01

    Presently, there are no global measurement constraints on the surface emissivity at wavelengths longer than 15 μm, even though this surface property in this far-IR region has a direct impact on the outgoing longwave radiation (OLR) and infrared cooling rates where the column precipitable water vapor (PWV) is less than 1 mm. Such dry conditions are common for high-altitude and high-latitude locations, with the potential for modeled climate to be impacted by uncertain surface characteristics. This paper explores the sensitivity of instantaneous OLR and cooling rates to changes in far-IR surface emissivity and how this unconstrained property impacts climate model projections. At high latitudes and altitudes, a 0.05 change in emissivity due to mineralogy and snow grain size can cause a 1.8–2.0 W m−2 difference in the instantaneous clear-sky OLR. A variety of radiative transfer techniques have been used to model the far-IR spectral emissivities of surface types defined by the International Geosphere-Biosphere Program. Incorporating these far-IR surface emissivities into the Representative Concentration Pathway (RCP) 8.5 scenario of the Community Earth System Model leads to discernible changes in the spatial patterns of surface temperature, OLR, and frozen surface extent. The model results differ at high latitudes by as much as 2°K, 10 W m−2, and 15%, respectively, after only 25 y of integration. Additionally, the calculated difference in far-IR emissivity between ocean and sea ice of between 0.1 and 0.2, suggests the potential for a far-IR positive feedback for polar climate change. PMID:25368189

  6. Far-infrared surface emissivity and climate

    DOE PAGESBeta

    Feldman, Daniel R.; Collins, William D.; Pincus, Robert; Huang, Xianglei; Chen, Xiuhong

    2014-11-03

    Presently, there are no global measurement constraints on the surface emissivity at wavelengths longer than 15 μm, even though this surface property in this far-IR region has a direct impact on the outgoing longwave radiation (OLR) and infrared cooling rates where the column precipitable water vapor (PWV) is less than 1 mm. Such dry conditions are common for high-altitude and high-latitude locations, with the potential for modeled climate to be impacted by uncertain surface characteristics. This paper explores the sensitivity of instantaneous OLR and cooling rates to changes in far-IR surface emissivity and how this unconstrained property impacts climate modelmore » projections. At high latitudes and altitudes, a 0.05 change in emissivity due to mineralogy and snow grain size can cause a 1.8–2.0 W m⁻² difference in the instantaneous clear-sky OLR. A variety of radiative transfer techniques have been used to model the far-IR spectral emissivities of surface types defined by the International Geosphere-Biosphere Program. Incorporating these far-IR surface emissivities into the Representative Concentration Pathway (RCP) 8.5 scenario of the Community Earth System Model leads to discernible changes in the spatial patterns of surface temperature, OLR, and frozen surface extent. The model results differ at high latitudes by as much as 2°K, 10 W m⁻², and 15%, respectively, after only 25 y of integration. The calculated difference in far-IR emissivity between ocean and sea ice of between 0.1 and 0.2, suggests the potential for a far-IR positive feedback for polar climate change.« less

  7. Far-infrared surface emissivity and climate.

    PubMed

    Feldman, Daniel R; Collins, William D; Pincus, Robert; Huang, Xianglei; Chen, Xiuhong

    2014-11-18

    Presently, there are no global measurement constraints on the surface emissivity at wavelengths longer than 15 μm, even though this surface property in this far-IR region has a direct impact on the outgoing longwave radiation (OLR) and infrared cooling rates where the column precipitable water vapor (PWV) is less than 1 mm. Such dry conditions are common for high-altitude and high-latitude locations, with the potential for modeled climate to be impacted by uncertain surface characteristics. This paper explores the sensitivity of instantaneous OLR and cooling rates to changes in far-IR surface emissivity and how this unconstrained property impacts climate model projections. At high latitudes and altitudes, a 0.05 change in emissivity due to mineralogy and snow grain size can cause a 1.8-2.0 W m(-2) difference in the instantaneous clear-sky OLR. A variety of radiative transfer techniques have been used to model the far-IR spectral emissivities of surface types defined by the International Geosphere-Biosphere Program. Incorporating these far-IR surface emissivities into the Representative Concentration Pathway (RCP) 8.5 scenario of the Community Earth System Model leads to discernible changes in the spatial patterns of surface temperature, OLR, and frozen surface extent. The model results differ at high latitudes by as much as 2°K, 10 W m(-2), and 15%, respectively, after only 25 y of integration. Additionally, the calculated difference in far-IR emissivity between ocean and sea ice of between 0.1 and 0.2, suggests the potential for a far-IR positive feedback for polar climate change.

  8. Far-infrared surface emissivity and climate

    SciTech Connect

    Feldman, Daniel R.; Collins, William D.; Pincus, Robert; Huang, Xianglei; Chen, Xiuhong

    2014-11-03

    Presently, there are no global measurement constraints on the surface emissivity at wavelengths longer than 15 μm, even though this surface property in this far-IR region has a direct impact on the outgoing longwave radiation (OLR) and infrared cooling rates where the column precipitable water vapor (PWV) is less than 1 mm. Such dry conditions are common for high-altitude and high-latitude locations, with the potential for modeled climate to be impacted by uncertain surface characteristics. This paper explores the sensitivity of instantaneous OLR and cooling rates to changes in far-IR surface emissivity and how this unconstrained property impacts climate model projections. At high latitudes and altitudes, a 0.05 change in emissivity due to mineralogy and snow grain size can cause a 1.8–2.0 W m⁻² difference in the instantaneous clear-sky OLR. A variety of radiative transfer techniques have been used to model the far-IR spectral emissivities of surface types defined by the International Geosphere-Biosphere Program. Incorporating these far-IR surface emissivities into the Representative Concentration Pathway (RCP) 8.5 scenario of the Community Earth System Model leads to discernible changes in the spatial patterns of surface temperature, OLR, and frozen surface extent. The model results differ at high latitudes by as much as 2°K, 10 W m⁻², and 15%, respectively, after only 25 y of integration. The calculated difference in far-IR emissivity between ocean and sea ice of between 0.1 and 0.2, suggests the potential for a far-IR positive feedback for polar climate change.

  9. Thermonuclear Supernovae: Probing Magnetic Fields by Positrons and Late-time IR Line Profiles

    NASA Astrophysics Data System (ADS)

    Penney, R.; Hoeflich, P.

    2014-11-01

    We show the importance of γ and positron transport for the formation of late-time spectra in Type Ia supernovae (SNe Ia). The goal is to study the imprint of magnetic fields (B) on late-time IR line profiles, particularly the [Fe II] feature at 1.644 μm, which becomes prominent two to three months after the explosion. As a benchmark, we use the explosion of a Chandrasekhar mass (M Ch) white dwarf (WD) and, specifically, a delayed detonation model that can reproduce the light curves and spectra for a Branch-normal SN Ia. We assume WDs with initial magnetic surface fields between 1 and 109 G. We discuss large-scale dipole and small-scale magnetic fields. We show that positron transport effects must be taken into account for the interpretation of emission features starting at about one to two years after maximum light, depending on the size of B. The [Fe II] line profile and its evolution with time can be understood in terms of the overall energy input by radioactive decay and the transition from a γ-ray to a positron-dominated regime. We find that the [Fe II] line at 1.644 μm can be used to analyze the overall chemical and density structure of the exploding WD up to day 200 without considering B. At later times, positron transport and magnetic field effects become important. After about day 300, the line profile allows one to probe the size of the B-field. The profile becomes sensitive to the morphology of B at about day 500. In the presence of a large-scale dipole field, a broad line is produced in M Ch mass explosions that may appear flat-topped or rounded depending on the inclination at which the SN is observed. Small or no directional dependence of the spectra is found for small-scale B. We note that narrow-line profiles require central 56Ni as shown in our previous studies. Persistent broad-line, flat-topped profiles require high-density burning, which is the signature of a WD close to M Ch. Good time coverage is required to separate the effects of optical

  10. Thermonuclear supernovae: probing magnetic fields by positrons and late-time IR line profiles

    SciTech Connect

    Penney, R.; Hoeflich, P. E-mail: rpenney@g.clemson.edu

    2014-11-01

    We show the importance of γ and positron transport for the formation of late-time spectra in Type Ia supernovae (SNe Ia). The goal is to study the imprint of magnetic fields (B) on late-time IR line profiles, particularly the [Fe II] feature at 1.644 μm, which becomes prominent two to three months after the explosion. As a benchmark, we use the explosion of a Chandrasekhar mass (M {sub Ch}) white dwarf (WD) and, specifically, a delayed detonation model that can reproduce the light curves and spectra for a Branch-normal SN Ia. We assume WDs with initial magnetic surface fields between 1 and 10{sup 9} G. We discuss large-scale dipole and small-scale magnetic fields. We show that positron transport effects must be taken into account for the interpretation of emission features starting at about one to two years after maximum light, depending on the size of B. The [Fe II] line profile and its evolution with time can be understood in terms of the overall energy input by radioactive decay and the transition from a γ-ray to a positron-dominated regime. We find that the [Fe II] line at 1.644 μm can be used to analyze the overall chemical and density structure of the exploding WD up to day 200 without considering B. At later times, positron transport and magnetic field effects become important. After about day 300, the line profile allows one to probe the size of the B-field. The profile becomes sensitive to the morphology of B at about day 500. In the presence of a large-scale dipole field, a broad line is produced in M {sub Ch} mass explosions that may appear flat-topped or rounded depending on the inclination at which the SN is observed. Small or no directional dependence of the spectra is found for small-scale B. We note that narrow-line profiles require central {sup 56}Ni as shown in our previous studies. Persistent broad-line, flat-topped profiles require high-density burning, which is the signature of a WD close to M {sub Ch}. Good time coverage is required to

  11. Infrared emission from comets.

    PubMed

    Krishna-Swamy, K S; Sandford, S A; Allamandola, L J; Witteborn, F C; Bregman, J D

    1989-05-01

    A brief discussion of the infrared observations from 4 to 20 micrometers of seven comets is presented. The observed infrared emission from comets depends primarily on their heliocentric distance. A model based on grain populations composed of a mixture of silicate and amorphous carbon particles in the mass ratio of about 40 to 1, with a power-law size distribution similar to that inferred for comet Halley, is applied to the observations. The model provides a good match to the observed heliocentric variation of both the 10 micrometers feature and the overall thermal emission from comets West and Halley. Matches to the observations of comet IRAS-Araki-Alcock and the antitail of comet Kohoutek require slightly larger grains. While the model does not match the exact profile and position of the 3.4 micrometers feature discovered in comet Halley, it does produce a qualitative fit to the observed variation of the feature's strength as a function of heliocentric distance. The calculations predict that the continuum under the 3.4 micrometers feature is due primarily to thermal emission from the comet dust when the comet is close to the Sun and to scattered solar radiation at large heliocentric distances, as is observed. A brief discussion of the determination of cometary grain temperatures from the observed infrared emission is presented. It is found that the observed shape of the emission curve from about 4 to 8 micrometers provides the best spectral region for estimating the cometary grain temperature distribution.

  12. Nighttime reactive nitrogen measurements from stratospheric infrared thermal emission observations

    NASA Technical Reports Server (NTRS)

    Abbas, Mian M.; Kunde, Virgil G.; Brasunas, J. C.; Herman, J. R.; Massie, Steven T.

    1991-01-01

    IR thermal emission spectra of the earth's atmosphere in the 700-2000/cm region were obtained with a cryogenically cooled high-resolution interferometer spectrometer on a balloon flight from Palestine, Texas, on September 15-16, 1986. The observations exhibit spectral features of a number of stratospheric constituents, including important species of the reactive nitrogen family. An analysis of the observed data for simultaneously measured vertical distributions of O3, H2O, N2O, NO2, N2O5, HNO3, and ClONO2 is presented. These measurements permit the first direct determination of the nighttime total reactive nitrogen concentrations, and the partitioning of the important elements of the NO(x) family. Comparisons of the total reactive nitrogen budget are made with the measurements by the ATMOS experiment and with the predictions of one-dimensional and two-dimensional photochemical models.

  13. New Insulating Antiferromagnetic Quaternary Iridates MLa10Ir4O24 (M = Sr, Ba).

    PubMed

    Zhao, Qingbiao; Han, Fei; Stoumpos, Constantinos C; Han, Tian-Heng; Li, Hao; Mitchell, J F

    2015-01-01

    Recently, oxides of Ir(4+) have received renewed attention in the condensed matter physics community, as it has been reported that certain iridates have a strongly spin-orbital coupled (SOC) electronic state, J eff = ½, that defines the electronic and magnetic properties. The canonical example is the Ruddlesden-Popper compound Sr2IrO4, which has been suggested as a potential route to a new class of high temperature superconductor due to the formal analogy between J eff = ½ and the S = ½ state of the cuprate superconductors. The quest for other iridium oxides that present tests of the underlying SOC physics is underway. In this spirit, here we report the synthesis and physical properties of two new quaternary tetravalent iridates, MLa10Ir4O24 (M = Sr, Ba). The crystal structure of both compounds features isolated IrO6 octahedra in which the electronic configuration of Ir is d(5). Both compounds order antiferromagnetically despite the lack of obvious superexchange pathways, and resistivity measurement shows that SrLa10Ir4O24 is an insulator. PMID:26129886

  14. New insulating antiferromagnetic quaternary iridates MLa10Ir4O24 (M=Sr, Ba)

    DOE PAGESBeta

    Zhao, Qingbiao; Han, Fei; Stoumpos, Constantinos C.; Han, Tian -Heng; Li, Hao; Mitchell, J. F.

    2015-07-01

    Recently, oxides of Ir4+ have received renewed attention in the condensed matter physics community, as it has been reported that certain iridates have a strongly spin-orbital coupled (SOC) electronic state, Jeff = ½, that defines the electronic and magnetic properties. The canonical example is the Ruddlesden-Popper compound Sr2IrO4, which has been suggested as a potential route to a new class of high temperature superconductor due to the formal analogy between Jeff = ½ and the S = ½ state of the cuprate superconductors. The quest for other iridium oxides that present tests of the underlying SOC physics is underway. Inmore » this spirit, here we report the synthesis and physical properties of two new quaternary tetravalent iridates, MLa10Ir4O24 (M = Sr, Ba). The crystal structure of both compounds features isolated IrO6 octahedra in which the electronic configuration of Ir is d5. As a result, both compounds order antiferromagnetically despite the lack of obvious superexchange pathways, and resistivity measurement shows that SrLa10Ir4O24 is an insulator.« less

  15. Compact hybrid IR/UV biological sensor

    NASA Astrophysics Data System (ADS)

    Leonard, Donald A.; Shaw, James F.; Smith, Christopher; Titterton, Paul J., Sr.; Neilson, Norm; Scofield, Russ; Carlisle, Sylvie A.; Warren, Russell E.; Cooper, David E.

    1999-01-01

    The sensor is a hybrid IR/UV lidar system that maps aerosol clouds, measures cloud wind speed and direction, and determines whether the cloud fluoresces. It is being developed by EOO, Inc. and SRI International under a DARPA SBIR. The hybrid IR/UV lidar system was conceived to operate from a small UAV platform for tactical battlefield missions. The IR sensor can detect and map aerosol clouds out to ranges of several kilometers. After detection, the UAV can close to within several hundred meters of the cloud and interrogate it with the UV sensor to identify whether the UV cloud fluoresces. Both sensors use the same basic IR laser source that is non-linearly shifted to the appropriate UV wavelength. The IR sensor also provides wind speed using edge-filter Doppler information. Parametric studies during the Phase I SBIR provided performance vs. form/fit trade-off for various platforms. The tactical UAV was chosen as the platform to guide the Phase II brassboard development. Other airborne and ground-based platforms suitable for surveillance or intelligence can be used. The paper will describe the brassboard system and the sensor performance as validated by test data.

  16. Infrared (IR) photon-sensitive spectromicroscopy in a cryogenic environment

    DOEpatents

    Pereverzev, Sergey

    2016-06-14

    A system designed to suppress thermal radiation background and to allow IR single-photon sensitive spectromicroscopy of small samples by using both absorption, reflection, and emission/luminescence measurements. The system in one embodiment includes: a light source; a plurality of cold mirrors configured to direct light along a beam path; a cold or warm sample holder in the beam path; windows of sample holder (or whole sample holder) are transparent in a spectral region of interest, so they do not emit thermal radiation in the same spectral region of interest; a cold monochromator or other cold spectral device configured to direct a selected fraction of light onto a cold detector; a system of cold apertures and shields positioned along the beam path to prevent unwanted thermal radiation from arriving at the cold monochromator and/or the detector; a plurality of optical, IR and microwave filters positioned along the beam path and configured to adjust a spectral composition of light incident upon the sample under investigation and/or on the detector; a refrigerator configured to maintain the detector at a temperature below 1.0K; and an enclosure configured to: thermally insulate the light source, the plurality of mirrors, the sample holder, the cold monochromator and the refrigerator.

  17. IR LASER BASED CHEMICAL SENSOR FOR THE COOPERATIVE MONITORING PROGRAM

    SciTech Connect

    Edward A Whitaker

    2005-08-08

    The purpose of this project was to investigate the device properties of the quantum cascade laser (QCL), a type of laser invented at Bell Laboratories, Lucent Technologies in the device physics research lab of Dr. Federico Capasso and more specifically to determine the remote sensing capability of this device. The PI and Stevens Institute of Technology collaborated with Dr. Capasso and Bell Laboratories to carry out this research project. The QCL is a unique laser source capable of generating laser radiation in the middle-infrared spectral region that overlaps the most important molecular absorption bands. With appropriate modulation techniques it is possible to use the laser to measure the concentration of many molecules of interest to the remote sensing community. In addition, the mid-IR emission wavelength is well suited to atmospheric transmission as mid-IR experiences much less scattering due to dust and fog. At the onset of this project little was known about several key device performance parameters of this family of lasers and the NNSA supported research enabled them to determine values of several of these characteristics.

  18. Fast rise time IR detectors for lepton colliders

    NASA Astrophysics Data System (ADS)

    Drago, A.; Bini, S.; Cestelli Guidi, M.; Marcelli, A.; Pace, E.

    2016-07-01

    Diagnostics is a fundamental issue for accelerators whose demands are continuously increasing. In particular bunch-by-bunch diagnostics is a key challenge for the latest generation of lepton colliders and storage rings. The Frascati Φ-factory, DAΦNE, colliding at 1.02 GeV in the centre of mass, hosts in the main rings few synchrotron radiation beamlines and two of them collect the synchrotron radiation infrared emission: SINBAD from the electron ring and 3+L from the positron ring. At DAΦNE each bucket is 2.7 ns long and particles are gathered in bunches emitting pulsed IR radiation, whose intensity in the long wavelength regime is directly proportional to the accumulated particles. Compact uncooled photoconductive HgCdTe detectors have been tested in both beamlines using dedicated optical layouts. Actually, the fast rise time of HgCdTe semiconductors give us the chance to test bunch-by-bunch devices for both longitudinal and transverse diagnostics. For the longitudinal case, single pixel detectors have been used, while for the transverse diagnostics, multi-pixel array detectors, with special custom design, are under test. This contribution will briefly describe the status of the research on fast IR detectors at DAΦNE, the results obtained and possible foreseen developments.

  19. Metamaterials with angle selective emissivity in the near-infrared.

    PubMed

    Bossard, Jeremy A; Werner, Douglas H

    2013-03-11

    Metamaterials have been previously studied for their ability to tailor the dispersive IR emissivity of a surface. Here, we investigate two metamaterial structures based on an electromagnetic band-gap surface and a dielectric resonator array for use as near-IR emitters with custom angle selectivity. A genetic algorithm is successfully employed to optimize the metamaterial structures to have minimum emissivity in the normal direction and high emissivity at custom off-normal angles specified by the designer. Two symmetry conditions are utilized to achieve emissivity patterns that are azimuthally stable or distinct in the two orthogonal plane cuts.

  20. Application of the mid-IR radio correlation to the Ĝ sample and the search for advanced extraterrestrial civilisations

    NASA Astrophysics Data System (ADS)

    Garrett, M. A.

    2015-09-01

    Wright et al. (2014, ApJ, 792, 26) have embarked on a search for advanced Karadashev Type III civilisations via the compilation of a sample of sources with extreme mid-IR emission and colours. The aim is to furnish a list of candidate galaxies that might harbour an advanced Kardashev Type III civilisation; in this scenario, the mid-IR emission is then primarily associated with waste heat energy by-products. I apply the mid-IR radio correlation to this Glimpsing Heat from Alien Technology (Ĝ) sample, a catalogue of 93 candidate galaxies compiled by Griffith et al. (2015, ApJS, 217, 25). I demonstrate that the mid-IR and radio luminosities are correlated for the sample, determining a k-corrected value of q22 = 1.35 ± 0.42. By comparison, a similar measurement for 124 galaxies drawn from the First Look Survey (FLS) has q22 = 0.87 ± 0.27. The statistically significant difference of the mean value of q22 for these two samples, taken together with their more comparable far-IR properties, suggests that the Ĝ sample shows excessive emission in the mid-IR. The fact that the Ĝ sample largely follows the mid-IR radio correlation strongly suggests that the vast majority of these sources are associated with galaxies in which natural astrophysical processes are dominant. This simple application of the mid-IR radio correlation can substantially reduce the number of false positives in the Ĝ catalogue since galaxies occupied by advanced Kardashev Type III civilisations would be expected to exhibit very high values of q. I identify nine outliers in the sample with q22> 2 of which at least three have properties that are relatively well explained via standard astrophysical interpretations e.g. dust emission associated with nascent star formation and/or nuclear activity from a heavily obscured AGN. The other outliers have not been studied in any great detail, and are deserving of further observation. I also note that the comparison of resolved mid-IR and radio images of galaxies

  1. Near-IR fluorescence and reflectance confocal microscopy for imaging of quantum dots in mammalian skin

    PubMed Central

    Mortensen, Luke J.; Glazowski, Christopher E.; Zavislan, James M.; DeLouise, Lisa A.

    2011-01-01

    Understanding the skin penetration of nanoparticles (NPs) is an important concern due to the increasing presence of NPs in consumer products, including cosmetics. Technical challenges have slowed progress in evaluating skin barrier and NP factors that contribute to skin penetration risk. To limit sampling error and other problems associated with histological processing, many researchers are implementing whole tissue confocal or multiphoton microscopies. This work introduces a fluorescence and reflectance confocal microscopy system that utilizes near-IR excitation and emission to detect near-IR lead sulfide quantum dots (QDs) through ex vivo human epidermis. We provide a detailed prediction and experimental analysis of QD detection sensitivity and demonstrate detection of QD skin penetration in a barrier disrupted model. The unique properties of near-IR lead-based QDs will enable future studies that examine the impact of further barrier-disrupting agents on skin penetration of QDs and elucidate mechanistic insight into QD tissue interactions at the cellular level. PMID:21698023

  2. Composite Fillers and their Influence on Emissivity

    NASA Astrophysics Data System (ADS)

    Mauer, Milan; Kalenda, Petr; Honner, Milan; Vacíková, Petra

    The research work presented in this paper shows influence of filler composition in inorganic composite on its emissivity. Development of system which will provide a very high emissivity (0.90 - 0.99) within a short wavelength range is the intention of our project. Active ingredients (Chromium Oxide, Iron powder, Kaolin, Silicon Carbide, Boron Carbide, Boron Nitride and Aluminum Nitride) were built in matrix of the composite. Furrier Transform Infra- Red (FTIR) Spectroscopy method was applied for measurement of spectral emissivity. Block hot plate was used for heating samples in relative emissivity measurement and laser beam in absolute emissivity measurement. These tests demonstrated that filler composition is able to influence emissive properties in range of short IR wavelength (1.5-4.0 μm) within 0.7 - 1.5 times (against the reference). Also influence of content of active ingredient in ceramic matrix on emissivity was measured. Content of active ingredients had no significant effect on emissivity.

  3. PAH emission variations within the resolved starbursts of NGC 253 and NGC 1808

    NASA Astrophysics Data System (ADS)

    Tacconi-Garman, L. E.; Sturm, E.; Lehnert, M.; Lutz, D.; Davies, R. I.; Moorwood, A. F. M.

    2005-03-01

    In order to better characterise the usefulness of PAH emission as a tracer of star formation, we have undertaken a programme of 3 μm narrowband imaging of a sample of nearby template galaxies covering a wide range of metallicity, star formation activity, and nuclear activity. In the present paper we present first results of this programme: high spatial resolution images of PAH feature emission and the adjacent continuum emission from the central regions of the nearby starburst galaxies NGC 253 and NGC 1808, taken with ISAAC at the VLT-UT1. Globally, the feature emission is seen to peak on the central starburst regions of both sources. On smaller scales, however, we see no general spatial correlation or anti-correlation between the PAH feature emission and the location of sites of recent star formation, suggesting that the degree to which PAH feature emission traces starburst activity is more complicated than previously hypothesized based on results from data with lower spatial resolution. We do find spatial correlations, though, when we consider the feature-to-continuum ratio, which is low at the positions of known super star clusters in NGC 1808 as well as at the position of the IR peak in NGC 253. We take this to imply a decrease in the efficiency of PAH emission induced by the star formation, caused either by mechanical energy input into the ISM, photoionisation of the PAH molecules, or photodissociation of the PAH molecules. All three hypotheses are discussed. In addition, for the first time we present observations of PAH feature emission in the superwind of a starbursting system (NGC 253), providing strong support that winds are heavily mass-loaded and entrain substantial amounts of ambient ISM. We have also found a plausible connection between observed NaD absorption, H2, and PAHs above the plane of NGC 253. This observation has important implications for enriching galaxy halos and possibly the intergalactic medium with small dust grains. Based on

  4. Passive IR flexi-scope with two spectral colors for household screening of gastrointestinal disorders

    NASA Astrophysics Data System (ADS)

    Byrd, Kenneth; Szu, Harold

    2006-04-01

    According to our generalized Shannon Sampling Theorem of developmental system biology, we should increase the sampling frequency of the passive Infrared (IR) spectrum ratio test, (I 8~12mm / I 3~5mm). This procedure proved to be effective in DCIS using the satellite-grade IR spectrum cameras for an early developmental symptom of the "angiogenesis" effect. Thus, we propose to augment the annual hospital checkup of, or biannual Colonoscopy, with an inexpensive non-imaging IR-Flexi-scope intensity measurement device which could be conducted regularly at a household residence without the need doctoral expertise or a data basis system. The only required component would be a smart PC, which would be used to compute the degree of thermal activities through the IR spectral ratio. It will also be used to keep track of the record and send to the medical center for tele-diagnosis. For the purpose of household screening, we propose to have two integrated passive IR probes of dual-IR-color spectrum inserted into the body via the IR fiber-optic device. In order to extract the percentage of malignancy, based on the ratio of dual color IR measurements, the key enabler is the unsupervised learning algorithm in the sense of the Duda & Hart Unlabelled Data Classifier without lookup table exemplars. This learning methodology belongs to the Natural Intelligence (NI) of the human brain, which can effortlessly reduce the redundancy of pair inputs and thereby enhance the Signal to Noise Ratio (SNR) better than any single sensor for the salient feature extraction. Thus, we can go beyond a closed data basis AI expert system to tailor to the individual ground truth without the biases of the prior knowledge.

  5. Epitaxial Growth of Ca2IrO4 Single-Crystal Thin-Films

    NASA Astrophysics Data System (ADS)

    Souri, Maryam; Gruenewald, John H.; Terzic, Jasminka; Cao, Gang; Brill, Joseph W.; Seo, Sung S. Ambrose

    2015-03-01

    Complex oxides containing 5 d transition metals including iridates have attracted substantial attention due to their potential to create novel electronic and magnetic states that originate from strong spin-orbit coupling and the electron-correlation of 5 d electrons. However, the progress of experimental research on the 5 d transition-metal oxides is hindered by the limited number of available materials. To further understand the layered iridates (A2IrO4, A: alkaline-earth elements) featuring the Jeff = 1/2 Mott state, we have synthesized epitaxial thin-films of Ca2IrO4. The single crystal Ruddlesden-Popper (R-P) phase of Can+1IrnO3n+1 (n =1) is thermodynamically unstable; hence, we have used epitaxial-stabilization strategies to grow metastable thin-films of Ca2IrO4. The R-P phase of Ca2IrO4 is synthesized on yttrium aluminum oxide and lanthanum aluminum oxide substrates by pulsed laser deposition. We have studied the electronic structure of these films by transport and optical spectroscopic measurements. The dc-resistivity shows that these Ca2IrO4 thin-films are insulating with activation energy of about 100 meV. The optical spectroscopy shows that the optical gap energy is about 0.5 eV. We will discuss the electronic structure of Ca2IrO4 by comparing with Sr2IrO4andBa2IrO4.

  6. Ir-induced activation of Au towards CO adsorption: Ir films deposited on Au{111}

    NASA Astrophysics Data System (ADS)

    Zhang, Tianfu; Driver, Stephen M.; Pratt, Stephanie J.; Jenkins, Stephen J.; King, David A.

    2016-06-01

    We have investigated the interaction of CO with Ir/Au{111} bimetallic surfaces, and the influence of morphology changes as Ir moves sub-surface into the Au bulk, using reflection-absorption infrared spectroscopy (RAIRS). The presence of Ir stabilises CO on exposed regions of the Au surface at temperatures up to around 200 K: we attribute this to low-coordinated Au sites, probably associated with lifting of the clean-surface 'herringbone' reconstruction by Ir deposition. The highest density of active Au sites is obtained after annealing the bimetallic surface to 500-600 K: we attribute this to morphology changes associated with the movement of Ir into bulk Au.

  7. IR signature management for the modern navy

    NASA Astrophysics Data System (ADS)

    Vaitekunas, David A.; Kim, Yoonsik

    2013-06-01

    A methodology for analysing the infrared (IR) signature and susceptibility of naval platforms using ShipIR/NTCS was presented by Vaitekunas (2010). This paper provides three key improvements: use of a larger climatic data set (N=100), a new target sub-image algorithm eliminating false detections from pixel-aliasing at the horizon, and a new seeker model interfacing with a line-by-line background clutter model. Existing commercial stealth technologies (exhaust stack suppression, low solar absorptive paints, extended hull film-cooling) are re-analysed using the new models and methods to produce a more rigorous and comprehensive analysis of their effectiveness based on the statistics of reduction in IR susceptibility. These methods and results combined with the cost of each stealth option should allow platform managers to select an appropriate level of infrared suppression and establish the design criteria for a new ship.

  8. Tunable mid IR plasmon in GZO nanocrystals.

    PubMed

    Hamza, M K; Bluet, J-M; Masenelli-Varlot, K; Canut, B; Boisron, O; Melinon, P; Masenelli, B

    2015-07-28

    Degenerate metal oxide nanoparticles are promising systems to expand the significant achievements of plasmonics into the infrared (IR) range. Among the possible candidates, Ga-doped ZnO nanocrystals are particularly suited for mid IR, considering their wide range of possible doping levels and thus of plasmon tuning. In the present work, we report on the tunable mid IR plasmon induced in degenerate Ga-doped ZnO nanocrystals. The nanocrystals are produced by a plasma expansion and exhibit unprotected surfaces. Tuning the Ga concentration allows tuning the localized surface plasmon resonance. Moreover, the plasmon resonance is characterized by a large damping. By comparing the plasmon of nanocrystal assemblies to that of nanoparticles dispersed in an alumina matrix, we investigate the possible origins of such damping. We demonstrate that it partially results from the self-organization of the naked particles and also from intrinsic inhomogeneity of dopants.

  9. Fiber Delivery of mid-IR lasers

    SciTech Connect

    Kriesel, J.M.; Gat, N.; Bernacki, Bruce E.; Myers, Tanya L.; Bledt, Carlos M.; Harrington, James P.

    2011-08-24

    Fiber optics for the visible to near infrared (NIR) wavelength regimes (i.e. = 0.42 {mu}m) have proven to be extremely useful for a myriad of applications such as telecommunications, illumination, and sensors because they enable convenient, compact, and remote delivery of laser beams. Similarly, there is a need for fiber optics operating at longer wavelengths. For example, systems operating in the mid-IR regime (i.e., = 314 {mu}m) are being developed to detect trace molecular species with far-reaching applications, such as detecting explosives on surfaces, pollutants in the environment, and biomarkers in the breath of a patient. Furthermore, with the increasing availability of quantum cascade lasers (QCLs) which are semiconductor lasers that operate in the mid-IR regime additional uses are rapidly being developed. Here, we describe the development of hollow-core fibers for delivery of high-quality mid-IR laser beams across a broad spectral range.

  10. Buckled silicene formation on Ir(111).

    PubMed

    Meng, Lei; Wang, Yeliang; Zhang, Lizhi; Du, Shixuan; Wu, Rongting; Li, Linfei; Zhang, Yi; Li, Geng; Zhou, Haitao; Hofer, Werner A; Gao, Hong-Jun

    2013-02-13

    Silicene, a two-dimensional (2D) honeycomb structure similar to graphene, has been successfully fabricated on an Ir(111) substrate. It is characterized as a (√7×√7) superstructure with respect to the substrate lattice, as revealed by low energy electron diffraction and scanning tunneling microscopy. Such a superstructure coincides with the (√3×√3) superlattice of silicene. First-principles calculations confirm that this is a (√3×√3)silicene/(√7×√7)Ir(111) configuration and that it has a buckled conformation. Importantly, the calculated electron localization function shows that the silicon adlayer on the Ir(111) substrate has 2D continuity. This work provides a method to fabricate high-quality silicene and an explanation for the formation of the buckled silicene sheet.

  11. IRAS 15099-5856: REMARKABLE MID-INFRARED SOURCE WITH PROMINENT CRYSTALLINE SILICATE EMISSION EMBEDDED IN THE SUPERNOVA REMNANT MSH15-52

    SciTech Connect

    Koo, Bon-Chul; Kim, Hyun-Jeong; Im, Myungshin; McKee, Christopher F.; Suh, Kyung-Won; Moon, Dae-Sik; Lee, Ho-Gyu; Onaka, Takashi; Burton, Michael G.; Hiramatsu, Masaaki; Bessell, Michael S.; Gaensler, B. M.; Lee, Jae-Joon; Jeong, Woong-Seob; Tatematsu, Ken'ichi; Kawabe, Ryohei; Ezawa, Hajime; Kohno, Kotaro; Wilson, Grant; Yun, Min S.

    2011-05-01

    We report new mid-infrared (MIR) observations of the remarkable object IRAS 15099-5856 using the space telescopes AKARI and Spitzer, which demonstrate the presence of prominent crystalline silicate emission in this bright source. IRAS 15099-5856 has a complex morphology with a bright central compact source (IRS1) surrounded by knots, spurs, and several extended ({approx}4') arc-like filaments. The source is seen only at {>=}10 {mu}m. The Spitzer mid-infrared spectrum of IRS1 shows prominent emission features from Mg-rich crystalline silicates, strong [Ne II] 12.81 {mu}m, and several other faint ionic lines. We model the MIR spectrum as thermal emission from dust and compare with the Herbig Be star HD 100546 and the luminous blue variable R71, which show very similar MIR spectra. Molecular line observations reveal two molecular clouds around the source, but no associated dense molecular cores. We suggest that IRS1 is heated by UV radiation from the adjacent O star Muzzio 10 and that its crystalline silicates most likely originated in a mass outflow from the progenitor of the supernova remnant (SNR) MSH 15-52. IRS1, which is embedded in the SNR, could have been shielded from the SN blast wave if the progenitor was in a close binary system with Muzzio 10. If MSH 15-52 is a remnant of Type Ib/c supernova (SN Ib/c), as has been previously proposed, this would confirm the binary model for SN Ib/c. IRS1 and the associated structures may be the relics of massive star death, as shaped by the supernova explosion, the pulsar wind, and the intense ionizing radiation of the embedded O star.

  12. A UV to mid-IR study of AGN selection

    SciTech Connect

    Chung, Sun Mi; Kochanek, Christopher S.; Assef, Roberto; Brown, Michael J. I.; Stern, Daniel; Jannuzi, Buell T.; Gonzalez, Anthony H.; Hickox, Ryan C.; Moustakas, John

    2014-07-20

    We classify the spectral energy distributions (SEDs) of 431,038 sources in the 9 deg{sup 2} Boötes field of the NOAO Deep Wide-Field Survey (NDWFS). There are up to 17 bands of data available per source, including ultraviolet (GALEX), optical (NDWFS), near-IR (NEWFIRM), and mid-infrared (IRAC and MIPS) data, as well as spectroscopic redshifts for ∼20,000 objects, primarily from the AGN and Galaxy Evolution Survey. We fit galaxy, active galactic nucleus (AGN), stellar, and brown dwarf templates to the observed SEDs, which yield spectral classes for the Galactic sources and photometric redshifts and galaxy/AGN luminosities for the extragalactic sources. The photometric redshift precision of the galaxy and AGN samples are σ/(1 + z) = 0.040 and σ/(1 + z) = 0.169, respectively, with the worst 5% outliers excluded. On the basis of the χ{sub ν}{sup 2} of the SED fit for each SED model, we are able to distinguish between Galactic and extragalactic sources for sources brighter than I = 23.5 mag. We compare the SED fits for a galaxy-only model and a galaxy-AGN model. Using known X-ray and spectroscopic AGN samples, we confirm that SED fitting can be successfully used as a method to identify large populations of AGNs, including spatially resolved AGNs with significant contributions from the host galaxy and objects with the emission line ratios of 'composite' spectra. We also use our results to compare with the X-ray, mid-IR, optical color, and emission line ratio selection techniques. For an F-ratio threshold of F > 10, we find 16,266 AGN candidates brighter than I = 23.5 mag and a surface density of ∼1900 AGN deg{sup –2}.

  13. The Nature of Active Galactic Nuclei with Velocity Offset Emission Lines

    NASA Astrophysics Data System (ADS)

    Müller-Sánchez, F.; Comerford, J.; Stern, D.; Harrison, F. A.

    2016-10-01

    We obtained Keck/OSIRIS near-IR adaptive optics-assisted integral-field spectroscopy to probe the morphology and kinematics of the ionized gas in four velocity-offset active galactic nuclei (AGNs) from the Sloan Digital Sky Survey. These objects possess optical emission lines that are offset in velocity from systemic as measured from stellar absorption features. At a resolution of ∼0.″18, OSIRIS allows us to distinguish which velocity offset emission lines are produced by the motion of an AGN in a dual supermassive black hole system, and which are produced by outflows or other kinematic structures. In three galaxies, J1018+2941, J1055+1520, and J1346+5228, the spectral offset of the emission lines is caused by AGN-driven outflows. In the remaining galaxy, J1117+6140, a counterrotating nuclear disk is observed that contains the peak of Paα emission 0.″2 from the center of the galaxy. The most plausible explanation for the origin of this spatially and kinematically offset peak is that it is a region of enhanced Paα emission located at the intersection zone between the nuclear disk and the bar of the galaxy. In all four objects, the peak of ionized gas emission is not spatially coincident with the center of the galaxy as traced by the peak of the near-IR continuum emission. The peaks of ionized gas emission are spatially offset from the galaxy centers by 0.″1–0.″4 (0.1–0.7 kpc). We find that the velocity offset originates at the location of this peak of emission, and the value of the offset can be directly measured in the velocity maps. The emission-line ratios of these four velocity-offset AGNs can be reproduced only with a mixture of shocks and AGN photoionization. Shocks provide a natural explanation for the origin of the spatially and spectrally offset peaks of ionized gas emission in these galaxies. Based on observations at the W. M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the

  14. Keck Long Wavelength Spectrometer Images of Luminous IR Galaxies

    NASA Astrophysics Data System (ADS)

    Jones, Barbara; Puetter, Richard C.; Smith, Harding E.; Stein, Wayne A.; Wang, Michael C.; Campbell, Randy

    1998-05-01

    We have used the UCSD/Keck Long Wavelength Spectrometer (LWS; Jones & Puetter 1993, Proc. S.P.I.E., 1946, 610) in its initial (72 x 64) imaging mode to observe the luminous IR Galaxies Mrk 231, Arp 220, and NGC 7469, as well as NGC 1068 at mid-infrared wavelengths from 8--18\\micron. Pixon-based image reconstruction techniques (Puetter 1995, Int. J. Image Sys. & Tech., 6, 314) have been employed to achieve resolution as high as 50 mas. The mid-infrared emission in Arp 220 is resolved into the two nuclei plus a faint knot of emission 0.5 arcsec SE of the western nucleus. The SEDs show that the the W nucleus dominates at the longest wavelengths and probably in the far-infrared. Silicate absorption at 10\\micron\\ is present in all three components, but is strongest in the E nucleus, suggesting that the emission comes from an optically thick shell around a very compact mid-IR source. The E nucleus is unresolved at 0.2 arcsec resolution. The nucleus of NGC 7469 is marginally resolved at 50mas resolution. On the average the nuclear emission is redder than the surrounding starburst ring; the active nucleus dominates at all mid-infrared wavelengths and the ratio of Nucleus/Starburst increases toward the FIR. Mrk 231 shows a compact, unresolved nucleus with a faint, resolved star-formation ring. These observations will be discussed in terms of the Sanders et al. (1988, ApJ, 325 74) model in which LIGs evolve from Starbursts to AGN. The LWS is being upgraded with a Boeing 128 x 128 BIB array which is expected to be delivered in early summer. A 128 x 128 element multiplexer has been installed and optical performance reverified; further temperature stability tests and signal-to-noise optimization are being performed with an engineering array. The upgraded spectrometer with 11" FOV for imaging and spectroscopic resolutions, R=100 and 1000, is expected to be recommissioned this summer and to be available for scheduling in second semester 1998.

  15. The UV + IR Hybrid Star Formation Rate Across NGC6946

    NASA Astrophysics Data System (ADS)

    Eufrasio, Rafael T.; Lehmer, Bret; Dwek, Eli; Arendt, Richard G.

    2016-01-01

    Knowledge of the star formation rate (SFR) of galaxies is essential to understand galaxy evolution and thus determining reliable, simple tracers of star-forming activity is of paramount importance to astrophysics. For instance, intrinsic ultraviolet (UV) emission from young stars is an excellent tracer of the SFR. Observed UV luminosities, however, have been strongly attenuated by intervening interstellar dust. Since emission from hot dust is readily available from IRAS, Spitzer, and WISE, it is common practice to combine mid-IR emission (around 25 μm) with observed UV in order to obtain an SFR diagnostic of the form Lobs(FUV) + acorr × Lobs(25 μm). Conventionally, a single correction acorr, previously determined for a sample of galaxies, is used. Here we test the reliability of this hybrid SFR diagnostic, allowing for a variable correction factor acorr. For this, we have performed broadband UV-to-IR SED fittings in order to model the star formation histories across the spiral galaxy NGC6946. We have obtained SFRs and stellar masses across the galaxy, from physical scales of 5 kpc down to 500 pc. We find that acorr varies significantly across the galaxy and increases with increasing specific star formation rate (sSFR), the ratio of SFR and stellar mass (or the ratio of young and old stars). The correction acorr does not seem to be correlated to the amount of attenuation AV. Variation of acorr is most likely caused by different mixes of young and old stellar populations across the galaxy. This finding agrees well with our previous results for the interacting spiral galaxy NGC 6872, for which we have demonstrated the variation of acorr and a its correlation with sSFR. Our results show the need of caution when using only two broadband filters in order to determine SFR of individual galaxies or sub-galactic regions. The dust emission most likely overestimates SFR for highly star-forming, high sSFR regions, and underestimates it for more quiescent, low sSFR regions.

  16. Independent contractor arrangements and IRS audits.

    PubMed

    Pelfrey, S; Theisen, B A

    1995-01-01

    As government auditors begin their challenges, nurse executives need to review their operations to remove any potential audit risks. Although a common practice for many institutions, the use of independent contractor arrangements may be ruled inappropriate. As a result, many individuals may be reclassified as employees, leading to Internal Revenue Service (IRS) assessments of penalties and back payroll taxes. It always is prudent to anticipate IRS actions and shore up any areas that may lead to tax assessments before they are imposed on the institution.

  17. WFC3 SS IR Internal Flats

    NASA Astrophysics Data System (ADS)

    MacKenty, John

    2012-10-01

    Part of side switch activities.Flat field ramps will be acquired through each of the IR channel's 15 filters. Sample sequences and exposure times are dictated by the Tungsten lamp flux levels observed in Thermal Vacuum testing. The order in which the filters are used within each Visit and from Visit to Visit was optimized to allow the observations to fit within 30 minute orbits, and also in order to investigate and track any persistence effects resulting from the varying illumination levels on the IR detector.ID: WF20

  18. FT-IR analysis of phosphorylated protein

    NASA Astrophysics Data System (ADS)

    Ishii, Katsunori; Yoshihashi, Sachiko S.; Chihara, Kunihiro; Awazu, Kunio

    2004-09-01

    Phosphorylation and dephosphorylation, which are the most remarkable posttranslational modifications, are considered to be important chemical reactions that control the activation of proteins. We examine the phosphorylation analysis method by measuring the infrared absorption peak of phosphate group that observed at about 1070cm-1 (9.4μm) with Fourier Transform Infrared Spectrometer (FT-IR). This study indicates that it is possible to identify a phosphorylation by measuring the infrared absorption peak of phosphate group observed at about 1070 cm-1 with FT-IR method. As long as target peptides have the same amino acid sequence, it is possible to identify the phosphorylated sites (threonine, serine and tyrosine).

  19. Compressive sensing in the EO/IR.

    PubMed

    Gehm, M E; Brady, D J

    2015-03-10

    We investigate the utility of compressive sensing (CS) to electro-optic and infrared (EO/IR) applications. We introduce the field through a discussion of historical antecedents and the development of the modern CS framework. Basic economic arguments (in the broadest sense) are presented regarding the applicability of CS to the EO/IR and used to draw conclusions regarding application areas where CS would be most viable. A number of experimental success stories are presented to demonstrate the overall feasibility of the approaches, and we conclude with a discussion of open challenges to practical adoption of CS methods.

  20. Infrared emission from interplanetary dust

    SciTech Connect

    Temi, P.; De Bernardis, P.; Masi, S.; Moreno, G.; Salama, A.

    1989-02-01

    Standard models of the interplanetary dust emission fail to account satisfactorily for IR observations. A new model of the dust, based on very simple assumptions on the grain structure (spherical and homogeneous) and chemical composition (astronomical silicates, graphite, blackbodies) is developed. Updated values of the refractive indexes have been included in the analysis. The predictions of the model (absolute values of the fluxes, spectral shape, elongation dependence of the emission) have then been compared with all the available IR observations performed by the ARGO (balloon-borne experiment by University of Rome), AFGL and Zodiacal Infrared Project (ZIP) (rocket experiments by Air Force Geophysics Laboratory, Bedford, Mass.), and IRAS satellite. Good agreement is found when homogeneous data sets from single experiments (e.g., ZIP and ARGO) are considered separately. 19 references.

  1. Monitoring the surface temperature of a turbine blade by IR pyrometry

    NASA Astrophysics Data System (ADS)

    Servouze, Yves

    The design features and performance envelope of an IR pyrometer for controlling the recooling systems of turbine blades are described. It is recommended that the sensors be mounted upstream and downstream of blades or rows of blades and that the mount used be capable of moving the sensor radially to map the entire surface of the blades. The optics focus the radiation onto a InAs IR element sensitive to temperatures in the 900-1100 K range with a response time of 1 microsec and an accuracy of 1 percent. Data handling techniques and equipment are described.

  2. IR Spectrometer Using 90-degree Off-axis Parabolic Mirrors

    SciTech Connect

    Robert M. Malone, Richard, G. Hacking, Ian J. McKenna, and Daniel H. Dolan

    2008-09-02

    A gated spectrometer has been designed for real-time, pulsed infrared (IR) studies at the National Synchrotron Light ource at the Brookhaven National Laboratory. A pair of 90-degree, off-axis parabolic mirrors are used to relay the light from an entrance slit to an output IR recording camera. With an initial wavelength range of 1500–4500 nm required, gratings could not be used in the spectrometer because grating orders would overlap. A magnesium oxide prism, placed between these parabolic mirrors, serves as the dispersion element. The spectrometer is doubly telecentric. With proper choice of the air spacing between the prism and the second parabolic mirror, any spectral region of interest within the InSb camera array’s sensitivity region can be recorded. The wavelengths leaving the second parabolic mirror are collimated, thereby relaxing the camera positioning tolerance. To set up the instrument, two different wavelength (visible) lasers are introduced at the entrance slit and made collinear with the optical axis via flip mirrors. After dispersion by the prism, these two laser beams are directed to tick marks located on the outside housing of the gated IR camera. This provides first-order wavelength calibration for the instrument. Light that is reflected off the front prism face is coupled into a high-speed detector to verify steady radiance during the gated spectral imaging. Alignment features include tick marks on the prism and parabolic mirrors. This instrument was designed to complement singlepoint pyrometry, which provides continuous time histories of a small collection of spots from shock-heated targets.

  3. Using Fourier transform IR spectroscopy to analyze biological materials

    PubMed Central

    Baker, Matthew J; Trevisan, Júlio; Bassan, Paul; Bhargava, Rohit; Butler, Holly J; Dorling, Konrad M; Fielden, Peter R; Fogarty, Simon W; Fullwood, Nigel J; Heys, Kelly A; Hughes, Caryn; Lasch, Peter; Martin-Hirsch, Pierre L; Obinaju, Blessing; Sockalingum, Ganesh D; Sulé-Suso, Josep; Strong, Rebecca J; Walsh, Michael J; Wood, Bayden R; Gardner, Peter; Martin, Francis L

    2015-01-01

    IR spectroscopy is an excellent method for biological analyses. It enables the nonperturbative, label-free extraction of biochemical information and images toward diagnosis and the assessment of cell functionality. Although not strictly microscopy in the conventional sense, it allows the construction of images of tissue or cell architecture by the passing of spectral data through a variety of computational algorithms. Because such images are constructed from fingerprint spectra, the notion is that they can be an objective reflection of the underlying health status of the analyzed sample. One of the major difficulties in the field has been determining a consensus on spectral pre-processing and data analysis. This manuscript brings together as coauthors some of the leaders in this field to allow the standardization of methods and procedures for adapting a multistage approach to a methodology that can be applied to a variety of cell biological questions or used within a clinical setting for disease screening or diagnosis. We describe a protocol for collecting IR spectra and images from biological samples (e.g., fixed cytology and tissue sections, live cells or biofluids) that assesses the instrumental options available, appropriate sample preparation, different sampling modes as well as important advances in spectral data acquisition. After acquisition, data processing consists of a sequence of steps including quality control, spectral pre-processing, feature extraction and classification of the supervised or unsupervised type. A typical experiment can be completed and analyzed within hours. Example results are presented on the use of IR spectra combined with multivariate data processing. PMID:24992094

  4. Analysis of Carbon Emission Characteristics of China

    NASA Astrophysics Data System (ADS)

    Zhang, Lifeng

    Since the opening-up, our economy develops fastly with the energy consume and the carbon emission increasing year by year. At present, China is the biggest country of the carbon emission in the world. We face the huge pressure to control the green house gases emissions. So, the text analyses the feature of carbon emission applying the indexs of the carbon emission aggregate, per captial carbon emission and the carbon emission elasticity efficient, and puts forward the countermeasures of lessoning the carbon emission.

  5. MID-INFRARED POLYCYCLIC AROMATIC HYDROCARBON AND H{sub 2} EMISSION AS A PROBE OF PHYSICAL CONDITIONS IN EXTREME PHOTODISSOCIATION REGIONS

    SciTech Connect

    Berne, O.; Goicoechea, J. R.; Fuente, A.; Pilleri, P.; Joblin, C.; Gonzalez-GarcIa, M.

    2009-11-20

    Mid-infrared (mid-IR) observations of polycyclic aromatic hydrocarbons (PAHs) and molecular hydrogen emission are a potentially powerful tool to derive physical properties of dense environments irradiated by intense UV fields. We present new, spatially resolved, Spitzer mid-IR spectroscopy of the high UV field and dense photodissociation region (PDR) around Monoceros R2, the closest ultracompact H II region, revealing the spatial structure of ionized gas, PAHs, and H{sub 2} emissions. Using a PDR model and PAH emission feature fitting algorithm, we build a comprehensive picture of the physical conditions prevailing in the region. We show that the combination of the measurement of PAH ionization fraction and of the ratio between the H{sub 2} 0-0 S(3) and S(2) line intensities, respectively, at 9.7 and 12.3 mum, allows us to derive the fundamental parameters driving the PDR: temperature, density, and UV radiation field when they fall in the ranges T = 250-1500 K, n {sub H} = 10{sup 4}-10{sup 6} cm{sup -3}, and G {sub 0} = 10{sup 3}-10{sup 5}, respectively. These mid-IR spectral tracers thus provide a tool to probe the similar but unresolved UV-illuminated surface of protoplanetary disks or the nuclei of starburst galaxies.

  6. Precision FT-IR laboratory measurements of atmospheric molecule

    NASA Astrophysics Data System (ADS)

    Sung, K.; Brown, L. R.; Crawford, T. J.

    2014-12-01

    Spectroscopic information is crucial a priori input to interpret atmospheric spectroscopic observations through radiative transfer modeling. The spectroscopic observations lead us to determine the physical and chemical conditions (e.g., atmospheric pressure, temperatures, composition, abundances …). In order to avoid false interpretations of the observed spectra, the molecular spectroscopic information (either line parameters or cross sections) must be sufficiently accurate and complete. To achieve this goal, we employ a broad-band Fourier transform spectrometer, Bruker IFS-125HR equipped with multiple detectors (He-cooled bolometers, N2-cooled MCT and InSb, warm InGaAs, Boron-doped silicates, photodiode) and beamsplitters (Mylars, KBr, CaF2, Quartz) sufficient to cover entire infrared spectra region from 20 to 15000 cm-1. We vacuum-couple up to 15 different absorption cells to the FT-IR, including five coolable cells with optical path lengths ranging from 0.02 m to 52 m; three of them are capable of reaching temperatures down to 50 K. We also have one heatable cell reaching 400 K. Finally, an extra vacuum chamber newly implemented to the Bruker 125HR enables both emission and absorption spectroscopy utilizing the emission port of the FT-IR. Recently, several studies of atmospheric molecules have been completed using the FT-IR at JPL in support of the Earth, terrestrial and planetary atmospheric remote sensing. These include analyses of C3H8 (propane) and 16O12C17O mid- and near-infrared regions, 13C12CH6 and 12C2H6 at longer wavelengths. In addition, we are studying the O2(A) line mixing and collision-induced absorption in the O2 A-band at 0.76 μm, as well as tempe