Science.gov

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 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.

  3. 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.

  4. 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.

  5. 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.

  6. Monitoring of near-IR emission features at the NTT and detection of the northern counterparts.

    NASA Astrophysics Data System (ADS)

    Schulz, R.; Encrenaz, T.; Stüwe, J. A.; Wiedemann, G.

    The evolution of the Jovian stratosphere after the impact of P/Shoemaker-Levy 9 was monitored spectroscopically in the 3.5 μm and 2.1 μm regions using the IRSPEC spectrometer at the ESO 3.5-m New Technology Telescope on La Silla between July 16 and 31, 1994. H3+ and H2 emissions were observed above some of the impact sites and the strongest of the monitored H3+ lines was also detected at the longitudes of the impact areas in the northern hemisphere. These counterparts of the impact sites were clearly visible between July 23 and 25, 1994. Later the longitudinal distribution of the emissions detected in the northern hemisphere does no longer show a correlation to the impact areas. The distribution of the H3+ and H2 emissions on the entire Jovian disk including the auroral regions is presented as a function of time.

  7. Unidentified Infrared Emission Features

    NASA Astrophysics Data System (ADS)

    Joblin, Christine

    2015-03-01

    When referring to unidentified infrared emission features, one has in mind the series of aromatic IR bands (AIBs) between 3.3 and 15 μm that are observed in emission in many environments where UV photons irradiate interstellar matter. These bands are now used by astronomers to classify objects and characterize local physical conditions. However, a deep analysis cannot proceed without understanding the properties of the band carriers. Large polycyclic aromatic hydrocarbon molecules are attractive candidates but interstellar species are still poorly characterized. Various studies emphasize the need for tackling the link between molecular aromatic species, aliphatic material and very small carbonaceous grains. Other unidentified emission features such as the 6.9, 21 and 30 μm bands could be involved in the evolutionary scenario.

  8. IR Plasma Emissions

    DTIC Science & Technology

    1990-04-01

    a current mailing list. Do not return copies of this report unless contractural obligations or notices on a specific document requires that it be...of the relatively cold 0? gas surrounding the fireball (i.e. 02(cold) + hv --> 20*) and the broad emission arises from shock heating of the emission...experimental data and calculations 14 and 0 data from other work35 ,36. Experimental spectra were acquired by Assous 33 in an inductively- heated

  9. 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.

  10. Surface temperature measurements of heterogeneous explosives by IR emission

    NASA Astrophysics Data System (ADS)

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

    1998-07-01

    We present measurements of the integrated IR emission (1-5 μm) from both the heterogeneous explosive PBX 9501 and pure HMX at calibrated temperatures from 30 °C to 250 °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 we report as the thermal emissivity. We 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. We 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.

  11. Direct emissivity measurements of IR materials

    NASA Astrophysics Data System (ADS)

    Kisler, Yanina; Kupferberg, Lenn C.; Mackenzie, Gordon; Chen, Chia M.

    1999-07-01

    Emissivity measurements of ZnS, Sapphire, ALON, MgO, and Yttria were performed in 3.9-4.0 micrometers and 4.4-4.9 micrometers bands, for temperatures between 300 degrees C and 600 degrees C. The average radiance was measured over each waveband. Emissivity was calculated as the ratio of the radiance of the sample to that of a black body source at the same temperature. The results of the emissivity measurements for the above-mentioned materials will be reported. Measurement techniques that allowed increasing the dynamic range of the measurement and significantly reducing the noise will be discussed.

  12. Stimulated IR emission in an optically pumped cesium vapour

    SciTech Connect

    Sitnikov, M G; Znamenskiy, Nikolay V; Manykin, Eduard A; Petrenko, Evgenii A; Grigoryan, Grigorii G

    2000-03-31

    It is demonstrated that the optical pumping of a Cs vapour with light pulses of a dye laser tunable within the range of 15390-17920 cm{sup -1} gives rise to high-power stimulated IR emission on several atomic transitions. Analysis of threshold, energy, and spectral characteristics of this emission allowed the mechanism underlying this effect to be explained. (active media. lasers)

  13. Surface Temperature Measurements of Heterogeneous Explosives by IR Emission

    NASA Astrophysics Data System (ADS)

    Henson, B. F.; Funk, D. J.; Laabs, G. W.; Asay, B. W.

    1997-07-01

    Solid phase temperature is a key observable for understanding chemical and physical properties of energetic materials. Material decomposition during prolonged heating and the rate and mechanism of energy release during explosive ignition are both strongly coupled to the temperature field in the solid. Toward the end of addressing these issues we are pursuing the remote measurement of temperature by the quantitative collection of IR emission from the material surface. We present measurements of the integrated IR emission (1-5 mm) from both the heterogeneous explosive PBX 9501 and pure components at calibrated temperatures from 100C to 250C. The IR power emitted as a function of temperature is that expected of a black body, attenuated by a unique temperature-independent constant for each component which we report as the thermal emissivity of that component in this spectral region. In addition, we report preliminary measurements of the thermal transients from the unconfined surface of both PBX9501 and pressed HMX during ignition after periods of prolonged heating. We demonstrate that the measurement of IR emission in this spectral region provides both a reliable probe of static surface temperature and a unique observable of dynamic temperature change during ignition.

  14. 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.

  15. 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.

  16. The distribution of maser emission in OH/IR stars

    NASA Technical Reports Server (NTRS)

    Welty, Alan D.; Fix, John D.; Mutel, Robert L.

    1987-01-01

    The 1612 MHz OH emission from five OH/IR stars has been mapped at three epochs over a 2.5 yr period of time. Although the stars were observed at very different phases in the radio light curve of each, there were no remarkable changes in the appearance of the maps. This probably implies that the properties of the masers do not range widely throughout a maser shell. The maps have been used to produce star-centered surface maps of the distribution of maser emission from each star. The surface maps generally are sparsely filled with OH emission and are dominated by relatively few (about 10) major clumps of emission. The presence of large regions of low intensity in the surface maps suggests that the number of individual emitting elements is relatively small or that there are a larger number of elements which are distributed in the shell in a distinctly nonrandom manner.

  17. 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

  18. 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.

  19. 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.

  20. Untangling the Near-IR Spectral Features in the Protoplanetary Environment of KH 15D

    NASA Astrophysics Data System (ADS)

    Arulanantham, Nicole A.; Herbst, William; Gilmore, Martha S.; Cauley, P. Wilson; Leggett, S. K.

    2017-01-01

    We report on Gemini/GNIRS observations of the binary T Tauri system V582 Mon (KH 15D) at three orbital phases. These spectra allow us to untangle five components of the system: the photosphere and magnetosphere of star B, the jet, scattering properties of the ring material, and excess near-infrared (near-IR) radiation previously attributed to a possible self-luminous planet. We confirm an early-K subgiant classification for star B and show that the magnetospheric He i emission line is variable, possibly indicating increased mass accretion at certain times. As expected, the H2 emission features associated with the inner part of the jet show no variation with orbital phase. We show that the reflectance spectrum for the scattered light has a distinctive blue slope and spectral features consistent with scattering and absorption by a mixture of water and methane ice grains in the 1–50 μm size range. This suggests that the methane frost line is closer than ∼5 au in this system, requiring that the grains be shielded from direct radiation. After correcting for features from the scattered light, jet, magnetosphere, and photosphere, we confirm the presence of leftover near-IR light from an additional source, detectable near minimum brightness. A spectral emission feature matching the model spectrum of a 10 MJ, 1 Myr old planet is found in the excess flux, but other expected features from this model are not seen. Our observations, therefore, tentatively support the picture that a luminous planet is present within the system, although they cannot yet be considered definitive.

  1. 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

  2. Formation of IR emission in HII regions around young stars

    NASA Astrophysics Data System (ADS)

    Pavlyuchenkov, Yaroslav; Kirsanova, Maria; Akimkin, Vitaly; Wiebe, Dmitry

    2013-07-01

    We investigate the formation of IR emission and corresponding intensity distributions at 8, 24, and 100 micron in HII regions around young massive stars. The evolution of an HII region is simulated using an advanced chemo-dynamical model. Three dust components are included in the model: large silicate grains, very small graphite grains (VSG), and polycyclic aromatic hydrocarbon (PAH) particles. The emergent SED and intensity distributions are calculated using our RT model where stochastic heating of VSG and PAHs is taken into account. The efficiency of two processes for stochastic heating of VSG and PAHs is studied: the absorption of star emission and interaction with hot gas. We compare the synthetic maps with the observed maps from Spitzer and Herschel for the RCW 120 HII region. It is shown that the model with constant PAH abundance cannot reproduce the ring-like appearance of the observed intensity distribution at 8 micron. In order to explain the observed IR distributions we inspect two models of dust evolution. The first model assumes that PAHs are destroyed inside an HII region. In the second model the drift of the dust particles caused by radiation pressure is taken into account. We show that the model with PAH destruction is consistent with observed profiles given appropriate choice of the PAH destruction time. On the contrary, the model with the dust drift is not consistent with observations.

  3. 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.

  4. Mass loss from OH/IR stars - Models for the infrared emission of circumstellar dust shells

    NASA Technical Reports Server (NTRS)

    Justtanont, K.; Tielens, A. G. G. M.

    1992-01-01

    The IR emission of a sample of 24 OH/IR stars is modeled, and the properties of circumstellar dust and mass-loss rate of the central star are derived. It is shown that for some sources the observations of the far-IR emission is well fitted with a lambda exp -1 law, while some have a steeper index of 1.5. For a few sources, the presence of circumstellar ice grains is inferred from detailed studies of the observed 10-micron feature. Dust mass-loss rates are determined from detailed studies for all the stars in this sample. They range from 6.0 x 10 exp -10 solar mass/yr for an optically visible Mira to 2.2 x 10 exp -6 solar mass/yr for a heavily obscured OH/IR star. These dust mass-loss rates are compared to those calculated from IRAS photometry using 12-, 25-, and 60-micron fluxes. The dust mass-loss rates are also compared to gas mass-loss rates determined from OH and CO observations. For stars with tenuous shells, a dust-to-gas ratio of 0.001 is obtained.

  5. Diversity of dwarf galaxy IR-submm emission patterns: CLUES from hydrodynamical simulations

    NASA Astrophysics Data System (ADS)

    Santos-Santos, Isabel M. E.; Domínguez-Tenreiro, Rosa; Granato, Gian Luigi; Brook, Chris B.; Obreja, Aura

    2017-06-01

    Context. The spectral energy distributions (SEDs) of low-mass low-metallicity (dwarf) galaxies are a challenging piece of the puzzle of galaxy formation in the near Universe. These SEDs show some particular features in the submillimeter to far-infrared (FIR) wavelength range compared to normal larger galaxies that cannot be explained by the current models. Aims: We aim to explain the particular emission features of low-mass low-metallicity galaxies in the IR-submm range, which are: a broadening of the IR peak, which implies a warmer dust component; an excess of emission in the submm ( 500 μm), that causes a flattening of the submm/FIR slope; and a very low intensity of polycyclic aromatic hydrocarbon emission features. Methods: The SEDs of a sample of 27 simulated dwarf galaxies were calculated using the GRASIL-3D radiative transfer code. This code has the particularity that it separately treats the radiative transfer through dust grains within molecular clouds and within the cirrus, the dense and diffuse components of the gas phase, respectively. The simulated galaxies have stellar masses ranging from 106-109M⊙, and were obtained from a single simulation run within a Local Group environment with initial conditions from the CLUES project. Results: We report a study of the IRAS, Spitzer, and Herschel bands luminosities, and of the star formation rates, dust, and gas (HI and H2) mass contents. We find a satisfactory agreement with observational data, with GRASIL-3D naturally reproducing the specific spectral features mentioned above. Conclusions: We conclude that the GRASIL-3D two-component dust model gives a physical interpretation of the emission of dwarf galaxies: molecular clouds and cirrus represent the warm and cold dust components, respectively, needed to reproduce observational data.

  6. 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.

  7. Young Debris Disks With Newly Discovered Emission Features

    NASA Astrophysics Data System (ADS)

    Ballering, N.

    2014-04-01

    We analyzed the Spitzer/IRS spectra of young A and F stars that host debris disks with previously unidentified silicate emission features. Such features probe small, warm dust grains in the inner regions of these young systems where terrestrial planet formation may be proceeding (Lisse et al. 2009). For most systems, these regions are too near their host star to be directly seen with high-contrast imaging and too warm to be imaged with submillimeter interferometers. Mid-infrared excess spectra - originating from the thermal emission of the debris disk dust - remain the best data to constrain the properties of the debris in these regions. For each target, we fit physically-motivated model spectra to the data. Typical spectra of unresolved debris disks are featureless and suffer severe degeneracies between the dust location and the grain properties; however, spectra with solid-state emission features provide significantly more information, allowing for a more accurate determination of the dust size, composition, and location (e.g. Chen et al. 2006; Olofsson et al. 2012). Our results shed light on the dynamic properties occurring in the terrestrial regions of these systems. For instance, the sizes of the smallest grains and the nature of the grain size distribution reveal whether the dust originates from steady-state collisional cascades or from stochastic collisions. The properties of the dust grains - such as their crystalline or amorphous structure - can inform us of grain processing mechanisms in the disk. The location of this debris illuminates where terrestrial planet forming activity is occurring. We used results from the Beta Pictoris - which has a well-resolved debris disk with emission features (Li et al. 2012) - to place our results in context. References: Chen et al. 2006, ApJS, 166, 351 Li et al. 2012, ApJ, 759, 81 Lisse et al. 2009, ApJ, 701, 2019 Olofsson et al. 2012, A&A, 542, A90

  8. Extended far-infrared emission associated with mass outflows from young stars: L1551 IRS 5

    NASA Technical Reports Server (NTRS)

    Edwards, S.; Strom, S. E.; Snell, R. L.; Jarrett, T. H.; Beichman, C. A.

    1986-01-01

    Coadded IRAS survey data have been examined in the L1551 region. Extended low-surface-brightness 60 and 1200-micron emission is aligned with the molecular outflow from L1551 IRS 5. The morphology and the uniform surface brightness and color temperature of the IR emission suggest that the wind from IRS 5 is the source of this emission. It is suggested that radiative heating of grains by photons generated at the stellar wind/cloud interface is a major contributor to the extended infrared emission.

  9. On Structural Features Necessary for Near-IR-Light Photocatalysts.

    PubMed

    Wang, Gang; Huang, Baibiao; Li, Zhujie; Wang, Zeyan; Qin, Xiaoyan; Zhang, Xiaoyang; Dai, Ying; Whangbo, Myung-Hwan

    2015-09-21

    In the search for photocatalysts that can directly utilize near-IR (NIR) light, we investigated three oxides Cu3(OH)4SO4 (antlerite), Cu4(OH)6SO4, and Cu2(OH)3Cl by photodecomposing 2,4-dichlorophenol over them under NIR irradiation and by comparing their electronic structures with that of the known NIR photocatalyst Cu2(OH)PO4. Both Cu3(OH)4SO4 and Cu4(OH)6SO4 are NIR photocatalysts, but Cu2(OH)3Cl is not. Thus, in addition to the presence of two different CuOm and Cu'On polyhedra linked with Cu-O-Cu' bridges, the presence of acceptor groups (e.g., SO4, PO4) linked to the metal oxygen polyhedra is necessary for NIR photocatalysts. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  10. Mid-IR emission of galaxies in the Virgo cluster. II. Integrated properties

    NASA Astrophysics Data System (ADS)

    Boselli, A.; Lequeux, J.; Sauvage, M.; Boulade, O.; Boulanger, F.; Cesarsky, D.; Dupraz, C.; Madden, S.; Viallefond, F.; Vigroux, L.

    1998-07-01

    We analyse the integrated properties of the Mid-IR emission of a complete, optically selected sample of galaxies in the Virgo cluster observed with the ISOCAM instrument on board the ISO satellite. The ISOCAM data allows us to construct the luminosity distribution at 6.75 and 15 mu m of galaxies for different morphological classes. These data are used to study the spectral energy distribution of galaxies of different type and luminosity in the wavelength range 2000 Angstroms - 100 mu m. The analysis shows that the Mid-IR emission up to 15 mu m of optically-selected, normal early-type galaxies (E, S0 and S0a) is dominated by the Rayleigh-Jeans tail of the cold stellar component. The Mid-IR emission of late-type galaxies is instead dominated by the thermal emission from dust. As in the Milky Way, the small dust grains emitting in the Mid-IR have an excess of emission if compared to big grains emitting in the Far-IR. While the Far-IR emission of galaxies increases with the intensity of the interstellar radiation field, their Mid-IR emission is non-linearly related to the UV radiation field. The spectral energy distributions of the target galaxies indicate that there is a linear relationship between the UV radiation field and the Mid-IR emission of galaxies for low or intermediate activities of star formation, while the emission from the hot dust seems to drop for strong UV fields. The Mid-IR colour of late-type galaxies is not related to their activity of star formation. The properties of the dust emission in the Mid-IR seem more related to the mass than to the morphological type of the target galaxy. Since the activity of star formation is anticorrelated to the mass of galaxies, this reflects a relationship between the emission of dust in the Mid-IR and the UV radiation field: galaxies with the lowest Mid-IR emission for a given UV field are low mass, dwarf galaxies. These observational evidences are easily explained if the carriers of the Unidentified Infrared Bands

  11. An Aromatic Feature Emission Inventory of the Local Volume

    NASA Astrophysics Data System (ADS)

    Marble, Andrew; LVL Team

    2010-01-01

    Using infrared photometry from the Spitzer Space Telescope, we perform the first inventory of aromatic feature emission for a large unbiased sample of galaxies in the local volume. The photometric methodology involved is calibrated and demonstrated to recover the aromatic fraction of the IRAC 8 micron flux with a standard deviation of 6% using a training set of 40 SINGS galaxies for which both equivalent photometry and suitable mid-infrared Spitzer IRS spectra were available. The resulting technique is then applied to the 258 galaxies from the Local Volume Legacy (LVL) survey, a large sample dominated by low-luminosity dwarf galaxies for which obtaining comparable MIR spectroscopy is not feasible. We find the total LVL luminosity due to five strong aromatic features in the 8 micron complex to be 2.47E10 solar luminosities with a mean volume density of 8.8E6 solar luminosities per cubic Mpc. Correspondingly, the same values for all mid-infrared aromatic features in the wavelength range 5.5-20 microns are approximately 1.9 times larger. Using oxygen abundances compiled from the literature, we report a correlation between aromatic feature strength and metallicity, albeit one with significant scatter.

  12. 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

  13. 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

  14. 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.

  15. Measurements of minor constituents in the middle atmosphere from IR limb emission spectra - A feasibility study

    NASA Astrophysics Data System (ADS)

    Oelhaf, H.; Fischer, H.

    1983-09-01

    The instrument requirements and limitations on the detection of the atmospheric trace constituents O3, CO2, H2O, CH4, CO, N2O, NO, NO2, HNO3, F-11, F-12, NH3, SO2, HF, and HCl from 4-100-micron IR limb emission spectra are investigated, summarizing the results of the full study undertaken as part of the EFS project for GIRL (Oelhaf and Fischer, 1983). The spectral intervals, tangent heights, and resolution of the synthetic spectra constructed for that study are listed in a table, and sample spectra are provided. A diagram illustrates the altitude ranges of detectability (above background) of the most important features. Factors limiting the detection of some species are discussed.

  16. 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.

  17. EVIDENCE FOR NON-STELLAR REST-FRAME NEAR-IR EMISSION ASSOCIATED WITH INCREASED STAR FORMATION IN GALAXIES AT z ∼ 1

    SciTech Connect

    Lange, Johannes U.; Van Dokkum, Pieter G.; Momcheva, Ivelina G.; Nelson, Erica J.; Leja, Joel; Brammer, Gabriel; Whitaker, Katherine E.; Franx, Marijn

    2016-03-01

    We explore the presence of non-stellar rest-frame near-IR (2–5 μm) emission in galaxies at z ∼ 1. Previous studies identified this excess in relatively small samples and suggested that such non-stellar emission, which could be linked to the 3.3 μm polycyclic aromatic hydrocarbons feature or hot dust emission, is associated with an increased star formation rate (SFR). In this Letter, we confirm and quantify the presence of an IR excess in a significant fraction of galaxies in the 3D-HST GOODS catalogs. By constructing a matched sample of galaxies with and without strong non-stellar near-IR emission, we find that galaxies with such emission are predominantly star-forming galaxies. Moreover, star-forming galaxies with an excess show increased mid- and far-IR and Hα emission compared to other star-forming galaxies without. While galaxies with a near-IR excess show a larger fraction of individually detected X-ray active galactic nuclei (AGNs), an X-ray stacking analysis, together with the IR-colors and Hα profiles, shows that AGNs are unlikely to be the dominant source of excess in the majority of galaxies. Our results suggest that non-stellar near-IR emission is linked to increased SFRs and is ubiquitous among star-forming galaxies. As such, the near-IR emission might be a powerful tool to measure SFRs in the era of the James Webb Space Telescope.

  18. Upper limit to the ultimate achievable emission wavelength in near-IR emitting cyclometalated iridium complexes.

    PubMed

    Penconi, Marta; Cazzaniga, Marco; Kesarkar, Sagar; Mussini, Patrizia R; Ceresoli, Davide; Bossi, Alberto

    2017-08-09

    Iridium complexes bearing cyclometalated (C^N) ligands are the current emitters of choice for efficient phosphorescent organic light emitting diodes (OLEDs). Homoleptic iridium complexes Ir(C^N)3 and the analogous heteroleptic ones carrying a β-diketonate ancillary ligand (C^N)2Ir(O^O) often exhibit similar photophysical properties and device performances; the choice among them usually depends both on the yield/ease of the respective synthetic preparations as well as on the device fabrication methods (i.e. vacuum-deposition or solution-process). In our recent study we found a significant spectral red shift on going from the homoleptic to the β-diketonate Ir(iii) derivatives. The NIR emitting complex Ir(iqbt)2dpm (λmax = 710 nm) has almost 20 nm red shifted emission compared to the homologue Ir(iqbt)3 making only the former a real NIR emitter. For comparison, we studied the Pt(iqbt)dpm complex as the suitable example to investigate metal ligand interactions. Noteworthily the Pt(iqbt)dpm emission perfectly overlaps that of the Ir(iqbt)2dpm. In this paper we provide an in-depth investigation of these systems by electrochemical and spectroscopic analyses and corroborate the results with DFT and TDDFT calculations to investigate whether the Pt(ii) complex can be used as a model system to predict how far the emission can be pushed in a Ir(iii) heteroleptic derivative bearing the same C^N ligand.

  19. 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

  20. 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

  1. Evidence for extended IR emission in NGC2798 and NGC6240

    NASA Technical Reports Server (NTRS)

    Wright, G. S.; Joseph, R. D.; James, P. A.; Robertson, N. A.

    1987-01-01

    Extended emission at 10 and 20 microns can be used to distinguish starbursts from monsters as the underlying energy source driving the luminous infrared emission in the central regions of galaxies. The spatial extent of the mid infrared emission in the interacting galaxy NCG 2798 and the merger NGC 6240 were investigated. The 10 and 20 micron profiles of the IR source in NGC 2798 are significantly wider than beam profiles measured on a standard star, supporting a starburst interpretation of its IR luminosity. For NGC 6240 there is marginal evidence for an extended 10 micron source, suggesting that a significant fraction of its IR luminosity could be produced by a burst of star formation.

  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. Dust-deficient Palomar-Green Quasars and the Diversity of AGN Intrinsic IR Emission

    NASA Astrophysics Data System (ADS)

    Lyu, Jianwei; Rieke, G. H.; Shi, Yong

    2017-02-01

    To elucidate the intrinsic broadband infrared (IR) emission properties of active galactic nuclei (AGNs), we analyze the spectral energy distributions (SEDs) of 87 z ≲ 0.5 Palomar-Green (PG) quasars. While the Elvis AGN template with a moderate far-IR correction can reasonably match the SEDs of the AGN components in ∼60% of the sample (and is superior to alternatives such as that by Assef), it fails on two quasar populations: (1) hot-dust-deficient (HDD) quasars that show very weak emission thoroughly from the near-IR to the far-IR, and (2) warm-dust-deficient (WDD) quasars that have similar hot dust emission as normal quasars but are relatively faint in the mid- and far-IR. After building composite AGN templates for these dust-deficient quasars, we successfully fit the 0.3–500 μm SEDs of the PG sample with the appropriate AGN template, an infrared template of a star-forming galaxy, and a host galaxy stellar template. 20 HDD and 12 WDD quasars are identified from the SED decomposition, including seven ambiguous cases. Compared with normal quasars, the HDD quasars have AGNs with relatively low Eddington ratios and the fraction of WDD quasars increases with AGN luminosity. Moreover, both the HDD and WDD quasar populations show relatively stronger mid-IR silicate emission. Virtually identical SED properties are also found in some quasars from z = 0.5 to 6. We propose a conceptual model to demonstrate that the observed dust deficiency of quasars can result from a change of structures of the circumnuclear tori that can occur at any cosmic epoch.

  4. 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.

  5. An Empirical Decomposition of Near-IR Emission into Galactic and Extragalactic Components

    NASA Technical Reports Server (NTRS)

    Dwek, Eli; Arendt, Richard G.

    2002-01-01

    We decompose the COBE/DIRBE observations of the near-IR sky brightness (minus zodiacal light) into Galactic stellar and interstellar medium (ISM) components and an extragalactic background. This empirical procedure allows us to estimate the 4.9 micron cosmic infrared background (CIB) as a function of the CIB intensity at shorter wavelengths. A weak indication of a rising CIB intensity at wavelengths greater than 3.5$ microns hints at interesting astrophysics in the CIB spectrum, or warns that the foreground zodiacal emission may be incompletely subtracted. Subtraction of only the stellar component from the zodiacal-light-subtracted all--sky map reveals the clearest 3.5 micron ISM emission map, which is found to be tightly correlated with the ISM emission at far-IR wavelengths.

  6. Interferometric Observations of Emission Features in the F-Corona

    NASA Astrophysics Data System (ADS)

    Gulyaev, R. A.; Shcheglov, P. V.

    1998-09-01

    In order to detect the resonance emissions of CaII ions created by the interplanetary dust vaporization, a suitable technique for interferometric observation of eclipsed sky around the Sun was developed. Successful observation has been carried out at the eclipse of February 26, 1998 in Guadeloupe. Field of view of the apparatus was extended up to 40 solar radii from the Sun. All the field on the negative obtained is covered by an interferometric pattern adequate to day-sky interferograms. Such a pattern must be due to the double scattering of the sunlight in the Earth's atmosphere. There is a number of emission features on the above background. First, unshifted K-line is seen up to about 10 solar radii. This is consistent with other indications on the occurences of the H and K emission lines in coronal spectrum. Probably, the unshifted K-emission is due to scattering in the Earth's atmosphere similar to the twilight emission. The most important features on the frame are Doppler-shifted K-emissions in the SW-quadrant of the circumsolar space within the range of 5 to 20 solar radii. The line displacements correspond to Doppler velocities for relevant heliocentric distances. We suppose that these features represent emissions expected with the dust particles evaporation. There are some more emission features close to the Sun which are not identified so far. The above observational results present first successful experiment on detection of manifestations of the dust vaporization near the Sun

  7. The Correlation of UV Extinction and IR Emission in Bright Visual Reflection Nebulae

    NASA Astrophysics Data System (ADS)

    Casey, Sean C.

    Reflection nebulae are natural laboratories for the study of interstellar grains. To investigate the variation in ultraviolet extinction with infrared emission, we propose to obtain lowdispersion IUE observations of latetype B stars within several bright visual reflection nebulae. Our proposed observations will compliment existing data obtained previously by IUE for reflection nebulae excited by early-type B stars. In addition, our proposal compliments the earlier infrared studies of reflection nebulae (Sellgren, Luan, & Werner 1990, Casey 1991) by adopting a parametric decomposition of UV extinction (Fitzpatrick and Massa 1990). A parametric study of UV extinction and IR emission must necessarily precede a detailed analysis of optical nebular grain properties or dusty nebular environments. Recent models of interstellar grains predict systematic variations in UV extinction with variations in the abundance of very small grains (Desert, Boulanger, and Puget 1990) and/or variations in equilibrium grain temperature (Hecht 1986). A systematic study of nebular UV extinction and IR emission will test many of these predictions. If galactic extinction results from the superposition of distinct grain populations, then we expect to find correlated variations between observations of UV extinction and IR emission in bright visual reflection nebulae.

  8. A tentative identification of methanol as the progenitor of the 3.52-micron emission feature in several comets

    NASA Technical Reports Server (NTRS)

    Hoban, Susan; Mumma, Michael; Reuter, Dennis C.; Disanti, Michael; Joyce, R. R.; Storrs, Alex

    1991-01-01

    Continuum emission has been detected during 3.44-3.64 micron spectral region observations of Comets P/Brorsen-Metcalf, Okazaki-Levy-Rudenko, and Levy. The spatial brightness profile of the 3.52-micron emission feature was measured and found to be consistent with uniform outflow from a central, unresolved source; the molecule generating the emission is either directly sublimated from the cometary surface or is a short-lived parent specie's dissociation product. The modeled IR spectrum of CH3OH implies the consistency of the observed spectra with a methanol origin for the 3.52 emission.

  9. A tentative identification of methanol as the progenitor of the 3.52-micron emission feature in several comets

    NASA Technical Reports Server (NTRS)

    Hoban, Susan; Mumma, Michael; Reuter, Dennis C.; Disanti, Michael; Joyce, R. R.; Storrs, Alex

    1991-01-01

    Continuum emission has been detected during 3.44-3.64 micron spectral region observations of Comets P/Brorsen-Metcalf, Okazaki-Levy-Rudenko, and Levy. The spatial brightness profile of the 3.52-micron emission feature was measured and found to be consistent with uniform outflow from a central, unresolved source; the molecule generating the emission is either directly sublimated from the cometary surface or is a short-lived parent specie's dissociation product. The modeled IR spectrum of CH3OH implies the consistency of the observed spectra with a methanol origin for the 3.52 emission.

  10. Circular polarization in 1612 MHz OH maser emission from OH/IR stars

    NASA Technical Reports Server (NTRS)

    Zell, Philip; Fix, John D.

    1991-01-01

    In order to study the incidence of circular polarization in the 1612 MHz OH emission from envelopes of OH/IR stars, the Arecibo radio telescope was used to obtain high-resolution, high signal-to-noise 1612 MHz spectra in both circular polarizations for several OH/IR stars. The method of Troland and Heiles (1982) was used to estimate the intensities of magnetic fields in the envelopes. The fields appear to have complex structures, and intensities on the order of 1-100 microG. The spectra are weakly polarized, probably as a result of weakly polarized emission from individual emitting elements. Integration over the Stokes parameter V yields nonzero results for three of the stars, suggesting that another polarizing mechanism (in addition to simple Zeeman splittings) is at work.

  11. Spectrally resolved confocal microscopy using lanthanide centred near-IR emission.

    PubMed

    Liao, Zhiyu; Tropiano, Manuel; Mantulnikovs, Konstantins; Faulkner, Stephen; Vosch, Tom; Sørensen, Thomas Just

    2015-02-11

    The narrow, near infrared (NIR) emission from lanthanide ions has attracted great interest, particularly with regard to developing tools for bioimaging, where the long lifetimes of lanthanide excited states can be exploited to address problems arising from autofluorescence and sample transparency. Despite the promise of lanthanide-based probes for near-IR imaging, few reports on their use are present in the literature. Here, we demonstrate that images can be recorded by monitoring NIR emission from lanthanide complexes using detectors, optical elements and a microscope that were primarily designed for the visible part of the spectrum.

  12. 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.

  13. Research of Recognition Method of Discrete Wavelet Feature Extraction and PNN Classification of Rats FT-IR Pancreatic Cancer Data.

    PubMed

    Wan, Chayan; Cao, Wenqing; Cheng, Cungui

    2014-01-01

    Sprague-Dawley (SD) rats' normal and abnormal pancreatic tissues are determined directly by attenuated total reflectance Fourier transform infrared (ATR-FT-IR) spectroscopy method. In order to diagnose earlier stage of SD rats pancreatic cancer rate with FT-IR, a novel method of extraction of FT-IR feature using discrete wavelet transformation (DWT) analysis and classification with the probability neural network (PNN) was developed. The differences between normal pancreatic and abnormal samples were identified by PNN based on the indices of 4 feature variants. When error goal was 0.01, the total correct rates of pancreatic early carcinoma and advanced carcinoma were 98% and 100%, respectively. It was practical to apply PNN on the basis of ATR-FT-IR to identify abnormal tissues. The research result shows the feasibility of establishing the models with FT-IR-DWT-PNN method to identify normal pancreatic tissues, early carcinoma tissues, and advanced carcinoma tissues.

  14. Research of Recognition Method of Discrete Wavelet Feature Extraction and PNN Classification of Rats FT-IR Pancreatic Cancer Data

    PubMed Central

    Wan, Chayan; Cao, Wenqing; Cheng, Cungui

    2014-01-01

    Sprague-Dawley (SD) rats' normal and abnormal pancreatic tissues are determined directly by attenuated total reflectance Fourier transform infrared (ATR-FT-IR) spectroscopy method. In order to diagnose earlier stage of SD rats pancreatic cancer rate with FT-IR, a novel method of extraction of FT-IR feature using discrete wavelet transformation (DWT) analysis and classification with the probability neural network (PNN) was developed. The differences between normal pancreatic and abnormal samples were identified by PNN based on the indices of 4 feature variants. When error goal was 0.01, the total correct rates of pancreatic early carcinoma and advanced carcinoma were 98% and 100%, respectively. It was practical to apply PNN on the basis of ATR-FT-IR to identify abnormal tissues. The research result shows the feasibility of establishing the models with FT-IR-DWT-PNN method to identify normal pancreatic tissues, early carcinoma tissues, and advanced carcinoma tissues. PMID:25548717

  15. 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.

  16. 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.

  17. 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.

  18. 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.

  19. Dust processing in photodissociation regions Mid-IR emission modelling of NGC2023N

    NASA Astrophysics Data System (ADS)

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

    2008-11-01

    This study is done in the context of dust evolution and its interaction with the gaseous phase throughout the interstellar medium evolution cycle. We focus on the mid-IR spectral variations of the dust emission across photodissociation regions, observed with both ISO and Spitzer satellites. We use a dust emission model coupled with a radiative transfer model in order to study the excitation effects on these spectral variations. We show that in NGC2023N, radiative transfer effects cannot account for the observed spectral variations. Thus, we interpret these variations in term of changes of the relative abundance between polycyclic aromatic hydrocarbons (PAHs, mid-IR bands carriers) and very small grains (VSGs, mid-IR continuum carriers). We conclude that the PAH/VSG abundance ratio is about 5 times lower in the dense deep part than in the diffuse illuminated part of the PDR where dust properties seem to be the same as in the diffuse high galactic latitude medium. Consequently, we conclude that dust must evolve from "dense properties" to "diffuse properties" at the small spatial scale of the dense illuminated ridge.

  20. New Infrared Emission Features and Spectral Variations in Ngc 7023

    NASA Technical Reports Server (NTRS)

    Werner, M. W.; Uchida, K. I.; Sellgren, K.; Marengo, M.; Gordon, K. D.; Morris, P. W.; Houck, J. R.; Stansberry, J. A.

    2004-01-01

    We observed the reflection nebula NGC 7023, with the Short-High module and the long-slit Short-Low and Long-Low modules of the Infrared Spectrograph on the Spitzer Space Telescope. We also present Infrared Array Camera (IRAC) and Multiband Imaging Photometer for Spitzer (MIPS) images of NGC 7023 at 3.6, 4.5, 8.0, and 24 m. We observe the aromatic emission features (AEFs) at 6.2, 7.7, 8.6, 11.3, and 12.7 m, plus a wealth of weaker features. We find new unidentified interstellar emission features at 6.7, 10.1, 15.8, 17.4, and 19.0 m. Possible identifications include aromatic hydrocarbons or nanoparticles of unknown mineralogy. We see variations in relative feature strengths, central wavelengths, and feature widths, in the AEFs and weaker emission features, depending on both distance from the star and nebular position (southeast vs. northwest).

  1. New Infrared Emission Features and Spectral Variations in Ngc 7023

    NASA Technical Reports Server (NTRS)

    Werner, M. W.; Uchida, K. I.; Sellgren, K.; Marengo, M.; Gordon, K. D.; Morris, P. W.; Houck, J. R.; Stansberry, J. A.

    2004-01-01

    We observed the reflection nebula NGC 7023, with the Short-High module and the long-slit Short-Low and Long-Low modules of the Infrared Spectrograph on the Spitzer Space Telescope. We also present Infrared Array Camera (IRAC) and Multiband Imaging Photometer for Spitzer (MIPS) images of NGC 7023 at 3.6, 4.5, 8.0, and 24 m. We observe the aromatic emission features (AEFs) at 6.2, 7.7, 8.6, 11.3, and 12.7 m, plus a wealth of weaker features. We find new unidentified interstellar emission features at 6.7, 10.1, 15.8, 17.4, and 19.0 m. Possible identifications include aromatic hydrocarbons or nanoparticles of unknown mineralogy. We see variations in relative feature strengths, central wavelengths, and feature widths, in the AEFs and weaker emission features, depending on both distance from the star and nebular position (southeast vs. northwest).

  2. 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.

  3. 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.

  4. Interferometric observations of emission features in the F-corona

    NASA Astrophysics Data System (ADS)

    Gulyaev, R. A.; Shcheglov, P. V.

    1999-03-01

    We are solving the problem of detection of the resonance emissions of Ca II ions created by the interplanetary dust sublimation. To this end, a suitable technique was developed for interferometric observations of the eclipsed sky around the Sun. Successful observations have been carried out during the eclipse of February 26, 1998 in Guadeloupe. On the negative obtained, all the field is covered by an interference pattern adequate to a daytime sky interferogram. Such a pattern must be due to the double scattering of the sunlight in the Earth's atmosphere. There is a number of emission features on the above background. Unshifted K-line of Ca II is seen up to about 10 solar radii. This is consistent with other evidences on the occurrence of the H and K emission lines in the coronal spectrum. The most important features on the photograph are Doppler-shifted K-emissions in the SW-quadrant of the circumsolar space within the range of 5 to 20 solar radii. The sign of the Doppler shift corresponds to direction of the planetary orbital motions. That is why, we suppose that these features just represent the emission associated with the sublimating dust. If so, it will be said about the discovery of a new component of the solar corona, namely the `S-corona' (from `sublimation').

  5. 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.

  6. OCCULTATION OF THE QUIESCENT EMISSION FROM Sgr A* BY IR FLARES

    SciTech Connect

    Yusef-Zadeh, F.; Wardle, M.; Bushouse, H.; Dowell, C. D.; Roberts, D. A.

    2010-11-20

    We have investigated the nature of flare emission from Sgr A* during multi-wavelength observations of this source that took place in 2004, 2005, and 2006. We present evidence for dimming of submillimeter and radio flux during the peak of near-IR flares. This suggests that the variability of Sgr A* across its wavelength spectrum is phenomenologically related. The model explaining this new behavior of flare activity could be consistent with adiabatically cooling plasma blobs that are expanding but also partially eclipsing the background quiescent emission from Sgr A*. When a flare is launched, the plasma blob is most compact and is brightest in the optically thin regime whereas the emission in radio/submillimeter wavelengths has a higher opacity. Absorption in the observed light curve of Sgr A* at radio/submillimeter flux is due to the combined effects of lower brightness temperature of plasma blobs with respect to the quiescent brightness temperature and high opacity of plasma blobs. This implies that plasma blobs are mainly placed in the magnetosphere of a disk-like flow or further out in the flow. The depth of the absorption being larger in submillimeter than in radio wavelengths implies that the intrinsic size of the quiescent emission increases with increasing wavelength which is consistent with previous size measurements of Sgr A*. Lastly, we believe that occultation of the quiescent emission of Sgr A* at radio/submillimeter by IR flares can be used as a powerful tool to identify flare activity at its earliest phase of its evolution.

  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. Wavelength calibration techniques and subtle surface and atmospheric absorption features in the Mariner 6, 7 IRS reflectance data

    NASA Technical Reports Server (NTRS)

    Bell, James F., III; Roush, T. L.; Martin, T. Z.; Pollack, James B.; Freedman, R.

    1994-01-01

    1994 marks the 25th anniversary of the Mariner 6 and 7 flyby missions to Mars. Despite its age, the Mariner 6,7 Infrared Spectrometer (IRS) data are a unique set of measurements that can provide important information about the Martian surface, atmospheric, and atmospheric aerosol composition. For certain mid-IR wavelengths, the IRS spectra are the only such spacecraft data obtained for Mars. At other wavelengths, IRS measured surface regions different from those measured by Mariner 9 or Phobos 2 and under different dust opacity conditions. We are interested in examining the IRS reflectance data in the 1.8 to 3.0 micron region because there are numerous diagnostic absorption features at these wavelengths that could be indicative of hydrated silicate minerals or of carbonate- or sulfate-bearing minerals. Groundbased telescopic data and recent Phobos ISM measurements have provided controversial and somewhat contradictory evidence for the existence of mineralogic absorption features at these wavelengths. Our goal is to determine whether any such features can be seen in the IRS data and to use their presence or absence to re-assess the quality and interpretations of previous telescopic and spacecraft measurements.

  9. The anomalous 3.43 and 3.53 micron emission features toward HD 97048 and Elias 1 - C-C vibrational modes of polycyclic aromatic hydrocarbons?

    NASA Technical Reports Server (NTRS)

    Schutte, W. A.; Tielens, A. G. G. M.; Allamandola, L. J.; Wooden, D. H.; Cohen, M.

    1990-01-01

    The 5-8 micron spectra obtained toward the two protostellar sources, HD 97048 and Elias 1 exhibit strong anomalous emission features at 3.43 and 3.53 microns. Combining these results with earlier data established that the emission in the general IR features is extended on at least a 20-arcsec scale. In view of the high energy density in the emission zone, as well as the apparent correspondence of the anomalous 3.43 and 3.53 micron features with weak emission shoulders associated with the general family of IR emission bands, an explanation for these observations in terms of C-C overtones and combination tones of large or dehydrogenated polycyclic aromatic hydrocarbons is judged to be provisionally suitable.

  10. IR detector for hydrocarbons concentration measurement in emissions during petroleum and oil products storage and transportation

    NASA Astrophysics Data System (ADS)

    Vasilyev, Andrey O.; Shemanin, Valeriy G.; Chartiy, Pavel V.

    2011-10-01

    A double beam IR detector is developed for light hydrocarbons concentration measurement in emissions from storage vessels during oil and oil products storage and transportation. It was concluded on the basis of chromatogram that main crude losses from evaporation are the share of hydrocarbons light ends from methane to decane. Detector operation is based on spectral transparency measurement in the infrared spectra absorption range. Operational wavelength of infrared radiation makes 3.4 μm. measurement principle is based on concentration calculation proceed from molecule absorption cross-section, optical path length between light emitted diode and reference and signal photodiodes as well as from value of measured signal transmitted through gaging volume. The novel of offering device is an actual paraffin hydrocarbons concentration measurement in emissions and continuous and automatic environment quality control.

  11. Herschel/PACS detection of far-IR OH emission towards the Orion Bar PDR

    NASA Astrophysics Data System (ADS)

    Goicoechea, J. R.; Joblin, C.; Contursi, A.; Berne, O.; Cernicharo, J.; Gerin, M.; Le Bourlot, J.; Bergin, E. A.; Bell, T. A.; Rollig, A.; HEXOS-GT-KP Team

    2011-05-01

    Due to its much improved angular resolution and sensitivity compared to previous far-IR space missions, Herschel observations are providing a new perspective of the chemistry and thermal balance in photodissociation regions (PDRs; the Orion Bar, the Horsehead, etc.). As part of a far-IR spectral scan with Herschel/PACS, we present the first detection of OH, a key molecule in the oxygen-network, towards the Orion Bar. Five OH rotational Λ-doublets involving energy levels out to Eu/k 511 K have been detected (at 65, 79, 84, 119 and 163um). The observed emission of rotationally excited OH lines is extended and correlates well with the high-J CO and CH+ J=3-2 line emission also detected by PACS, thus pointing towards a common origin, but apparently does not correlate with the observed water vapour emission. Nonlocal, non-LTE radiative transfer models including excitation by the ambient FIR radiation field suggest that OH arises in a small filling factor component of warm (Tk~160-220 K) and dense (nH~106-7 cm-3) gas with source-averaged OH column densities of ~1015 cm-2. High density and temperature photochemical models predict such enhanced OH columns at low depths (AV~1) and small spatial scales, where OH formation is driven by gas-phase endothermic reactions of atomic oxygen with molecular hydrogen. We interpret the extended OH emission as coming from unresolved structures exposed to FUV radiation near the Bar edge (photoevaporating clumps or filaments) and not from the lower density ``interclump'' medium. FUV photodissociation leads to OH/H2O abundance ratios (>1) much higher than those expected in equally warm regions without enhanced FUV radiation fields.

  12. 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

  13. Panchromatic Light Capture and Efficient Excitation Transfer Leading to Near-IR Emission of BODIPY Oligomers.

    PubMed

    Sharma, Ritambhara; Gobeze, Habtom B; D'Souza, Francis; Ravikanth, Mangalampalli

    2016-08-18

    All-BODIPY-based (BODIPY=boron-dipyrromethene) donor-acceptor systems capable of wide-band absorbance leading to efficient energy transfer in the near-IR region are reported. A covalently linked 3-pyrrolyl BODIPY-BODIPY dimer building block bearing an ethynyl group at the meso-aryl position is synthesized and coupled with three different monomeric BODIPY/pyrrolyl BODIPY building blocks with a bromo/iodo group under Pd(0) coupling conditions to obtain three covalently linked 3-pyrrolyl-BODIPY-based donor-acceptor oligomers in 19-29 % yield. The oligomers are characterized in detail by 1D and 2D NMR spectroscopy, high-resolution mass spectrometry, and optical spectroscopy. Due to the presence of different functionalized BODIPY derivatives in the oligomers, panchromatic light capture (300-725 nm) is witnessed. Fluorescence studies reveal singlet-singlet energy transfer from BODIPY monomer to BODIPY dimer leading to emission in the 700-800 nm range. Theoretical modeling according to the Förster mechanism predicts ultrafast energy transfer due to good spectral overlap of the donor and acceptor entities. Femtosecond transient absorption studies confirm this to be the case and thus show the relevance of the currently developed all-BODIPY-based energy-funneling supramolecular sytems with near-IR emission to solar-energy harvesting applications. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  14. 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.

  15. Emission properties of plasmas induced by near IR laser pulses in the far VUV

    NASA Astrophysics Data System (ADS)

    Khater, Mohamed

    2013-07-01

    Influence of pulsed laser energy on emission characteristics of laser plasmas induced in various inert atmospheres and pressures is demonstrated by emission spectroscopy in the far vacuum UV zone (around 100 nm). In this context, argon and helium were employed and their pressures were controlled in the range 0.005-5.0 mbar. A Q-switched Nd:YAG laser emitting in the near IR at 1064 nm was employed in the experiments. The laser energy was varied between 200 and 800 mJ and focused onto a reference steel sample within a vacuum-tight chamber. The radiation emitted from the line plasmas generated was recorded from a section located 2.5 mm from the target surface. Under any gas composition and pressure studied, line and background emission intensities as well as signal-to-background ratios showed significant dependence on the laser energy. For example, at 800 mJ the highest spectral line intensity was obtained in argon atmosphere at a pressure of about 0.5 mbar, while helium at the same pressure produced the largest signal-to-background ratio using lower laser pulse energy of 400 mJ. In any case, the nature and characteristics of laser plasma-based emission in the far vacuum UV are similar to those recorded in the UV-visible range.

  16. An Atomically Precise Au10 Ag2 Nanocluster with Red-Near-IR Dual Emission.

    PubMed

    Lei, Zhen; Guan, Zong-Jie; Pei, Xiao-Li; Yuan, Shang-Fu; Wan, Xian-Kai; Zhang, Jin-Yuan; Wang, Quan-Ming

    2016-08-01

    A red-near-IR dual-emissive nanocluster with the composition [Au10 Ag2 (2-py-C≡C)3 (dppy)6 ](BF4 )5 (1; 2-py-C≡C is 2-pyridylethynyl, dppy=2-pyridyldiphenylphosphine) has been synthesized. Single-crystal X-ray structural analysis reveals that 1 has a trigonal bipyramidal Au10 Ag2 core that contains a planar Au4 (2-py-C≡C)3 unit sandwiched by two Au3 Ag(dppy)3 motifs. Cluster 1 shows intense red-NIR dual emission in solution. The visible emission originates from metal-to-ligand charge transfer (MLCT) from silver atoms to phosphine ligands in the Au3 Ag(dppy)3 motifs, and the intense NIR emission is associated with the participation of 2-pyridylethynyl in the frontier orbitals of the cluster, which is confirmed by a time-dependent density functional theory (TD-DFT) calculation. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  17. Study of the emission of PAHs in 7.7μm and IR emission for a sample of galaxies at high redshift

    NASA Astrophysics Data System (ADS)

    Zambrano, R.; Higuera G., M. A.

    2017-07-01

    This study investigates a possible correlation between the star formation rate (SFR) from the PAHs emission in the line of 7.7μm and IR emission for a sample of galaxies at high redshift obtained by the Spitzer Space Telescope. Profiles emission of PAHs for the sample were extracted using the PAHFIT tool, designed to decomposing Spitzer IRS spectra and written in the IDL programming language, in order to determine the luminosity and the star formation rate for each of the galaxies.

  18. 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.

  19. 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.

  20. 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.

  1. 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.

  2. An Extraordinary Group of 3.6micron Galaxies with Extremely Bright, Extended Far-IR Emission

    NASA Astrophysics Data System (ADS)

    Yan, Lin

    2013-08-01

    Based on WISE, Spitzer and recent Herschel far-IR data, we have discovered W0010+32, a remarkable object with extremely bright (detected by IRAS) and extended far-IR emission, coinciding with a group of 3.6micron sources with very faint optical magnitudes. The bright 70micron emission was resolved into two peaks, separated by 10arcseconds. The photo-z estimates based on optical and IR data are largely uncertain, ranging from 0.7 to >2. The bright far-IR emission from W0010+32 could either be magnified by the gravitational lensing of a foreground cluster of galaxies or is a rare case of a cluster of intrinsically luminous hyperLIRGs. Either case offers a rare window on the rapid transformation of galaxies and clusters during a short episode of the most energetic activity. To unravel the mystery of W0010+32, we request 0.5 nights of Keck I time to obtain J, H & K-band multi-object near-IR spectra using MOSFIRE. The proposed near-IR spectra will detect emission lines ! from galaxies with SFR as low as 0.4-3.4Msun/yr at z 1-2.3. This data will enable the following critical measurements: (1) redshifts of galaxies, and determine if it is indeed a group/cluster, (2) metallicities and AGN content based on emission line ratios and widths, (3) unobscured SFR based on Halpha line fluxes as well as dust extinctions based on spectral lines and continuum slopes, (4) kinematic velocity measurements with spatially and spectrally resolved emission lines (gas outflows) commonly seen among extreme starbursts.

  3. Optical emission spectroscopic study of plasma plumes generated by IR CO2 pulsed laser on carbon targets

    NASA Astrophysics Data System (ADS)

    Camacho, J. J.; Díaz, L.; Santos, M.; Reyman, D.; Poyato, J. M. L.

    2008-05-01

    Optical emission spectroscopy studies, in the spectral range ultraviolet-visible-near infrared (UV-Vis-NIR), were performed to investigate thermal and dynamical properties of a plume produced by laser ablation of a graphite target. Ablation is carried out using a high-power IR CO2 pulsed laser at λ = 9.621 µm, power density ranging from 0.22 to 5.36 GW cm-2 and air pressures around 4 Pa. The strong emission observed in the plasma region is mainly due to electronic relaxation of excited C, ionic fragments C+, C2+ and C3+ and molecular features of C2(d 3Πg-a 3Πu Swan band system). The medium-weak emission is mainly due to excited atomic N, H, O, ionic fragment C4+ and molecular features of C2( E\\,^1\\Sigma _g^+\\--A\\,^{1}\\Pi _u ; Freymark system), C2( D\\,^1\\Sigma _u^+\\--X\\,^1\\Sigma _g^+ ; Mulliken system), CN(D 2Π-A 2Π), C2(e 3Πg-a 3Πu Fox-Herzberg system), C2(C 1Πg-A 1Πu Deslandres-d'Azambuja system), OH(A 2Σ+-X 2Π), CH(C 2Σ+-X 2Π), NH(A 3Π-X 3Σ-), CN(B 2Σ+-X 2Σ+ violet system), CH(B 2Σ+-X 2Π), CH(A 2Δ-X 2Π), C2( A\\,^{1}\\Pi_u\\--X\\,^{1}\\Sigma ^{+}_g ; Phillips system) and CN(A 2Π-X 2Σ+ red system). An excitation temperature Texc = 23 000 ± 1900 K and electron densities in the range (0.6-5.6) × 1016 cm-3 were estimated by means of C+ ionic lines. The characteristics of the spectral emission intensities from different species have been investigated as functions of the ambient pressure and laser irradiance. Estimates of vibrational temperatures of C2 and CN electronically excited species under various laser irradiance conditions are made.

  4. Radiative Transfer Modeling of the Mid-IR/Far-IR Dust Emissions of the Symbiotic Mira, V* R Aqr

    NASA Astrophysics Data System (ADS)

    Omelian, Eric B.; Sankrit, Ravi; Helton, L. Andrew; Gorti, Uma; Wagner, R. Mark

    2017-01-01

    We present RADMC-3D models of the symbiotic system V* R Aqr, which consists of a Mira variable and white dwarf. Thermal radiative transfer modeling is performed using RADMC-3D to characterize the mid-IR/far-IR Spectral Energy Distributions (SEDs) of the system at two different phases of the visible light curve. Near maximum visible light (Mira phase of 1.0), we utilize the Infrared Space Observatory (ISO) Short Wave Spectrometer/Long Wave Spectrometer observations (2.3 - 197 mu-m) and contrast them to the recently obtained near minimum visible light (~0.4 Mira phase) observations from the Stratospheric Observatory for Infrared Astronomy (SOFIA)/Faint Object infraRed CAmera for the SOFIA Telescope (FORCAST) (6.4 - 37.1 mu-m). Initial spectra and photometry from the SOFIA/FORCAST observations of the central Mira indicate that flux values are about 50% of that measured by the ISO SWS/LWS observations. Dust models utilizing a spherical shell and amorphous silicates are used to generate synthetic SEDs, which are compared with the ISO and FORCAST observations in order to constrain the properties of the shell (such as its dust mass and temperature) at different phases of the Mira variability. Our proposed monitoring of the V* R Aqr system will establish a characterization baseline of the SEDs as the system approaches its upcoming eclipse and periastron passage.

  5. An alternative mechanism for production of emission features in some infrared objects

    NASA Technical Reports Server (NTRS)

    Apruzese, J. P.

    1975-01-01

    Two dust-envelope models of the M supergiant VX Sgr, which exhibits a prominent emission feature at 10 microns, are presented. The models indicate that, for certain envelope sizes, the presence of the observed emission feature does not necessarily indicate that the emitting grains possess a similar feature in their emissivity profile. The mechanism which may in some cases be producing the observed emission feature is discussed.

  6. 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.

  7. 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.

  8. Application of IRS-1D data in water erosion features detection (case study: Nour roud catchment, Iran).

    PubMed

    Solaimani, K; Amri, M A Hadian

    2008-08-01

    The aim of this study was capability of Indian Remote Sensing (IRS) data of 1D to detecting erosion features which were created from run-off. In this study, ability of PAN digital data of IRS-1D satellite was evaluated for extraction of erosion features in Nour-roud catchment located in Mazandaran province, Iran, using GIS techniques. Research method has based on supervised digital classification, using MLC algorithm and also visual interpretation, using PMU analysis and then these were evaluated and compared. Results indicated that opposite of digital classification, with overall accuracy 40.02% and kappa coefficient 31.35%, due to low spectral resolution; visual interpretation and classification, due to high spatial resolution (5.8 m), prepared classifying erosion features from this data, so that these features corresponded with the lithology, slope and hydrograph lines using GIS, so closely that one can consider their boundaries overlapped. Also field control showed that this data is relatively fit for using this method in investigation of erosion features and specially, can be applied to identify large erosion features.

  9. The Spectacular Radio-Near-IR-X-Ray Jet of 3C 111: the X-Ray Emission Mechanism and Jet Kinematics

    NASA Technical Reports Server (NTRS)

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

    2016-01-01

    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 subparsec 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.

  10. 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.

  11. 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

  12. 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.

  13. Spectral emissivity features of plants: Prospects for the Hyperspectral Thermal Emission Spectrometer (HyTES) sensor

    NASA Astrophysics Data System (ADS)

    Meerdink, S.; Roberts, D. A.; Hook, S. J.

    2016-12-01

    The Thermal Infrared (TIR) spectrum has not been widely adopted for vegetation studies due to the limited availability of TIR sensors, low signal to noise ratios, and subtle features of plant spectra. However, recent improvements in TIR sensor design, atmospheric correction, and temperature emissivity separation have begun to achieve the necessary data quality for discerning TIR spectral features in plants. These technical developments make it possible to re-examine the TIR emissivity characteristics of plants. The Hyperspectral Thermal Emission Spectrometer (HyTES) airborne sensor has 256 bands that measures radiance between 7.5 - 12 μm and can be used to retrieve spectral emissivity with high precision. Here we evaluate: 1) TIR spectral variation between plant species at leaf scale; 2) TIR spectral signatures of plant canopies using HyTES imagery; and 3) TIR spectra scaling capabilities from leaf to canopy. HyTES imagery was acquired over Huntington Gardens in Pasadena, California, US on 1/25/2016 with a spatial resolution of 2 m. Leaf samples were collected on 2/2/16 from a diversity of trees species that had canopies larger than 10 m in diameter. Leaf spectra were collected using a Nicolet Model 4700 Interferometer Spectrometer fitted with a Labsphere gold coated integrating sphere which measured emissivity from 2.5 - 15.4 µm. While plant features are subtler and have lower reflectance in the TIR than the visible shortwave infrared spectrum, plants showed considerable spectral diversity at the leaf and canopy level using HyTES imagery. These analyses support the first steps of using HyTES imagery for future remote sensing vegetation studies.

  14. Nanometer-scale features produced by electric-field emission

    NASA Astrophysics Data System (ADS)

    McBride, S. E.; Wetsel, G. C., Jr.

    1991-12-01

    Nanometer-scale features have been formed in air on metallic surfaces with various tip/sample material combinations (W/Au, Au/Au, Au/Pt, and W/Pt) using a scanning tunneling microscope (STM) instrument. The instrument has sufficient stability, computer control, and in-process measurement capability to record important processing signals while creating nanoscale patterns. The sample surface can be quantitatively characterized using both tunneling spectroscopy and imaging before and after pulsing the tip-sample voltage (Vt). Images show that the form of the created features ranges from craters to mounds when Vt exceeds a threshold value, Vc, which is dependent on the tunneling resistance (R). Results of measurement of Vc vs R combined with results of the measurement of tip displacement versus Vt allow the determination of the threshold electric field (Ec). For the W tip and the Pt sample, Ec has been determined to be 0.23 V/Å. Electric fields of this magnitude are sufficient to remove atoms by high-field emission.

  15. POLYCYCLIC AROMATIC HYDROCARBON EMISSION IN SPITZER/IRS MAPS. I. CATALOG AND SIMPLE DIAGNOSTICS

    SciTech Connect

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

    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.

  16. 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.

  17. Feature Extraction for Pose Estimation. A Comparison Between Synthetic and Real IR Imagery

    DTIC Science & Technology

    1991-12-01

    based aspect ratios. Each technique is discussed below. Three-Dimensional Moments. Representative of this work is the work by Sadjadi (74) and Casasent...propriate" due to "immense variety and inconsistency presented by intensity distributions." 14 Furthermore, relative to IR models, Sadjadi (73) mentions...118. Bellingham, WA, 1990. 73. Sadjadi , Firooz A. and Bazados, Mike "A Perspective on ATR Evaluation Technology," Proceedings of the SPIE - The

  18. THE SPATIAL EXTENT OF (U)LIRGS IN THE MID-INFRARED. II. FEATURE EMISSION

    SciTech Connect

    DIaz-Santos, T.; Charmandaris, V.; Armus, L.; Stierwalt, S.; Haan, S.; Howell, J. H.; Petric, A. O.; Surace, J. A.; Mazzarella, J. M.; Veilleux, S.; Murphy, E. J.; Appleton, P.; Evans, A. S.; Sanders, D. B.

    2011-11-01

    We present results from the second part of our analysis of the extended mid-infrared (MIR) emission of the GOALS sample based on 5-14 {mu}m low-resolution spectra obtained with the Infrared Spectrograph on Spitzer. We calculate the fraction of extended emission (FEE) as a function of wavelength for all galaxies in the sample, FEE{sub {lambda}}, defined as the fraction of the emission that originates outside of the unresolved central component of a source, and spatially separate the MIR spectrum of a galaxy into its nuclear and extended components. We find that the [Ne II]12.81 {mu}m emission line is as compact as the hot dust MIR continuum, while the polycyclic aromatic hydrocarbon (PAH) emission is more extended. In addition, the 6.2 and 7.7 {mu}m PAH emission is more compact than that of the 11.3 {mu}m PAH, which is consistent with the formers being enhanced in a more ionized medium. The presence of an active galactic nucleus (AGN) or a powerful nuclear starburst increases the compactness and the luminosity surface density of the hot dust MIR continuum, but has a negligible effect on the spatial extent of the PAH emission on kpc-scales. Furthermore, it appears that both processes, AGN and/or nuclear starburst, are indistinguishable in terms of how they modify the integrated PAH-to-continuum ratio of the FEE in (ultra)luminous infrared galaxies ((U)LIRGs). Globally, the 5-14 {mu}m spectra of the extended emission component are homogeneous for all galaxies in the GOALS sample. This suggests that, independently of the spatial distribution of the various MIR features, the physical properties of star formation occurring at distances farther than 1.5 kpc from the nuclei of (U)LIRGs are very similar, resembling local star-forming galaxies with L{sub IR} < 10{sup 11} L{sub sun}, as well as star-formation-dominated ULIRGs at z {approx} 2. In contrast, the MIR spectra of the nuclear component of local ULIRGs and LIRGs are very diverse. These results imply that the observed

  19. 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.

  20. A new emission feature in IRAS spectra and the polycyclic aromatic hydrocarbon spectrum

    NASA Technical Reports Server (NTRS)

    Cohen, M.; Tielens, A. G. G. M.; Allamandola, L. J.

    1985-01-01

    IRAS spectra of those sources which show strong 7.7 and 11.3 micron emission features also show a plateau of emission extending from 11.3 to about 13.0 microns. Like the 11.3 micron feature, this new feature is attributed to the CH out-of-plane bending mode in polycyclic aromatic hydrocarbons (PAHs). Its discovery reinforces the identification of the 'unidentified infrared emission features' as emission from PAHs. The wavelength of this new feature suggests that interstellar PAHs are not as partially hydrogenated as hitherto thought. It also constrains their molecular structure.

  1. 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.

  2. Mid-IR Properties of an Unbiased AGN Sample of the Local Universe. I. Emission-Line Diagnostics

    NASA Astrophysics Data System (ADS)

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

    2010-01-01

    We 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 μm, [Ne II] 12.81μm , [Ne III] 15.56 μm and [Ne V] μm, and hard X-ray show no differences between Seyfert 1 and Seyfert 2 populations, although six newly discovered BAT AGN are shown to be under-luminous in [O IV], most likely the result of dust extinction in the host galaxy. The correlations between all the mid-infrared emission lines and BAT luminosities are statistically significant. The mid-infrared emission line fluxes are highly correlated, with the worst correlations for [Ne V]-[Ne II] and [O IV]-[Ne II], as a result of enhanced [Ne II] in some sources due to nuclear stellar activity, however the tightness of these mid-infrared correlations 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 [Ne III] an [O IV] lines do not unambiguously identify AGNs as stand-along diagnostics, however the BAT AGNs fall into a distinctive region when comparing the [Ne III]/[Ne II] and the [O IV]/[Ne III] quantities. While it is likely that detection of [Ne V] indicates the presence of an AGN, the [Ne V] line is weak compared to [O IV] and may not be detected in weak AGN. We suggest that a composite method using [Ne II], [Ne III], and [O IV] provides a more robust diagnostic.

  3. IR Structured Emission-Based Speciation, Thermometry, and Tomography of CO and H2O in High-Pressure Combustors

    DTIC Science & Technology

    2006-05-01

    combustors and augmentors, but is impacted by soot emission interference in staged combustors. The current work is motivated primarily by the...typically of order 10. Time averaged spatial maps can be constructed using a scanning mechanism, similar to that used for gas samplers , to scan the...entrance slit . The light enters the spectrograph, is dispersed, and reimaged with 1:3 demagnification onto the focal plane of a Santa Barbara ImageIR

  4. Harmonic and anharmonic features of IR and NIR absorption and VCD spectra of chiral 4-X-[2.2]paracyclophanes.

    PubMed

    Abbate, Sergio; Castiglioni, Ettore; Gangemi, Fabrizio; Gangemi, Roberto; Longhi, Giovanna; Ruzziconi, Renzo; Spizzichino, Sara

    2007-08-02

    The vibrational absorption spectra and vibrational circular dichroism (VCD) spectra of both enantiomers of 4-X-[2.2]paracyclophanes (X = COOCD3, Cl, I) have been recorded for a few regions in the range of 900-12000 cm(-1). The analysis of the VCD spectra for the two IR regions, 900-1600 cm(-1) and 2800-3200 cm(-1), is conducted by comparing with DFT calculations of the corresponding spectra; the latter region reveals common motifs of vibrational modes for the three molecules for aliphatic CH stretching fundamentals, whereas in the mid-IR region, one is able to identify specific signatures arising from the substituent groups X. In the CH stretching region between 2900 and 2800 cm(-1), we identify and interpret a group of three IR VCD bands due to HCH bending overtone transitions in Fermi resonance with CH stretching fundamental transitions. The analysis of the NIR region between approximately 8000 and approximately 9000 cm(-1) for X = COOCD3 reveals important features of the aromatic CH stretching overtones that are of value since the aromatic CH stretching fundamentals are almost silent. The intensifying of such overtones is attributed to electrical anharmonicity terms, which are evaluated here by ab initio methods and compared with literature data.

  5. 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.

  6. Sensitivity of Venus surface emissivity retrieval to model variations of CO2 opacity, cloud features, and deep atmosphere temperature field

    NASA Astrophysics Data System (ADS)

    Kappel, David; Arnold, Gabriele; Haus, Rainer

    2012-07-01

    The Visible and Infrared Thermal Imaging Spectrometer (VIRTIS) aboard ESA's Venus Express space probe has acquired a wealth of nightside emission spectra from Venus and provides the first global database for systematic atmospheric and surface studies in the IR. The infrared mapping channel (VIRTIS-M-IR) sounds the atmosphere and surface at high spatial and temporal resolution and coverage. Quantitative analyses of data call for a sophisticated radiative transfer simulation model of Venus' atmosphere to be used in atmospheric and surface parameter retrieval procedures that fit simulated spectra to the measured data. The surface emissivity can be retrieved from VIRTIS-M-IR measurements in the transparency windows around 1 μm, but it is not easy to derive, since atmospheric influences strongly interfere with surface information. There are mainly three atmospheric model parameters that may affect quantitative results of surface emissivity retrievals: CO_2 opacity, cloud features, and deep atmosphere temperature field. The CO_2 opacity with respect to allowed transitions is usually computed by utilizing a suitable line data base and certain line shape models that consider collisional line mixing. Both line data bases and shape models are not well established from measurements under the environmental conditions in the deep atmosphere of Venus. Pressure-induced additional continuum absorption introduces further opacity uncertainties. The clouds of Venus are usually modeled by a four-modal distribution of spherical droplets of about 75% sulfuric acid, where each mode is characterized by a different mean and standard deviation of droplet size distribution and a different initial altitude abundance profile. The influence of possible cloud mode variations on surface emissivity retrieval results is investigated in the paper. Future retrieval procedures will aim at a separation of cloud mode and surface emissivity variations using different atmospheric windows sounded by

  7. SPATIALLY RESOLVED POLYCYCLIC AROMATIC HYDROCARBON EMISSION FEATURES IN NEARBY, LOW METALLICITY, STAR-FORMING GALAXIES

    SciTech Connect

    Haynes, Korey; Cannon, John M.; Skillman, Evan D.; Gehrz, Robert; Jackson, Dale C. E-mail: khaynes5@gmu.ed E-mail: gehrz@astro.umn.ed

    2010-11-20

    Low-resolution, mid-infrared Spitzer/IRS spectral maps are presented for three nearby, low-metallicity dwarf galaxies (NGC 55, NGC 3109, and IC 5152) for the purpose of examining the spatial distribution and variation of polycyclic aromatic hydrocarbon (PAH) emission. The sample straddles a metallicity of 12 + log(O/H) {approx} 8, a transition point below which PAH intensity empirically drops and the character of the interstellar medium changes. We derive quantitative radiances of PAH features and atomic lines on both global and spatially resolved scales. The Spitzer spectra, combined with extensive ancillary data from the UV through the mid-infrared, allow us to examine changes in the physical environments and in PAH feature radiances down to a physical scale of {approx}50 pc. We discuss correlations between various PAH emission feature and atomic line radiances. The (6.2 {mu}m)/(11.3 {mu}m), (7.7 {mu}m)/(11.3 {mu}m), (8.6 {mu}m)/(11.3 {mu}m), (7.7 {mu}m)/(6.2 {mu}m), and (8.6 {mu}m)/(6.2 {mu}m) PAH radiance ratios are found to be independent of position across all three galaxies, although the ratios do vary from galaxy to galaxy. As seen in other galaxies, we find no variation in the grain size distribution as a function of local radiation field strength. Absolute PAH feature intensities as measured by a ratio of PAH/(24 {mu}m) radiances are seen to vary both positionally within a given galaxy and from one galaxy to another when integrated over the full observed extent of each system. We examine direct comparisons of CC mode PAH ratios (7.7 {mu}m)/(6.2 {mu}m) and (8.6 {mu}m)/(6.2 {mu}m) to the mixed (CC/CH) mode PAH ratio (7.7 {mu}m)/(11.3 {mu}m). We find little variation in either mode and no difference in trends between modes. While the local conditions change markedly over the observed regions of these galaxies, the properties of PAH emission show a remarkable degree of uniformity.

  8. Structural features of alkali and barium aluminofluorophosphate glasses studied by IR spectroscopy

    SciTech Connect

    Urusovskaya, L.N.; Smirnova, E.V.

    1995-03-01

    IR reflection spectra of the Al(PO{sub 3}){sub 3}-MeF{sub x} glasses (Me=Li, Na, K, Ba) with the maximum content of fluoride varied for each specific glass within certain concentration limits are considered. Analysis of the spectra for glasses obtained upon variation in the content of alkali metal fluoride introduced into these glasses has demonstrated that the increase in the MeF{sub x} content leads to breaking the chain groupings and forming the [PO{sub 3}F]{sup 2-} groups, whereas the rise in concentration of barium fluoride in the Al(PO{sub 3}){sub 3}-BaF{sub 2} glasses brings about the stabilization of the chain structures.

  9. 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

  10. 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

    2016-07-04

    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. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  11. Remote sensing of the surface emissivity at 9 microns over the globe. [over desert regions with IR Interferometer Spectrometer data

    NASA Technical Reports Server (NTRS)

    Prabhakara, C.; Dalu, G.

    1976-01-01

    The infrared spectral measurements made by the Nimbus 4 infrared interferometer spectrometer (Iris) for a period of about 10 months are used to study the surface emissivity properties over the globe. It is found that the surface emissivity at 9 microns, as measured by Iris with a circular field of view of about 100-km diameter, is significantly less than unity over arid and semiarid areas. The spectral features in the 8-12-micron window observed over these lands reveal emissivity characteristics essentially due to quartz (SiO2). It is found that these emissivity features are significantly weakened by the presence of clay, clay horizons, or pedogenic horizons in the soil. Low emissivity is observed over sandy or sandy loam areas (psamments) with no clay or pedogenic horizons.

  12. Remote sensing of the surface emissivity at 9 microns over the globe. [over desert regions with IR Interferometer Spectrometer data

    NASA Technical Reports Server (NTRS)

    Prabhakara, C.; Dalu, G.

    1976-01-01

    The infrared spectral measurements made by the Nimbus 4 infrared interferometer spectrometer (Iris) for a period of about 10 months are used to study the surface emissivity properties over the globe. It is found that the surface emissivity at 9 microns, as measured by Iris with a circular field of view of about 100-km diameter, is significantly less than unity over arid and semiarid areas. The spectral features in the 8-12-micron window observed over these lands reveal emissivity characteristics essentially due to quartz (SiO2). It is found that these emissivity features are significantly weakened by the presence of clay, clay horizons, or pedogenic horizons in the soil. Low emissivity is observed over sandy or sandy loam areas (psamments) with no clay or pedogenic horizons.

  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

    2011-02-07

    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.

  14. Near-IR emissions in the upper Jovian atmosphere after SL-9 impact: Indications of possible northern counterparts

    NASA Astrophysics Data System (ADS)

    Schulz, R.; Encrenaz, Th.; Stüwe, J. A.; Wiedemann, G.

    The evolution of the Jovian atmosphere as a result of the impact of SL-9 was monitored in the near-IR at the 3.5-m New Technology Telescope at ESO, La Silla, from July 22-31, 1994. At the beginning of the observational run the spectra around 3.5 µm show enhanced H3+ emissions at -44° and +44° latitude, which are distributed similarly in longitude. Later, most of the H3+ emission is present in the northern polar region while it has faded at -44°. In the 2.1 µm range all spectra obtained at -44° lat. show a continuum associated to the impact sites on which in some cases the H2 quadrupole line is indicated. The spatial distribution of the H2 emission in the northern hemisphere does not show a clear correlation to the impact sites.

  15. Near-IR emissive chlorin-bacteriochlorin energy-transfer dyads with a common donor and acceptors with tunable emission wavelength.

    PubMed

    Yu, Zhanqian; Ptaszek, Marcin

    2013-11-01

    Design, synthesis, and optical properties of a series of novel chlorin-bacteriochlorin energy transfer dyads are described. Each dyad is composed of a common red-absorbing (645-646 nm) chlorin, as an energy donor, and a different near-IR emitting bacteriochlorin, as an energy acceptor. Each bacteriochlorin acceptor is equipped with a different set of auxochromes, so that each of them emits at a different wavelength. Dyads exhibit an efficient energy transfer (≥0.77) even for chlorin-bacteriochlorin pairs with large (up to 122 nm) separation between donor emission and acceptor absorption. Excitation of the chlorin donor results in relatively strong emission of the bacteriochlorin acceptor, with a quantum yield Φf range of 0.155-0.23 in toluene and 0.12-0.185 in DMF. The narrow, tunable emission band of bacteriochlorins enables the selection of a series of three dyads with well-resolved emissions at 732, 760, and 788 nm, and common excitation at 645 nm. Selected dyads have been also converted into bioconjugatable N-succinamide ester derivatives. The optical properties of the described dyads make them promising candidates for development of a family of near-IR fluorophores for simultaneous imaging of multiple targets, where the whole set of fluorophores can be excited with the common wavelength, and fluorescence from each can be independently detected.

  16. Measurement of the Shape of the Optical-IR Spectrum of Prompt Emission from Gamma-Ray Bursts

    NASA Astrophysics Data System (ADS)

    Grossan, Bruce; Kistubayev, M.; Smoot, G.; Scherr, L.

    2017-06-01

    While the afterglow phase of gamma-ray bursts (GRBs) has been extensively measured, detections of prompt emission (i.e. during bright X-gamma emission) are more limited. Some prompt optical measurements are regularly made, but these are typically in a single wide band, with limited time resolution, and no measurement of spectral shape. Some models predict a synchrotron self-absorption spectral break somewhere in the IR-optical region. Measurement of the absorption frequency would give extensive information on each burst, including the electron Lorentz factor, the radius of emission, and more (Shen & Zhang 2008). Thus far the best prompt observations have been explained invoking a variety of models, but often with a non-unique interpretation. To understand this apparently heterogeneous behavior, and to reduce the number of possible models, it is critical to add data on the optical - IR spectral shape.Long GRB prompt X-gamma emission typically lasts ~40-80 s. The Swift BAT instrument rapidly measures GRB positions to within a few arc minutes and communicates them via the internet within a few seconds. We have measured the time for a fast-moving D=700 mm telescope to point and settle to be less than 9 s anywhere on the observable sky. Therefore, the majority of prompt optical-IR emission can be measured responding to BAT positions with this telescope. In this presentation, we describe our observing and science programs, and give our design for the Burst Simultaneous Three-channel Instrument (BSTI), which uses dichroics to send eparate bands to 3 cameras. Two EMCCD cameras, give high-time resolution in B and V; a third camera with a HgCdTe sensor covers H band, allowing us to study extinguished bursts. For a total exposure time of 10 s, we find a 5 sigma sensitivity of 21.3 and 20.3 mag in B and R for 1" seeing and Kitt Peak sky brightness, much fainter than typical previous prompt detections. We estimate 5 sigma H-band sensitivity for an IR optimized telescope to be

  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. Long term stable deep red light-emitting electrochemical cells based on an emissive, rigid cationic Ir(iii) complex

    DOE PAGES

    Namanga, Jude E.; Gerlitzki, Niels; Mallick, Bert; ...

    2017-02-17

    Here, the new cationic iridium complex [Ir(bzq)2(biq)][PF6] (bzq = benzo[h]quinolinato and biq = 2,2'-biquinoline) has been synthesized for application as an emitter in light emitting electrochemical cells (LECs). The molecular structure and crystal packing of this complex were established by single X-ray diffraction (SXRD). The electrochemical and photophysical properties of the complex were examined to determine the frontier orbital energies as well as the optical transitions that led to photoemission. The complex was found to emit at 644 nm and 662 nm for powder and thin films, respectively. A high powder photoluminescence quantum yield of 25% was determined, which ismore » attributed to a reduction in vibrational modes of the complex due to the use of the rigid cyclometalated (C^N) bzq ligand. A LEC with [Ir(bzq)2(biq)][PF6] as the emitter was fabricated which showed a deep red emission (662 nm) with a luminance of 33.65 cd m–2, yielding a current efficiency of 0.33 cd A–1 and a power efficiency of 0.2 lm W–1. Most importantly, the LEC based on [Ir(bzq)2(biq)][PF6] demonstrated a lifetime of 280 hours which is among the longest device lifetimes reported for any deep red light emitting LEC.« less

  20. Spitzer observations of SN 2014J and properties of mid-IR emission in Type Ia supernovae

    NASA Astrophysics Data System (ADS)

    Johansson, J.; Goobar, A.; Kasliwal, M. M.; Helou, G.; Masci, F.; Tinyanont, S.; Jencson, J.; Cao, Y.; Fox, O. D.; Kromer, M.; Amanullah, R.; Banerjee, D. P. K.; Joshi, V.; Jerkstrand, A.; Kankare, E.; Prince, T. A.

    2017-04-01

    SN 2014J in M 82 is the closest Type Ia supernova (SN Ia) in decades. The proximity allows for detailed studies of supernova physics and provides insights into the circumstellar and interstellar environment. In this work, we analyse Spitzer mid-infrared (mid-IR) data of SN 2014J in the 3.6 and 4.5 μm wavelength range, together with several other nearby and well-studied SNe Ia. We compile the first composite mid-IR light-curve templates from our sample of SNe Ia, spanning the range from before peak brightness well into the nebular phase. Our observations indicate that SNe Ia form a very homogeneous class of objects at these wavelengths. Using the low-reddening supernovae for comparison, we constrain possible thermal emission from circumstellar dust around the highly reddened SN 2014J. We also study SNe 2006X and 2007le, where the presence of matter in the circumstellar environment has been suggested. No significant mid-IR excess is detected, allowing us to place upper limits on the amount of pre-existing dust in the circumstellar environment. For SN 2014J, Mdust ≲ 10- 5 M⊙ within rdust ∼ 1017 cm, which is insufficient to account for the observed extinction. Similar limits are obtained for SNe 2006X and 2007le.

  1. Looking for a Relation Between Black hole Mass and Radio/IR Emission in Active Galactic Nuclei

    NASA Astrophysics Data System (ADS)

    Gorjian, Varoujan; GAVRT-Spitzer Team

    2007-12-01

    We have combined space-based Spitzer data at 8 um with ground-based, continuum radio data to search for a relation between the ratio of radio to infrared emission and the black hole mass in a sample of twenty-one 3C Active Galactic Nuclei. The radio data were collected at 2.3 GHz (S-band) and 8.5 GHz (X-band), by middle and high-school students using the Goldstone-Apple Valley Radio Telescope (GAVRT). The IR data were collected with the IRAC imaging instrument on Spitzer. The GAVRT students carried out the initial data analysis at both IR and radio wavelengths. GAVRT is a science-education partnership between NASA/JPL and the Lewis Center for Educational Research, which allows K-12 students to participate in real research as part of their standard classroom education. The GAVRT-Spitzer Team is a collaboration among GAVRT, the Spitzer Science Center, and K-12 students across the country to carry out research projects utilizing both radio and IR data.

  2. Pulsar polarization: weak sources and emission features at 430 MHz

    SciTech Connect

    Rankin, J.M.; Benson, J.M.

    1981-03-01

    We have measured the Stokes parameters of the average profiles of 31 pulsars at 430 MHz. The three pulsars in our sample with interpulse emission (0823+26, 0950+08, and 1929+10) have measurable linear polarization angles. In particular, PSR 0950+08 exhibits a polarization angle signature that rotates smoothly and continuously through 180/sup 0/ across the interpulse-- main pulse waveform. Of the remaining 28 pulsars, 17 have simple profile shapes and 11 have double or complex profiles. The highest levels of linear polarization (60% to 83%) are found in four pulsars with simple profiles. The remaining 24 objects have linear polarizations more or less evenly distributed between 0% and 45%, and show no correlation of linear emission with pulse shape. Switching between dominant linear emission modes is revealed through sudden 90/sup 0/ shifts in the linear polarization angle, usually at the leading and/or trailing edges of the profiles. Interference between orthogonal emission states apparently causes much of the linear depolarization in this sample of objects. We further measure levels of circular polarization between 0% and 25% in these objects. Approximately one-half of the objects have circular levels less than approx.10%. The circular polarization fractions appear to be independent of both pulse shape and linear polarization level.

  3. 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.

  4. 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

  5. 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.

  6. A stable auroral red (SAR) arc with multiple emission features

    NASA Astrophysics Data System (ADS)

    Mendillo, Michael; Finan, Robert; Baumgardner, Jeffrey; Wroten, Joei; Martinis, Carlos; Casillas, Marcus

    2016-10-01

    Stable auroral red (SAR) arcs offer subvisible evidence for storm time linkages between the inner magnetosphere and the midlatitude ionosphere. A SAR arc's defining characteristics are horizon-to-horizon east-west extent, a few degrees of latitude in meridional extent, emission only at the oxygen 6300Å line, and minimal brightness changes during a night—effects readily provided by steady heat conduction from the ring current-plasmapause interaction region. Here we describe a typical SAR arc (brightness 300 rayleighs) with several superimposed patches of emission in two oxygen lines (with a 6300Å/5577Å ratio of 40). We find no evidence for highly localized heating effects but rather evidence from GPS satellites supporting low-energy electron precipitation as the SAR arc modulating mechanism. Seven brightness peaks with average longitude spacing of 4° define a new spatial pattern for SAR arc studies.

  7. Carriers of the mid-IR emission bands in PNe reanalysed. Evidence of a link between circumstellar and interstellar aromatic dust

    NASA Astrophysics Data System (ADS)

    Joblin, C.; Szczerba, R.; Berné, O.; Szyszka, C.

    2008-10-01

    Context: It has been shown that the diversity of the aromatic emission features can be rationalized into different classes of objects, in which differences between circumstellar and interstellar matter are emphasised. Aims: We probe the links between the mid-IR emitters observed in planetary nebulae (PNe) and their counterparts in the interstellar medium in order to probe a scenario in which the latter have been formed in the circumstellar environment of evolved stars. Methods: The mid-IR (6-14 μm) emission spectra of PNe and compact H II regions were analysed on the basis of previous work on photodissociation regions (PDRs). Galactic, Large Magellanic Cloud (LMC), and Small Magellanic Cloud (SMC) objects were considered in our sample. Results: We show that the mid-IR emission of PNe can be decomposed as the sum of six components. Some components made of polycyclic aromatic hydrocarbon (PAH) and very small grain (VSG) populations are similar to those observed in PDRs. Others are fitted in an evolutionary scenario involving the destruction of the aliphatic component observed in the post-AGB stage, as well as strong processing of PAHs in the extreme conditions of PNe that leads to a population of very large ionized PAHs. This species called PAHx are proposed as the carriers of a characteristic band at 7.90 μm. This band can be used as part of diagnostics that identify PNe in nearby galaxies and is also observed in galactic compact H II regions. Conclusions: These results support the formation of the aromatic very small dust particles in the envelopes of evolved stars, in the Milky Way, as well as in the LMC and SMC, and their subsequent survival in the interstellar medium. This work is based on observations made with the Spitzer Space Telescope, which is operated by the Jet Propulsion Laboratory, California Institute of Technology under a contract with NASA. Based on observations with ISO, an ESA project with instruments funded by ESA Member States (especially the

  8. A Broad 22 Micron Emission Feature in the Carina Nebula H ii Region.

    PubMed

    Chan; Onaka

    2000-04-10

    We report the detection of a broad 22 µm emission feature in the Carina Nebula H ii region by the Infrared Space Observatory (ISO) short-wavelength spectrometer. The feature shape is similar to that of the 22 µm emission feature of newly synthesized dust observed in the Cassiopeia A supernova remnant. This finding suggests that both of the features are arising from the same carrier and that supernovae are probably the dominant production sources of this new interstellar grain. A similar broad emission dust feature is also found in the spectra of two starburst galaxies from the ISO archival data. This new dust grain could be an abundant component of interstellar grains and can be used to trace the supernova rate or star formation rate in external galaxies. The existence of the broad 22 µm emission feature complicates the dust model for starburst galaxies and must be taken into account correctly in the derivation of dust color temperature. Mg protosilicate has been suggested as the carrier of the 22 µm emission dust feature observed in Cassiopeia A. The present results provide useful information in studies on the chemical composition and emission mechanism of the carrier.

  9. An Earth-like correspondence between Saturn's auroral features and radio emission.

    PubMed

    Kurth, W S; Gurnett, D A; Clarke, J T; Zarka, P; Desch, M D; Kaiser, M L; Cecconi, B; Lecacheux, A; Farrell, W M; Galopeau, P; Gérard, J-C; Grodent, D; Prangé, R; Dougherty, M K; Crary, F J

    2005-02-17

    Saturn is a source of intense kilometre-wavelength radio emissions that are believed to be associated with its polar aurorae, and which provide an important remote diagnostic of its magnetospheric activity. Previous observations implied that the radio emission originated in the polar regions, and indicated a strong correlation with solar wind dynamic pressure. The radio source also appeared to be fixed near local noon and at the latitude of the ultraviolet aurora. There have, however, been no observations relating the radio emissions to detailed auroral structures. Here we report measurements of the radio emissions, which, along with high-resolution images of Saturn's ultraviolet auroral emissions, suggest that although there are differences in the global morphology of the aurorae, Saturn's radio emissions exhibit an Earth-like correspondence between bright auroral features and the radio emissions. This demonstrates the universality of the mechanism that results in emissions near the electron cyclotron frequency narrowly beamed at large angles to the magnetic field.

  10. Resolution of the 7.7 micrometers emission feature in NGC 7027

    NASA Technical Reports Server (NTRS)

    Bregman, J. D.; Witteborn, F. C.; Rank, D. M.; Wooden, D.; Allamandola, Louis J.; Tielens, Alexander G. G. M.

    1986-01-01

    The unidentified infrared (UIR) features are a group of emission bands observed in a variety of objects, which can be characterized as having moderate density gas (densities from 1000 to 1,000,000/cu.cm.) and a nearby ultraviolet source. The origin of the features is still uncertain, but the current evidence points to Polycyclic Aromatic Hydrocarbons (PAHs) as the source of the UIR features. Problems with identifying PAHs as the source of the UIR features are discussed.

  11. More interstellar emission features at 3.3-3.6 micrometers!

    NASA Technical Reports Server (NTRS)

    Tokunaga, A. T.; Nagata, T.; Sellgren, K.; Smith, R. G.; Onaka, T.; Nakada, Y.; Sakata, A.; Wada, S.

    1986-01-01

    The present data set consists of 3.20 to 3.55 micron spectra of HD44179, NGC 7027, BD+30 3639, and Elias 1 obtained with a cooled-grating array spectrometer (CGAS) at the NASA Infrared Telescope Facility. Emission features and details of the emission feature profiles are presented for high resolution spectra. Greater complexity is shown than might be expected. It is significant that the 3.29 micron feature has an invariant central wavelength, even at high resolution, and this strongly supports the case for a very specific substance or mixture of substances which is giving rise to this feature.

  12. 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.

  13. Time variations of UV emission features of Be stars

    NASA Technical Reports Server (NTRS)

    Bahng, J. D. R.

    1975-01-01

    The UV spectra of three Be stars (gamma Cas, sigma Tau, eta Cen) were studied. Of the six Be stars observed in the first four lines of the Balmer series, three stars showed at least one of the Balmer lines to be variable in the equivalent width amounting to a few percent with time scales of 3 to 30 minutes. Photoelectric spectrum scans of five southern Wolf-Rayet stars showed night-to-night variations. A simple model is proposed to account for the behavior of these emission lines. Scans of gamma square Vel showed rapid variations of emission strengths of He II 4686 and C III - IV 4650. These variations have time scales of 1 minute and longer. Night-to-night variations were also found. Scans of four Be stars in H alpha showed a definite variation of 3 to 4 percent, with time scales of 1 minute and longer in sigma Tau. In 48 Per and kappa Dra the variations are not as well established. No variation of any significance was found for nu Gem.

  14. 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.

  15. Field-emission microscopy of the surface of an Ir-C-Cs point emitter

    NASA Astrophysics Data System (ADS)

    Bernatskii, D. P.; Pavlov, V. G.

    2013-12-01

    The emissive properties of an iridium-based point emitter with various forms of carbon (chemisorbed species, two-dimensional graphite structures) and cesium atoms adsorbed on the surface has been studied by the field-electron emission microscopy (FEM) and field-desorption microscopy (FDM) techniques. The FEE and FDM images of the emitter surface corresponding to various phase states of carbon have been obtained. It is established that two-dimensional graphite structures grow predominantly in the regions of (100) and (111) faces of iridium.

  16. Direct observation of phonon emission from hot electrons: spectral features in diamond secondary electron emission.

    PubMed

    O'Donnell, Kane M; Edmonds, Mark T; Ristein, Jürgen; Rietwyk, Kevin J; Tadich, Anton; Thomsen, Lars; Pakes, Christopher I; Ley, Lothar

    2014-10-01

    In this work we use high-resolution synchrotron-based photoelectron spectroscopy to investigate the low kinetic energy electron emission from two negative electron affinity surfaces of diamond, namely hydrogenated and lithiated diamond. For hydrogen-terminated diamond electron emission below the conduction band minimum (CBM) is clearly observed as a result of phonon emission subsequent to carrier thermalization at the CBM. In the case of lithiated diamond, we find the normal conduction band minimum emission peak is asymmetrically broadened to higher kinetic energies and argue the broadening is a result of ballistic emission from carriers thermalized to the CBM in the bulk well before the onset of band-bending. In both cases the spectra display intensity modulations that are the signature of optical phonon emission as the main mechanism for carrier relaxation. To our knowledge, these measurements represent the first direct observation of hot carrier energy loss via photoemission.

  17. On the Search for Mid-IR and Pure Rotational H3+ Emission in Jupiter's Northern Aurora

    NASA Astrophysics Data System (ADS)

    Trafton, Laurence M.; Miller, Steve; Lacy, John H.; Greathouse, Thomas K.

    2017-06-01

    The first identification of astronomical spectral emission from the H3+ ion was made in Jupiter’s southern auroral region in the first overtone band near 2 μm (Drossart et al. 1989; Nature 340, 539). Trafton et al. (1989; ApJ 343, L73) also detected H3+ emission from this band near each of Jupiter’s auroral poles, but without identifying it. Shortly thereafter, Maillard et al (1990; ApJ 363, L37) detected the fundamental band emission near 4 μm. In order to determine the non-LTE column abundance of H3+, which is Jupiter’s primary ionospheric coolant, we searched in 2001-2002, initially above 10 μm, for emission lines from the H3+ pure rotational and ν1 -> ν2 difference band. This was done near the northern auroral “hot spot” at System III longitude 180 deg based on predicted theoretical frequencies. The results were reported by Trafton et al. (2009; Icarus 203, 189). No pure rotational lines were detected but there were marginal detections of two metastable difference band lines. The IR-inactive ν1 levels are populated in thermal equilibrium so these difference band lines are proxies for the pure rotational lines in establishing the total H3+ column. These marginal results are consistent with a vibrational relaxation of the ν2 level by a factor of ~6, consistent with the non-LTE calculation of Melin et al. (2005; Icarus 178, 97).We report here results from subsequent observations of Jupiter’s H3+ hot spot spectrum below 10 μm, where better detectivity was expected from the lower thermal background. However, this was offset by the reduced availability of emission from known hydrocarbons, leading to acquisition and guiding difficulty, which was resolved by offsetting from a Galilean satellite. The observations were made with the TEXES high-resolution mid-IR spectrograph at the IRTF telescope on Oct 1, 6, and 8 of 2012. Of the 18 lines predicted for this wavelength regime, half avoided blending with lines apparent in Jupiter’s auroral spectrum or

  18. 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.

  19. Narrow polarized components in the OH 1612-MHz maser emission from supergiant OH-IR sources

    NASA Technical Reports Server (NTRS)

    Cohen, R. J.; Downs, G.; Emerson, R.; Grimm, M.; Gulkis, S.; Stevens, G.

    1987-01-01

    High-resolution (300 Hz) OH 1612-MHz spectra of the supergiant OH-IR sources VY CMa, VX Sgr, IRC 10420, and NML Cyg are presented. Linewidths as small as 550 Hz (0.1 km/s) are found for narrow components in the spectra. The present results are consistent with current models for maser line-narrowing and for the physical properties in the OH maser regions. A significant degree of circular polarization is noted in many of the narrow components. The circular polarization suggests the presence of magnetic fields of about 1 mG in the circumstellar envelopes which would be strong enough to influence the outflow from the stars, and which may explain asymmetries found in the circumstellar envelopes.

  20. Modeling vehicle emissions in different types of Chinese cities: importance of vehicle fleet and local features.

    PubMed

    Huo, Hong; Zhang, Qiang; He, Kebin; Yao, Zhiliang; Wang, Xintong; Zheng, Bo; Streets, David G; Wang, Qidong; Ding, Yan

    2011-10-01

    We propose a method to simulate vehicle emissions in Chinese cities of different sizes and development stages. Twenty two cities are examined in this study. The target year is 2007. Among the cities, the vehicle emission factors were remarkably different (the highest is 50-90% higher than the lowest) owing to their distinct local features and vehicle technology levels, and the major contributors to total vehicle emissions were also different. A substantial increase in vehicle emissions is foreseeable unless stronger measures are implemented because the benefit of current policies can be quickly offset by the vehicle growth. Major efforts should be focused on all cities, especially developing cities where the requirements are lenient. This work aims a better understanding of vehicle emissions in all types of Chinese cities. The proposed method could benefit national emission inventory studies in improving accuracy and help in designing national and local policies for vehicle emission control.

  1. 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.; hide

    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.

  2. Turbine engine exhaust gas measurements using in-situ FT-IR emission/transmission spectroscopy

    NASA Astrophysics Data System (ADS)

    Marran, David F.; Cosgrove, Joseph E.; Neira, Jorge; Markham, James R.; Rutka, Ronald; Strange, Richard R.

    2001-02-01

    12 An advanced multiple gas analyzer based on in-situ Fourier transform infrared spectroscopy has been used to successfully measure the exhaust plume composition and temperature of an operating gas turbine engine at a jet engine test stand. The sensor, which was optically coupled to the test cell using novel broadband hollow glass waveguides, performed well in this harsh environment (high acoustical noise and vibration, considerable temperature swings in the ambient with engine operation), providing quantitative gas phase information. Measurements were made through the diameter of the engine's one meter exhaust plume, about 0.7 meters downstream of the engine exit plane. The sensor performed near simultaneous infrared transmission and infrared emission measurements through the centerline of the plume. Automated analysis of the emission and transmission spectra provided the temperature and concentration information needed for engine tuning and control that will ensure optimal engine operation and reduced emissions. As a demonstration of the utility and accuracy of the technique, carbon monoxide, nitric oxide, water, and carbon dioxide were quantified in spite of significant variations in the exhaust gas temperature. At some conditions, unburned fuel, particulates (soot/fuel droplets), methane, ethylene and aldehydes were identified, but not yet quantified.

  3. Orientation effects on spectral emission features of quasars

    NASA Astrophysics Data System (ADS)

    Bisogni, Susanna; Marconi, Alessandro; Risaliti, Guido

    2017-01-01

    We present an analysis of the orientation effects in Sloan Digital Sky Survey (SDSS) quasar composite spectra. In a previous work, we have shown that the equivalent width (EW) of the [O III] λ5007 Å (vacuum rest wavelength 5008.24 Å) line is a reliable indicator of the inclination of the accretion disc. Here, we have selected a sample of ˜12 000 quasars from the SDSS 7th Data Release and divided it in subsamples with different values of EW_{[{O {III}]}}. 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_{[{O {III}]}} as an orientation indicator. Moreover, we suggest that orientation effects could explain, at least partially, the origin of the anticorrelation between [O III] and Fe II intensities, i.e. the well-known eigenvector 1.

  4. 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.

  5. Infrared multiphoton dissociation of acrolein. Time-resolved observation of CO ( v = 1) IR emission at 4.7 μm

    NASA Astrophysics Data System (ADS)

    Chowdhury, P. K.; Rama Rao, K. V. S.; Mittal, J. P.

    1994-02-01

    In contrast to the photochemistry of electronically excited acrolein producing vinyl and formyl radicals via CC bond rupture, multiphoton vibrationally excited molecules undergo concerted dissociation generating CO and ethylene. Vibrational excitation in the CO product is detected immediately following the CO 2 laser pulse by observing IR emission at 4.7 μm. The decay of the IR emission was studied as a function of acrolein pressure. A vibrational-vibrational relaxation rate constant of CO ( v=1) by acrolein is found to be 1240 ± 200 Torr -1 s -1.

  6. 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.

  7. Search for the infrared emission features from deuterated interstellar polycyclic aromatic hydrocarbons

    SciTech Connect

    Onaka, Takashi; Mori, Tamami I.; Sakon, Itsuki; Ohsawa, Ryou; Kaneda, Hidehiro; Okada, Yoko; Tanaka, Masahiro

    2014-01-10

    We report the results of a search for emission features from interstellar deuterated polycyclic aromatic hydrocarbons (PAHs) in the 4 μm region with the Infrared Camera (IRC) on board AKARI. No significant excess emission is seen in 4.3-4.7 μm in the spectra toward the Orion Bar and M17 after the subtraction of line emission from the ionized gas. A small excess of emission remains at around 4.4 and 4.65 μm, but the ratio of their intensity to that of the band emission from PAHs at 3.3-3.5 μm is estimated as 2%-3%. This is an order of magnitude smaller than the values previously reported and also those predicted by the model of deuterium depletion onto PAHs. Since the subtraction of the ionized gas emission introduces an uncertainty, the deuterated PAH features are also searched for in the reflection nebula GN 18.14.0, which does not show emission lines from ionized gas. We obtain a similar result that excess emission in the 4 μm region, if present, is about 2% of the PAH band emission in the 3 μm region. The present study does not find evidence for the presence of the large amount of deuterated PAHs that the depletion model predicts. The results are discussed in the context of deuterium depletion in the interstellar medium.

  8. A heterotrimetallic Ir(III), Au(III) and Pt(II) complex incorporating cyclometallating bi- and tridentate ligands: simultaneous emission from different luminescent metal centres leads to broad-band light emission.

    PubMed

    Muñoz-Rodríguez, Rebeca; Buñuel, Elena; Fuentes, Noelia; Williams, J A Gareth; Cárdenas, Diego J

    2015-05-14

    Di- and tri-nuclear metal complexes incorporating gold(III), iridium(III) and platinum(II) units linked via a 1,3,5-triethynylbenzene core are reported, together with the corresponding mononuclear complexes as models. The gold(III) and platinum(II) units comprise tridentate, cyclometallating, C^N^C and N^N^C-coordinating ligands, respectively, with the Ar-C≡C- directly bound to the metal at the fourth coordination site. The iridium moiety is an Ir(ppy)2(acac) unit bound to the triethynylbenzene through a phenyl substituent at the 3-position of the acac ligand. The multinuclear compounds are prepared, using a modular synthetic strategy, from the monometallic complexes. All of the compounds are luminescent in solution at room temperature, and their photophysical properties were studied. The triplet excited state energies of the mononuclear complexes lie in the order Au > Ir > Pt. Consistent with this order, energy transfer from Au to Ir and from Au to Pt is observed, leading to quenching of the Au emission in the gold-containing multinuclear complexes. Energy transfer from Ir to Pt occurs at a rate that only partially quenches the Ir-based emission. As a result, the dinuclear Ir-Pt and trinuclear Au-Ir-Pt complexes display broad emission across most of the visible region of the spectrum.

  9. Ag nanoparticles enhanced near-IR emission from Er3+ ions doped glasses

    NASA Astrophysics Data System (ADS)

    Qi, Jiani; Xu, Tiefeng; Wu, Yi; Shen, Xiang; Dai, Shixun; Xu, Yinsheng

    2013-10-01

    Vitreous materials containing rare-earth (RE) ions and metallic nanoparticles (NPs) attract considerable interest because the presence of the NPs may lead to an intensification of luminescence. In this work, the characteristics of 1.54 μm luminescence for the Er3+ ions doped bismuthate glasses containing Ag NPs were studied under 980 nm excitation. The surface plasmon resonance (SPR) band of Ag NPs appears from 500 to 1500 nm. Transmission electron microscopic (TEM) image reveals that the Ag NPs are dispersed homogeneously with the size from 2 to 7 nm. The strength parameters Ωt(t = 2, 4, 6), spontaneous emission probability (A), radiative lifetime (τ) and stimulated emission section (σem) of Er3+ ions were calculated by the Judd-Ofelt theory. When the glass contains 0.2 wt% AgCl, the 1.54 μm fluorescence intensity of Er3+ reaches a maximum value, which is 7.2 times higher than that of glass without Ag NPs. The Ag NPs embedded glasses show significantly fluorescence enhancement of Er3+ ions by local field enhancement from SPR.

  10. Maps of Dust IR Emission for Use in Estimation of Reddening and CMBR Foregrounds

    NASA Astrophysics Data System (ADS)

    Schlegel, D. J.; Finkbeiner, D. P.; Davis, Marc

    1997-12-01

    We present a full sky 100micron map that is a reprocessed composite of the COBE/DIRBE and IRAS/ISSA maps, with the zodiacal foreground and confirmed point sources removed. We have constructed a map of the dust temperature, so that the 100micron map can be converted to a map proportional to dust column density. The dust temperature varies from 17 K to 21 K, which is modest but does modify the estimate of the dust column by a factor of 5. The result of these manipulations is a map with DIRBE-quality calibration and IRAS resolution. A wealth of filamentary detail is apparent on many different scales at all Galactic latitudes. In high latitude regions, the dust map correlates well with maps of HI emission, but deviations are significant. To generate the full sky dust maps, we must first remove zodiacal light contamination as well as a possible cosmic infrared background (CIB). For the 100micron map no signficant CIB is detected, but in the 140micron and 240micron maps, where the zodiacal contamination is weaker, we detect the CIB at surprisingly high flux levels of 30 +/- 8 {nW/m}(2/sr) at 140\\micron, and 16 \\pm 3.4 {nW/m}^2/sr at 240micron (95% confidence), which is an integrated flux ~ 2 times that extrapolated from optical galaxies in the Hubble Deep Field. The primary use of these maps is likely to be as a new estimator of Galactic extinction. To calibrate our maps, we assume a standard reddening law, and use the colors of elliptical galaxies. We demonstrate that the new maps are twice as accurate as the older Burstein-Heiles reddening estimates in regions of low and moderate reddening. The maps are expected to be significantly more accurate in regions of high reddening. These dust maps will also be useful for estimating millimeter emission that contaminates CMBR experiments and for estimating soft X-ray absorption.

  11. 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.

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

    PubMed

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

    2015-07-24

    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.

  13. Dynamics of Molecular Emission Features from Nanosecond, Femtosecond Laser and Filament Ablation Plasmas

    SciTech Connect

    Harilal, Sivanandan S.; Yeak, J.; Brumfield, Brian E.; Suter, Jonathan D.; Phillips, Mark C.

    2016-06-15

    The evolutionary paths of molecular species and nanoparticles in laser ablation plumes are not well understood due to the complexity of numerous physical processes that occur simultaneously in a transient laser-plasma system. It is well known that the emission features of ions, atoms, molecules and nanoparticles in a laser ablation plume strongly depend on the laser irradiation conditions. In this letter we report the temporal emission features of AlO molecules in plasmas generated using a nanosecond laser, a femtosecond laser and filaments generated from a femtosecond laser. Our results show that, at a fixed laser energy, the persistence of AlO is found to be highest and lowest in ns and filament laser plasmas respectively while molecular species are formed at early times for both ultrashort pulse (fs and filament) generated plasmas. Analysis of the AlO emission band features show that the vibrational temperature of AlO decays rapidly in filament assisted laser ablation plumes.

  14. 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.

  15. IRAS low-resolution spectral observations of the 10 and 18 micron silicate emission feature

    NASA Technical Reports Server (NTRS)

    Simpson, Janet P.

    1991-01-01

    The IRAS LRS Atlas contains 8-23 micron spectra of 1816 stars with silicate emission features. In order to study the shapes of the silicate dust features, the 117 stars whose emission features appear to be optically thin and which have the best signal-to-noise ratio at the longest wavelengths were analyzed. Simple spherical dust shell models were calculated in both the optically thin and the slightly optical thick approximations. From the comparison of the predicted spectra of the dust and stellar continuum, the emissivity function Kappa(lambda) was derived. In the different stars, the shape of the 10-micron feature is either narrow or broad and it is peaked either at about 9.7 microns or at 10 microns. Either particle size effects (particles above 0.75 microns in radius) or optical depth effects (central optical depth about 1) could broaden the 10-micron feature. Chemical composition differences no doubt are also important, particularly as regards the position of the peak of the 10-micron feature. The stars with the peak at 10 microns are more closely confined to the Galactic plane than the stars with the peak at 9.7 microns. The shape of the 18-micron feature is essentially the same in all stars, and can be used to extend the interstellar extinction curve past 13 to 22 microns.

  16. 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.

  17. 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.

  18. 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.

  19. 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.

  20. 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.

  1. 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.

  2. DYNAMICS OF ATOMIC AND MOLECULAR EMISSION FEATURES FROM NANOSECOND, FEMTOSECOND LASER AND FILAMENT PRODUCED PLASMAS

    SciTech Connect

    Harilal, Sivanandan S.; Yeak, J.; Brumfield, Brian E.; Phillips, Mark C.

    2016-08-08

    In this presentation, the persistence of atomic, and molecular emission features and its relation to fundamental properties (temperature and density) of ablation plumes generated using various irradiation methods (ns, fs, filaments) will be discussed in detail along with its implications for remote sensing applications.

  3. High-resolution spectra of the 3.29 micron interstellar emission feature - A summary

    NASA Technical Reports Server (NTRS)

    Tokunaga, A. T.; Sellgren, K.; Smith, R. G.; Nagata, T.; Sakata, A.; Nakada, Y.

    1991-01-01

    High spectral resolution observations of the 3.29-micron interstellar emission feature show two types of profiles. Type 1 has a central wavelength of 3.289-micron and is observed in extended objects such as planetary nebulae and H II regions. Type 2 has a central wavelength of 3.296 microns and is observed around a small number of stellar sources. Type 2 has a full width at half-maximum of 0.020 micron; Type 1 has a broader FWHM, perhaps as much as 0.042 micron, but this is uncertain because of contamination by Pf(delta) emission. These profiles are tabulated for comparison to laboratory data. It is found that no proposed identification for the 3.29-micron emission feature definitely matches the observational spectra, although amorphous aromatic materials and heated polycyclic aromatic hydrocarbons tend to fit the best.

  4. 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.

  5. A 21 micron emission feature in four proto-planetary nebulae

    NASA Technical Reports Server (NTRS)

    Kwok, Sun; Volk, Kevin M.; Hrivnak, Bruce J.

    1989-01-01

    The discovery of an unidentified emission feature at 21 microns in the LRS spectra of four IRAS sources is reported. These objects all show large FIR excesses due to a circumstellar dust envelope surrounding a carbon-rich central star and are likely to be in the evolutionary phase between the asymptotic giant branch and planetary nebula stages. The strength of the feature and the carbon richness of the objects suggest that this feature is due to the bending mode of a transient carbon-bearing molecule.

  6. SOFIA-EXES Mid-IR Observations of [Fe II] Emission from the Extended Atmosphere of Betelgeuse

    NASA Astrophysics Data System (ADS)

    Harper, G. M.; DeWitt, C.; Richter, M. J.; Greathouse, T. K.; Ryde, N.; Guinan, E. F.; O’Gorman, E.; Vacca, W. D.

    2017-02-01

    We present a NASA-DLR SOFIA-Echelon Cross Echelle Spectrograph (EXES) and NASA Infrared Telescope Facility-Texas Echelon Cross Echelle Spectrograph (TEXES) mid-IR R≃ {{50,000}} spectral study of forbidden Fe ii transitions in the early-type M supergiants, Betelgeuse (α Ori: M2 Iab) and Antares (α Sco: M1 Iab + B3 V). With EXES, we spectrally resolve the ground term [Fe ii] 25.99 μm (a{}6{D}J=7/2{--9/2}: {E}{up}=540 K) emission from Betelgeuse. We find a small centroid blueshift of 1.9 ± 0.4 {km} {{{s}}}-1 that is a significant fraction (20%) of the current epoch wind speed, with a FWHM of 14.3 ± 0.1 {km} {{{s}}}-1. The TEXES observations of [Fe ii] 17.94 μm (a{}4{F}J=7/2-9/2: {E}{up}={{3400}} K) show a broader FWHM of 19.1 ± 0.2 {km} {{{s}}}-1, consistent with previous observations, and a small redshift of 1.6 ± 0.6 {km} {{{s}}}-1 with respect to the adopted stellar center-of-mass velocity of {V}{CoM}=20.9+/- 0.3 {km} {{{s}}}-1. To produce [Fe ii] 25.99 μm blueshifts of 20% wind speed requires that the emission arises closer to the star than existing thermal models for α Ori’s circumstellar envelope predict. This implies a more rapid wind cooling to below 500 K within 10{R}* ({θ }* =44 mas, dist = 200 pc) of the star, where the wind has also reached a significant fraction of the maximum wind speed. The line width is consistent with the turbulence in the outflow being close to the hydrogen sound speed. EXES observations of [Fe ii] 22.90 μm (a{}4{D}J=5/2{--7/2}: {E}{up}={{11,700}} K) reveal no emission from either star. These findings confirm the dominance of cool plasma in the mixed region where hot chromospheric plasma emits copiously in the UV, and they also constrain the wind heating produced by the poorly understood mechanisms that drive stellar outflows from these low variability and weak-dust signature stars.

  7. Improving the classification accuracy for IR spectroscopic diagnosis of stomach and colon malignancy using non-linear spectral feature extraction methods.

    PubMed

    Lee, Sanguk; Kim, Kyoungok; Lee, Hyeseon; Jun, Chi-Hyuck; Chung, Hoeil; Park, Jong-Jae

    2013-07-21

    Non-linear feature extraction methods, neighborhood preserving embedding (NPE) and supervised NPE (SNPE), were employed to effectively represent the IR spectral features of stomach and colon biopsy tissues for classification, and improve the classification accuracy for diagnosis of malignancy. The motivation was to utilize the NPE and SNPE's capability of capturing non-linear spectral behaviors by simultaneously preserving local relationships in order that minute spectral differences among classes would be effectively recognized. NPE and SNPE derive an optimal embedding feature such that the local neighborhood structure can be preserved in reduced spaces (variables). The IR spectra collected from stomach and colon tissues were represented by several new variables through NPE and SNPE, and also by using the principal component analysis (PCA). Then, the feature-extracted variables were subsequently classified into normal, adenoma and cancer tissues by using both k-nearest neighbor (k-NN) and support vector machine (SVM), and the resulting accuracies were compared with each other. In both cases, the combination of SNPE-SVM provided the best classification performance, and the accuracy was substantially improved compared to when PCA-SVM was used. Overall results demonstrate that NPE and SNPE could be potential feature-representation strategies useful in biomedical diagnosis based on vibrational spectroscopy where effective recognition of minute spectral differences is critical.

  8. 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.

  9. Do the Infrared Emission Features Need UV Excitation? The PAH Model in UV-poor Reflection Nebulae

    NASA Astrophysics Data System (ADS)

    Li, A.; Draine, B. T.

    2001-12-01

    One of the major challenges of identifying the 3.3, 6.2, 7.7, 8.6, and 11.3μ m interstellar infrared emission bands with polycyclic aromatic hydrocarbon (PAH) molecules has been the recent detection of these bands in regions with little ultraviolet (UV) illumination since small, neutral PAH molecules have little or no absorption at visible wavelengths and thus are excited primarily by UV photons. The ``astronomical'' PAH model (Li & Draine 2001), incorporating the experimental result that the visual absorption edge shifts to longer wavelength upon ionization and/or as the PAH size increases (Allamandola, Hudgins, & Sandford 1999), is shown to be able to closely reproduce the observed infrared emission bands of vdB 133, a UV-poor reflection nebula (Uchida, Sellgren, & Werner 1998) as well as the 6.2, 7.7, and 11.3μ m band ratios of the UV-deficient ring in the Andromeda galaxy M31 (Pagani et al. 1999). It is also shown that ``astronomical'' PAHs can be heated sufficiently by a T eff=3000 K black-body to emit at 6.2, 7.7, 8.6, and 11.3μ m. Illustrative mid-IR emission spectra are calculated for reflection nebulae illuminated by cool stars with T eff=3600, 4500, 5000 K. These will allow comparison with future Space Infrared Telescope Facility (SIRTF) observations of vdB 135 (T eff=3600 K), vdB 47 (T eff=4500 K), and vdB 101 (T eff=5000 K) (Houck 2001). This research was supported in part by NASA grant NAG5-7030 and NSF grant AST-9619429. { References:} Allamandola, L.J., Hudgins, D.M., & Sandford, S.A. 1999, ApJ, 511, L115 Houck, J.R. 2001, SIRTF Observations of the Mid IR Features in Reflection Nebulae, {\\sf http://sirtf.caltech.edu/ROC/pid19} Li, A., & Draine, B.T. 2001, ApJ, 554, 778 Pagani, L., et al. 1999, A&A, 351, 447 Uchida, K.I., Sellgren, K., & Werner, M.W. 1998, ApJ, 493, L109

  10. 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.

  11. 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.

  12. The Physical Properties of a Cold HI Feature Observed Transitioning from Absorption to Emission

    NASA Astrophysics Data System (ADS)

    Kerton, C. R.

    2004-12-01

    Large scale surveys of neutral hydrogen HI 21-cm line emission from the Galactic plane at approximately 1' resolution have revealed an extensive population of HI self-absorption features, i.e., presumably cold HI seen in absorption against warmer background HI. Determining the spin temperature of such features primarily depends upon some sort of radiative transfer modeling that constrains various parameters. We present here observations from the high-latitude extension of the Canadian Galactic Plane Survey (CGPS) of a HISA feature that is seen to transition from absorption into emission thus allowing a straightforward determination of both its spin temperature and optical depth. Using a simple radiative transfer model we derive a spin temperature of Ts=45±4 K and an optical depth of τ = 0.7. We also show how observations made at the transition point can be used to tightly constrain the results from multicomponent radiative transfer models. One of the main scientific projects in Galactic astronomy with the Arecibo L-band Feed Array (GALFA) is the detection and characterization of cold HI structures seen both in self-absorption and in emission. Since GALFA observations will include both high and low Galactic latitude regions we expect that many additional cold HI features will be seen transitioning from absorption to emission as the background HI emission drops off at higher latitude and thus be amenable to the analysis techniques presented here. This research is funded by Iowa State University. Funding for the CGPS is provided by NSERC Canada and NRC Canada.

  13. Task-specific tailored multiple-reflection mirror systems for sensitivity enhancement of spectroscopic measurements: application for aircraft engine exhaust emission measurements with FT-IR spectro

    NASA Astrophysics Data System (ADS)

    Brockmann, Klaus; Kurtenbach, Ralf; Kriesche, Volker; Wiesen, Peter; Heland, Joerg; Schaefer, Klaus

    1999-09-01

    Multi-path reflection mirror systems in White- or Herriott- type configuration have been widely used to enhance the absorption path-length and thus the sensitivity of laboratory spectroscopic systems, e.g. for smog chamber studies and molecular spectroscopy. Field studies, for instance using mobile tunable diode laser spectroscopy have widened the range of applications of these mirror systems for specific measurement tasks. In this paper a special designed White-type system mounted in two racks with 5 m base-length and adjustable optical path-length up to 74 passes is described. This system has been tested and successfully used to enhance the sensitivity of non-intrusive FT-IR measurements of aircraft engine exhaust emissions in the harsh environment of an engine test bed. The open cell around the engine plume including the transfer optics for the adaption of the spectrometers in a separate room allowed manual switching between passive FT-IR emission measurements, FT-IR absorption measurements with the cell, and, by covering the infrared source (globar) with a shutter, multi-path FT-IR emission measurements. Tests prior to the aircraft engine measurements were made to investigate the influence of different path- lengths, the position of the plume in the White cell, soot in the exhaust gas, and vibrations of the mirrors. The FT-IR spectra from all three measurement modes using the White cell during the engine measurements were found to be of good quality and the results of the analyses were comparable to the results from intrusive measurement systems.

  14. 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.

  15. 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)

  16. Uncontrolled methane emissions from a MSW landfill surface: influence of landfill features and side slopes.

    PubMed

    Di Trapani, Daniele; Di Bella, Gaetano; Viviani, Gaspare

    2013-10-01

    Sanitary landfills for Municipal Solid Waste (MSW) disposal have been identified as one of the most important anthropogenic sources of methane (CH4) emissions; in order to minimize its negative effects on the environment, landfill gas (LFG) recovery is a suitable tool to control CH4 emissions from a landfill site; further, the measurement of CH4 emissions can represent a good way to evaluate the effectiveness of LFG recovering systems. In general, LFG will escape through any faults in the landfill capping or in the LFG collection system. Indeed, some areas of the capping can be more permeable than others (e.g. portions of a side slope), especially when considering a temporarily capped zone (covered area that is not expected to receive any further waste for a period of at least 3 months, but for engineering reasons does not have a permanent cap yet). These areas, which are characterized by abnormal emissions, are usually defined as "features": in particular, a feature is a small, discrete area or an installation where CH4 emissions significantly differ from the surrounding zones. In the present study, the influence that specific features have on CH4 emissions has been investigated, based on direct measurements carried out in different seasons by means of a flux chamber to the case study of Palermo (IT) landfill (Bellolampo). The results showed that the flux chamber method is reliable and easy to perform, and the contoured flux maps, obtained by processing the measured data were found to be a suitable tool for identifying areas with abnormal (high) emissions. Further, it was found that a relationship between methane emission rates and landfill side slope can be established. Concerning the influence of the temporary HDPE cover system on CH4 recovery efficiency, it contributed to a significant decrease of the free surface area available for uncontrolled emissions; this aspect, coupled to the increase of the CH4 volumes collected by the LFG recovery system, led to a

  17. 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.

  18. 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.

  19. Features of gadolinium and ytterbium extraction by tributyl phosphate from concentrated nitric acid solutions. II. IR spectra of lanthanide extracts

    SciTech Connect

    Nikitina, G.P.; Seredkina, N.V.; Kistopadov, A.A.

    1995-03-01

    Equilibrium organic phases in extraction systems consisting of tributyl phosphate (TBP) (neat or 1.8 M in CCl{sub 4}) and 8-12 M nitric acid containing Gd or Yb or lanthanide-free have been studied by IR spectroscopy. It was shown that under these conditions lanthanides are extracted as complex trisolvates Ln(NO{sub 3})9{sub 3}{center_dot}mHNO{sub 3}{center_dot}3TBP with m = 3-6. Nitric acid molecules are H-bonded to oxygen atoms of coordinated nitrate ions and do not substitute TBP molecules in coordination sphere of the metal ion.

  20. Polarization features of solar radio emission and possible existence of current sheets in active regions

    NASA Technical Reports Server (NTRS)

    Gopalswamy, N.; Zheleznyakov, V. V.; White, S. M.; Kundu, M. R.

    1994-01-01

    We show that it is possible to account for the polarization features of solar radio emission provided the linear mode coupling theory is properly applied and the presence of current sheets in the corona is taken into account. We present a schematic model, including a current sheet that can explain the polarization features of both the low frequency slowly varying component and the bipolar noise storm radiation; the two radiations face similar propagation conditions through a current sheet and hence display similar polarization behavior. We discuss the applications of the linear mode coupling theory to the following types of solar emission: the slowly varying component, the microwave radio bursts, metric type U bursts, and bipolar noise storms.

  1. Wavelet-based Characterization of Small-scale Solar Emission Features at Low Radio Frequencies

    NASA Astrophysics Data System (ADS)

    Suresh, A.; Sharma, R.; Oberoi, D.; Das, S. B.; Pankratius, V.; Timar, B.; Lonsdale, C. J.; Bowman, J. D.; Briggs, F.; Cappallo, R. J.; Corey, B. E.; Deshpande, A. A.; Emrich, D.; Goeke, R.; Greenhill, L. J.; Hazelton, B. J.; Johnston-Hollitt, M.; Kaplan, D. L.; Kasper, J. C.; Kratzenberg, E.; Lynch, M. J.; McWhirter, S. R.; Mitchell, D. A.; Morales, M. F.; Morgan, E.; Ord, S. M.; Prabu, T.; Rogers, A. E. E.; Roshi, A.; Udaya Shankar, N.; Srivani, K. S.; Subrahmanyan, R.; Tingay, S. J.; Waterson, M.; Wayth, R. B.; Webster, R. L.; Whitney, A. R.; Williams, A.; Williams, C. L.

    2017-07-01

    Low radio frequency solar observations using the Murchison Widefield Array have recently revealed the presence of numerous weak short-lived narrowband emission features, even during moderately quiet solar conditions. These nonthermal features occur at rates of many thousands per hour in the 30.72 MHz observing bandwidth, and hence necessarily require an automated approach for their detection and characterization. Here, we employ continuous wavelet transform using a mother Ricker wavelet for feature detection from the dynamic spectrum. We establish the efficacy of this approach and present the first statistically robust characterization of the properties of these features. In particular, we examine distributions of their peak flux densities, spectral spans, temporal spans, and peak frequencies. We can reliably detect features weaker than 1 SFU, making them, to the best of our knowledge, the weakest bursts reported in literature. The distribution of their peak flux densities follows a power law with an index of -2.23 in the 12-155 SFU range, implying that they can provide an energetically significant contribution to coronal and chromospheric heating. These features typically last for 1-2 s and possess bandwidths of about 4-5 MHz. Their occurrence rate remains fairly flat in the 140-210 MHz frequency range. At the time resolution of the data, they appear as stationary bursts, exhibiting no perceptible frequency drift. These features also appear to ride on a broadband background continuum, hinting at the likelihood of them being weak type-I bursts.

  2. On the Origin of the 3.3 μm Unidentified Infrared Emission Feature

    NASA Astrophysics Data System (ADS)

    Sadjadi, Seyedabdolreza; Zhang, Yong; Kwok, Sun

    2017-08-01

    The 3.3 μm unidentified infrared emission feature is commonly attributed to the C-H stretching band of aromatic molecules. Astronomical observations have shown that this feature is composed of two separate bands at 3.28 and 3.30 μm, and the origin of these two bands is unclear. In this paper, we perform vibrational analyses based on quantum mechanical calculations of 153 organic molecules, including both pure aromatic molecules and molecules with mixed aromatic/olefinic/aliphatic hydridizations. We find that many of the C-H stretching vibrational modes in polycyclic aromatic hydrocarbon (PAH) molecules are coupled. Even considering the uncoupled modes only, the correlation between the band intensity ratios and the structure of the PAH molecule is not observed, and the 3.28 and 3.30 μm features cannot be directly interpreted in the PAH model. Based on these results, the possible aromatic, olefinic, and aliphatic origins of the 3.3 μm feature are discussed. We suggest that the 3.28 μm feature is assigned to aromatic C-H stretch whereas the 3.30 μm feature is olefinic. From the ratio of these two features, the relative olefinic to aromatic content of the carrier can be determined.

  3. On- and off-axis spectral emission features from laser-produced gas breakdown plasmas

    NASA Astrophysics Data System (ADS)

    Harilal, S. S.; Skrodzki, P. J.; Miloshevsky, A.; Brumfield, B. E.; Phillips, M. C.; Miloshevsky, G.

    2017-06-01

    Laser-heated gas breakdown plasmas or sparks emit profoundly in the ultraviolet and visible region of the electromagnetic spectrum with contributions from ionic, atomic, and molecular species. Laser created kernels expand into a cold ambient with high velocities during their early lifetime followed by confinement of the plasma kernel and eventually collapse. However, the plasma kernels produced during laser breakdown of gases are also capable of exciting and ionizing the surrounding ambient medium. Two mechanisms can be responsible for excitation and ionization of the surrounding ambient: photoexcitation and ionization by intense ultraviolet emission from the sparks produced during the early times of their creation and/or heating by strong shocks generated by the kernel during its expansion into the ambient. In this study, an investigation is made on the spectral features of on- and off-axis emission of laser-induced plasma breakdown kernels generated in atmospheric pressure conditions with an aim to elucidate the mechanisms leading to ambient excitation and emission. Pulses from an Nd:YAG laser emitting at 1064 nm with a pulse duration of 6 ns are used to generate plasma kernels. Laser sparks were generated in air, argon, and helium gases to provide different physical properties of expansion dynamics and plasma chemistry considering the differences in laser absorption properties, mass density, and speciation. Point shadowgraphy and time-resolved imaging were used to evaluate the shock wave and spark self-emission morphology at early and late times, while space and time resolved spectroscopy is used for evaluating the emission features and for inferring plasma physical conditions at on- and off-axis positions. The structure and dynamics of the plasma kernel obtained using imaging techniques are also compared to numerical simulations using the computational fluid dynamics code. The emission from the kernel showed that spectral features from ions, atoms, and

  4. 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

  5. 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

  6. 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. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  7. 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.

  8. Understanding the water emission in the mid- and far-IR from protoplanetary disks around T Tauri stars

    NASA Astrophysics Data System (ADS)

    Antonellini, S.; Kamp, I.; Riviere-Marichalar, P.; Meijerink, R.; Woitke, P.; Thi, W.-F.; Spaans, M.; Aresu, G.; Lee, G.

    2015-10-01

    Aims: We investigate which properties of protoplanetary disks around T Tauri stars affect the physics and chemistry in the regions where mid- and far-IR water lines originate and their respective line fluxes. We search for diagnostics for future observations. Methods: With the code ProDiMo, we build a series of models exploring a large parameter space, computing rotational and ro-vibrational transitions of water in nonlocal thermodynamic equilibrium (non-LTE). We select a sample of transitions in the mid-IR regime and the fundamental ortho and para water transitions in the far-IR. We investigate the chemistry and the local physical conditions in the line emitting regions. We calculate Spitzer spectra for each model and compare far-IR and mid-IR lines. In addition, we use mid-IR colors to tie the water line predictions to the dust continuum. Results: Parameters affecting the water line fluxes in disks by more than a factor of three are : the disk gas mass, the dust-to-gas mass ratio, the dust maximum grain size, interstellar medium (ISM) UV radiation field, the mixing parameter of Dubrulle settling, the disk flaring parameter, and the dust size distribution. The first four parameters affect the mid-IR lines much more than the far-IR lines. Conclusions: A key driver behind water spectroscopy is the dust opacity, which sets the location of the water line emitting region. We identify three types of parameters, including those (1) affecting global disk opacity and opacity function (maximum dust size and dust size distribution); (2) affecting global disk opacity (dust-to-gas mass ratio, Dubrulle settling, disk gas mass); and (3) not affecting disk opacity (flaring parameter, ISM UV radiation field, fraction of PAHs). Parameters, such as dust-to-gas ratio, ISM radiation field, and dust size distribution, affect the mid-IR lines more, while the far-IR transitions are more affected by the flaring index. The gas mass greatly affects lines in both regimes. Higher spectral

  9. Possible detection of an emission feature near 584 A in the direction of G191-B2B

    SciTech Connect

    Green, J.; Bowyer, S.; Jelinsky, P. )

    1990-04-01

    A possible spectral emission feature is reported in the direction of the nearby hot white dwarf G191-B2B at 581.5 + or - 6 A with a significance of 3.8 sigma. This emission has been identified as He I 584.3 A. The emission cannot be due to local geocoronal emission or interplanetary backscatter of solar He I 584 A emission because the feature is not detected in a nearby sky exposure. Possible sources for this emission are examined, including the photosphere of G191-B2B, the comparison star G191-B2A, and a possible nebulosity near or around G191-B2B. The parameters required to explain the emission are derived for each case. All of these explanations require unexpected physical conditions; hence we believe this result must receive confirming verification despite the statistical likelihood of the detection. 15 refs.

  10. Possible detection of an emission feature near 584 A in the direction of G191-B2B

    NASA Technical Reports Server (NTRS)

    Green, James; Bowyer, Stuart; Jelinsky, Patrick

    1990-01-01

    A possible spectral emission feature is reported in the direction of the nearby hot white dwarf G191-B2B at 581.5 + or - 6 A with a significance of 3.8 sigma. This emission has been identified as He I 584.3 A. The emission cannot be due to local geocoronal emission or interplanetary backscatter of solar He I 584 A emission because the feature is not detected in a nearby sky exposure. Possible sources for this emission are examined, including the photosphere of G191-B2B, the comparison star G191-B2A, and a possible nebulosity near or around G191-B2B. The parameters required to explain the emission are derived for each case. All of these explanations require unexpected physical conditions; hence we believe this result must receive confirming verification despite the statistical likelihood of the detection.

  11. Narrowband Radio Emission As A Possible Feature of Before CMEs Onset Processes

    NASA Astrophysics Data System (ADS)

    Fridman, V.; Sheiner, O.; Grechin, S.

    The narrow band events in microwave radio emission were discovered during the ob- servations by RT-22 CrAO on August 12, 1989 before CMEs registration has been done. The observations were carried out using the sweeping spectrograph in 13-17 GHz range with frequency resolution of 100 MHz and sweeping time of less then 1 sec. It is well known that the period preceding the CMEs formation is characterized by sporadic radio emission of different types. We have found the existence of fast changes in temporal behavior of radio emission during the burst. They are character- ized by consistent origin of narrow-band (<1 GHz) components of emission with flux amplitude of about 1 sfu, moving from high to low frequencies in 1-3 seconds. We detected the shift of spectral maximum to short waves and appearance of narrow-band (<800 MHz) features during the CMEs formation. The results are being discussed within the framework of known models of radioemission of active region and bursts. Their application to possible conditions in formation of CMEs is also addressed in this research. This work is being supported by the Federal Science and Technology Programme "Astronomy" and the Russian Foundation for Fundamental Research.

  12. 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.

  13. A feature point identification method for positron emission particle tracking with multiple tracers

    NASA Astrophysics Data System (ADS)

    Wiggins, Cody; Santos, Roque; Ruggles, Arthur

    2017-01-01

    A novel detection algorithm for Positron Emission Particle Tracking (PEPT) with multiple tracers based on optical feature point identification (FPI) methods is presented. This new method, the FPI method, is compared to a previous multiple PEPT method via analyses of experimental and simulated data. The FPI method outperforms the older method in cases of large particle numbers and fine time resolution. Simulated data show the FPI method to be capable of identifying 100 particles at 0.5 mm average spatial error. Detection error is seen to vary with the inverse square root of the number of lines of response (LORs) used for detection and increases as particle separation decreases.

  14. Fractal Model of a Compact Intracloud Discharge. II. Specific Features of Electromagnetic Emission

    NASA Astrophysics Data System (ADS)

    Davydenko, S. S.; Iudin, D. I.

    2016-12-01

    We examine the features of the electromagnetic emission of a compact intracloud discharge (CID) within the framework of the fractal approach [1] described in the first part of the article. Compact intracloud discharge is considered as the result of electric interaction of two bipolar streamer-type structures previously developed in the regions of a strong electric field inside the thundercloud. To estimate the electromagnetic emission of the discharge, the complex tree-like structure of the electric currents at the preliminary and main stages of CID was represented as the sum of a relatively slowly varying large-scale linear mean component and fast small-scale constituents corresponding to the initial formation of elementary conductive channels of the discharge tree. Mean linear current of the discharge is considered as an effective source of the VLF/LF emission at both the preliminary and main stages of a CID. Electrostatic, induction, and radiation components of the electric field at different distances from the mean current are calculated taking into account specific features of both stages of the discharge within the framework of the transmission-line model. It is shown that at the preliminary stage only the electrostatic component can mainly be detected, whereas at the main stage all the above components of the electric field can be reliably measured. Dependence of the radiation electric field at the main stage on the length of the discharge channel and propagation velocity of the current front is analyzed. It is found that due to the bi-directional expansion of the current at the main stage of a CID the radiation field pulse remains narrow in a wide range of discharge parameters. The small-scale currents corresponding to the initial breakdown between the neighboring cells of the discharge domain are considered as the sources of HF/VHF radiation. It is shown that HF/VHF emission at the preliminary stage is negligible as compared to emission at the main stage

  15. Double features in mean pulsar profiles and the nature of their radio emission

    NASA Astrophysics Data System (ADS)

    Melikidze, George I.; Gil, Janusz

    In the talk presented at this Workshop by J.Dyks, the author claimed that the long-sought Rosetta Stone needed to decipher the nature of pulsar radio emission has been finally identified as the double features in averaged pulsar profiles. The author argued that highly symmetric bifurcated features are produced by a split-fan beams of extraordinary-mode curvature radiation emitted by thin microscopic streams of magnetospheric plasma conducted by a very narrow bundle of magnetic field lines. We examined arguments leading to these intriguing conclusions and found a number of flaws. At least one of them is fatal, namely there is not enough available energy within such thin microscopic plasma streams.

  16. Noninvasive express diagnostics of pulmonary diseases based on control of patient's gas emission using methods of IR and terahertz laser spectroscopy

    NASA Astrophysics Data System (ADS)

    Starikova, M. K.; Bulanova, A. A.; Bukreeva, E. B.; Karapuzikov, A. A.; Karapuzikov, A. I.; Kistenev, Y. V.; Klementyev, V. M.; Kolker, D. B.; Kuzmin, D. A.; Nikiforova, O. Y.; Ponomarev, Yu. N.; Sherstov, I. V.; Boyko, A. A.

    2013-11-01

    Pulmonary diseases diagnostics always occupies one of the key positions in medicine practices. A large variety of high technology methods are used today, but none of them cannot be used for early screening of pulmonary diseases. We discuss abilities of methods of IR and terahertz laser spectroscopy for noninvasive express diagnostics of pulmonary diseases on a base of analysis of absorption spectra of patient's gas emission, in particular, exhaled air. Experience in the field of approaches to experimental data analysis and hard-ware realization of gas analyzers for medical applications is also discussed.

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

    USDA-ARS?s Scientific Manuscript database

    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...

  18. 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.

  19. 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.

  20. 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.

  1. 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.

  2. 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.

  3. High sensitive and high resolution investigations of the Jovian S-burst emission modulation features

    NASA Astrophysics Data System (ADS)

    Litvinenko, G. V.; Konovalenko, A. A.; Rucker, H. O.; Lecacheux, A.; Vinogradov, V. V.

    2007-08-01

    In spite of the long history of studying, the Jovian S-burst radiation still represents an event which needs to be investigated in detail. Many questions concerning this complex phenomenon are opened. One of the interesting problems is the different modulation features appearing on the dynamic spectra in dependence on the time resolution achieved in the experiment and also on the visualization time scale. It seems that in every concrete case the physical mechanism of the modulation is different. In connection to this the following statistical sets need to be fully collected and analyzed for each modulation effects: 1) observed conditions: dependence or independence on Jupiter - Io - observer position, season time, day-night time, the Solar activity; 2) observed parameters: sign and value of the frequency drift, lane's curvature, modulation depth, distances between the nearest lanes and their variety, scale of the modulation; 3) polarization properties. During the last years the new high sensitive recording facilities, such as the digital spectro-polarimiter (DSP) and waveform receiver (WFR) were created and installed into the largest decameter band antenna array UTR-2 (Kharkov, Ukraine). It can be noted that in the present time this combination (antenna + equipments) gives the best sensitiveness, band of analysis, dynamic range, time and frequency resolutions. The using of mentioned above technique allowed detecting new time-frequency features of the Jovian S-bursts. Several bright new results concerning the modulations were obtained. With the creation of new giant low frequency antenna array (LOFAR) and low wavelength array (LWA) the new possibilities of high level study of the Jovian DAM emission will appear. For instance, the combination of LOFAR and already existing instruments (max base in order of 2000 km) will permit to determine the spatial parameters and localization of an emission source. Future results may prove useful for the general understanding of

  4. High-spectral resolution observations of the 3.29 micron emission feature: Comparison to QCC and PAHs

    NASA Technical Reports Server (NTRS)

    Tokunaga, Alan T.; Sellgren, Kris; Sakata, Akira; Wada, S.; Onaka, Takashi; Nakada, Y.; Nagata, T.

    1989-01-01

    Two of the most promising explanations for the origin of the interstellar emission features observed at 3.29, 3.4, 6.2, 7.7, 8.6, and 11.3 microns are: quenched carbonaceous composite (QCC) and polycyclic aromatic hydrocarbons (PAHs). High resolution spectra are given of the 3.29 micron emission feature which were taken with the Cooled Grating Array Spectrometer at the NASA Infrared Telescope Facility and previously published. These spectra show that the peak wavelength of the 3.29 micron feature is located at 3.295 + or - 0.005 micron and that it is coincident with the peak absorbance of QCC. The peak wavelength of the 3.29 micron feature appears to be the same in all of the sources observed thus far. However, the width of the feature in HD 44179 and Elias 1 is only 0.023 micron, which is smaller than the 0.043 micron width in NGC 7027, IRAS 21282+5050, the Orion nebula, and BD+30 deg 3639. Spectra of NGC 7027, QCC, and PAHs is shown. QCC matches the 3.29 micron interstellar emission feature very closely in the wavelength of the peak, and it produces a single feature. On the other hand, PAHs rarely match the peak of the interstellar emission feature, and characteristically produce multiple features.

  5. 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.

  6. Complementary online aerosol mass spectrometry and offline FT-IR spectroscopy measurements: Prospects and challenges for the analysis of anthropogenic aerosol particle emissions

    NASA Astrophysics Data System (ADS)

    Faber, Peter; Drewnick, Frank; Bierl, Reinhard; Borrmann, Stephan

    2017-10-01

    The aerosol mass spectrometer (AMS) is well established in investigating highly time-resolved dynamics of submicron aerosol chemical composition including organic aerosol (OA). However, interpretation of mass spectra on molecular level is limited due to strong fragmentation of organic substances and potential reactions inside the AMS ion chamber. Results from complementary filter-based FT-IR absorption measurements were used to explain features in high-resolution AMS mass spectra of different types of OA (e.g. cooking OA, cigarette smoking OA, wood burning OA). Using this approach some AMS fragment ions were validated in this study as appropriate and rather specific markers for a certain class of organic compounds for all particle types under investigation. These markers can therefore be used to get deeper insights in the chemical composition of OA based on AMS mass spectra in upcoming studies. However, the specificity of other fragment ions such as C2H4O2+ (m/z 60.02114) remains ambiguous. In such cases, complementary FT-IR measurements allow the interpretation of highly time-resolved AMS mass spectra at the level of molecular functional groups. Furthermore, this study discusses the challenges in reducing inorganic interferences (e.g. from water and ammonium salts) in FT-IR spectra of atmospheric aerosols to decrease spectral uncertainties for better comparisons and, thus, to get more robust results.

  7. Dust Attenuation of the Nebular Regions of z ~ 2 Star-forming Galaxies: Insight from UV, IR, and Emission Lines

    NASA Astrophysics Data System (ADS)

    De Barros, S.; Reddy, N.; Shivaei, I.

    2016-04-01

    We use a sample of 149 spectroscopically confirmed UV-selected galaxies at z ˜ 2 to investigate the relative dust attenuation of the stellar continuum and the nebular emission lines. For each galaxy in the sample, at least one rest-frame optical emission line (Hα/[N ii] λ6583 or [O iii] λ5007) measurement has been taken from the litterature, and 41 galaxies have additional Spitzer/MIPS 24 μm observations that are used to infer infrared luminosities. We use a spectral energy distribution (SED) fitting code that predicts nebular line strengths when fitting the stellar populations of galaxies in our sample, and we perform comparisons between the predictions of our models and the observed/derived physical quantities. We find that on average our code is able to reproduce all the physical quantities (e.g., UV β slopes, infrared luminosities, emission line fluxes), but we need to apply a higher dust correction to the nebular emission compared to the stellar emission for the largest star formation rate (SFR) (log SFR/M⊙ yr-1 > 1.82, Salpeter initial mass function). We find a correlation between SFR and the difference in nebular and stellar color excesses, which could resolve the discrepant results regarding nebular dust correction at z ˜ 2 from previous studies.

  8. Near-IR emission of Er3+ ions in CsCl-Ga-Ge-S glasses excited by visible light

    NASA Astrophysics Data System (ADS)

    Bunton, J.; Calvez, L.; Kadan, V.; Blonskyi, I.; Shpotyuk, O.; Golovchak, R.

    2017-10-01

    Fluorescence of 65GeS2-25Ga2S3-10CsCl glasses doped with Er has been investigated at room and liquid nitrogen temperatures. Strong emission lines at ∼1 and ∼1.5 μm are observed at room temperature in Er-doped samples when excited with ∼530 nm wavelength. At cryogenic temperature, this fluorescence is observed even at lower excitation wavelengths (∼400-450 nm). The other observed emission and absorption lines agree well with known energy level transitions of Er3+ ions incorporated in the glass matrix and temperature behavior of absorption spectra. The difference between room and liquid nitrogen temperature up-conversion emission is observed under femtosecond pulsed 800 nm laser excitation.

  9. 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.

  10. 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

  11. 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

  12. The carriers of the unidentified infrared emission features: Clues from polycyclic aromatic hydrocarbons with aliphatic sidegroups

    NASA Astrophysics Data System (ADS)

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

    2017-04-01

    The unidentified infrared emission (UIE) features at 3.3, 6.2, 7.7, 8.6, 11.3 and 12.7 μ m are ubiquitously seen in a wide variety of astrophysical regions in the Milky Way and nearby galaxies as well as distant galaxies at redshifts z ≳ 4. The UIE features are characteristic of the stretching and bending vibrations of aromatic hydrocarbon materials. The 3.3 μ m feature which results from the C-H stretching vibration in aromatic species is often accompanied by a weaker feature at 3.4 μ m. The 3.4 μ m feature is often thought to result from the C-H stretch of aliphatic groups attached to the aromatic systems. The ratio of the observed intensity of the 3.3 μ m aromatic C-H feature (I3.3) to that of the 3.4 μ m aliphatic C-H feature (I3.4) allows one to estimate the aliphatic fraction (e.g., NC, aliph/NC, arom, the number of C atoms in aliphatic units to that in aromatic rings) of the carriers of the UIE features, provided that the intrinsic oscillator strengths (per chemical bond) of the 3.3 μ m aromatic C-H stretch (A3.3) and the 3.4 μ m aliphatic C-H stretch (A3.4) are known. In this review we summarize the computational results on A3.3 and A3.4 and their implications for the aromaticity and aliphaticity of the UIE carriers. We use density functional theory and second-order perturbation theory to derive A3.3 and A3.4 from the infrared vibrational spectra of seven polycyclic aromatic hydrocarbon (PAH) molecules with various aliphatic substituents (e.g., methyl-, dimethyl-, ethyl-, propyl-, butyl-PAHs, and PAHs with unsaturated alkyl chains). The mean band strengths of the aromatic (A3.3) and aliphatic (A3.4) C-H stretches are derived and then employed to estimate the aliphatic fraction of the carriers of the UIE features by comparing the ratio of the intrinsic band strength of the two stretches (A3.4/A3.3) with the ratio of the observed intensities (I3.4/I3.3). We conclude that the UIE emitters are predominantly aromatic, as revealed by the observationally

  13. 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.

  14. 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.

  15. 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}.

  16. Fourier Transform Emission Spectroscopy of the A' 1Pi-X1Sigma+ and A1Pi-X1Sigma+ Systems of IrN.

    PubMed

    Ram; Bernath

    1999-02-01

    The emission spectrum of IrN has been investigated in the 10 000-20 000 cm-1 region at 0.02 cm-1 resolution using a Fourier transform spectrometer. The bands were excited in an Ir hollow cathode lamp operated with a mixture of 2 Torr of Ne and a trace of N2. Numerous bands have been classified into two transitions labeled as A1Pi-X1Sigma+ and A' 1Pi-X1Sigma+ by analogy with the isoelectronic PtC molecule. Ten bands involving vibrational levels up to Kv = 4 in the ground and excited states have been identified in the A1Pi-X1Sigma+ transition. This electronic transition has been previously observed by [A. J. Marr, M. E. Flores, and T. C. Steimle, J. Chem. Phys. 104, 8183-8196 (1996)]. To lower wavenumbers, five additional bands with R heads near 12 021, 12 816, 13 135, 14 136, and 15 125 cm-1 have been assigned as the 0-1, 3-3, 0-0, 1-0, and 2-0 bands, respectively, of the new A' 1Pi-X1Sigma+ transition. A rotational analysis of these bands has been carried out and equilibrium constants for the ground and excited states have been extracted. The Kv = 2 and 3 vibrational levels of the A' 1Pi state interact with the Kv = 0 and 1 levels of the A1Pi state and cause global perturbations in the bands. The ground state equilibrium constants for 193IrN are: omegae = 1126.176360(61) cm-1, omegaexe = 6.289697(32) cm-1, Be = 0.5001033(20) cm-1, alphae = 0.0032006(20) cm-1, and re = 1.6068276(32) Å. Copyright 1999 Academic Press.

  17. Rocketborne cryogenic (10 K) high-resolution interferometer spectrometer flight HIRIS: auroral and atmospheric IR emission spectra.

    PubMed

    Stair, A T; Pritchard, J; Coleman, I; Bohne, C; Williamson, W; Rogers, J; Rawlins, W T

    1983-04-01

    A Michelson interferometer spectrometer cooled to 10 degrees by liquid helium was flown into an IBC class III aurora on 1 April 1976 from Poker Flat, Alas. The sensor, HIRIS, covered the spectral range 455-2500 wave numbers (4-22 microm) with a spectral resolution of 1.8 cm(-1) and an NESR of 5 x 10-12 W/cm2 scrm(-1) at 1000 cm(-1). An atmospheric emission spectrum was obtained every 0.7 sec over an altitude range of 70-125 km. Atmospheric spectra were obtained of CO2 (nu3), NO (Deltanu = 1), O3 (nu3) and CO2 (nu2). Auroral produced excitations were observed for each band, this being the first known measurement of auroral enhancements of O3 (nu3), 9.6 microm, and CO2 (nu2), 15 microm, emissions.

  18. Visible red, NIR and Mid-IR emission studies of Ho3+ doped Zinc Alumino Bismuth Borate glasses

    NASA Astrophysics Data System (ADS)

    Mahamuda, Sk.; Swapna, K.; Packiyaraj, P.; Srinivasa Rao, A.; Vijaya Prakash, G.

    2013-12-01

    Zinc Alumino Bismuth Borate (ZnAlBiB) glasses doped with different concentrations of Holmium were prepared by conventional melt quenching technique. The glassy nature of these glasses has been confirmed through the XRD spectral measurements. The FTIR spectra recorded for undoped glass revealed the information related to the functional groups involved in the host glass. Optical absorption, excitation and photoluminescence spectra of these glasses have been recorded at room temperature. The Judd-Ofelt theory has been applied successfully to characterize the absorption spectra of the ZnAlBiB glasses. From this theory various radiative properties such as radiative transition probability (AR), radiative lifetimes (τR), branching ratios (βR) and spectroscopic quality factor (χ) for the prominent emission levels 5F5 → 5I7, 5F5 → 5I8 and 5I7 → 5I8 have been evaluated. The photoluminescence spectra revealed the quenching of luminescence intensity beyond 1.0 mol% of Ho3+ ion concentration in ZnAlBiB glasses. To investigate the lasing potentiality of 5F5 → 5I7, 5F5 → 5I8 and 5I7 → 5I8 transitions, the effective band width (Δλp) and the stimulated emission cross-section (σse) were determined. The CIE chromaticity co-ordinates were also evaluated from the emission spectra for all the glasses to understand the suitability of these materials for visible red laser emission in principle.

  19. 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

  20. Polycyclic Aromatic Hydrocarbon Emission in Spitzer/IRS Maps. II. A Direct Link between Band Profiles and the Radiation Field Strength

    NASA Astrophysics Data System (ADS)

    Stock, D. J.; Peeters, E.

    2017-03-01

    We decompose the observed 7.7 μm polycyclic aromatic hydrocarbon (PAH) emission complexes in a large sample of over 7000 mid-infrared spectra of the interstellar medium using spectral cubes observed with the Spitzer/IRS-SL instrument. In order to fit the 7.7 μm PAH emission complex we invoke four Gaussian components, which are found to be very stable in terms of their peak positions and widths across all of our spectra, and subsequently define a decomposition with fixed parameters, which gives an acceptable fit for all the spectra. We see a strong environmental dependence on the interrelationships between our band fluxes—in the H ii regions all four components are intercorrelated, while in the reflection nebulae (RNs) the inner and outer pairs of bands correlate in the same manner as previously seen for NGC 2023. We show that this effect arises because the maps of RNs are dominated by emission from strongly irradiated photodissociation regions, while the much larger maps of H ii regions are dominated by emission from regions much more distant from the exciting stars, leading to subtly different spectral behavior. Further investigation of this dichotomy reveals that the ratio of two of these components (centered at 7.6 and 7.8 μm) is linearly related to the UV-field intensity (log G 0). We find that this relationship does not hold for sources consisting of circumstellar material, which are known to have variable 7.7 μm spectral profiles.

  1. Run-away electron preionized diffuse discharge as a source of efficient laser emission in the IR, UV, VUV

    NASA Astrophysics Data System (ADS)

    Panchenko, A. N.; Panchenko, N. A.; Tarasenko, V. F.

    2017-05-01

    REP DD was suggested as an excitation source of various gas lasers. The efficient lasing was obtained in the IR, UV, and VUV spectral ranges. The ultimate intrinsic efficiency of non-chain chemical lasers on HF(DF) molecules was achieved. REP DD pumped N2 laser with an ultimate electrical efficiency of 0.2% was developed. Lasing on N2 molecules with 2 or 3 peaks in successive REP DD current oscillations was obtained for the first time. The laser action on F2* at 157 nm and rare gas fluorides (KrF*, XeF*) under REP DD pumping was obtained for the first time, as well. It has been shown that the volume stage of REP DD in mixtures with fluorine can last over 50 ns during several current half-cycles. Therewith, the efficiency and the pulse duration of lasers on rare gas fluorides and VUV F2* laser parameters under REP DD excitation are comparable with those obtained in suitable transverse discharges. The results allow the conclusion that the REP DD homogeneity in mixtures with F2 and SF6 is high enough for attaining high laser efficiency.

  2. 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.

  3. Optical Emission Spectroscopy in PECVD Helps Modulate Key Features in Biofunctional Coatings for Medical Implants

    NASA Astrophysics Data System (ADS)

    Santos, Miguel; Michael, Praveesuda; Filipe, Elysse; Wise, Steven; Bilek, Marcela; University of Sydney Collaboration

    2015-09-01

    We explore the use of optical emission spectroscopy (OES) diagnostic tools as a process feedback control strategy in plasma-assisted deposition of biofunctional coatings. Hydrogenated carbon nitride coatings are deposited on medical-grade metallic substrates using radio-frequency (rf) discharges sustained in C2H2/N2/Ar gaseous mixtures. The discharge is generated by capacitively coupling the rf power (supplied at f = 13.56 MHz) to the plasma and the substrates are electrically biased using a pulse generator to provide microsecond square profiled pulses at voltages in the range |Vbias| = 250 V - 1000 V. Nitrogen content and CN bonding configurations in the coatings follow similar trends to those of CN radicals and nitrogen molecular ions in the discharge. OES is used as a non-intrusive diagnostic technique to identify a suitable window of process parameters and ultimately achieve biofunctional interfaces compatible with current clinical demands. Importantly, we demonstrate that key features of the coatings can be modulated and made suitable for blood and/or tissue contacting medical implants, such as coronary stents and orthopaedic implants. The coatings are mechanically robust, inherently non-thrombogenic and can be readily modified, enabling an easy functionalization through the immobilization of biological molecules in a bioactive conformation.

  4. Significance of ambient conditions in uranium absorption and emission features of laser ablation plasmas

    DOE PAGES

    Skrodzki, P. J.; Shah, N. P.; Taylor, N.; ...

    2016-10-02

    This study employs laser ablation (LA) to investigate mechanisms for U optical signal variation under various environmental conditions during laser absorption spectroscopy (LAS) and optical emission spectroscopy (OES). Potential mechanisms explored for signal quenching related to ambient conditions include plasma chemistry (e.g., uranium oxide formation), ambient gas confinement effects, and other collisional interactions between plas-ma constituents and the ambient gas. LA-LAS studies show that the persistence of the U ground state population is significantly reduced in the presence of air ambient compared to nitrogen. LA-OES yields congested spectra from which the U I 356.18 nm transition is prominent and servesmore » as the basis for signal tracking. LA-OES signal and per-sistence vary negligibly between the test gases (air and N2), unlike the LA-LAS results. The plume hydrodynamic features and plume fundamental properties showed similar results in both air and nitrogen ambient. In conclusion, investigation of U oxide formation in the laser-produced plasma suggests that low U concentration in a sample hinders consistent detection of UO molecular spectra.« less

  5. Significance of ambient conditions in uranium absorption and emission features of laser ablation plasmas

    NASA Astrophysics Data System (ADS)

    Skrodzki, P. J.; Shah, N. P.; Taylor, N.; Hartig, K. C.; LaHaye, N. L.; Brumfield, B. E.; Jovanovic, I.; Phillips, M. C.; Harilal, S. S.

    2016-11-01

    This study employs laser ablation (LA) to investigate mechanisms for U optical signal variation under various environmental conditions during laser absorption spectroscopy (LAS) and optical emission spectroscopy (OES). Potential mechanisms explored for signal quenching related to ambient conditions include plasma chemistry (e.g., uranium oxide formation), ambient gas confinement effects, and other collisional interactions between plasma constituents and the ambient gas. LA-LAS studies show that the persistence of the U ground state population is significantly reduced in the presence of air ambient compared to nitrogen. LA-OES yields congested spectra from which the U I 356.18 nm transition is prominent and serves as the basis for signal tracking. LA-OES signal and persistence vary negligibly between the test gases (air and N2), unlike the LA-LAS results. The plume hydrodynamic features and plume fundamental properties showed similar results in both air and nitrogen ambient. Investigation of U oxide formation in the laser-produced plasma suggests that low U concentration in a sample hinders consistent detection of UO molecular spectra.

  6. Significance of ambient conditions in uranium absorption and emission features of laser ablation plasmas

    SciTech Connect

    Skrodzki, P. J.; Shah, N. P.; Taylor, N.; Hartig, K. C.; LaHaye, N. L.; Brumfield, B. E.; Jovanovic, I.; Phillips, M. C.; Harilal, S. S.

    2016-11-01

    This study employs laser ablation (LA) to investigate mechanisms for U optical signal variation under various environmental conditions during laser absorption spectroscopy (LAS) and optical emission spectroscopy (OES). Potential explored mechanisms for signal quenching related to ambient conditions include plasma chemistry (e.g., uranium oxide formation), ambient gas confinement effects, and other collisional interactions between plasma constituents and the ambient gas. LA-LAS studies show that the persistence of the U ground state population is significantly reduced in the presence of air ambient compared to nitrogen. LA-OES results yield congested spectra from which the U I 356.18 nm transition is prominent and serves as the basis for signal tracking. LA-OES signal and persistence vary negligibly between the test gases (air and N2), unlike the LA-LAS results. The plume hydrodynamic features and plume fundamental properties showed similar results in both air and nitrogen ambient. Investigation of U oxide formation in the laser-produced plasma suggests that low U concentration in a sample hinders consistent detection of UO molecular spectra.

  7. Significance of ambient conditions in uranium absorption and emission features of laser ablation plasmas

    SciTech Connect

    Skrodzki, P. J.; Shah, N. P.; Taylor, N.; Hartig, K. C.; LaHaye, N. L.; Brumfield, B. E.; Jovanovic, I.; Phillips, M. C.; Harilal, S. S.

    2016-10-02

    This study employs laser ablation (LA) to investigate mechanisms for U optical signal variation under various environmental conditions during laser absorption spectroscopy (LAS) and optical emission spectroscopy (OES). Potential mechanisms explored for signal quenching related to ambient conditions include plasma chemistry (e.g., uranium oxide formation), ambient gas confinement effects, and other collisional interactions between plas-ma constituents and the ambient gas. LA-LAS studies show that the persistence of the U ground state population is significantly reduced in the presence of air ambient compared to nitrogen. LA-OES yields congested spectra from which the U I 356.18 nm transition is prominent and serves as the basis for signal tracking. LA-OES signal and per-sistence vary negligibly between the test gases (air and N2), unlike the LA-LAS results. The plume hydrodynamic features and plume fundamental properties showed similar results in both air and nitrogen ambient. In conclusion, investigation of U oxide formation in the laser-produced plasma suggests that low U concentration in a sample hinders consistent detection of UO molecular spectra.

  8. N2 emission in steady-state N2O + CO and NO + CO reactions on Ir(110) by means of angle-resolved desorption

    NASA Astrophysics Data System (ADS)

    Matsushima, Tatsuo; Kokalj, Anton

    2017-08-01

    This paper confirms the intermediate N2O(a) pathway to N2 in the NO reduction on iridium surfaces. The spatial distributions of desorbing product N2 have been compared with each other in steady-state N2O + CO and NO + CO reactions on Ir(110) by means of angle-resolved desorption. In the former reaction, the N2 emission is fairly concentrated on the normally directed plane in the [001] direction and split into two-directional ways, being collimated at 46-58° off normal. In the latter reaction, the N2 desorption consists of a normally directed component and two-directional components. The former component shows remarkable anisotropy; i.e., the distribution is sharp on the normally directed plane in the [001] direction and broad on the plane perpendicular to it. This component originates from the association of adsorbed nitrogen atoms. The other components are collimated at around 54° off normal towards the [001] and [ 00 1 bar ] directions and they come from the decomposition of intermediate N2O(a). The off-normal components significantly share the total N2 emission below approximately 550 K. At higher temperatures, these become minor and mostly invisible above 650 K. The desorption of counter-product CO2 is normally directed and shows anisotropy in both reactions.

  9. 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

  10. Hn PAHs and the 2940 and 28050/cm (3.40 and 3.51 Microns) Infrared Emission Features

    NASA Technical Reports Server (NTRS)

    Bernstein, Max; Sandford, Scott; Allamandola, Louis; Witteborn, Fred (Technical Monitor)

    1996-01-01

    The 3150-2700/cm (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. It is demonstrated that 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 (3.25 and 3.7 microns) in the spectra of many planetary nebulae, reflection nebulae, and HII 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 (3.39-3.70 microns) region and briefly discuss their astrophysical implications.

  11. 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].

  12. 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].

  13. 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.

  14. Ab initio calculation of X-ray emission and IR spectra of the hydrofullerene C 60H 36

    NASA Astrophysics Data System (ADS)

    Bulusheva, L. G.; Okotrub, A. V.; Antich, A. V.; Lobach, A. S.

    2001-05-01

    Two isomers of the hydrofullerene C 60H 36 with T and D3 d symmetry were calculated using ab initio Hartree-Fock self-consistent field (HF-SCF). The T symmetry isomer in which the benzenoid rings occupy tetrahedral positions is predicted to be lower in energy than the other considered isomer. Simulated CK α spectra of the isomers were compared with the X-ray fluorescence spectrum of the hydrofullerene C 60H 36 prepared by the transfer hydrogenation method. The short-wave maximum intensity of the CK α spectrum of C 60H 36 was shown to be sensitive to the number of π electrons in the high-occupied levels of the molecule. Although the theoretical spectra are similar in appearance, the T isomer seems to be in better accordance with the experiment. Furthermore, the computed infrared frequencies and intensities for this isomer were found to correlate well with features in the measured spectrum of C 60H 36. The most intense peak in the low-frequency spectral region was shown to correspond to the skeletal vibrations of the benzenoid rings.

  15. Automated ablation of dental composite using an IR pulsed laser coupled to a plume emission spectral feedback system.

    PubMed

    Jang, Andrew T; Chan, Kenneth H; Fried, Daniel

    2017-09-01

    The purpose of this study is to assemble a laser system for the selective removal of dental composite from tooth surfaces, that is feasible for clinical use incorporating a spectral feedback system, a scanning system, articulating arm and a clinical hand-piece, and evaluate the performance of that system on extracted teeth. Ten extracted teeth were collected and small fillings were placed on the occlusal surface of each tooth. A clinical system featuring a CO2 laser operating at 50 Hz and spectral optical feedback was used to remove the composite. Removal was confirmed using a cross polarized optical coherence tomography (CP-OCT) system designed for clinical use. The system was capable of rapidly removing composite from small preparations on tooth occlusal surfaces with a mean loss of enamel of less than 20 μm. We have demonstrated that spectral feedback can be successfully employed in an automated system for composite removal by incorporating dual photodiodes and a galvanometer controlled CO2 laser. Additionally, the use of registered OCT images presents as a viable method for volumetric benchmarking. Overall, this study represents the first implementation of spectral feedback into a clinical hand-piece and serves as a benchmark for a future clinical study. Lasers Surg. Med. 49:658-665, 2017. © 2017 Wiley Periodicals, Inc. © 2017 Wiley Periodicals, Inc.

  16. The MOSDEF Survey: Metallicity Dependence of PAH Emission at High Redshift and Implications for 24 μm Inferred IR Luminosities and Star Formation Rates at z ∼ 2

    NASA Astrophysics Data System (ADS)

    Shivaei, Irene; Reddy, Naveen A.; Shapley, Alice E.; Siana, Brian; Kriek, Mariska; Mobasher, Bahram; Coil, Alison L.; Freeman, William R.; Sanders, Ryan L.; Price, Sedona H.; Azadi, Mojegan; Zick, Tom

    2017-03-01

    We present results on the variation of 7.7 μm polycyclic aromatic hydrocarbon (PAH) emission in galaxies spanning a wide range in metallicity at z ∼ 2. For this analysis, we use rest-frame optical spectra of 476 galaxies at 1.37 ≤ z ≤ 2.61 from the MOSFIRE Deep Evolution Field (MOSDEF) survey to infer metallicities and ionization states. Spitzer/MIPS 24 μm and Herschel/PACS 100 and 160 μm observations are used to derive rest-frame 7.7 μm luminosities ({L}7.7) and total IR luminosities ({L}{IR}), respectively. We find significant trends between the ratio of {L}7.7 to {L}{IR} (and to dust-corrected star formation rate [SFR]) and both metallicity and [O iii]/[O ii] ({{{O}}}32) emission line ratio. The latter is an empirical proxy for the ionization parameter. These trends indicate a paucity of PAH emission in low-metallicity environments with harder and more intense radiation fields. Additionally, {L}7.7/{L}{IR} is significantly lower in the youngest quartile of our sample (ages of ≲500 Myr) compared to older galaxies, which may be a result of the delayed production of PAHs by AGB stars. The relative strength of {L}7.7 to {L}{IR} is also lower by a factor of ∼2 for galaxies with masses {M}* < {10}10 {M}ȯ , compared to the more massive ones. We demonstrate that commonly used conversions of {L}7.7 (or 24 μm flux density, f 24) to {L}{IR} underestimate the IR luminosity by more than a factor of 2 at {M}* ∼ {10}9.6{--10.0} {M}ȯ . We adopt a mass-dependent conversion of {L}7.7 to {L}{IR} with {L}7.7/{L}{IR} = 0.09 and 0.22 for {M}* ≤slant {10}10 and > {10}10 {M}ȯ , respectively. Based on the new scaling, the SFR–M * relation has a shallower slope than previously derived. Our results also suggest a higher IR luminosity density at z ∼ 2 than previously measured, corresponding to a ∼30% increase in the SFR density.

  17. Observations of Ellerman bomb emission features in He i D3 and He i 10 830 Å

    NASA Astrophysics Data System (ADS)

    Libbrecht, Tine; Joshi, Jayant; Rodríguez, Jaime de la Cruz; Leenaarts, Jorrit; Ramos, Andrés Asensio

    2017-02-01

    Context. Ellerman bombs (EBs) are short-lived emission features, characterised by extended wing emission in hydrogen Balmer lines. Until now, no distinct signature of EBs has been found in the He i 10 830 Å line, and conclusive observations of EBs in He i D3 have never been reported. Aims: We aim to study the signature of EBs in neutral helium triplet lines. Methods: The observations consisted of ten consecutive SST/TRIPPEL raster scans close to the limb, featuring the Hβ, He i D3 and He i 10 830 Å spectral regions. We also obtained raster scans with IRIS and made use of the SDO/AIA 1700 Å channel. We used Hazel to invert the neutral helium triplet lines. Results: Three EBs in our data show distinct emission signatures in neutral helium triplet lines, most prominently visible in the He i D3 line. The helium lines have two components: a broad and blueshifted emission component associated with the EB, and a narrower absorption component formed in the overlying chromosphere. One of the EBs in our data shows evidence of strong velocity gradients in its emission component. The emission component of the other two EBs could be fitted using a constant slab. Our analysis hints towards thermal Doppler motions having a large contribution to the broadening for helium and IRIS lines. We conclude that the EBs must have high temperatures to exhibit emission signals in neutral helium triplet lines. An order of magnitude estimate places our observed EBs in the range of T 2 × 104-105 K. Movies associated to Figs. 3-5 are available at http://www.aanda.org

  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.

  19. IR emission and electrical conductivity of Nd/Nb-codoped TiOx (1.5 < x < 2) thin films grown by pulsed-laser deposition

    NASA Astrophysics Data System (ADS)

    Tchiffo-Tameko, C.; Cachoncinlle, C.; Perriere, J.; Nistor, M.; Petit, A.; Aubry, O.; Pérez Casero, R.; Millon, E.

    2016-12-01

    The effect of the co-doping with Nd and Nb on electrical and optical properties of TiOx films is reported. The role of oxygen vacancies on the physical properties is also evidenced. The films are grown by pulsed-laser deposition onto (001) sapphire and (100) silicon substrates. The substrate temperature was fixed at 700 °C. To obtain either stoichiometric (TiO2) or highly oxygen deficient (TiOx with x < 1.6) thin films, the oxygen partial pressure was adjusted at 10-1 and 10-6 mbar, respectively. 1%Nd-1%Nb, 1%Nd-5%Nb and 5%Nd-1%Nb co-doped TiO2 were used as bulk ceramic target. Composition, structural and morphological properties of films determined by Rutherford backscattering spectroscopy, X-ray diffraction and scanning electron microscopy, are correlated to their optical (UV-vis transmission and photoluminescence) and electrical properties (resistivity at room temperature). The most intense Nd3+ emission in the IR domain is obtained for stoichiometric films. Codoping Nd-TiOx films by Nb5+ ions is found to decrease the photoluminescence efficiency. The oxygen pressure during the growth allows to tune the optical and electrical properties: insulating and highly transparent (80% in the visible range) Nd/Nb codoped TiO2 films are obtained at high oxygen pressure, while conductive and absorbent films are grown under low oxygen pressure (10-6 mbar).

  20. IR Spectroscopy of PAHs in Dense Clouds

    NASA Astrophysics Data System (ADS)

    Allamandola, Louis; Bernstein, Max; Mattioda, Andrew; Sandford, Scott

    2007-05-01

    Interstellar PAHs are likely to be a component of the ice mantles that form on dust grains in dense molecular clouds. PAHs frozen in grain mantles will produce IR absorption bands, not IR emission features. A couple of very weak absorption features in ground based spectra of a few objects embedded in dense clouds may be due to PAHs. Additionally spaceborne observations in the 5 to 8 ?m region, the region in which PAH spectroscopy is rich, reveal unidentified new bands and significant variation from object to object. It has not been possible to properly evaluate the contribution of PAH bands to these IR observations because the laboratory absorption spectra of PAHs condensed in realistic interstellar mixed-molecular ice analogs is lacking. This experimental data is necessary to interpret observations because, in ice mantles, the interaction of PAHs with the surrounding molecules effects PAH IR band positions, widths, profiles, and intrinsic strengths. Furthermore, PAHs are readily ionized in pure H2O ice, further altering the PAH spectrum. This laboratory proposal aims to remedy the situation by studying the IR spectroscopy of PAHs frozen in laboratory ice analogs that realistically reflect the composition of the interstellar ices observed in dense clouds. The purpose is to provide laboratory spectra which can be used to interpret IR observations. We will measure the spectra of these mixed molecular ices containing PAHs before and after ionization and determine the intrinsic band strengths of neutral and ionized PAHs in these ice analogs. This will enable a quantitative assessment of the role that PAHs can play in determining the 5-8 ?m spectrum of dense clouds and will directly address the following two fundamental questions associated with dense cloud spectroscopy and chemistry: 1- Can PAHs be detected in dense clouds? 2- Are PAH ions components of interstellar ice?

  1. COS-B observations of gamma-ray emission from local galactic features

    NASA Technical Reports Server (NTRS)

    Bignami, G. F.; Barbareschi, L.; Caraveo, P. A.; Bloemen, J. B. G. M.; Hermsen, W.; Buccheri, R.; Kanbach, G.; Mayer-Hasselwander, H. A.; Lebrun, F.; Paul, J. A.

    1981-01-01

    Evidence for large scale correlations between the high-energy photon sky and the known local distribution of diffuse interstellar matter is discussed. Evidence is presented of correlations with the Gould's Belt and the Dolidze Belt. The correlations indicate that the emission of gamma rays at medium latitudes can be explained by the distribution of interstellar matter, and the interaction of CR with interstellar matter can explain the mechanism of the gamma-ray emission by regarding the emissivity as a global average of the two systems since they contain most of the local dense cloud.

  2. COS-B observations of gamma-ray emission from local galactic features

    NASA Technical Reports Server (NTRS)

    Bignami, G. F.; Barbareschi, L.; Caraveo, P. A.; Bloemen, J. B. G. M.; Hermsen, W.; Buccheri, R.; Kanbach, G.; Mayer-Hasselwander, H. A.; Lebrun, F.; Paul, J. A.

    1981-01-01

    Evidence for large scale correlations between the high-energy photon sky and the known local distribution of diffuse interstellar matter is discussed. Evidence is presented of correlations with the Gould's Belt and the Dolidze Belt. The correlations indicate that the emission of gamma rays at medium latitudes can be explained by the distribution of interstellar matter, and the interaction of CR with interstellar matter can explain the mechanism of the gamma-ray emission by regarding the emissivity as a global average of the two systems since they contain most of the local dense cloud.

  3. 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.

  4. Kβ X-Ray Emission and K X-Ray Absorption of Chlorine in K2ReCl6, K2OsCl6, K2IrCl6 and K2PtCl6

    NASA Astrophysics Data System (ADS)

    Sugiura, Chikara

    1990-06-01

    The chlorine Kβ bemission spectra of a series of compounds K2MCl6 (M=Re, Os, Ir and Pt) and the chlorine K absorption-edge spectrum of K2ReCl6 are measured and presented along with the chlorine K absorption-edge spectra of K2OsCl6, K2IrCl6 and K2PtCl6, reported previously. The emission spectra consist of a prominent peak with a low-energy shoulder. The absorption-edge spectrum of K2ReCl6 is composed of a sharp double peak and an intense broad structure.

  5. Synthesis of fluorescent dendrimers with aggregation-induced emission features through a one-pot multi-component reaction and their utilization for biological imaging.

    PubMed

    Luo, Weihua; Jiang, Ruming; Liu, Meiying; Wan, Qing; Tian, Jianwen; Wen, Yuanqing; Cao, Qian-Yong; Hui, Junfeng; Zhang, Xiaoyong; Wei, Yen

    2017-09-09

    Hyperbranched polymers have attracted wide research attention owing to their unique topological structure, physicochemical properties and great potential for applications such asadditives, drug delivery, catalysts and nanotechnology. Among these, the polyamidoamine(PAMAM) dendrimers are some of the most important dendrimers. However, the synthesis and biomedical applications of fluorescent PAMAM dendrimers have received only limited attention. In this work, we present a rather effective and convenient approach for synthesis of fluorescent PAMAM dendrimers with aggregation-induced emission (AIE) properties through a one-pot catalyst-free Mannich reaction under rather mild experimental conditions (e.g., low reaction temperature, air atmosphere in the presence of water). The obtained AIE-active amphiphiles (PhE-PAD) could self-assemble into fluorescent organic nanoparticles (FONs). The obtained AIE-active FONs (PhE-PAD FONs) were fully characterized, and their successful construction was confirmed by (1)H NMR spectroscopy, FT-IR spectroscopy and transmission electron microscopy. Fluorescence and UV-Visible absorption spectroscopy results demonstrated that the final PhE-PAD FONs showed strong yellow fluorescence, desirable photostability and good water dispersity. The cell viability evaluation and confocal laser scanning microscope imaging results suggested that PhE-PAD FONs possessed low cytotoxicity and excellent biocompatibility. Taken together, these results demonstrate that we have developed a facile and efficient strategy for the fabrication of AIE-active FONs, which possess many desirable features for biomedical applications. Copyright © 2017 Elsevier Inc. All rights reserved.

  6. Propagation features of chorus-like emissions and their satellite observations

    NASA Astrophysics Data System (ADS)

    Chum, J.; Jiricek, F.; Smilauer, J.; Shklyar, D.

    2003-04-01

    After a brief introduction to chorus-like emission, we present an overview of MAGION 5 satellite observations of these emissions in the inner magnetosphere of the Earth. From the extensive VLF data recorded onboard the MAGION 5 satellite, we show examples of different types of discrete elements, representing rising and falling tones, and discuss their spectral properties such as the bandwidth and the characteristic frequency as compared to the equatorial electron gyrofrequency. Next we focus on the analysis of a possibility of satellite observation of discrete elements assuming nonducted wave propagation from the source. As for the characteristic dimension of the generation region, we apply the figures obtained from the correlation analysis of chorus emission recorded by four satellites in CLUSTER experiment. We conclude that different frequencies in the chorus element should be emitted in a certain span of wave normal angles, so that the whole element could be observed far from the generation region.

  7. 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.

  8. Transient Fe Emission features in AGN: A new diagnostic of Accreting Systems

    NASA Astrophysics Data System (ADS)

    Turner, T. J.; Reeves, J. R.; George, I. M.; Kraemer, S. B.

    2004-08-01

    Chandra and XMM data have revealed narrow and highly redshifted Fe K emission lines in a handful of AGN. Rapid flux variability and energy shifts of the lines have lead to speculations for their origin ranging from hotspots on the accretion disk to emission from decelerating ejected blobs of gas traveling close to the escape velocity. Whichever scenario proves true, these lines are invaluable in tracing gas close to the black hole, and arguably less subject to the ambiguities which have plagued interpretation of broad `disk lines'. I review observations of such lines to date and discuss progress possible with current and future instrumentation.

  9. 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.

  10. 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

  11. 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.

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

    NASA Technical Reports Server (NTRS)

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

    2016-01-01

    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 micron 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) x 10(exp 29)/s] 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) x 10(exp 29)/s] and para-water [Q(H2O)PARA, (0.87+/-0.21) x 10(exp 29)/s] 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.

  13. Catalog of the H-alpha + N II forbidden-line emission features in the Kepler SNR

    SciTech Connect

    Dodorico, S.; Bandiera, R.; Danziger, J.; Focardi, P.

    1986-06-01

    A deep image of the Kepler SNR has been obtained in the light of H-alpha + N II forbidden-line with the faint object spectrograph and camera (EFOSC) and a CCD detector at the ESO 3.6 m telescope. The visibility of the optically emitting knots of ionized gas has been greatly enhanced by subtraction of the continuum radiation. Features as faint as 2 percent of the night-sky brightness have been identified and a half-shell of emission is clearly revealed. The total H-alpha luminosity of the ionized gas is estimated to be 8.3 x 10 to the 45th photons/s at a distance of 5 kpc implying a mass of ionized hydrogen of about 0.02 solar mass. An automatic searching program has been used to identify and list individual emission features in the continuum-subtracted image. A catalog with accurate celestial positions and approximate fluxes for 64 emission-line knots is given. 13 references.

  14. The 2-Year Checkup on 10 SNe IIn Discovered by Spitzer to Exhibit Late-Time (is greater than 100 Day) IR Emission

    NASA Technical Reports Server (NTRS)

    Fox, Ori Dosovitz; Chevalier, R. A.; Skrutskie, A. V.; Filippenko, A. V.; Silverman, J. M.; Ganeshalingam, M.

    2012-01-01

    Two years ago, a warm Spitzer survey of sixty-eight SNe IIn identified between the years 1998-2008 discovered 10 events with unreported late-time infrared (IR) excesses, in some cases more than 5 years post-explosion. These data nearly double the database of existing mid-IR observations of SNe IIn and offer important clues regarding the SN circumstellar.

  15. VUV and Optical Emission Characterization of Fluorocarbon SiO2 Etch Processes and Correlation to Etch Feature Quality

    NASA Astrophysics Data System (ADS)

    Hsueh, H.; Dandapani, E.; McGrath, R.; Messier, R.; Ji, B.; Karwacki, E.

    2000-10-01

    Fluorocarbon discharges used for SiO2 etch were characterized using optical (OES) and VUV emission spectroscopy. Actinometry was used to monitor atomic fluorine concentration (N_F) as power, pressure and gas mix were varied. Thermal oxide films were photolithographically patterned to define 0.5-2.0 μ m trench features, and then etched in an AMAT Mark II reactor. Etch rate, selectivity and feature critical dimension were measured using SEM and other techniques. DC self-bias was also recorded for each set of process conditions. Good etch features, etch rates of 1175 Åmin, and selectivity of 7.9 were obtained for reactor operation at 750 W, 80 mTorr, and with a gas mixture of CF_4/CHF_3/Ar at 85/10/5 sccm. Etch rate, selectivity and feature critical dimensions observed have been correlated to actinometric estimates of N_F, to self-bias voltage and to OES and VUV emissions. While varying process conditions around the reference values defined above, NF was found to increase monotonically between 0.75 and 1.2x10^13/cm^3 as pressure was increased from 70 to 100 mTorr, as power was increased from 650 to 850 W, and as CF4 gas fraction was increased from 5the reference gas mixture, etch rate was found to increase (1150 to 1550 Åmin) with increasing power, and to decrease (1550 to 550 Åmin) with increasing pressure. In these cases, etch rate trend tracked the self-bias voltage established. However, when CF4 gas fraction was increased from 5Åmin, while NF concentration increased by only 15self-bias varied by only 8feature profiles, and associated reaction processes will be presented.

  16. INTERSTELLAR CARBODIIMIDE (HNCNH): A NEW ASTRONOMICAL DETECTION FROM THE GBT PRIMOS SURVEY VIA MASER EMISSION FEATURES

    SciTech Connect

    McGuire, Brett A.; Loomis, Ryan A.; Charness, Cameron M.; Corby, Joanna F.; Blake, Geoffrey A.; Hollis, Jan M.; Lovas, Frank J.; Jewell, Philip R.; Remijan, Anthony J.

    2012-10-20

    In this work, we identify carbodiimide (HNCNH), which is an isomer of the well-known interstellar species cyanamide (NH{sub 2}CN), in weak maser emission, using data from the Green Bank Telescope PRIMOS survey toward Sgr B2(N). All spectral lines observed are in emission and have energy levels in excess of 170 K, indicating that the molecule likely resides in relatively hot gas that characterizes the denser regions of this star-forming region. The anticipated abundance of this molecule from ice mantle experiments is {approx}10% of the abundance of NH{sub 2}CN, which in Sgr B2(N) corresponds to {approx}2 Multiplication-Sign 10{sup 13} cm{sup -2}. Such an abundance results in transition intensities well below the detection limit of any current astronomical facility and, as such, HNCNH could only be detected by those transitions which are amplified by masing.

  17. Analysis of Spectral Features of Seawaterbiooptical Components Fluorescence from the Excitation-emission Matrix

    NASA Astrophysics Data System (ADS)

    Salyuk, P. A.; Nagorny, I. G.

    The paper presents the method for processing of excitation-emission matrix of sea water and the allocation of the spectral characteristics of different types of colored dissolved organic matter (CDOM) and phytoplankton cells in seawater. The method consists of identification of regularly observed fluorescence peaks of CDOM in marine waters of different type and definition of the spectral ranges, where the predominant influence of these peaks are observed.

  18. Mira Variable Stars from LAMOST DR4 Data: Emission Features, Temperature Types, and Candidate Selection

    NASA Astrophysics Data System (ADS)

    Yao, Yuhan; Liu, Chao; Deng, Licai; de Grijs, Richard; Matsunaga, Noriyuki

    2017-09-01

    Based on an extensive spectral study of a photometrically confirmed sample of Mira variables, we find a relationship between the relative Balmer emission-line strengths and spectral temperatures of O-rich Mira stars. The {F}{{H}δ }/{F}{{H}γ } flux ratio increases from less than unity to five as stars cool down from M0 to M10, which is likely driven by increasing TiO absorption above the deepest shock-emitting regions. We also discuss the relationship between the equivalent widths of the Balmer emission lines and the photometric luminosity phase of our Mira sample stars. Using our 291 Mira spectra as templates for reference, 191 Mira candidates are newly identified from the LAMOST DR4 catalog. We summarize the criteria adopted to select Mira candidates based on emission-line indices and molecular absorption bands. This enlarged spectral sample of Mira variables has the potential to contribute significantly to our knowledge of the optical properties of Mira stars and will facilitate further studies of these late-type, long-period variables.

  19. 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.

  20. 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

  1. PAHFIT: Properties of PAH Emission

    NASA Astrophysics Data System (ADS)

    Smith, J. D.; Draine, Bruce

    2012-10-01

    PAHFIT is an IDL tool for decomposing Spitzer IRS spectra of PAH emission sources, with a special emphasis on the careful recovery of ambiguous silicate absorption, and weak, blended dust emission features. PAHFIT is primarily designed for use with full 5-35 micron Spitzer low-resolution IRS spectra. PAHFIT is a flexible tool for fitting spectra, and you can add or disable features, compute combined flux bands, change fitting limits, etc., without changing the code. PAHFIT uses a simple, physically-motivated model, consisting of starlight, thermal dust continuum in a small number of fixed temperature bins, resolved dust features and feature blends, prominent emission lines (which themselves can be blended with dust features), as well as simple fully-mixed or screen dust extinction, dominated by the silicate absorption bands at 9.7 and 18 microns. Most model components are held fixed or are tightly constrained. PAHFIT uses Drude profiles to recover the full strength of dust emission features and blends, including the significant power in the wings of the broad emission profiles. This means the resulting feature strengths are larger (by factors of 2-4) than are recovered by methods which estimate the underlying continuum using line segments or spline curves fit through fiducial wavelength anchors.

  2. 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

  3. 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.

  4. Satellite emission features in two Seyfert galaxies: New evidence that radio-quiet AGN possess subrelativistic winds

    NASA Technical Reports Server (NTRS)

    Stocke, John T.; Shull, Michael; Granados, Arno F.; Sachs, Elise R.

    1994-01-01

    Hubble Space Telescope (HST) Faint Object Spectrograph (FOS) spectra are presented for three bright Seyfert galaxies including one (PG 1351+64) which possesses blue-displaced absorption features in C IV, Si IV, N V, and Ly-alpha (but not in Mg II) similar to those seen at high redshift in the broad-absorption-line (BAL) quasi-stellar objects (QSOs). Several features of the absorptions in PG 1351+64, including variability seen in archival International Ultraviolet Explorer (IUE) data, confirm their similarity to the BAL clouds rather than to the 'associated absorber' phenomenon which they superficially resemble. In PG 1351+64 'satellite' emission lines (called herein E1 and E2) have been detected nearly symmetrically placed at +/- 4000 km/s around the Mg II emission line; this velocity is just larger than the most blue-displaced of the BALs, suggesting that these two phenomena are related. The satellite line luminosity, L(E1) approximately = (3 x 10(exp 41) erg/s)/sq. h(sub 75), requires a cloud emission measure n(sub e)(exp 2)V(sub c) approximately = (1 x 10(exp 64)/cc)/sq. h(sub 75) at T approximately = 30,000 K. We believe the Mg II lines are produced by 50-90 km/s shocks driven into dense (approximately 10(exp 6)/cc, pre-shock) clouds by the ram pressure of a 0.1 solar mass/yr wind leaving the nucleus at velocity 4000 km/s. The detection of satellite lines in Mg II, the detection of the blue-shifted cloud in H-alpha and H-beta and the nondetection of this cloud in C IV restricts the cloud shocks to velocities v(sub c) less than or = 90 km/s and requires a cloud/wind density contrast greater than or = 10(exp 3). In this model, the emitting clouds are located at distances of R(sub eff) approximately = 10(exp 18-19) cm from the nucleus and are entrained and shock-accelerated to approximately 4000 km/s. The possible detection of similar 'satellite' emission features in the non-BAL Seyfert, Ton 951, suggests that the subrelativistic wind that accelerates BAL clouds

  5. 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 of CO2. Absolute emission cross sections for these multiplets were measured from threshold to 350 eV. The electrostatically focussed electron gun used in this series of experiments is described in detail. The atomic multiplets which were produced by dissociative excitation of CO2 and the cross sections at 100 eV are given. The dependence of the excitation functions on electron energy shows that these multiplets are produced by electric-dipole-allowed transitions in CO2.

  6. 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.

  7. Features of angular dependence of secondary electron emission from metal single crystals

    NASA Astrophysics Data System (ADS)

    Minnebaev, K. F.; Khaidarov, A. A.; Ivanenko, I. P.; Minnebaev, D. K.; Yurasova, V. E.

    2017-09-01

    The dependence of secondary electron emission coefficient σ on the angle α of primary electron incidence onto single crystals of metals with different crystalline lattice has been studied for undisturbed surface and for disturbed one by sputtering. We used the single crystals of Cu (fcc), Mo (bcc), Zn (hcp) and Ni4Mo (tetragonal lattice). It was shown that the coefficient σ is smaller for the disturbed surface, than for initial one due to absorption of secondary and scattered electrons by the lateral surfaces of hills and cones which are formed as a result of sputtering. For the initial surfaces (of Cu, Mo and Ni4Mo) the maxima of σ(α) in the low-index directions of the crystal lattice arise as a result of primary and secondary electron scattering on the atoms in open channels. At the same time, for the preliminary highly oxidized single crystal surface (of Zn) the minimum of σ in the direction of open channel was observed. The last can be explained by a reduction of work function of surface, and increase in penetration depth of electrons in open channel and by a rise of electron-phonon interaction. Angular dependences of secondary electron emission for a sputtered surface have a more complicated structure with the additional maxima and minima caused by interaction of secondary and scattered electrons with a cone-shaped relief.

  8. 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.

  9. Observable Emission Features of Black Hole GRMHD Jets on Event Horizon Scales

    NASA Astrophysics Data System (ADS)

    Pu, Hung-Yi; Wu, Kinwah; Younsi, Ziri; Asada, Keiichi; Mizuno, Yosuke; Nakamura, Masanori

    2017-08-01

    The general-relativistic magnetohydrodynamical (GRMHD) formulation for black hole-powered jets naturally gives rise to a stagnation surface, where inflows and outflows along magnetic field lines that thread the black hole event horizon originate. We derive a conservative formulation for the transport of energetic electrons, which are initially injected at the stagnation surface and subsequently transported along flow streamlines. With this formulation the energy spectra evolution of the electrons along the flow in the presence of radiative and adiabatic cooling is determined. For flows regulated by synchrotron radiative losses and adiabatic cooling, the effective radio emission region is found to be finite, and geometrically it is more extended along the jet central axis. Moreover, the emission from regions adjacent to the stagnation surface is expected to be the most luminous as this is where the freshly injected energetic electrons are concentrated. An observable stagnation surface is thus a strong prediction of the GRMHD jet model with the prescribed non-thermal electron injection. Future millimeter/submillimeter (mm/sub-mm) very-long-baseline interferometric observations of supermassive black hole candidates, such as the one at the center of M87, can verify this GRMHD jet model and its associated non-thermal electron injection mechanism.

  10. 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.

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

    PubMed Central

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

    2015-01-01

    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

  12. Features of CO2 fracturing deduced from acoustic emission and microscopy in laboratory experiments

    NASA Astrophysics Data System (ADS)

    Ishida, Tsuyoshi; Chen, Youqing; Bennour, Ziad; Yamashita, Hiroto; Inui, Shuhei; Nagaya, Yuya; Naoi, Makoto; Chen, Qu; Nakayama, Yoshiki; Nagano, Yu

    2016-11-01

    We conducted hydraulic fracturing (HF) experiments on 170 mm cubic granite specimens with a 20 mm diameter central hole to investigate how fluid viscosity affects HF process and crack properties. In experiments using supercritical carbon dioxide (SC-CO2), liquid carbon dioxide (L-CO2), water, and viscous oil with viscosity of 0.051-336.6 mPa · s, we compared the results for breakdown pressure, the distribution and fracturing mechanism of acoustic emission, and the microstructure of induced cracks revealed by using an acrylic resin containing a fluorescent compound. Fracturing with low-viscosity fluid induced three-dimensionally sinuous cracks with many secondary branches, which seem to be desirable pathways for enhanced geothermal system, shale gas recovery, and other processes.

  13. PRODAN dual emission feature to monitor BHDC interfacial properties changes with the external organic solvent composition.

    PubMed

    Agazzi, Federico M; Rodriguez, Javier; Falcone, R Dario; Silber, Juana J; Correa, N Mariano

    2013-03-19

    We have investigated the water/benzyl-n-hexadecyldimethylammonium chloride (BHDC)/n-heptane:benzene reverse micelles (RMs) interfaces properties using 6-propionyl-2-(N,N-dimethyl)aminonaphthalene, PRODAN, as molecular probe. We have used absorption and emission (steady-state and time-resolved) spectroscopy of PRODAN to monitor the changes in the RMs interface functionalities upon changing the external organic solvent blend. We demonstrate that PRODAN is a useful probe to investigate how the external solvent composition affects the micelle interface properties. Our results show that changes in the organic solvent composition in water/BHDC/n-heptane:benzene RMs have a dramatic effect on the photophysics of PRODAN. Thus, increasing the aliphatic solvent content over the aromatic one produces PRODAN partition and PRODAN intramolecular electron transfer (ICT) processes. Additionally, the water presence in these RMs makes the PRODAN ICT process favored with the consequent decreases in the LE emission intensity and a better definition of the charge transfer (CT) band. All this evidence suggests that the benzene molecules are expelled out of the interface, and the water-BHDC interactions are stronger with more presence of water molecules in the polar part of the interface. Thus, we demonstrate that a simple change in the composition of the external phase promotes remarkable changes in the RMs interface. Finally, the results obtained with PRODAN together with those reported in a previous work in our lab reveal that the external phase is important when trying to control the properties of RMs interface. It should be noted that the external phase itself, besides the surfactant and the polar solvent sequestrated, is a very important control variable that can play a key role if we consider smart application of these RMs systems.

  14. Optical characteristics of aerosol trioxide dialuminum at the IR wavelength range

    NASA Astrophysics Data System (ADS)

    Voitsekhovskaya, O. K.; Shefer, O. V.; Kashirskii, D. E.

    2015-11-01

    In this work, a numerical study of the transmission function, extinction coefficient, scattering coefficient, and absorption coefficient of the aerosol generated by the jet engine emissions was performed. Analyzing the calculation results of the IR optical characteristics of anthropogenic emissions containing the dialuminum trioxide was carried out. The spectral features of the optical characteristics of the medium caused by the average size, concentration and complex refractive index of the particles were illustrated.

  15. Tidal Distortion of the Envelope of an AGB Star IRS 3 near Sgr A*

    NASA Astrophysics Data System (ADS)

    Yusef-Zadeh, F.; Wardle, M.; Cotton, W.; Schödel, R.; Royster, M. J.; Roberts, D. A.; Kunneriath, D.

    2017-03-01

    We present radio and millimeter continuum observations of the Galactic center taken with the Very Large Array (VLA) and ALMA at 44 and 226 GHz, respectively. We detect radio and millimeter emission from IRS 3, lying ∼4.″5 NW of Sgr A*, with a spectrum that is consistent with the photospheric emission from an AGB star at the Galactic center. Millimeter images reveal that the envelope of IRS 3, the brightest and most extended 3.8 μm Galactic center stellar source, consists of two semicircular dust shells facing the direction of Sgr A*. The outer circumstellar shell, at a distance of 1.6 × 104 au, appears to break up into “fingers” of dust directed toward Sgr A*. These features coincide with molecular CS (5–4) emission and a near-IR extinction cloud distributed between IRS 3 and Sgr A*. The NE–SW asymmetric shapes of the IRS 3 shells seen at 3.8 μm and radio are interpreted as structures that are tidally distorted by Sgr A*. Using the kinematics of CS emission and the proper motion of IRS 3, the tidally distorted outflowing material from the envelope after 5000 yr constrains the distance of IRS 3 to ∼0.7 pc in front of or ∼0.5 pc behind Sgr A*. This suggests that the mass loss by stars near Sgr A* can supply a reservoir of molecular material near Sgr A*. We also present dark features in radio continuum images coincident with the envelope of IRS 3. These dusty stars provide examples in which high-resolution radio continuum images can identify dust-enshrouded stellar sources embedded in an ionized medium.

  16. Extraction of features from ultrasound acoustic emissions: a tool to assess the hydraulic vulnerability of Norway spruce trunkwood?

    PubMed Central

    Rosner, Sabine; Klein, Andrea; Wimmer, Rupert; Karlsson, Bo

    2011-01-01

    Summary • The aim of this study was to assess the hydraulic vulnerability of Norway spruce (Picea abies) trunkwood by extraction of selected features of acoustic emissions (AEs) detected during dehydration of standard size samples. • The hydraulic method was used as the reference method to assess the hydraulic vulnerability of trunkwood of different cambial ages. Vulnerability curves were constructed by plotting the percentage loss of conductivity vs an overpressure of compressed air. • Differences in hydraulic vulnerability were very pronounced between juvenile and mature wood samples; therefore, useful AE features, such as peak amplitude, duration and relative energy, could be filtered out. The AE rates of signals clustered by amplitude and duration ranges and the AE energies differed greatly between juvenile and mature wood at identical relative water losses. • Vulnerability curves could be constructed by relating the cumulated amount of relative AE energy to the relative loss of water and to xylem tension. AE testing in combination with feature extraction offers a readily automated and easy to use alternative to the hydraulic method. PMID:16771986

  17. 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.

  18. [Analysis on the impact of composting with different proportions of corn stalks and pig manure on humic acid fractions and IR spectral feature].

    PubMed

    Sun, Xiang-Ping; Li, Guo-Xue; Xiao, Ai-Ping; Shi, Hong; Wang, Yi-Ming; Li, Yang-Yang

    2014-09-01

    Using pig manure and corn straw as raw materials for high-temperature composting, setting three different treat- ments: C/N 15, C/N 25, and C/N 35. Composting period is 120 days, which contains 30 days for ventilation cycle by forced continuous ventilation. Sampled on 0, 22, 30, 60, 90, 120th days, they were analyzed by elemental analysis and IR spectroscopy to study effect of different lignin content on compost humic acid (HA) composition and molecular structure. The results showed that the change in composting humic acid C focused on the first 30 days, while after composting, the O/C of compost HA increased, H/C decreased, and N content increased. Low C/N (15) and higher C/N ratio (35) had higher degree of oxidation than the C/N 25 in compost HA. FTIR indicated that the infrared spectrum shapes with different lignin content treatment are similar during the composting process, but the peak intensity is obviously different. Research results proved that the composting stage is more conducive to enhanced aromatic in compost HA. After composting, C/N 15 had less polysaccharide and fat ingredients and more aromatic structural components in compost HA, compared with C/N 25 and 35. In addition, compost HA of C/N 15 had higher degree of humification and its structure was more stable.

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

    NASA Astrophysics Data System (ADS)

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

    2015-02-01

    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.

  20. 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

  1. 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

  2. [CH4 emission features of leading super-rice varieties and their relationships with the varieties growth characteristics in Yangtze Delta of China].

    PubMed

    Yan, Xiao-Jun; Wang, Li-Li; Jiang, Yu; Deng, Ai-Xing; Tian, Yun-Lu; Zhang, Wei-Jian

    2013-09-01

    A pot experiment was conducted to study the CH4 emission features of fourteen leading super-rice varieties (six Japonica rice varieties and eight Indica hybrid rice varieties) and their relationships with the varieties growth characteristics in Yangtze Delta. Two distinct peaks of CH4 emission were detected during the entire growth period of the varieties, one peak occurred at full-tillering stage, and the other appeared at booting stage. The average total CH4 emission of Japonica rice varieties was 37.6% higher than that of the Indica hybrid rice varieties (P<0.01), and the differences in the CH4 emission between rice types occurred at the post-anthesis phase. For all the varieties, there was a significant positive correlation between the total CH4 emission and the maximum leaf area, but the correlations between the CH4 emission and the other growth characteristics varied with variety type. The total CH4 emission of Japonica rice varieties had a significant positive correlation with plant height, while the correlations between the total CH4 emission of Indica hybrid rice varieties and their plant height were not significant. The total CH4 emission of Indica hybrid rice varieties had significant negative correlations with the total aboveground biomass, grain yield, and harvest index, but the correlations were not significant for Japonica rice varieties. The lower CH4 emission of Indica hybrid rice varieties was likely due to their significantly higher root biomass, as compared with Japonica rice varieties.

  3. Textural features of (18)F-fluorodeoxyglucose positron emission tomography scanning in diagnosing aortic prosthetic graft infection.

    PubMed

    Saleem, Ben R; Beukinga, Roelof J; Boellaard, Ronald; Glaudemans, Andor W J M; Reijnen, Michel M P J; Zeebregts, Clark J; Slart, Riemer H J A

    2017-05-01

    The clinical problem in suspected aortoiliac graft infection (AGI) is to obtain proof of infection. Although (18)F-fluorodeoxyglucose ((18)F-FDG) positron emission tomography scanning (PET) has been suggested to play a pivotal role, an evidence-based interpretation is lacking. The objective of this retrospective study was to examine the feasibility and utility of (18)F-FDG uptake heterogeneity characterized by textural features to diagnose AGI. Thirty patients with a history of aortic graft reconstruction who underwent (18)F-FDG PET/CT scanning were included. Sixteen patients were suspected to have an AGI (group I). AGI was considered proven only in the case of a positive bacterial culture. Positive cultures were found in 10 of the 16 patients (group Ia), and in the other six patients, cultures remained negative (group Ib). A control group was formed of 14 patients undergoing (18)F-FDG PET for other reasons (group II). PET images were assessed using conventional maximal standardized uptake value (SUVmax), tissue-to-background ratio (TBR), and visual grading scale (VGS). Additionally, 64 different (18)F-FDG PET based textural features were applied to characterize (18)F-FDG uptake heterogeneity. To select candidate predictors, univariable logistic regression analysis was performed (α = 0.16). The accuracy was satisfactory in case of an AUC > 0.8. The feature selection process yielded the textural features named variance (AUC = 0.88), high grey level zone emphasis (AUC = 0.87), small zone low grey level emphasis (AUC = 0.80), and small zone high grey level emphasis (AUC = 0.81) most optimal for distinguishing between groups I and II. SUVmax, TBR, and VGS were also able to distinguish between these groups with AUCs of 0.87, 0.78, and 0.90, respectively. The textural feature named short run high grey level emphasis was able to distinguish group Ia from Ib (AUC = 0.83), while for the same task the TBR and VGS were not found to be predictive

  4. Detection of the 3.4 micron emission feature in comets P/Brorsen-Metcalf and Okazaki-Levy-Rudenko (1989r) and an observational summary

    NASA Technical Reports Server (NTRS)

    Brooke, T. Y.; Tokunaga, A. T.; Knacke, R. F.

    1990-01-01

    A survey was performed of the 3 micron spectral region of comets, including the broad 3.4 micron emission feature due to C-N bonds in organic molecules. One goal is to determine how the strength of the emission band varies with heliocentric distance r in comets. This depends on both the production rate of the organic molecules and the emission mechanism, neither of which is well determined at present. The observations to date are consistent with cometary organics being present in all comets at comparable abundances relative to water. Loss of contrast in the 3.4 micron feature as comets get closer to the sun is then easily explained by dilution by thermal emission from the continuum grains, whose flux rises more steeply with heliocentric distance than that of organics.

  5. Near-ir spectroscopy of Jupiter at the time of comet Shoemaker-Levy 9 Impacts: Emissions of CH4, H3 + and H2

    NASA Astrophysics Data System (ADS)

    Encrenaz, Th.; Schulz, R.; Stüwe, J. A.; Wiedemann, G.; Drossart, P.; Crovisier, J.

    Near-infrared emissions of the SL9 impact sites of Jupiter have been recorded on July 16-18, 1994, at ESO (La Silla, Chile). A very strong emission of methane was recorded between 3.50 and 3.56 µm, shortly after impact H, showing evidence for a temporary increase of the Jovian stratospheric temperature. Emissions of H2 (2.12 µm) and H3+ (3.53 µm) were also detected above some of the impact sites, several hours after the impacts. The observed H3+ emissions, however, seem to be at least partly contaminated by the southern aurora. A strong continuum was also detected at 2.12 µm over most of the impact sites, presumably due to intense scattering of reflected sunlight by stratospheric haze.

  6. 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.

  7. 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.

  8. IRS Legacy Survey of the Green Valley in COSMOS

    NASA Astrophysics Data System (ADS)

    Scoville, Nicholas; Aussel, Herve; Capak, Peter; Frayer, David; Ilbert, Olivier; Kneib, Jean-Paul; Le Floc'h, Emeric; McCracken, Henry; Salvato, Mara; Sanders, David; Schinnerer, Eva; Sheth, Kartik; Surace, Jason; Yan, Lin

    2008-03-01

    We propose IRS low resolution spectroscopy is obtained for a complete flux-limited sample of 55 MIPS 24micron selected galaxies in the HST/ACS-COSMOS survey field at z = 0.65-0.85. All of the galaxies have S(24) > 0.7 mJy and confirmed IRAC counterparts. The IRS observations yield the PAH and silicate features, the mid-IR continuum SED and the Ne emission lines (for the brighter sources). These tracers provide diagnostics for the nature of the energy sources (starburst and/or AGN) in these dust obscured galaxies. This COSMOS IRS Legacy survey samples the full range of optical (e.g. U-V) color and absolute optical magnitude exhibited by luminous infrared-selected galaxies at our selected redshifts. Our sample of 24 micron sources allow us to better understand the role played by IR-selected galaxies in galaxy evolution, and provide a critical test of evolutionary models which suggest that sources in the Green Valley represent a transition stage as dusty spirals in the Blue Cloud merge and evolve into massive gas-poor elipticals on the Red Sequence.

  9. Mid-Infrared Spectral Properties of IR QSOs

    SciTech Connect

    Xia, X. Y.; Cao, C.; Mao, S.; Deng, Z. G.

    2008-10-10

    We analyse mid-infrared (MIR) spectroscopic properties for 19 ultra-luminous infrared quasars (IR QSOs) in the local universe based on the spectra from the Infrared Spectrograph on board the Spitzer Space Telescope. The MIR properties of IR QSOs are compared with those of optically-selected Palomar-Green QSOs (PG QSOs) and ultra-luminous infrared galaxies (ULIRGs). The average MIR spectral features from {approx}5 to 30 {mu}m, including the spectral slopes, 6.2 {mu}m PAH emission strengths and [NeII] 12.81 {mu}m luminosities of IR QSOs, differ from those of PG QSOs. In contrast, IR QSOs and ULIRGs have comparable PAH and [NeII] luminosities. These results are consistent with IR QSOs being at a transitional stage from ULIRGs to classical QSOs. We also find the correlation between the EW (PAH 6.2 {mu}m) and outflow velocities suggests that star formation activities are suppressed by feedback from AGNs and/or supernovae.

  10. 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

  11. 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.

    PubMed

    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. 1193-889cm(-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

  12. Heterogeneity of Monosymptomatic Resting Tremor in a Prospective Study: Clinical Features, Electrophysiological Test, and Dopamine Transporter Positron Emission Tomography

    PubMed Central

    Zheng, Hua-Guang; Zhang, Rong; Li, Xin; Li, Fang-Fei; Wang, Ya-Chen; Wang, Xue-Mei; Lu, Ling-Long; Feng, Tao

    2015-01-01

    Background: The relationship between monosymptomatic resting tremor (mRT) and Parkinson's disease (PD) remains controversial. In this study, we aimed to assess the function of presynaptic dopaminergic neurons in patients with mRT by dopamine transporter positron emission tomography (DAT-PET) and to evaluate the utility of clinical features or electrophysiological studies in differential diagnosis. Methods: Thirty-three consecutive patients with mRT were enrolled prospectively. The Unified Parkinson's Disease Rating Scale and electromyography were tested before DAT-PET. Striatal asymmetry index (SAI) was calculated, and a normal DAT-PET was defined as a SAI of <15%. Scans without evidence of dopaminergic deficits (SWEDDs) were diagnosed in patients with a subsequent normal DAT-PET and structural magnetic resonance imaging. Results: Twenty-eight mRT patients with a significant reduction in uptake of DAT binding in the striatum were diagnosed with PD, while the remained 5 with a normal DAT-PET scan were SWEDDs. As for UPRDS, the dressing and hygiene score, walking in motor experiences of daily living (Part II) and motor examination (Part III) were significant different between two groups (P < 0.05 and P < 0.01, respectively). Bilateral tremor was more frequent in the SWEDDs group (P < 0.05). The frequency of resting tremor and the amplitude of postural tremor tend to be higher in the SWEDDs group (P = 0.08 and P = 0.05, respectively). Conclusions: mRT is heterogeneous in presynaptic nigrostriatal dopaminergic degeneration, which can be determined by DAT-PET brain imaging. Clinical and electrophysiological features may provide clues to distinguish PD from SWEDDs. PMID:26112718

  13. Heterogeneity of Monosymptomatic Resting Tremor in a Prospective Study: Clinical Features, Electrophysiological Test, and Dopamine Transporter Positron Emission Tomography.

    PubMed

    Zheng, Hua-Guang; Zhang, Rong; Li, Xin; Li, Fang-Fei; Wang, Ya-Chen; Wang, Xue-Mei; Lu, Ling-Long; Feng, Tao

    2015-07-05

    The relationship between monosymptomatic resting tremor (mRT) and Parkinson's disease (PD) remains controversial. In this study, we aimed to assess the function of presynaptic dopaminergic neurons in patients with mRT by dopamine transporter positron emission tomography (DAT-PET) and to evaluate the utility of clinical features or electrophysiological studies in differential diagnosis. Thirty-three consecutive patients with mRT were enrolled prospectively. The Unified Parkinson's Disease Rating Scale and electromyography were tested before DAT-PET. Striatal asymmetry index (SAI) was calculated, and a normal DAT-PET was defined as a SAI of <15%. Scans without evidence of dopaminergic deficits (SWEDDs) were diagnosed in patients with a subsequent normal DAT-PET and structural magnetic resonance imaging. Twenty-eight mRT patients with a significant reduction in uptake of DAT binding in the striatum were diagnosed with PD, while the remained 5 with a normal DAT-PET scan were SWEDDs. As for UPRDS, the dressing and hygiene score, walking in motor experiences of daily living (Part II) and motor examination (Part III) were significant different between two groups (P < 0.05 and P < 0.01, respectively). Bilateral tremor was more frequent in the SWEDDs group (P < 0.05). The frequency of resting tremor and the amplitude of postural tremor tend to be higher in the SWEDDs group (P = 0.08 and P = 0.05, respectively). mRT is heterogeneous in presynaptic nigrostriatal dopaminergic degeneration, which can be determined by DAT-PET brain imaging. Clinical and electrophysiological features may provide clues to distinguish PD from SWEDDs.

  14. Computational insights into the photophysical and electroluminescence properties of homoleptic fac-Ir(C^N)3 complexes employing different phenyl-derivative-featuring phenylimidazole-based ligands for promising phosphors in OLEDs.

    PubMed

    Li, Jieqiong; Wang, Li; Sun, Kenan; Zhang, Jinglai

    2016-02-21

    The electronic structures and photophysical properties of three homoleptic iridium(iii) complexes IrL3 with C^N ligands, including 2a (L = 1-(2,6-diisopropylphenyl)-2-phenyl-1H-imidazole), 5a (L = 1-(2,6-dimethylphenyl)-2-phenyl-1H-imidazole), and 6a (L = 1-(3,5-diisopropylbiphenyl-4-yl)-2-phenyl-1H-imidazole), are investigated by means of the density functional method. Furthermore, seven new complexes are theoretically designed, including 1a (L = 1,2-diphenyl-1H-imidazole), 3a (L = 1-(2,6-dimethoxyphenyl)-2-phenyl-1H-imidazol), 4a (L = 2-(2-phenyl-1H-imidazol-1-yl)isophthalaldehyde), 1b (L = 2-(biphenyl-3-yl)-1H-imidazole), 2b (L = 2-(2',6'-diisopropylbiphenyl-3-yl)-1H-imidazole), 3b (L = 2-(2',6'-dimethoxybiphenyl-3-yl)-1H-imidazole), and 4b (L = 3'-(1H-imidazol-2-yl)biphenyl-2,6-dicarbaldehyde), to explore the influence of different substituents and different substituted positions on the electronic structures, phosphorescence properties, and organic light-emitting diode (OLED) performance. The HOMO-LUMO energy gap is greatly decreased by introduction of the -CHO group into the phenyl ring (4a and 4b see -sketched structures for all the investigated Ir(iii) complexes). As a result, their absorption and emission spectra present red-shifting leading them to be potential red-emitting phosphors. Other complexes are all blue-emitting materials, indicating that the effect of the substituted position on the emitting color is negligible. However, the addition of the substituent on the para-position of the phenyl ring in the phenylimidazole ligand would increase the quantum yield and electroluminescence (EL) performance compared with that on the imidazole ring.

  15. 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.

  16. GSH 006-15+7: a local Galactic supershell featuring transition from H I emission to absorption

    NASA Astrophysics Data System (ADS)

    Moss, V. A.; McClure-Griffiths, N. M.; Braun, R.; Hill, A. S.; Madsen, G. J.

    2012-04-01

    We report on the discovery of a new Galactic supershell, GSH 006-15+7, from the Galactic All-Sky Survey data. Observed and derived properties are presented, and we find that GSH 006-15+7 is one of the nearest physically large supershells known, with dimensions of ˜780 × 520 pc at a distance of ˜ 1.5 kpc. The shell wall appears in HI emission at b≲-6?5 and in HI self-absorption (HISA) at b≳-6?5. We use this feature along with HISA diagnostics to estimate an optical depth of τ˜ 3, a spin temperature of ˜40 K and a swept-up mass of M˜ 3 × 106 M⊙. We also investigate the origin of GSH 006-15+7, assessing the energy contribution of candidate powering sources and finding evidence in favour of a formation energy of ˜1052 erg. We find that this structure provides evidence for the transfer of mass and energy from the Galactic disc into the halo.

  17. DUST ATTENUATION OF THE NEBULAR REGIONS OF z ∼ 2 STAR-FORMING GALAXIES: INSIGHT FROM UV, IR, AND EMISSION LINES

    SciTech Connect

    De Barros, S.; Reddy, N.; Shivaei, I.

    2016-04-01

    We use a sample of 149 spectroscopically confirmed UV-selected galaxies at z ∼ 2 to investigate the relative dust attenuation of the stellar continuum and the nebular emission lines. For each galaxy in the sample, at least one rest-frame optical emission line (Hα/[N ii] λ6583 or [O iii] λ5007) measurement has been taken from the litterature, and 41 galaxies have additional Spitzer/MIPS 24 μm observations that are used to infer infrared luminosities. We use a spectral energy distribution (SED) fitting code that predicts nebular line strengths when fitting the stellar populations of galaxies in our sample, and we perform comparisons between the predictions of our models and the observed/derived physical quantities. We find that on average our code is able to reproduce all the physical quantities (e.g., UV β slopes, infrared luminosities, emission line fluxes), but we need to apply a higher dust correction to the nebular emission compared to the stellar emission for the largest star formation rate (SFR) (log SFR/M{sub ⊙} yr{sup −1} > 1.82, Salpeter initial mass function). We find a correlation between SFR and the difference in nebular and stellar color excesses, which could resolve the discrepant results regarding nebular dust correction at z ∼ 2 from previous studies.

  18. Multiplicity and disks within the high-mass core NGC 7538IRS1. Resolving cm line and continuum emission at 0.06″ × 0.05″ resolution

    NASA Astrophysics Data System (ADS)

    Beuther, H.; Linz, H.; Henning, Th.; Feng, S.; Teague, R.

    2017-09-01

    Context. High-mass stars have a high degree of multiplicity and most likely form via disk accretion processes. The detailed physics of the binary and disk formation are still poorly constrained. Aims: We seek to resolve the central substructures of the prototypical high-mass star-forming region NGC 7538IRS1 at the highest possible spatial resolution in line and continuum emission to investigate the protostellar environment and kinematics. Methods: Using the Karl G. Jansky Very Large Array (VLA) in its most extended configuration at 24 GHz has allowed us to study the NH3 and thermal CH3OH emission and absorption as well as the cm continuum emission at an unprecedented spatial resolution of 0.06″ × 0.05″, corresponding to a linear resolution of 150 AU at a distance of 2.7 kpc. Results: A comparison of these new cm continuum data with previous VLA observations from 23 yr ago reveals no recognizable proper motions. If the emission were caused by a protostellar jet, proper motion signatures should have been easily identified. In combination with the high spectral indices S ∝ να (α between 1 and 2), this allows us to conclude that the continuum emission is from two hypercompact Hii regions separated in projection by about 430 AU. The NH3 spectral line data reveal a common rotating envelope indicating a bound high-mass binary system. In addition to this, the thermal CH3OH data show two separate velocity gradients across the two hypercompact Hii regions. This indicates two disk-like structures within the same rotating circumbinary envelope. Disk and envelope structures are inclined by 33 °, which can be explained by initially varying angular momentum distributions within the natal, turbulent cloud. Conclusions: Studying high-mass star formation at sub-0.1″ resolution allows us to isolate multiple sources as well as to separate circumbinary from disk-like rotating structures. These data show also the limitations in molecular line studies in investigating the

  19. 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.

  20. A novel excited-state intramolecular proton transfer (ESIPT) dye with unique near-IR keto emission and its application in detection of hydrogen sulfide.

    PubMed

    Xu, Pengfei; Gao, Tang; Liu, Meihui; Zhang, Hailiang; Zeng, Wenbin

    2015-03-21

    A new ESIPT dye of benzothiazole with a conjugative electron acceptor was discovered and synthesized. Due to its unique NIR keto emission and a large Stokes shift, it was used to develop a fluorescent probe for sensitive and selective detection of hydrogen sulfide.

  1. Palagonitic Mars from Rock Rinds to Dust: Evidence from Visible, Near-IR, and Thermal Emission Spectra of Poorly Crystalline Materials

    NASA Technical Reports Server (NTRS)

    Morris, R. V.; Graff, T. G.; Mertzman, S. A.; Lane, M. D.; Christensen, P. R.

    2003-01-01

    Visible and near-IR (VNIR) spectral data for Martian bright regions are characterized by a general shape consisting of a ferric absorption edge extending from about 400 to 750 nm and relatively constant reflectivity extending from about 750 nm to beyond 2000 nm . Among terrestrial geologic materials, the best spectral analogues are certain palagonic tephras from Mauna Kea Volcano (Hawaii). By definition, palagonite is a yellow or orange isotropic mineraloid formed by hydration and devitrification of basaltic glass. The ferric pigment in palagonite is nanometer-sized ferric oxide particles (np-Ox) dispersed throughout the hydrated basaltic glass matrix. The hydration state of the np-Ox particles is not known, and the best Martian spectral analogues contain allophane-like materials and not crystalline phyllosilicates. We show here that laboratory VNIR and TES spectra of palagonitic alteration rinds developed on basaltic rocks are spectral endmembers that provide a consistent explanation for both VNIR and TES data of Martian dark regions.

  2. An Apparent Anomalous Diffuse gamma-ray emission feature, and its Possible Association with the the worm GW18.5+2.8

    NASA Astrophysics Data System (ADS)

    Dixon, D. D.; Hartmann, D. H.; Samimi, J.

    1999-04-01

    We present results of an analysis of EGRET data which indicate the presence of a possible anomalous diffuse emission feature. The analysis method nonparametrically estimates statistically significant residuals in a Poisson dataset relative to a given null hypothesis. Here, our null hypothesis consisted of a model for Galactic diffuse gamma-ray emission, the estimated isotropic gamma-ray background, a symmetric halo component, and the point sources from the Lamb and Macomb GeV EGRET source catalog. The resultant residual shows an apparently diffuse feature emanating northward from the Galactic plane in the region l ~ 15(o) - 21(o) . Examination of COMPTEL skymaps indicate a very bright but unidentified MeV source which coincides with the footpoint of the GeV feature. Further, the location and longitudinal extent of this feature is highly coincident with that of the ``worm'' GW 18.5+2.8 (Heiles, Reach, and Koo 1996, ApJ, 466, 191), a large radio feature which includes the Stockert Chimney. A powerful HII region, M16, lies at the base of GW 18.5+2.8. We discuss the possibility that cosmic-rays from massive stellar processes may be responsible for the gamma-ray emission.

  3. Detection of the 3.4 micron emission feature in Comets P/Brorsen-Metcalf and Okazaki-Levy-Rudenko (1989r) and an observational summary

    NASA Technical Reports Server (NTRS)

    Brooke, T. Y.; Tokunaga, A. T.; Knacke, R. F.

    1991-01-01

    The 3.4 micron emission feature due to cometary organics was detected in Comets P/Brorsen-Metcalf and Okazaki-Levy-Rudenko (1989r). Features-to-continuum ratios in these two comets were higher than those expected from the trend seen in other comets to date. Three micron spectra of eight comets are reviewed. The 3.4 micron band flux is better correlated with the water production rate than with the dust production rate in this sample of comets. High feature-to-continuum ratios in P/Brorsen-Metcalf and Okazaki-Levy-Rudenko can be explained by the low dust-to-gas ratios of these two comets. The observations to date are consistent with cometary organics being present in all comets (even those for which no 3.4 micron feature was evident) at comparable abundances with respect to water. The emission mechanism and absolute abundance of the organics are not well determined; either gas-phase fluorescence or thermal emission from hot grains is consistent with the heliocentric distance dependence of the 3.4 micron band flux. There is an overall similarity in the spectral profiles of the 3.4 micron feature in comets; however, there are some potentially significant differences in the details of the spectra.

  4. 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

  5. Hydrogenated Polycyclic Aromatic Hydrocarbons and the 2940 and 2850 Wavenumber (3.40 and 3.51 micron) Infrared Emission Features

    NASA Technical Reports Server (NTRS)

    Bernstein, Max P.; Sandford, Scott A.; Allamadola, Louis J.

    1996-01-01

    The 3150-2700/cm (3.17-3.70 micron) range of the spectra of a number of Ar-matrix-isolated PAHs containing excess H atoms (H(sub n)-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 (3.25 and 3.7 micron) 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 (3.39-3.70 micron) region and briefly discuss their astrophysical implications.

  6. [Specific features of interpretation of myocardial perfusion single-photon emission computed tomography with computed tomographic absorption correction].

    PubMed

    Ansheles, A A

    2014-01-01

    To study the capabilities of a hybrid single-photon emission computed tomography/computed tomography (SPECT/CT) system during myocardial perfusion imaging study, to evaluate the impact of absorption correction (AC), and to reveal factors influencing the contribution of AC to the diagnostic result of the study. The study included 167 patients who underwent myocardial perfusion SPECT with and without CT AC. Differences between AC and non-AC studies were visually analyzed; the results of the analysis were used to form groups of visual differences. The supposed factors influencing the contribution of AC were studied, by assigning visual differences to a particular group. The possible variants of the impact of AC were described in the baseline scintigrams. AC made a significant contribution in 68% of cases. With AC, the perfusion defects visible during non-AC study recovered in 80% of these cases. The factors predicting substantial differences between the AC and non-AC studies included weight, end diastolic volume, male sex, patients with small focal perfusion defects and transient ischemia, and inadequate injected activity. Factors, such as body mass index, large perfusion defects, CT subsystem and orbit settings, and time from the injection of a radiotracer to the initiation of a study, had no substantial impact on the contribution of AC. During AC studies, SRS and transient ischemic dilatation were significantly higher than during non-AC studies, requiring a shift of standard criteria. There were some methodical features of interpretation of myocardial perfusion SPECT using CT correction. Myocardial SPECT with AC enhances the diagnostic value of the technique, simplifies the interpretation of myocardial perfusion SPECT, and reduces the number of false-positive and questionable results.

  7. Epic changes in the IRS46 mid-infrared spectrum; an inner disk chemistry study

    NASA Astrophysics Data System (ADS)

    Lahuis, F.; Kamp, I.; Thi, W. F.; van Dishoeck, E. F.; Woitke, P.

    2011-05-01

    The Spitzer-IRS detection of highly abundant hot (Tex>400 K) molecular gas toward the low-mass star IRS 46 (Lahuis et al. 2006) was cause for great excitement. Strong absorption bands of gas-phase C_2H_2, HCN and CO_2 provided the first observational test of chemical models in the planet-forming zone of a circumstellar disk as well as a direct measure of the temperature and density in this zone. Subsequently, the same molecules have been observed in absorption toward the young star GV Tau (Gibb et al. 2007) and in emission (together with hot abundant H_2O and OH) toward a number of T Tauri stars (Carr & Najita 2008, Salyk et al. 2008, Pontoppidan et al. 2010). Follow-up Spitzer-IRS observations of IRS 46 at 5 epochs taken during 2008 and 2009 show dramatic changes of the mid-IR properties. The mid-IR continuum and the strength of hot water emission lines (detected in the newly reduced data) have increased (up to a factor of two) while the above mentioned absorption features have decreased (up to a factor of five) in strength (see figure below). At the same time GV Tau does not show any significant changes in flux or the strength of its molecular absorption bands. Starting with the parameters of the SED model as presented by Lahuis et al. (2006), we use the proptoplanetary disk model ProDiMo (Woitke et al. 2009, Kamp et al. 2010) to model the chemical composition of the inner few AU of the IRS 46 disk. In addition, the nature of the changes observed in the mid-IR spectra of IRS 46 are investigated using these models.

  8. 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.

  9. 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.

  10. Polarization features of the ELF emissions excited in the outer ionosphere through modification of the ionospheric F-region by high-power HF radio emission

    NASA Astrophysics Data System (ADS)

    Belov, Alexey

    indent=1cm The results of in-situ measurements performed by the onboard equipment of the DEMETER satellite show that the guided ELF emissions can be excited through modification of the ionospheric F-region by high-power HF radio emission from the SURA heating facility. The power spectra of the excited ELF waves have a sharp upper frequency cutoff at the local proton gyrofrequency. In this work, we study the propagation and polarization characteristics of the observed ELF emissions using multicomponent measurement of electric and magnetic fields from the DEMETER satellite. For analysis we make use of singular value decomposition (SVD) technique. It is shown that the polar angle of the observed emissions wave vector with respect to ambient magnetic field is less than pi/6. The waves propagate upward in the left-hand-polarized mode. The wave polarization changes from right- to left-handed at the so-called crossover frequency. The obtained results improve the understanding of the generation mechanisms of observed ELF emissions. This work was supported by the Russian Foundation for Basic Research (project No. 12-02-00747-a), and the Government of the Russian Federation (contract No. 11.G34.31.0048).

  11. Emission spectroscopy of IR laser-induced processes in ultra-dense deuterium D(0): Rotational transitions in D(0) with spin values s = 2, 3 and 4

    NASA Astrophysics Data System (ADS)

    Holmlid, Leif

    2017-02-01

    The emission spectrum induced in ultra-dense deuterium D(0) by a 1064 nm pulsed YAG laser with 0.4 J pulses is strongly dependent on the amount of D(0) formed. With D2 pressure below 10-2 mbar at the D(0) generator and no D(0) layer on the metal surface, line spectra can be observed with numerous lines due to metal and gas atoms. When a D(0) layer exists on the generator surface, these lines disappear. A different pattern of emission lines and bands is then found. Several peaks are observed which agree well with the rotational transitions of rotating D-D pairs in D(0) from theory. The peak widths are approximately 20 cm-1. A prominent peak at 760 nm corresponds to spin state s = 3 in D(0) from a rotational transition J = 1 → 0. This gives an experimental D-D distance in this state of 5.052 ± 0.003 pm that is only 0.25% larger than predicted by theory and calculations. The existence of these rotational lines strongly supports the cluster model of D(0) described previously. At a few hundred mbar pressure, a red-emitting apparently self-focused beam is formed by the laser beam. The expected Balmer lines are weak or absent.

  12. Structure and Dynamics of Cloud Boundaries as Seen in the Far-IR Emission Lines of [O I], [C II], and [N II

    NASA Astrophysics Data System (ADS)

    Langer, William

    We propose to observe and analyze the envelope in interstellar clouds where the transition takes place from the ionized boundary layer (IBL) to the Photon Dominated Region (PDR) surrounding the dense star forming molecular cores. These layers produce most of the far-infrared emission in the Galaxy and are regions where not only does the UV and EUV produced by stars get absorbed, but also where cloud growth takes place by a variety of agglomeration and collisional process. We will use SOFIA GREAT to observe the [O I] 63 micron line of neutral oxygen at high spectral resolution in nine lines of sight containing over 30 cloud components observed with Herschel HIFI in the [C II] line of ionized carbon, C+, and the [N II] line of ionized nitrogen, N+. We will combine the [O I] spectra with data in hand from Herschel HIFI observations of [C II] and [N II], and ground-based HI and CO isotopologues, and [C I] where available, and use them to separate out the contributions from different layers. The results can test static and dynamic models of the IBL and PDR transitions, inform models of cloud growth, and evaluate the contributions of various layers to Galactic FIR line emission.

  13. 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

  14. 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

  15. CBSD version 2 component models of the IR celestial background

    NASA Astrophysics Data System (ADS)

    Kennealy, John P.; Glaudell, Gene A.

    1990-12-01

    CBSD Version 2 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 inter-stellar 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.

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

    NASA Technical Reports Server (NTRS)

    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.; hide

    2016-01-01

    We present late time multi-wavelength observations of Swift J1644+57, suggested to be a relativistic tidal disruption flare (TDF). Our observations extend to greater than 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 (sup -70). Beyond this point weak X-rays continue to be detected at an approximately constant luminosity of L (sub X) approximately equal to 5 times 10 (sup 42) ergs per second and are marginally inconsistent with a continuing decay of t (sup minus 5 divided by 3), similar to that seen prior to the switch-off. Host photometry enables us to infer a black hole mass of M (mass) (sub BH (black hole) equal to 3 times 10 (sup 6) the mass of the sun, 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 to 50 days, with a peak magnitude (corrected for host galaxy extinction) of M (sub R) approximately equal to minus 22 to minus 23. The luminosity of the bump is significantly higher than seen in other, nonrelativisticTDFs 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.

  17. 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.

  18. LATE TIME MULTI-WAVELENGTH OBSERVATIONS OF SWIFT J1644+5734: A LUMINOUS OPTICAL/IR BUMP AND QUIESCENT X-RAY EMISSION

    SciTech Connect

    Levan, A. J.; Brown, G. C.; Lyman, J. D.; Stanway, E. R.; Tanvir, N. R.; Page, K. L.; O’Brien, P. T.; Wiersema, K.; Metzger, B. D.; Cenko, S. B.; 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{sup −70}. Beyond this point weak X-rays continue to be detected at an approximately constant luminosity of L{sub X} ∼ 5 × 10{sup 42} erg s{sup −1} and are marginally inconsistent with a continuing decay of t{sup −5/3}, similar to that seen prior to the switch-off. Host photometry enables us to infer a black hole mass of M{sub BH} = 3 × 10{sup 6} M{sub ⊙}, 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 M{sub R} ∼ −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.

  19. IR Spectroscopy of PANHs in Dense Clouds

    NASA Astrophysics Data System (ADS)

    Allamandola, Louis; Mattioda, Andrew; Sandford, Scott

    2008-03-01

    Interstellar PAHs are likely to be frozen into ice mantles on dust grains in dense clouds. These PAHs will produce IR absorption bands, not emission features. A couple of very weak absorption features in ground based spectra of a few objects in dense clouds may be due to PAHs. It is now thought that aromatic molecules in which N atoms are substituted for a few of the C atoms in a PAH's hexagonal skeletal network (PANHs) may well be as abundant and ubiquitous throughout the interstellar medium as PAHs. Spaceborne observations in the 5 to 8 um region, the region in which PAH spectroscopy is rich, reveal unidentified new bands and significant variation from object to object. It is not possible to analyze these observations because lab spectra of PANHs and PAHs condensed in realistic interstellar ice analogs are lacking. This lab data is necessary to interpret observations because, in ice mantles, the surrounding molecules affect PANH and PAH IR band positions, widths, profiles, and intrinsic strengths. Further, PAHs (and PANHs?) are readily ionized in pure H2O ice, further altering the spectrum. This proposal starts to address this situation by studying the IR spectra of PANHs frozen in laboratory ice analogs that reflect the composition of the interstellar ices observed in dense clouds. Thanks to Spitzer Cycle-4 support, we are now measuring the spectra of PAHs in interstellar ice analogs to provide laboratory spectra that can be used to interpret IR observations. Here we propose to extend this work to PANHs. We will measure the spectra of these interstellar ice analogs containing PANHs before and after ionization and determine the band strengths of neutral and ionized PANHs in these ices. This will enable a quantitative assessment of the role that PANHs can play in the 5-8 um spectrum of dense clouds and address the following two fundamental questions associated with dense cloud spectroscopy and chemistry: 1- Can PANHs be detected in dense clouds? 2- Are PANH ions

  20. 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.

  1. Integrated IR sensors

    NASA Astrophysics Data System (ADS)

    Tom, Michael; Trujillo, Edward

    1994-06-01

    Integrated infrared (IR) sensors which exploit modular avionics concepts can provide features such as operational flexibility, enhanced stealthiness, and ease of maintenance to meet the demands of tactical, airborne sensor systems. On-board, tactical airborne sensor systems perform target acquisition, tracking, identification, threat warning, missile launch detection, and ground mapping in support of situation awareness, self-defense, navigation, target attack, weapon support, and reconnaissance activities. The use of sensor suites for future tactical aircraft such as US Air Force's multirole fighter require a blend of sensor inputs and outputs that may vary over time. It is expected that special-role units of these tactical aircraft will be formed to conduct tasks and missions such as anti-shipping, reconnaissance, or suppression of enemy air defenses.

  2. Methane Emission and Net Ecosystem Exchange in Melt and Permafrost-Plateau Bog Features Within the Discontinuous Permafrost Zone of Northern Alberta, Canada

    NASA Astrophysics Data System (ADS)

    Whiting, G. J.

    2003-12-01

    Recent evidence indicates northern latitude permafrost is degrading in response to changing climate conditions (elevated temperatures and changing moisture input) which may significantly alter the processing of peatland carbon. As the permafrost melts, the bog surface subsides to the level of the surrounding water table creating a collapse scar with saturated surface conditions. Previously frozen peat is now available for decomposition and may become part of methanogenic processes elevating methane pools and emissions. Increased primary production in the collapse scar provides a sink for carbon dioxide and may counterbalance the greenhouse effect of a greater methane emission from these sites. However, increased primary production may stimulate methanogenesis and provide a positive feedback to even greater methane emissions. It is this balance of methane (CH4) and CO2 exchange that was examined within 7 melt features in northwestern Alberta during the growing season of 2002 (May to October). To measure CH4 and CO2 exchange, clear phytochambers (0.28 m3) were placed on sampling frames (0.43m2) inserted into the peat surface. Each site had 4 sampling frames (plots) in the melt feature and 4 plots in the permafrost plateau. Methane emission was measured by headspace grab samples analyzed on a FID-GC and net ecosystem CO2 exchange (NEE) was estimated utilizing a LiCor 6200 portable photosynthesis system. During peak methane emission in late August, melt scars ranged between 2 to 10 mg CH4 m-2h-1 as compared to the highly variable (near zero) permafrost plateau maximum exchange of 0.15 (emitted) to -0.15 (oxidized) mg CH4 m-2h-1. Along a transect within the melt at two sites, methane emission and NEE peaked 2 meters from the permafrost plateau edge as compared to plots adjacent to the edge or near the middle of the melt feature (20m from the permafrost plateau). During late August, NEE during full sunlight ranged from a low uptake of 80 mg CO2 m-2h-1 in permafrost

  3. High Spectral and Spatial Resolution Near-IR Spectroscopy of M1-92

    NASA Astrophysics Data System (ADS)

    Trammell, S. R.; Goodrich, R. W.

    1997-05-01

    We present high spectral and spatial resolution near-IR spectroscopy of the bipolar proto-planetary nebula M1-92. The spectra were obtained using the high resolution spectrograph, CSHELL, at the NASA Infrared Telescope Facility on Mauna Kea. The goal of this project was to spatially resolve the location of the H_2 emission present in this object and to determine its relative velocity as a function of nebular position. Previous optical spectropolarimetry of M1-92 revealed that the line emission seen in the bipolar lobes is indicative of shock heating with V_s = 40 - 100 km s(-1) (Trammell et al. 1993). Subsequent high resolution optical spectroscopy demonstrated that this shock emission is associated with a high velocity outflow (Solf 1994). Narrow-band HST images of this object show a highly collimated outflow originating near the central star and impacting the bipolar lobes (Trammell and Goodrich 1996). Using a 1arcsec slit placed along the bipolar axis, we mapped the velocity field of the Br gamma and H_2 2.122 micron emission lines in M1-92. In both cases, high velocity components (> 100 km s(-1) ) of emission are evident. The high velocity components of emission are co-spatial with the collimated outflow seen in the lobes of M1-92 in the HST images. Further, the outflow velocities derived for the near-IR emission lines are consistent with those estimated from the optical emission line ratios and found using optical spectroscopy. These results suggest that the near-IR H_2 emission is associated with the collimated outflow seen in the lobes of M1-92. We discuss several mechanisms that could be responsible for producing the kinematic features observed in M1-92, in particular the action of a precessing, episodic jet.

  4. 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.

  5. 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.

  6. 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.

  7. New lanthanide complexes for sensitized visible and near-IR light emission: synthesis, 1H NMR, and X-ray structural investigation and photophysical properties.

    PubMed

    Quici, Silvio; Marzanni, Giovanni; Forni, Alessandra; Accorsi, Gianluca; Barigelletti, Francesco

    2004-02-23

    We describe the syntheses, the 1H NMR studies in CD3OD and D2O as solvent, the X-ray characterization, and the luminescence properties in D2O solution of the two complexes Eu.1 and Er.1, where 1 is a dipartite ligand that includes (i) a 1,4,7,10-tetraazacyclododecane-1,4,7-triacetic acid (DO3A) unit serving as hosting site for the metal center; and (ii) a phenanthroline unit which plays the role of light antenna for the sensitization process of the metal centered luminescence. In a previous report (Inorg. Chem. 2002, 41, 2777), we have shown that for Eu.1 there are no water molecules within the first coordination sphere. X-ray and 1H NMR results reported here are consistent with full saturation of the nine coordination sites within the Eu.1 and Er.1 complexes. In addition, these studies provide important details regarding the conformations, square antiprism (SAP) and twisted square antiprism (TSAP), adopted in solution by these complexes. The luminescence results are consistent with both an effective intersystem crossing (ISC) at the light absorbing phenanthroline unit (lambda(exc) = 278 nm) and an effective energy transfer (en) process from the phenanthroline donor to the cation acceptor (with unit or close to unit efficiency for both steps). In D2O solvent, the overall sensitization efficiency, phi(se), is 0.3 and 5 x 10(-6), for Eu.1 (main luminescence peaks at 585, 612, 699 nm) and Er.1 (luminescence peak at 1530 nm), respectively. The photophysical properties of both complexes are discussed with reference to their structural features as elucidated by the obtained 1H NMR and X-ray results.

  8. Analysis of the AlCl Absorption Feature and the Searchlight Emission Effect Observed in Solid-Propellant Rocket Plumes

    DTIC Science & Technology

    1992-09-01

    phase function was approximated by the Henyey - Greenstein function ...searchlight emission are supported by Monte Carlo radiative transfer calculations using the measured plume extinction profile. It is concluded that...Press, New York, 1980. 25. Kamiuto, K. "Study of the Henyey - Greenstein Approximation to Scattering Phase Functions ." Journal of

  9. The spacing of the interstellar 6.2 and 7.7 micron emission features as an indicator of polycyclic aromatic hydrocarbon size

    NASA Technical Reports Server (NTRS)

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

    1999-01-01

    A database of astrophysically relevant, infrared spectral measurements on a wide variety of neutral as well as positively and negatively charged polycyclic aromatic hydrocarbons (PAHs), ranging in size from C10H8 through C48H20, is now available to extend the interstellar PAH model. Beyond simply indicating general characteristics of the carriers, this collection of data now makes it possible to conduct a more thorough interpretation of the details of the interstellar spectra and thereby derive deeper insights into the nature of the emitting material and conditions in the emission zones. This Letter is the first such implementation of this spectral database. The infrared spectra of PAH cations, the main PAH form in the most energetic emission zones, are usually dominated by a few strong features in the 1650-1100 cm-1 (6.1-9.1 microns) region that tend to cluster the vicinity of the interstellar emission bands at 1610 and 1320 cm-1 (6.2 and 7.6 microns), but with spacings typically somewhat less than that observed in the canonical interstellar spectrum. However, the spectra in the database show that this spacing increases steadily with molecular size. Extrapolation of this trend indicates that PAHs in the 50-80 carbon atom size range are entirely consistent with the observed interstellar spacing. Furthermore, the profile of the 1610 cm-1 (6.2 microns) interstellar band indicates that PAHs containing as few as 20 carbon atoms contribute to this feature.

  10. 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.

  11. The Spacing of the Interstellar 6.2 Microns and 7.7 Microns Emission Features as an Indicator of PAH Size

    NASA Technical Reports Server (NTRS)

    Hudgins, Douglas M.; Allamandola, L. J.; Mead, Susan (Technical Monitor)

    1998-01-01

    A database of astrophysically relevant, infrared spectral measurements on a wide variety of neutral as well as positively and negatively charged polycyclic aromatic hydrocarbons ranging in size from C10H8 through C48H20 is now available to extend the interstellar PAH model. Beyond simply indicating general characteristics of the carriers, this collection of data now makes it possible to conduct a more thorough interpretation of the details of the interstellar spectra and thereby derive deeper insights into the nature of the emitting material and conditions in the emission zones. This paper is the first such implementation of this spectral database. The infrared spectra of PAH cations, the main PAH form in the most energetic emission zones, are usually dominated by a few strong features in the 1650 - 1100 per centimeter (6.1 - 9.1 microns) region which tend to cluster in the vicinity of the interstellar emission bands at 1610 per centimeter and 1320 per centimeter (6.2 and 7.6 microns) but with spacings typically somewhat less than that observed in the canonical interstellar spectrum. However, the spectra in the database show that this spacing increases steadily with molecular size. Extrapolation of this trend indicates that PAHS in the 50 to 80 carbon atom size range are entirely consistent with the observed interstellar spacing. Furthermore, the profile of the 1610 per centimeter (6.2 microns) interstellar band indicates that PAHS containing as few as 20 carbon atoms contribute to this feature.

  12. Improving Detection of Axillary Lymph Nodes by Computer-Aided Kinetic Feature Identification in Positron Emission Tomography

    DTIC Science & Technology

    2004-08-01

    Detection of Early Metastasized Molecular Feature (IDEMMF) system; and test and evaluate the prototype with phantom , animal study and clinical patient...reported below. 5 2.1.1 TAC feature extraction Using dynamic phantom data with known ground truth, we tested, to a certain degree, how the time activity...averaged time activity curve. We have performed an experimental study with a realistic liver phantom . In the liver phantom three artificial spherical

  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. 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.

  15. Dust content in compact HII regions (NGC 7538-IRS1, IRS2, and IRS3)

    NASA Astrophysics Data System (ADS)

    Akabane, K.; Kuno, N.

    2005-02-01

    The luminosity of the central star of the compact HII regions of NGC 7538 was estimated from the solid angle of the IR sources subtended relative to the central star, and was found to be 5˜ 10 times as intense as that of IR sources. Under the single central star approximation, the luminosity gives a stellar UV photon rate NU(*) (s-1) of ˜3.0 × 1048, ˜1.5 × 1049, ˜5.1 × 1049, and ˜1.7 × 1047 for the compact HII regions of NGC 7538-IRS1(A/2), B, IRS2, and IRS3, respectively. NU (*) and the observed electron density, ne, provide the dust opacity of the ionizing photon, τSd, for the optical path out to the Strömgren sphere radius rS, assuming a gas with standard dust content. Ionizing photon opacity over the same optical path but with the actual dust content τSda is also derived from ri / rS, where ri is the radius of the ionized sphere, which is estimated from NU(*) and the observed volume emission measure ne2 (4 π ri3/3) (Spitzer \\cite{Spitzer1978}). An observational trend of γ NU(*) / 4π ri2 1/2 ˜ constant, where γ = τSda / τSd}, was obtained for the 4 compact HII regions of the NGC 7538(N). Fourteen selected compact HII regions from data catalogued by VLA observations were examined for this trend, and a similar result was obtained. A limit of γ as 15 ≥ γ ≥ 0.1 was given for the 14 selected sources. The size of the dust-depleted cavity of the NGC 7538(N) suggested by Chini et al. (\\cite{Chini1986}) coincides with that of the ionized sphere of the IRS2 of the region.

  16. 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.

  17. Development of an extra-vehicular (EVA) infrared (IR) camera inspection system

    NASA Astrophysics Data System (ADS)

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

    2006-04-01

    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.

  18. Toward Efficient and Metal-Free Emissive Devices: A Solution-Processed Host-Guest Light-Emitting Electrochemical Cell Featuring Thermally Activated Delayed Fluorescence.

    PubMed

    Lundberg, Petter; Lindh, E Mattias; Tang, Shi; Edman, Ludvig

    2017-08-30

    The next generation of emissive devices should preferably be efficient, low-cost, and environmentally sustainable, and as such utilize all electrically generated excitons (both singlets and triplets) for the light emission, while being free from rare metals such as iridium. Here, we report on a step toward this vision through the design, fabrication, and operation of a host-guest light-emitting electrochemical cell (LEC) featuring an organic thermally activated delayed fluorescence (TADF) guest that harvests both singlet and triplet excitons for the emission. The rare-metal-free active material also consists of a polymeric electrolyte and a polymeric compatibilizer for the facilitation of a cost-efficient and scalable solution-based fabrication, and for the use of air-stable electrodes. We report that such TADF-LEC devices can deliver uniform green light emission with a maximum luminance of 228 cd m(-2) when driven by a constant-current density of 770 A m(-2), and 760 cd m(-2) during a voltage ramp, which represents a one-order-of-magnitude improvement in comparison to previous TADF-emitting LECs.

  19. 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. Copyright © 2014 Elsevier Ltd. All rights reserved.

  20. 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.

  1. 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.

  2. Optimized IR synchrotron beamline design.

    PubMed

    Moreno, Thierry

    2015-09-01

    Synchrotron infrared beamlines are powerful tools on which to perform spectroscopy on microscopic length scales but require working with large bending-magnet source apertures in order to provide intense photon beams to the experiments. Many infrared beamlines use a single toroidal-shaped mirror to focus the source emission which generates, for large apertures, beams with significant geometrical aberrations resulting from the shape of the source and the beamline optics. In this paper, an optical layout optimized for synchrotron infrared beamlines, that removes almost totally the geometrical aberrations of the source, is presented and analyzed. This layout is already operational on the IR beamline of the Brazilian synchrotron. An infrared beamline design based on a SOLEIL bending-magnet source is given as an example, which could be useful for future IR beamline improvements at this facility.

  3. Identification of the emission features near 3.5 microns in the pre main sequence star HD 97048

    NASA Technical Reports Server (NTRS)

    Baas, F.; Allamandola, L. J.; Geballe, T. R.; Persson, S. E.; Lacy, J. H.

    1982-01-01

    The spectrum of HD97048 was measured with a resolving power of 450 between 3.37 and 3.64 microns. The prominent feature near 3.5 microns is well resolved, with a peak at 3.53 microns and a wing extending to a shorter wavelength. The weaker feature near 3.4 microns is found to peak at 3.43 microns, in contrast to the 3.40 micron feature seen in other astronomical objects. The observed spectrum strongly resembles laboratory spectra of mixtures of monomeric and dimeric formaldehyde embedded in low temperature solids. Of various possible excitation mechanisms, ultraviolet pumped infrared fluorescence of formaldehyde in interstellar grains provides the best explanation for the observed spectrum of HD 97048.

  4. XMM-Newton and INTEGRAL study of the SFXT IGR J18483-0311 in quiescence: hint of a cyclotron emission feature?

    NASA Astrophysics Data System (ADS)

    Sguera, V.; Ducci, L.; Sidoli, L.; Bazzano, A.; Bassani, L.

    2010-02-01

    We report the results from archival XMM-Newton and INTEGRAL observations of the Supergiant Fast X-ray Transient (SFXT) IGR J18483-0311 in quiescence. The 18-60 keV hard X-ray behaviour of the source is presented here for the first time; it is characterized by a spectral shape (Γ ~ 2.5) similar to that during outburst activity, and the lowest measured luminosity level is ~1034 erg s-1. The 0.5-10 keV luminosity state, measured by XMM-Newton during the apastron passage, is about one order of magnitude lower and it is reasonably fitted by an absorbed blackbody model yielding parameters consistent with previous measurements. In addition, we find evidence (~3.5σ significance) of an emission-like feature at ~3.3 keV in the quiescent 0.5-10 keV source spectrum. The absence of any known or found systematic effects, which could artificially introduce the observed feature, gives us confidence about its non-instrumental nature. We show that its physical explanation in terms of atomic emission line appears unlikely, and conversely we attempt to ascribe it to an electron cyclotron emission line which would imply a neutron star magnetic field of the order of ~3 × 1011 G. Importantly, such direct estimation is in very good agreement with that independently inferred by us in the framework of accretion from a spherically symmetric stellar wind. If firmly confirmed by future longer X-ray observations, this would be the first detection ever of a cyclotron feature in the X-ray spectrum of an SFXT, with important implications on theoretical models.

  5. The Spitzer discovery of a galaxy with infrared emission solely due to AGN activity

    NASA Astrophysics Data System (ADS)

    Hony, S.; Kemper, F.; Woods, P. M.; van Loon, J. Th.; Gorjian, V.; Madden, S. C.; Zijlstra, A. A.; Gordon, K. D.; Indebetouw, R.; Marengo, M.; Meixner, M.; Panuzzo, P.; Shiao, B.; Sloan, G. C.; Roman-Duval, J.; Mullaney, J.; Tielens, A. G. G. M.

    2011-07-01

    Aims: We present an analysis of a galaxy (SAGE1CJ053634.78-722658.5) at a redshift of 0.14 of which the infrared (IR) emission is entirely dominated by emission associated with the active galactic nucleus. Methods: We present the 5-37 μm Spitzer/IRS spectrum and broad wavelength spectral energy distribution (SED) of SAGE1CJ053634.78-722658.5, an IR point-source detected by Spitzer/SAGE. The source was observed in the SAGE-Spec program and was included to determine the nature of sources with deviant IR colours. The spectrum shows a redshifted (z = 0.14 ± 0.005) silicate emission feature with an exceptionally high feature-to-continuum ratio and weak polycyclic aromatic hydrocarbon (PAH) emission bands. We compare the source with models of emission from dusty tori around AGNs. We present a diagnostic diagram that will help to identify similar sources based on Spitzer/MIPS and Herschel/PACS photometry. Results: The SED of SAGE1CJ053634.78-722658.5 is peculiar because it lacks far-IR emissiondue to cold dust and a clear stellar counterpart. We find that the SED and the IR spectrum can be understood as emission originating from the inner ~10 pc around an accreting black hole. There is no need to invoke emission from the host galaxy, either from the stars or from the interstellar medium, although a possible early-type host galaxy cannot be excluded based on the SED analysis. The hot dust around the accretion disk gives rise to a continuum, which peaks at 4 μm, whereas the strong silicate features may arise from optically thin emission of dusty clouds within ~10 pc around the black hole. The weak PAH emission does not appear to be linked to star formation, as star formation templates strongly over-predict the measured far-IR flux levels. Conclusions: The SED of SAGE1CJ053634.78-722658.5 is rare in the local universe but may be more common in the more distant universe. The conspicuous absence of host-galaxy IR emission places limits on the far-IR emission arising from

  6. 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.

  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. Specific features of explosive decomposition of pentaerythritol tetranitrate exposed to an electron beam with an explosive emission cathode

    NASA Astrophysics Data System (ADS)

    Aduev, B. P.; Belokurov, G. M.; Krechetov, A. G.; Liskov, I. Yu.

    2017-07-01

    A comparative examination of the critical energy density of explosive decomposition of pentaerythritol tetranitrate exposed either to an electron beam of a GIN-600 accelerator (240 keV, 20 ns) with an explosive emission cathode or to this beam combined with metal low-temperature diode plasma has been performed. It has been demonstrated that the contribution of plasma to the development of explosive decomposition is appreciable at explosion probabilities P ≤ 0.2. At higher energy densities and explosion probabilities P ≥ 0.5, the contribution of plasma to the overall beam energy density did not exceed 10%.

  9. Variable uptake feature of focal nodular hyperplasia in Tc-99m phytate hepatic scintigraphy/single-photon emission computed tomography-A parametric analysis.

    PubMed

    Hsu, Yu-Ling; Chen, Yu-Wen; Lin, Chia-Yang; Lai, Yun-Chang; Chen, Shinn-Cherng; Lin, Zu-Yau

    2015-12-01

    Tc-99m phytate hepatic scintigraphy remains the standard method for evaluating the functional features of Kupffer cells. In this study, we demonstrate the variable uptake feature of focal nodular hyperplasia (FNH) in Tc-99m phytate scintigraphy. We reviewed all patients who underwent Tc-99m phytate hepatic scintigraphy between 2008 and 2012 in Kaohsiung Medical University Hospital, Kaohsiung, Taiwan. Cases with FNH were diagnosed on the basis of pathology or at least one or more prior imaging with a periodic clinical follow-up. All patients received a standard protocol of dynamic flow study and planar and Tc-99m phytate single-photon emission computed tomography (E. CAM; Siemens). The correlation of variable nodular radioactivity with parameters such as tumor size and localization was analyzed. In total, 15 lesions of 14 patients in the clinic were diagnosed as FNH. The tumor size was approximately 2.9-7.4 cm (mean size 4.6 cm). Four lesions were larger than 5 cm. The major anatomic distribution was in the right hepatic lobe (10 lesions), particularly in the superior segments (7 lesions). Tc-99m phytate single-photon emission computed tomography imaging for determining the functional features of Kupffer cells included cool/cold (8 lesions), isoradioactive/warm (6 lesions), and hot (1 lesion) patterns of uptake. We did not observe any statistically significant correlation between variable nodular radioactivity and tumor size (p=0.68) or localization (p=0.04). Herein, we demonstrate the variable uptake feature of FNH in Tc-99m phytate scintigraphy. In small FNH tumors (< 5 cm), increased or equal uptake still provided specificity for the differential diagnosis of hepatic solid tumors.

  10. 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.

  11. 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.

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

    NASA Technical Reports Server (NTRS)

    Sekanina, Z.; Larson, S. M.

    1984-01-01

    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.

  13. 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

  14. Southern hemisphere all-sky imaging investigations into the latitude extent of the 6300 Å emission feature associated with the midnight temperature maximum

    NASA Astrophysics Data System (ADS)

    Colerico, M. J.; Mendillo, M.

    2001-05-01

    An all-sky imaging system has been in operation in Arequipa, Peru, (16.2\\symbol{23}S, 71.35\\symbol{23}W) from October 1993 - October 2000 conducting routine observations of 6300 Å airglow emissions. Using this imaging system, Colerico et al. [1996] reported on the persistent occurrence of an enhanced 6300 Å emission feature with an apparent north-south propagation through the field of view past 24\\symbol{23}S near local midnight. This enhanced airglow feature was referred to as the midnight brightness wave (MBW). The authors concluded that MBW was the airglow signature of the thermospheric midnight temperature maximum (MTM), a highly variable, large scale neutral temperature anomaly which occurs at low latitudes. The MTM is accompanied by a pressure increase and a signature reversal/abatement in the meridional winds from equatorward to poleward. Poleward winds serve to move plasma down magnetic field lines to altitudes where it can dissociatively recombine and produce 6300 Å emissions. Additional imaging systems in operation south of Arequipa in Tucuman, Argentina, (26.5\\symbol{23}S, 65.15\\symbol{23}W) and El Leoncito, Argentina, (31.8\\symbol{23}S, 69.0\\symbol{23}W) extend the latitude range over which MBW events can be observed to 39\\symbol{23}S. In this paper, we use the combined latitude range of the three imaging systems to investigate the latitudinal extent of the MTM's influence on upper atmospheric parameters. Observations of MBW propagation past 39\\symbol{23}S suggest that the MTM's influence may be felt at mid-latitudes in the southern hemisphere.

  15. Spitzer mid-IR spectroscopy of powerful 2Jy and 3CRR radio galaxies. II. AGN power indicators and unification

    SciTech Connect

    Dicken, D.; Tadhunter, C.; Morganti, R.; Axon, D.; Robinson, A.; Magagnoli, M.; Kharb, P.; Ramos Almeida, C.; Hardcastle, M.; Nesvadba, N. P. H.; Singh, V.; Kouwenhoven, M. B. N.; Rose, M.; Spoon, H.; Inskip, K. J.; Holt, J.

    2014-06-20

    It remains uncertain which continuum and emission line diagnostics best indicate the bolometric powers of active galactic nuclei (AGNs), especially given the attenuation caused by the circumnuclear material and the possible contamination by components related to star formation. Here we use mid-IR spectra along with multiwavelength data to investigate the merit of various diagnostics of AGN radiative power, including the mid-IR [Ne III] λ25.89 μm and [O IV] λ25.89 μm fine-structure lines, the optical [O III] λ5007 forbidden line, and mid-IR 24 μm, 5 GHz radio, and X-ray continuum emission, for complete samples of 46 2Jy radio galaxies (0.05 < z < 0.7) and 17 3CRR FRII radio galaxies (z < 0.1). We find that the mid-IR [O IV] line is the most reliable indicator of AGN power for powerful radio-loud AGNs. By assuming that the [O IV] is emitted isotropically, and comparing the [O III] and 24 μm luminosities of the broad- and narrow-line AGNs in our samples at fixed [O IV] luminosity, we show that the [O III] and 24 μm emission are both mildly attenuated in the narrow-line compared to the broad-line objects by a factor of ≈2. However, despite this attenuation, the [O III] and 24 μm luminosities are better AGN power indicators for our sample than either the 5 GHz radio or the X-ray continuum luminosities. We also detect the mid-IR 9.7 μm silicate feature in the spectra of many objects but not ubiquitously: at least 40% of the sample shows no clear evidence for these features. We conclude that, for the majority of powerful radio galaxies, the mid-IR lines are powered by AGN photoionization.

  16. Near-IR Photoluminescence of C60().

    PubMed

    Strelnikov, Dmitry V; Kern, Bastian; Kappes, Manfred M

    2017-10-05

    We have observed that C60(+) ions isolated in cryogenic matrices show distinct near-IR photoluminescence upon excitation in the near-IR range. By contrast, UV photoexcitation does not lead to measurable luminescence. Near-IR C60(+) photoluminescence is a one-photon process. The emission is mainly concentrated in one band and corresponds to (2)A1u ← (2)E1g relaxation. We present experimental data for the Stokes shift, power, and temperature dependencies as well as the quantum efficiency of the photoluminescence. Our findings may be relevant for astronomy, considering recent unequivocal assignment of five diffuse interstellar bands to near-IR absorption bands of C60(+).

  17. Mid-IR water and silicate relation in protoplanetary disks

    NASA Astrophysics Data System (ADS)

    Antonellini, S.; Bremer, J.; Kamp, I.; Riviere-Marichalar, P.; Lahuis, F.; Thi, W.-F.; Woitke, P.; Meijerink, R.; Aresu, G.; Spaans, M.

    2017-01-01

    Context. Mid-IR water lines from protoplanetary disks around T Tauri stars have a detection rate of 50%. Models have identified multiple physical properties of disks such as dust-to-gas mass ratio, dust size power law distribution, disk gas mass, disk inner radius, and disk scale height as potential explanations for the current detection rate. Aims: In this study, we aim to break degeneracies through constraints obtained from observations. We search for a connection between mid-IR water line fluxes and the strength of the 10 μm silicate feature. Methods: We analyze observed water line fluxes from three blends at 15.17, 17.22 and 29.85 μm published earlier and compute the 10 μm silicate feature strength from Spitzer spectra to search for possible trends. We use a series of published ProDiMo thermo-chemical models, to explore disk dust and gas properties, and also the effects of different central stars. In addition, we produced two standard models with different dust opacity functions, and one with a parametric prescription for the dust settling. Results: Our series of models that vary properties of the grain size distribution suggest that mid-IR water emission anticorrelates with the strength of the 10 μm silicate feature. The models also show that the increasing stellar bolometric luminosity simultaneously enhance the strength of this dust feature and the water lines fluxes. No correlation is found between the observed mid-IR water lines and the 10 μm silicate strength. Two-thirds of the targets in our sample show crystalline dust features, and the disks are mainly flaring. Our sample shows the same difference in the peak strength between amorphous and crystalline silicates that was noted in earlier studies, but our models do not support this intrinsic difference in silicate peak strength. Individual properties of our models are not able to reproduce the most extreme observations, suggesting that more complex dust properties (e.g., vertically changing) are

  18. 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

  19. 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.

  20. Results from VUV Spectroscopy of Neutral Diamondoid Molecules and IR Spectroscopy of the Cationic Species

    NASA Astrophysics Data System (ADS)

    Pirali, Olivier; Boyé-Peronne, Séverine; Douin, Stéphane; Galue, Hector Alvaro; Oomens, Jos; Garcia, Gustavo; Nahon, Laurent; Vervloet, Michel

    2009-06-01

    Due to their stability, diamond materials are expected to be present in different environments of the interstellar medium. Indeed, nanometer size diamond cristals have been extracted from carbonaceous chondrites and two emission features (observed at 3.43 μm and 3.53 μm) in the spectra of HD 97048 and Elias1 have been assigned to these species. Despite high astrophysical relevance, very few is known about the structural properties and dynamics of the molecular building blocks of larger species : the diamondoid molecules. These molecules consist of sp3 hybridized carbon cages where dangling bonds are terminated by hydrogen atoms. The infrared spectra of neutral molecules conforted the assignment of the 3.43 μm and 3.53 μm emission features to nanometer size diamondoid systems. In order to improve the understanding of the possible process leading to the IR emission features, we recorded the IR spectra of the deshydrogenated cationic species of adamantane, diamantane and triamantane (using Infrared Multi Photon Dissociation technique with the free electron laser FELIX) as well as the VUV spectra of adamantane and diamantane (obtained thanks to the Threshold Photo Electron Photo Ion Coincidence technique at the DESIRS beamline of the synchrotron SOLEIL). We will show the results of these spectra and the preliminary analysis. Saslaw and Gaustad, Nature, 221, 160 (1969) Lewis et al., Nature, 326, 160 (1987) van Kerckhoven et al., Astronomy and Astrophysic, 384, 568 (2002) Pirali et al., The Astrophysical Journal, 661, 919 (2007)

  1. 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.

  2. Monte Carlo simulation of the basic features of the GE Millennium MG single photon emission computed tomography gamma camera.

    PubMed

    Vieira, L; Vaz, T F; Costa, D C; Almeida, P

    2014-01-01

    To describe and validate the simulation of the basic features of GE Millennium MG gamma camera using the GATE Monte Carlo platform. Crystal size and thickness, parallel-hole collimation and a realistic energy acquisition window were simulated in the GATE platform. GATE results were compared to experimental data in the following imaging conditions: a point source of (99m)Tc at different positions during static imaging and tomographic acquisitions using two different energy windows. The accuracy between the events expected and detected by simulation was obtained with the Mann-Whitney-Wilcoxon test. Comparisons were made regarding the measurement of sensitivity and spatial resolution, static and tomographic. Simulated and experimental spatial resolutions for tomographic data were compared with the Kruskal-Wallis test to assess simulation accuracy for this parameter. There was good agreement between simulated and experimental data. The number of decays expected when compared with the number of decays registered, showed small deviation (≤ 0.007%). The sensitivity comparisons between static acquisitions for different distances from source to collimator (1, 5, 10, 20, 30 cm) with energy windows of 126-154 keV and 130-158 keV showed differences of 4.4%, 5.5%, 4.2%, 5.5%, 4.5% and 5.4%, 6.3%, 6.3%, 5.8%, 5.3%, respectively. For the tomographic acquisitions, the mean differences were 7.5% and 9.8% for the energy window 126-154 keV and 130-158 keV. Comparison of simulated and experimental spatial resolutions for tomographic data showed no statistically significant differences with 95% confidence interval. Adequate simulation of the system basic features using GATE Monte Carlo simulation platform was achieved and validated. Copyright © 2013 Elsevier España, S.L. and SEMNIM. All rights reserved.

  3. 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.

  4. Infrared emission modeling for vinyl PAHs

    NASA Astrophysics Data System (ADS)

    Maurya, Anju; Rastogi, Shantanu

    Polycyclic Aromatic Hydrocarbon (PAH) molecules are source of the infrared emission features at 3.3, 6.2, 7.7, 8.6, 11.2, 12.7 and 16.4 microns that are ubiquitously observed in diverse astrophysical objects. There are variations in the profile of these emission features between sources ranging from star forming regions to late type stars and also extra galactic sources. The profile variations point towards the presence of a variety of PAHs in different population in different objects. In order to simulate the emission spectra from different sources the vibrational spectra of a wide variety of PAH molecules have been studied. The modeled emission spectra gives good match for some bands but simultaneous fit for all features is not obtained. In particular the 6.2 micron feature, assigned to C-C stretch mode, is not fitted well. We therefore also study PAHs with vinyl side groups. Quantum chemical calculations using DFT/B3LYP in conjugation with optimum basis are performed to obtain the IR spectra of vinyl PAHs. Modeling of emission is done assuming excitation by a UV photon and cascade emission through vibrational levels that are obtained theoretically. It is expected that due to the presence of C = C in vinyl group the aromatic C-C might shift closer to 6.2 micron. A closer match with the observed spectra will provide a better insight about the physical conditions and molecular evolution in the object.

  5. SPITZER MID-IR SPECTRA OF DUST DEBRIS AROUND A AND LATE B TYPE STARS: ASTEROID BELT ANALOGS AND POWER-LAW DUST DISTRIBUTIONS

    SciTech Connect

    Morales, Farisa Y.; Werner, M. W.; Bryden, G.; Stapelfeldt, K. R.; Beichman, C. A.; Grogan, K.; Plavchan, P.; Rieke, G. H.; Su, K. Y. L.; Chen, C. H.; Kenyon, S. J.; Moro-Martin, A.; Wolf, S.

    2009-07-10

    Using the Spitzer/Infrared Spectrograph (IRS) low-resolution modules covering wavelengths from 5 to 35 {mu}m, we observed 52 main-sequence A and late B type stars previously seen using Spitzer/Multiband Imaging Photometer (MIPS) to have excess infrared emission at 24 {mu}m above that expected from the stellar photosphere. The mid-IR excess is confirmed in all cases but two. While prominent spectral features are not evident in any of the spectra, we observed a striking diversity in the overall shape of the spectral energy distributions. Most of the IRS excess spectra are consistent with single-temperature blackbody emission, suggestive of dust located at a single orbital radius-a narrow ring. Assuming the excess emission originates from a population of large blackbody grains, dust temperatures range from 70 to 324 K, with a median of 190 K corresponding to a distance of 10 AU. Thirteen stars however, have dust emission that follows a power-law distribution, F {sub {nu}} = F {sub 0}{lambda}{sup {alpha}}, with exponent {alpha} ranging from 1.0 to 2.9. The warm dust in these systems must span a greater range of orbital locations-an extended disk. All of the stars have also been observed with Spitzer/MIPS at 70 {mu}m, with 27 of the 50 excess sources detected (signal-to-noise ratio > 3). Most 70 {mu}m fluxes are suggestive of a cooler, Kuiper Belt-like component that may be completely independent of the asteroid belt-like warm emission detected at the IRS wavelengths. Fourteen of 37 sources with blackbody-like fits are detected at 70 {mu}m. The 13 objects with IRS excess emission fit by a power-law disk model, however, are all detected at 70 {mu}m (four above, three on, and six below the extrapolated power law), suggesting that the mid-IR IRS emission and far-IR 70 {mu}m emission may be related for these sources. Overall, the observed blackbody and power-law thermal profiles reveal debris distributed in a wide variety of radial structures that do not appear to be

  6. IR decoys modeling method based on particle system

    NASA Astrophysics Data System (ADS)

    Liu, Jun-yu; Wu, Kai-feng; Dong, Yan-bing

    2016-10-01

    Due to the complexity in combustion processes of IR decoys, it is difficult to describe its infrared radiation characteristics by deterministic model. In this work, the IR decoys simulation based on particle system was found. The measured date of the IR decoy is used to analyze the typical characteristic of the IR decoy. A semi-empirical model of the IR decoy motion law has been set up based on friction factors and a IR decoys simulation model has been build up based on particle system. The infrared imaging characteristic and time varying characteristic of the IR decoy were simulated by making use of the particle feature such as lifetime, speed and color. The dynamic IR decoys simulation is realized with the VC++6.0 and OpenGL.

  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. Moisture map by IR thermography

    NASA Astrophysics Data System (ADS)

    Grinzato, E.; Cadelano, G.; Bison, P.

    2010-10-01

    A new approach to moisture detection in buildings by an optical method is presented. Limits of classical and new methods are discussed. The state of the art about the use of IR thermography is illustrated as well. The new technique exploits characteristics of the materials and takes into account explicitly the heat and mass exchange between surface and environment. A set of experiments in controlled laboratory conditions on different materials is used to better understand the physical problem. The testing procedure and the data reduction are illustrated. A case study on a heritage building points up the features of this technique.

  9. The Unusual Hydrocarbon Emission From the Early Carbon Star HD 100764: The Connection Between Aromatics and Aliphatics

    DTIC Science & Technology

    2007-08-01

    ABSTRACT We have used the Infrared Spectrograph (IRS) on the Spitzer Space Telescope to obtain spectra of HD 100764, an apparently single carbon star...8217 Received 2006 December 23; accepted 2007 April 9 ABSTRACT We have used the Infrared Spectrograph (IRS) on the Spitzer Space Telescope to obtain spectra...emission near 7.65 jim, physical environments. Gillett et al. (1973) first detected what and a broad feature centered at ,- 8.2im. It remains unclear

  10. Facile Fabrication of PEGylated Fluorescent Organic Nanoparticles with Aggregation-Induced Emission Feature via Formation of Dynamic Bonds and Their Biological Imaging Applications.

    PubMed

    Long, Zi; Liu, Meiying; Wan, Qing; Mao, Liucheng; Huang, Hongye; Zeng, Guangjian; Wan, Yiqun; Deng, Fengjie; Zhang, Xiaoyong; Wei, Yen

    2016-10-01

    Driven by the high demand for sensitive and specific tools for optical imaging, fluorescent nanoprobes with various working mechanisms and advanced functionalities are flourishing at an incredible speed. This work reports the design and fabrication of aggregation-induced emission (AIE)-active fluorescent organic nanoparticles (FNPs) via forming dynamic phenyl borate between diol containing hydrophobic AIE dye (APD-PhCHO) and phenylboronic acid pendant hydrophilic polymers (PEGMA-VPBA) within 30 min. The final AIE-active APD-PhCHO-PEGMA-VPBA FNPs display high water dispersibility and strong fluorescence emission because of their amphiphilic properties and AIE feature. Biological evaluation suggests that APD-PhCHO-PEGMA-VPBA FNPs possess negative effect on HeLa cells and desirable optical properties for biological imaging. More importantly, phenyl borate is a dynamic bond with pH and glucose responsiveness. Furthermore, different functions can be designed and introduced into these AIE-active systems through adoption of different monomers for good applicability of free radical polymerization. Therefore, this work provides a novel platform for preparation of multifunctional AIE-active nanosystems with responsiveness for various biomedical applications. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  11. 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.

  12. 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.

  13. 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.

  14. 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.

  15. 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

  16. PAH Emission From ULIRGs: Evidence For Unusual Grain Properties?

    NASA Astrophysics Data System (ADS)

    Marshall, Jason A.; Armus, L.; Spoon, H. W. W.

    2007-12-01

    The tremendous power emerging from ultraluminous infrared galaxies (ULIRGs) is driven both by high levels of star-formation activity and AGN-related accretion. Observations of star-forming regions in the Milky Way and external star-forming galaxies provide evidence that the first of these energy generation mechanisms often also gives rise to emission from PAH molecules in the form of characteristic mid-IR features. Given the composite nature of ULIRGs, it is not surprising that many also exhibit significant emission from PAHs. Perhaps more surprising, however, is that some ULIRGs believed to be powered primarily by AGNs also show emission from PAHs, although typically at lower levels relative to their total dust output. To investigate the nature of the PAH emission from galaxies powered either by star-formation or AGN accretion alone, as well as emission from composite systems such as ULIRGs powered by both mechanisms, we present a detailed study of the PAH emission spectra from galaxies of each type. We use the CAFE spectral energy distribution decomposition software we have developed to derive and extinction correct the spectra of PAH emission from a sample of 100 galaxies with Spitzer/IRS observations, and use the results of this analysis to calculate the ratios of the various mid-IR PAH feature luminosities. In particular, we investigate to what extent these relative feature strengths vary as a function of the optical classification of galaxies, and we inquire into whether or not the derived feature strength ratios provide evidence for unusual grain properties in the extreme conditions within ULIRGs.

  17. NEW MASER EMISSION FROM NONMETASTABLE AMMONIA IN NGC 7538

    SciTech Connect

    Hoffman, Ian M.; Kim, Stella Seojin

    2011-09-20

    We present the first interferometric observations at 18.5 GHz of IRS 1 in NGC 7538. These observations include images of the nonmetastable {sup 14}NH{sub 3} (9, 6) masers with a synthesized beam of 2 arcsec and images of the continuum emission with a synthesized beam of 150 mas. Of the maser emission, the previously known feature near v {sub LSR} = -60 km s{sup -1} is spectrally resolved into at least two components and we observe several new maser emission features near v {sub LSR} = -57 km s{sup -1}. The new maser emission near -57 km s{sup -1} lies 250 {+-} 90 mas northwest of the maser emission near -60 km s{sup -1}. All of the masers are angularly unresolved indicating brightness temperatures T{sub B} > 2000 K. We are also able to conclusively associate the ammonia masers with the position of IRS 1. The excitation of these rare ammonia masers is discussed in the context of the rich maser environment of IRS 1.

  18. IR in Norway

    NASA Astrophysics Data System (ADS)

    Haakenaasen, Randi; Lovold, Stian

    2003-01-01

    Infrared technology in Norway started at the Norwegian Defense Research Establishment (FFI) in the 1960s, and has since then spread to universities, other research institutes and industry. FFI has a large, integrated IR activity that includes research and development in IR detectors, optics design, optical coatings, advanced dewar design, modelling/simulation of IR scenes, and image analysis. Part of the integrated activity is a laboratory for more basic research in materials science and semiconductor physics, in which thin films of CdHgTe are grown by molecular beam epitaxy and processed into IR detectors by various techniques. FFI also has a lot of experience in research and development of tunable infrared lasers for various applications. Norwegian industrial activities include production of infrared homing anti-ship missiles, laser rangefinders, various infrared gas sensors, hyperspectral cameras, and fiberoptic sensor systems for structural health monitoring and offshore oil well diagnostics.

  19. IR Linearity Monitor

    NASA Astrophysics Data System (ADS)

    Hilbert, Bryan

    2012-10-01

    These observations will be used to monitor the signal non-linearity of the IR channel, as well as to update the IR channel non-linearity calibration reference file. The non-linearity behavior of each pixel in the detector will be investigated through the use of full frame and subarray flat fields, while the photometric behavior of point sources will be studied using observations of 47 Tuc. This is a continuation of the Cycle 19 non-linearity monitor, program 12696.

  20. IR linearity monitor

    NASA Astrophysics Data System (ADS)

    Hilbert, Bryan

    2013-10-01

    These observations will be used to monitor the signal non-linearity of the IR channel, as well as to update the IR channel non-linearity calibration reference file. The non-linearity behavior of each pixel in the detector will be investigated through the use of full frame and subarray flat fields, while the photometric behavior of point sources will be studied using observations of 47 Tuc. This is a continuation of the Cycle 20 non-linearity monitor, program 13079.

  1. 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.

  2. Modeling Dead OH/IR stars

    NASA Astrophysics Data System (ADS)

    Lorenz-Martins, S.; Ortiz, R.; Khouri, T.; de Araujo, F. X.

    2007-11-01

    OH/IR stars present several OH maser emission lines which are formed in the outer regions of their circumstellar dust envelopes. These stars can be recognized at large distances, based only on radio and infrared observations. They can therefore be used as kinematic tracers in galaxies. The emission at 1612 MHz is the strongest line and presents a double profile (Δv = 20--50 km/s), although in the planetary nebulae phase this line is sometimes no longer detected. In this work we calculate radiative transfer models to describe the dust envelopes of a sample of OH/IR stars. In this sample, the maser emission at 1612 MHz has disappeared. We also included some OH/IR stars in which this maser emission was recently detected. The results show that the physical parameters of the dust envelopes of almost the whole sample are those expected for normal oxygen-rich AGB stars. However, three sources have a different pattern: they present a double-peaked energy dustribution which may be due to an evolved dust envelope.

  3. The jet of the BL Lacertae object PKS 0521-365 in the near-IR: MAD adaptive optics observations

    NASA Astrophysics Data System (ADS)

    Falomo, R.; Pian, E.; Treves, A.; Giovannini, G.; Venturi, T.; Moretti, A.; Arcidiacono, C.; Farinato, J.; Ragazzoni, R.; Diolaiti, E.; Lombini, M.; Tavecchio, F.; Brast, R.; Donaldson, R.; Kolb, J.; Marchetti, E.; Tordo, S.

    2009-07-01

    Context: BL Lac objects are low-power active nuclei exhibiting a variety of peculiar properties caused by the presence of a relativistic jet and orientation effects. Aims: We present adaptive optics near-IR images at high spatial resolution of the nearby BL Lac object PKS 0521-365, which is known to display a prominent jet both at radio and optical frequencies. Methods: The observations were obtained in Ks-band using the ESO multi-conjugated adaptive optics demonstrator at the Very Large Telescope. This allowed us to obtain images with 0.1 arcsec effective resolution. We performed a detailed analysis of the jet and its related features from the near-IR images, and combined them with images previously obtained with HST in the R band and by a re-analysis of VLA radio maps. Results: We find a remarkable similarity in the structure of the jet at radio, near-IR, and optical wavelengths. The broad-band emission of the jet knots is dominated by synchrotron radiation, while the nucleus also exhibits a significant inverse Compton component. We discovered the near-IR counterpart of the radio hotspot and found that the near-IR flux is consistent with being a synchrotron emission from radio to X-ray wavelengths. The bright red object (red-tip), detached but well aligned with the jet, is well resolved in the near-IR and has a linear light profile. Since it has no radio counterpart, we propose that it is a background galaxy not associated with the jet. Conclusions: The new adaptive optics near-IR images and previous observations at other frequencies allow us to study the complex environment around the remarkable BL Lac object PKS 0521-365. These data exemplify the capabilities of multi conjugate adaptive optics observations of extragalactic extended sources. Based on observations collected at ESO, Paranal, Chile, as part of MAD Guaranteed Time Observations.

  4. 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.

  5. 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

  6. 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

  7. 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.

  8. 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.

  9. 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.

  10. 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.

  11. USA B and W`s IR-CFB coal-fired boiler operating experiences

    SciTech Connect

    Kavidass, S.; Maryamchik, M.; Kanoria, M.; Price, C.S.

    1998-12-31

    This paper updates operating experience of two Babcock and Wilcox (B and W) coal-fired, internal recirculation circulating fluidized-bed (IR-CFB) boilers. The first boiler is located at Southern Illinois University (SIU) in Carbondale, Illinois and is designed for 35 MWt output for cogeneration application, utilizing high sulfur, low ash Illinois coal. The second boiler is located at Kanoria Chemicals and Industries Ltd. (KCIL) in Renukoot, India and is designed for 81 MWt output for captive power requirements, firing high ash, low sulfur coal. This boiler was supplied by Thermax B and W (TBW) Ltd., a joint venture company of B and W and Thermax in India. The CFB technology is selected for these two units based on the fuel and environmental considerations. This paper discusses the various aspects of the two IR-CFB boilers` design features, performance, and operating experience including emissions.

  12. Analysis of the Jovian sporadic decameter emission features on the base of the new data obtained with the high frequency-time resolution waveform receiver.

    NASA Astrophysics Data System (ADS)

    Litvinenko, G. V.; Zakharenko, V. V.; Konovalenko, A. A.; Vinogradov, V. V.; Rucker, H. O.

    2009-04-01

    The Jovian sporadic decameter radiation (DAM) represents a phenomenon which is still fully unstudied. The dynamic spectrum has a very complex structure with many unclear properties. The details of how decameter radio bursts are generated in the magnetosphere of Jupiter are still a matter of debate. One of the possible way to understand the physical features of S-bursts as well as mechanism responsible for generation is to increase the temporal and frequency resolutions and look at the S-burst signal from macroscopic viewpoint to a microsecond timescale. Modern progress in electronics and computer technologies allows creating the super effective registration systems with high frequency and temporal resolutions (Digital Signal Processors (DSP) and the Waveform Receiver (WFR)). In the present time in the Ukraine was realized the combination of telescope (UTR-2) and equipment (WFR) with the possible best parameters for the Jovian decameter emission investigations: sensitiveness (antenna effective area is near 100 000 m2), frequency resolution (12 kHz), time resolution (less than 200 ns), dynamic range (70 dB). In November 2008 it was continuous registered 4 hours of Io-B S-burst strong storm with UTR-2 and waveform receiver. The obtained data of the Jovian S-burst radio emission were processed as with Fourier as well as with wavelet transform methods. The main goal of these investigations was to detect and analyze the "superfine" internal content of the individual S-burst as well as macroscopic properties of radiation. Fine structure was investigated on the base of two possible physical mechanisms: 1) the narrow-band random noise process; 2) the wide-band pulse process with frequency and time modulations. For the last case the "de-dispersion" methodology was successively used. The statistical examinations (including the correlation analysis) of the fine internal structures were carried out on a broad basis of the different simple and complex S-burst events. The

  13. Infrared absorption and emission characteristics of interstellar PAHs. [Polycyclic Aromatic Hydrocarbon

    NASA Technical Reports Server (NTRS)

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

    1987-01-01

    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 and are responsible for the emission.

  14. 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.

  15. Infrared absorption and emission characteristics of interstellar PAHs. [Polycyclic Aromatic Hydrocarbon

    NASA Technical Reports Server (NTRS)

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

    1987-01-01

    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 and are responsible for the emission.

  16. 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.

  17. Local Mode Analysis: Decoding IR Spectra by Visualizing Molecular Details.

    PubMed

    Massarczyk, M; Rudack, T; Schlitter, J; Kuhne, J; Kötting, C; Gerwert, K

    2017-02-08

    Integration of experimental and computational approaches to investigate chemical reactions in proteins has proven to be very successful. Experimentally, time-resolved FTIR difference-spectroscopy monitors chemical reactions at atomic detail. To decode detailed structural information encoded in IR spectra, QM/MM calculations are performed. Here, we present a novel method which we call local mode analysis (LMA) for calculating IR spectra and assigning spectral IR-bands on the basis of movements of nuclei and partial charges from just a single QM/MM trajectory. Through LMA the decoding of IR spectra no longer requires several simulations or optimizations. The novel approach correlates the motions of atoms of a single simulation with the corresponding IR bands and provides direct access to the structural information encoded in IR spectra. Either the contributions of a particular atom or atom group to the complete IR spectrum of the molecule are visualized, or an IR-band is selected to visualize the corresponding structural motions. Thus, LMA decodes the detailed information contained in IR spectra and provides an intuitive approach for structural biologists and biochemists. The unique feature of LMA is the bidirectional analysis connecting structural details to spectral features and vice versa spectral features to molecular motions.

  18. Photochemical Tuning of Tris-Bidentate Acridine- and Phenazine-Based Ir(III) Complexes.

    PubMed

    Deraedt, Quentin; Loiseau, Frédérique; Elias, Benjamin

    2016-11-01

    Five new Ir(III) complexes of the type [Ir(ppy)2L](+) (where ppy = 2-phenylpyridine, L = bidentate N^N ligand) bearing linear and elbow-shaped acridine- and phenazine-based extended planar aromatic ligands have been successfully synthesized and characterized. The electrochemical and photochemical studies revealed that all complexes allow emission in the range 589-601 nm from excited states corresponding to a charge transfer between an Ir-ppy fragment and the extended planar ligand. Luminescence quenching occurs in water for [Ir(ppy)2dpac](+) (Ir-DPAC), [Ir(ppy)2dpacF2](+) (Ir-DPACF 2 ), [Ir(ppy)2dpacF4](+) (Ir-DPACF 4 ) and [Ir(ppy)2bdppz](+) (Ir-BDPPZ), while solely partial quenching is observed for [Ir(ppy)2npp](+) (Ir-NPP). This "light-switch" effect has been ascribed to the possible formation of a non-emissive mono-hydrogen-bonded excited state for the four complexes. The "elbow shaped" of Ir-NPP is believed to prevent the non-chelating nitrogen atom of the npp ligand to form H-bond with solvent molecules. The results emphasized the potential of small chemical modifications of the extended planar ligand on the properties of the corresponding Ir(III) complexes. Their tunable properties make them ideal candidates for applications such as DNA photoprobes.

  19. 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.

  20. 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.

  1. Mid and Near-IR Absorption Spectra of PAH Neutrals and Ions in H20 Ice to Facilitate their Astronomical Detection

    NASA Technical Reports Server (NTRS)

    Bernstein, Max P.; Sandford, Scott A.; Allamandola, Louis J.

    2004-01-01

    Polycyclic aromatic hydrocarbons (PAHs) are believed to be the most abundant and widespread class of organic compounds in the universe, having been observed in emission towards energetic regions and absorption towards colder ones.We will present IR spectra of PAHs and their cations in H20 ice measured in the laboratory in the hopes that this will facilitate the detection of these features in the interstellar medium.

  2. Mid and Near-IR Absorption Spectra of PAH Neutrals and Ions in H20 Ice to Facilitate their Astronomical Detection

    NASA Technical Reports Server (NTRS)

    Bernstein, Max P.; Sandford, Scott A.; Allamandola, Louis J.

    2004-01-01

    Polycyclic aromatic hydrocarbons (PAHs) are believed to be the most abundant and widespread class of organic compounds in the universe, having been observed in emission towards energetic regions and absorption towards colder ones.We will present IR spectra of PAHs and their cations in H20 ice measured in the laboratory in the hopes that this will facilitate the detection of these features in the interstellar medium.

  3. 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.

  4. 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.

  5. 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.

  6. Flexible high-performance IR camera systems

    NASA Astrophysics Data System (ADS)

    Hoelter, Theodore R.; Petronio, Susan M.; Carralejo, Ronald J.; Frank, Jeffery D.; Graff, John H.

    1999-07-01

    Indigo Systems Corporation has developed a family of standard readout integrated circuits (ROIC) for use in IR focal plane arrays (FPAs) imaging systems. These standard ROICs are designed to provide a compete set of operating features for camera level FPA control, while also providing high performance capability with any of several detector materials. By creating a uniform electrical interface for FPAs, these standard ROICs simplify the task of FPA integration with imaging electronics and physical packages. This paper begins with a brief description of the features of four Indigo standard ROICs and continues with a description of the features, design, and measured performance of indium antimonide, quantum well IR photo- detectors and indium gallium arsenide imaging system built using the described standard ROICs.

  7. IR Gain Monitor

    NASA Astrophysics Data System (ADS)

    Hilbert, Bryan

    2012-10-01

    The gain of the IR channel of WFC3 will be measured using a series of internal flat fields. Using knowledge gained from ground testing and previous cycles, we propose to collect flat field ramps which will be used to create photon transfer curves and give a measure of the gain.

  8. IR gain monitor

    NASA Astrophysics Data System (ADS)

    Hilbert, Bryan

    2013-10-01

    The gain of the IR channel of WFC3 will be measured using a series of internal flat fields. Using knowledge gained from ground testing and previous cycles, we propose to collect flat field ramps which will be used to create photon transfer curves and give a measure of the gain. This continues the strategy of last cycle's gain monitor, in proposal 13080.

  9. 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.

  10. Systematic modeling for the insulin signaling network mediated by IRS(1) and IRS(2).

    PubMed

    Huang, Can; Wu, Ming; Du, Jun; Liu, Di; Chan, Christina

    2014-08-21

    The hepatic insulin signaling mediated by insulin receptor substrates IRS1 and IRS2 plays a central role in maintaining glucose homeostasis under different physiological conditions. Although functions of individual components in the signaling network have been extensively studied, our knowledge is still limited with regard to how the signals are integrated and coordinated in the complex network to render their functional roles. In this study, we construct systematic models for the insulin signaling network mediated by IRS1 and IRS2, through the integration of current knowledge in the literature into mathematical models of insulin signaling pathways. We hypothesize that the specificity of the IRS signaling mechanisms emerges from the wiring and kinetics of the entire network. A discrete dynamic model is first constructed to account for the numerous dynamic features in the system, i.e., complex feedback circuits, different regulatory time-scales and cross-talks between pathways. Our simulation shows that the wiring of the network determines different functions of IRS1 and IRS2. We further collate and reconstruct a kinetic model of the network as a system of ordinary differential equations to provide an informative model for predicting phenotypes. A sensitivity analysis is applied to identify essential regulators for the signaling process.

  11. An EW technology research of jamming IR imaging guided missiles

    NASA Astrophysics Data System (ADS)

    Wu, Xiu-qin; Rong, Hua; Liang, Jing-ping; Chen, Qi; Chen, Min-rong

    2009-07-01

    The IR-Imaging-Guided Weapons have been playing an important role in the modern warfare by means of select attacking the vital parts of targets with the features of highly secret attacking, high precision, and excellent anti-jamming capability ,therefore, they are viewed to be one of the promising precisely guided weapons ,receiving great concern through out the world. This paper discusses the characteristics of IR-Imaging guidance systems at the highlight of making a study of correlated technologies of jamming IR-Imaging-Guided Weapons on the basis of elaborating the operational principles of IR-Imaging-guided Weapons.

  12. 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.

  13. VizieR Online Data Catalog: IR spectroscopy of AGN & starbursts (Samsonyan+, 2016)

    NASA Astrophysics Data System (ADS)

    Samsonyan, A.; Weedman, D.; Lebouteiller, V.; Barry, D.; Sargsyan, L.

    2016-10-01

    A sample of 379 extragalactic sources is presented that has mid-infrared, high-resolution spectroscopy from the Spitzer Infrared Spectrograph (IRS) and also spectroscopy of the [CII]158μm line from the Herschel Photodetector Array Camera and Spectrometer (PACS). The emission line profiles of [NeII]12.81μm, [NeIII]15.55μm, and [CII]158μm are presented, and intrinsic line widths are determined (full width half maximum of Gaussian profiles after instrumental correction). All line profiles, together with overlays comparing the positions of PACS and IRS observations, are made available in the Cornell Atlas of Spitzer IRS Sources (CASSIS). Sources are classified from active galactic nucleus (AGN) to starburst based on equivalent widths of the 6.2μm polycyclic aromatic hydrocarbon feature. It is found that intrinsic line widths do not change among classifications for [CII], with median widths of 207km/s for AGNs, 248km/s for composites, and 233km/s for starbursts. The [NeII] line widths also do not change with classification, but [NeIII] lines are progressively broader from starburst to AGN. A few objects with unusually broad lines or unusual redshift differences in any feature are identified. (1 data file).

  14. Intelligent multi-spectral IR image segmentation

    NASA Astrophysics Data System (ADS)

    Lu, Thomas; Luong, Andrew; Heim, Stephen; Patel, Maharshi; Chen, Kang; Chao, Tien-Hsin; Chow, Edward; Torres, Gilbert

    2017-05-01

    This article presents a neural network based multi-spectral image segmentation method. A neural network is trained on the selected features of both the objects and background in the longwave (LW) Infrared (IR) images. Multiple iterations of training are performed until the accuracy of the segmentation reaches satisfactory level. The segmentation boundary of the LW image is used to segment the midwave (MW) and shortwave (SW) IR images. A second neural network detects the local discontinuities and refines the accuracy of the local boundaries. This article compares the neural network based segmentation method to the Wavelet-threshold and Grab-Cut methods. Test results have shown increased accuracy and robustness of this segmentation scheme for multi-spectral IR images.

  15. 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.

  16. 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.

  17. Relationship between Quantitative Adverse Plaque Features from Coronary CT Angiography and Downstream Impaired Myocardial Flow Reserve by 13N-Ammonia Positron Emission Tomography: A Pilot Study

    PubMed Central

    Dey, Damini; Zamudio, Mariana Diaz; Schuhbaeck, Annika; Orozco, Luis Eduardo Juarez; Otaki, Yuka; Gransar, Heidi; Li, Debiao; Germano, Guido; Achenbach, Stephan; Berman, Daniel S.; Meave, Aloha; Alexanderson, Erick; Slomka, Piotr J.

    2016-01-01

    Background We investigated the relationship of quantitative plaque features from coronary CT Angiography (CTA) and coronary vascular dysfunction by impaired myocardial flow reserve (MFR) by 13N-Ammonia Positron Emission Tomography (PET). Methods and Results Fifty-one patients (32 men, 62.4±9.5 years) underwent combined rest-stress 13N-ammonia PET and CTA scans by hybrid PET/CT. Regional MFR was measured from PET. From CTA, 153 arteries were evaluated by semi-automated software, computing arterial non-calcified plaque (NCP), low-density NCP (NCP<30 HU), calcified and total plaque volumes, and corresponding plaque burden (plaque volumex100%/vessel volume), stenosis, remodeling index, contrast density difference (maximum difference in luminal attenuation per unit area in the lesion), and plaque length. Quantitative stenosis, plaque burden and myocardial mass were combined by boosted ensemble machine-learning algorithm into a composite risk score to predict impaired MFR (MFR≤2.0) by PET, in each artery. Nineteen patients (37%) had impaired regional MFR in at least one territory, (41/153 vessels). Patients with impaired regional MFR had higher arterial NCP (32.4 vs.17.2 %), low-density NCP (7 vs 4 %) and total plaque burden (37 vs 19.3 %, p<0.02). In multivariable analysis with 10-fold cross-validation, NCP burden was the most significant predictor of impaired MFR (Odds Ratio 1.35, p=0.021). For prediction of impaired MFR with 10-fold cross-validation, receiver-operating-characteristics-area-under-the-curve for the composite score was 0.83 (95%CI:0.79–0.91), greater than for quantitative stenosis (0.66, 95%CI:0.57–0.76, p = 0.005). Conclusions Compared to stenosis, arterial NCP burden and a composite score combining quantitative stenosis and plaque burden from CTA significantly improves identification of downstream regional vascular dysfunction. PMID:26467104

  18. High-performance supported Ir-oxohydroxide water oxidation electrocatalysts.

    PubMed

    Massue, Cyriac; Pfeifer, Verena; Huang, Xing; Noack, Johannes; Tarasov, Andrey; Cap, Sebastien; Schlögl, Robert

    2017-02-05

    The synthesis of a highly active and yet stable electrocatalyst for the anodic oxygen evolution reaction (OER) remains a major challenge for acidic water splitting on an industrial scale. Addressing this challenge, we obtained an outstanding high-performance OER-electrocatalyst by loading Ir on conductive antimony-doped tin oxide (ATO)-nanoparticles via a microwave (MW)-supported hydrothermal route. The obtained Ir-phase was identified as an XRD-amorphous, highly hydrated Ir(III/IV)-oxohydroxide. In order to identify chemical and structural features responsible for the high activity and exceptional stability under acidic OER-conditions at loadings as low as 20 μg(Ir) cm-2, we used stepwise thermal treatment to gradually alter the XRD-amorphous Ir-phase via dehydroxylation and crystallization of IrO2. This resulted in dramatic depletion of OER-performance, indicating that the outstanding electrocatalytic properties of the MW-produced Ir(III/IV)-oxohydroxide are prominently linked to the nature of the produced Ir-phase. This finding is in contrast with the often reported stable but poor OER-performance of crystalline IrO2-based compounds produced via more classical calcination routes. Our investigation demonstrates the immense potential of Ir-oxohydroxide-based OER electrocatalysts for stable high-current water electrolysis under acidic conditions.

  19. Pulsed IR inductive lasers

    NASA Astrophysics Data System (ADS)

    Razhev, A. M.; Churkin, D. S.; Kargapol'tsev, E. S.

    2014-07-01

    Pulsed inductive discharge is a new alternative method of pumping active gas laser media. The work presents results of experimental investigations of near, mid, and far IR inductive gas lasers (H2, HF, and CO2) operating at different transitions of atoms and molecules with different mechanisms of formation of inversion population. The excitation systems of a pulsed inductive cylindrical discharge (pulsed inductively coupled plasma) and pulsed RF inductive discharge in the gases are developed. Various gas mixtures including H2, N2, He, Ne, F2, NF3, and SF6 are used. Characteristics of near IR H2 laser radiation are investigated. Maximal pulse peak power of 7 kW is achieved. The possibility of using a pulsed inductive discharge as a new method of pumping HF laser active medium is demonstrated. The pulsed RF inductive CO2 laser is created and a total efficiency of 17% is achieved.

  20. Dunes in IR

    NASA Image and Video Library

    2017-03-09

    This image captured by NASA's 2001 Mars Odyssey spacecraft shows an infrared image of Kaiser Crater and the dune field on the crater floor. Brighter tones in the image are warmer surfaces. The basaltic dunes are dark in the visible, but bright in infrared. Orbit Number: 66814 Latitude: -47.0992 Longitude: 19.782 Instrument: IR Captured: 2017-01-05 08:54 http://photojournal.jpl.nasa.gov/catalog/PIA21504

  1. IR Detectors Technology

    DTIC Science & Technology

    2007-11-02

    per response, including the time for reviewing instructions, searching existing data sources, gathering and maintaining the data needed, and...2 1. Introduction The final report summarizes the results of continuing research and development of CZT substrates for fabrication of IR focal...agreed, that tasks 3 and 4 will be done in the first half of September based on time availability of the polishing lab and the summary will be sent

  2. The VISTA IR camera

    NASA Astrophysics Data System (ADS)

    Dalton, Gavin B.; Caldwell, Martin; Ward, Kim; Whalley, Martin S.; Burke, Kevin; Lucas, John M.; Richards, Tony; Ferlet, Marc; Edeson, Ruben L.; Tye, Daniel; Shaughnessy, Bryan M.; Strachan, Mel; Atad-Ettedgui, Eli; Leclerc, Melanie R.; Gallie, Angus; Bezawada, Nagaraja N.; Clark, Paul; Bissonauth, Nirmal; Luke, Peter; Dipper, Nigel A.; Berry, Paul; Sutherland, Will; Emerson, Jim

    2004-09-01

    The VISTA IR Camera has now completed its detailed design phase and is on schedule for delivery to ESO"s Cerro Paranal Observatory in 2006. The camera consists of 16 Raytheon VIRGO 2048x2048 HgCdTe arrays in a sparse focal plane sampling a 1.65 degree field of view. A 1.4m diameter filter wheel provides slots for 7 distinct science filters, each comprising 16 individual filter panes. The camera also provides autoguiding and curvature sensing information for the VISTA telescope, and relies on tight tolerancing to meet the demanding requirements of the f/1 telescope design. The VISTA IR camera is unusual in that it contains no cold pupil-stop, but rather relies on a series of nested cold baffles to constrain the light reaching the focal plane to the science beam. In this paper we present a complete overview of the status of the final IR Camera design, its interaction with the VISTA telescope, and a summary of the predicted performance of the system.

  3. Tunable plasmonic emission of radiation in graphene

    NASA Astrophysics Data System (ADS)

    Atwater, Harry

    2015-03-01

    Materials at finite temperatures emit electromagnetic radiation due to the thermally induced motion of particles and quasiparticles. The radiated power is dictated by the electromagnetic energy density and emissivity, which are ordinarily fixed properties of the material and temperature. Recent experiments have shown, however, that the emissivity of a material may be modified through surface patterning to allow for thermal radiation that is coherent, unidirectional and spectrally narrow. We show that electronically tunable, dynamic control of emissivity can be achieved in blackbody radiators whose surface is coated with a thin layer of variable emissivity. Specifically, we experimentally demonstrate tunable electronic control of blackbody emission from graphene plasmonic resonators on a silicon nitride substrate at temperatures up to 250° C. We show that the graphene resonators produce antenna-coupled blackbody radiation, manifest as narrow spectral emission peaks in the mid-IR. By continuously varying the nanoresonator carrier density, the frequency and intensity of these spectral features can be modulated via an electrostatic gate. We describe these phenomena as plasmonically enhanced radiative emission originating from loss channels associated with both plasmon decay in the graphene sheet and from vibrational modes in the SiNx. This work opens the door for future devices that may control blackbody radiation at timescales beyond the limits of conventional thermo-optic modulation.

  4. Rabe Crater Dunes IR

    NASA Image and Video Library

    2009-10-20

    The Thermal Emission Imaging System aboard NASA Mars Odyssey captured this daytime infrared image of Rabe Crater shows the large dune field located within the crater. Note that the dunes are not confined to the lowest elevation depressions on the

  5. 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 ⊙.

  6. 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.

  7. Symbolic fusion of MMW and IR imagery

    NASA Astrophysics Data System (ADS)

    Eggleston, Peter A.; Kohl, Charles A.

    1988-01-01

    This paper describes the software architecture used to construct a multisensor knowledge-based Autonomous Target Recognizer (ATR). An Intermediate Symbolic Representation (SR) of processed data is employed to provide a very powerful method of associative access over data events and their features, thereby supporting data fusion algorithms at the symbolic level. This architecture supports data fusion from multiple sensors, and its operation is described here using MMW range and IR intensity data.

  8. Symbolic Fusion Of MMW And IR Imagery

    NASA Astrophysics Data System (ADS)

    Eggleston, Peter A.; Kohl, Charles A.

    1989-01-01

    This paper describes the software architecture used to construct a multi-sensor knowledge-based Autonomous Target Recognizer (ATR). An Intermediate Symbolic Representation (ISR) of processed data is employed to provide a very powerful method of associative access over data events and their features, thereby supporting data fusion algorithms at the symbolic level. This architecture supports data fusion from multiple sensors, and its operation is described here using MMW range and IR intensity data.

  9. IR Earth Flats Pathfinder

    NASA Astrophysics Data System (ADS)

    McCullough, Peter

    2009-07-01

    This program is an experimental path finder for Cycle 18 calibration. {The WFC3 UVIS version of this is program 11914 and contains additional detail in its description}. Infrared-wavelength flat fields will be obtained by observing the dark side of the Earth during periods of full moon illumination. The observations will consist of full-frame streaked WFC3 IR imagery: per single "dark-sky" orbit, we anticipate achieving Poisson S/N > 100 per pixel in each of three to five exposures, depending on sample sequence {SPARS25 or SPARS50}.Why not use the Sunlit Earth? It is too bright for WFC3 IR full-frame minimum exposure time of 3 sec. Similarly, for NICMOS the sunlit-Earth is too bright which saturates the detector too quickly and/or induces abnormal behaviors such as super-shading {Gilmore 1998, NIC 098-011}. In the narrowband IR filters the sunlit earth sometimes is faint enough to not saturate immediately, but based upon predictions {Cox et al. 1987 "Standard Astronomical Sources for HST: 6. Spatially Flat Fields."} and observations {Gilmore 1998}, we consider sunlit Earth unlikely to be successful unless it is twilight.Other possibilities? Cox et al.'s Section II.D addresses many other possible sources for flat fields, rejecting them for a variety of reasons. A remaining possibility would be the totally eclipsed moon. Such eclipses provide approximately 2 hours {1 HST orbit} of opportunity per year, so they are too rare to be generically useful. An advantage of the moon over the Earth is that the moon subtends less than 0.25 square degree, whereas the Earth subtends a steradian or more, so scattered light and light prior to the unshuttered exposure presents additional problems for the Earth. Also, we're unsure if HST can point 180 deg from the Sun.

  10. 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.

  11. 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.

  12. 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.

  13. IR polarimetry and far-IR imaging

    NASA Astrophysics Data System (ADS)

    McMillan, Robert W.; Kirkland, James H.; Milton, Osborne J., Jr.; Holder, E. J.

    2004-10-01

    The exploitation of infrared polarimetry has been shown to yield good results when applied to target discrimination in military applications and to civilian remote sensing problems. Similarly, numerous workers have shown that imaging sensors operating in the far infrared spectral bands may be useful in such counter-terror applications as concealed weapon and biological and chemical agent detection. Unfortunately, these detection and discrimination techniques have not been exploited because of the lack of suitable sensors capable of making the necessary measurements with acceptable sensitivity. In this paper we present and discuss several methods for measuring the polarization signature of a target scene using sensors with no moving parts. We also present and analyze a far infrared imaging system based on an uncooled bolometer focal plane array. The methods of measuring polarization signature with no moving parts include a coherent in-phase and quadrature approach suitable for both broad- and narrow-band sensors, a broadband sensor using channeled spectropolarimetry, a variant of this latter method that involves correlation of the spectral signatures with those of known targets, and another variant that uses an electro-optic or an acousto-optic modulator. A focal plane array of uncooled bolometers has been proposed before as a far infrared imaging system. One problem with such devices is that they are not sensitive enough to detect the low-intensity emission from a room-temperature blackbody in the far infrared bands. A potential solution to this problem is to use a high- or low-temperature blackbody to illuminate the scene to be imaged. In this paper, methods of measuring the infrared polarimetric signature and the far-infrared spatial signature of a scene will be presented and discussed.

  14. 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.

  15. 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.

  16. 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.

  17. 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.

  18. 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

  19. 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

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

    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.

  20. 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.

  1. Spatial Variations of PAH Properties in M17SW Revealed by Spitzer/IRS Spectral Mapping

    NASA Astrophysics Data System (ADS)

    Yamagishi, M.; Kaneda, H.; Ishihara, D.; Oyabu, S.; Suzuki, T.; Onaka, T.; Nagayama, T.; Umemoto, T.; Minamidani, T.; Nishimura, A.; Matsuo, M.; Fujita, S.; Tsuda, Y.; Kohno, M.; Ohashi, S.

    2016-12-01

    We present Spitzer/IRS mid-infrared spectral maps of the Galactic star-forming region M17 as well as IRSF/SIRIUS Brγ and Nobeyama 45 m/FOREST 13CO (J = 1-0) maps. The spectra show prominent features due to polycyclic aromatic hydrocarbons (PAHs) at wavelengths of 6.2, 7.7, 8.6, 11.3, 12.0, 12.7, 13.5, and 14.2 μm. We find that the PAH emission features are bright in the region between the H ii region traced by Brγ and the molecular cloud traced by 13CO, supporting that the PAH emission originates mostly from photo-dissociation regions. Based on the spatially resolved Spitzer/IRS maps, we examine spatial variations of the PAH properties in detail. As a result, we find that the interband ratio of PAH 7.7 μm/PAH 11.3 μm varies locally near M17SW, but rather independently of the distance from the OB stars in M17, suggesting that the degree of PAH ionization is mainly controlled by local conditions rather than the global UV environments determined by the OB stars in M17. We also find that the interband ratios of the PAH 12.0 μm, 12.7 μm, 13.5 μm, and 14.2 μm features to the PAH 11.3 μm feature are high near the M17 center, which suggests structural changes of PAHs through processing due to intense UV radiation, producing abundant edgy irregular PAHs near the M17 center.

  2. Reprocessing WFC3/IR Exposures Affected by Time-Variable Backgrounds

    NASA Astrophysics Data System (ADS)

    Brammer, G.

    2016-11-01

    The background seen in WFC3/IR observations frequently shows strong time-dependent behavior above the constant flux expected for zodiacal continuum light. This is often caused by an emission line of helium at 1.083 μm excited in the sun-illuminated upper atmosphere, when seen in the filters (F105W, F110W) and grisms (G102, G141) sensitive to the feature. The default behavior of the calwf3 pipeline assumes constant source-plus-background fluxes when it performs up-the-ramp fitting to identify cosmic rays and determine the average count rate within a MULTIACCUM IR exposure. calwf3 provides undesirable results in the presence of strongly variable backgrounds, primarily in the form of elevated and non-Gaussian noise in the FLT products. Here we describe methods to improve the noise properties of the reduced products. In the first, we simply turn off the calwf3 crcorr step, treating the IR detector as if it were a CCD, i.e., accumulating flux and reading it out at the end of the exposure. Next, we artificially flatten the ramps in the IMA products and then allow calwf3 to proceed as normal fitting the ramp and identifying CRs. Either of these procedures enable recovery of datasets otherwise corrupted beyond repair and have no discernible effects on photometry of sources in deep combined images.

  3. Far-ir Spectroscopy Of Various Mineral Groups: Providing Laboratory Data For Herschel

    NASA Astrophysics Data System (ADS)

    Brusentsova, Tatyana; Peale, R.; Maukonen, D.; Figueiredo, P.; Harlow, G.; Ebel, D.; Lisse, C.

    2011-01-01

    To aid in interpreting data from Herschel Space Observatory Photodetector Array Camera and Spectrometer (PACS), we have collected mass absorption coefficient spectra in the wavelength range 15 to 250 micron of micron-sized powders for more than 140 mineral species representing various mineral groups. Mineral groups investigated included nesosilicates (olivines, garnets, phenakite), inosilicates (pyroxenes, pyroxenoids, amphiboles), sorosilicates, cyclosilicates, tectosilicates (silicas, feldspars), phyllosilicates, carbonates, sulfides, and oxides. The mineral samples were selected from AMNH mineral collection, chemical and crystallographic identity of all minerals was confirmed by means of electron microprobe and grain and powder XRD. Samples were ground to micron dimensions and the micron size distribution was ensured by Stokes settling, verified by scanning electron microscopy. Milligram quantities of mineral sample were dispersed in polyethylene powder and melted into pellets. Spectra were collected using a Fourier spectrometer with globar source, mylar beamsplitter, and a 4 K bolometer. Temperature dependence of the spectra down to 15 K revealed sharpening and blue-shifts of the characteristic absorption lines, and in some cases, resolution of additional features not seen at room temperature. Mineral spectra in the far-IR region are highly characteristic of mineral group, crystal structure and chemical composition. The spectral data obtained in this study, together with the accompanying mineral characterization data, will be added to Planetary Data System database to be used for mineral identification in cosmic dust populations, based on far-IR emission spectra of collected by Herschel and similar space IR missions.

  4. 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

  5. Coherent IR radar technology

    NASA Astrophysics Data System (ADS)

    Gschwendtner, A. B.; Harney, R. C.; Hull, R. J.

    Recent progress in the development of coherent IR radar equipment is reviewed, focusing on the Firepond laser radar installation and the more compact systems derived for it. The design and capabilities of Firepond as a long-range satellite-tracking device are outlined. The technological improvements necessary to make laser radar mobile are discussed: a lightweight, stable 5-10-W transmitter laser for both CW and pulsed operation, a 12-element HgCdTe detector array, an eccentric-pupil Ritchey-Chretien telescope, and a combination of near-field phase modification and anamorphic expansion to produce a fan beam of relatively uniform intensity. Sample images obtained with a prototype system are shown, and the applicability of the mobile system to range-resolved coherent DIAL measurement is found to be similar to that of a baseline DIAL system.

  6. 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.

  7. IR line scanner on UAV

    NASA Astrophysics Data System (ADS)

    Liu, Shi-chao; Qin, Jie-xin; Qi, Hong-xing; Xiao, Gong-hai

    2011-08-01

    This paper introduces the designing principle and method of the IR line scanner on UAV in three aspects of optical-mechanical system, electronics system and processing software. It makes the system achieve good results in practical application that there are many features in the system such as light weight, small size, low power assumption, wide field of view, high instantaneous field of view, high noise equivalent temperature difference, wirelessly controlled and so on. The entire system is designed as follows: Multi-element scanner is put into use for reducing the electrical noise bandwidth, and then improving SNR; Square split aperture scanner is put into use for solving the image ratation distortion, besides fit for large velocity to height ratio; DSP is put into use for non-uniformity correction and background nosie subtraction, and then improving the imagery quality; SD card is put into use as image data storage media instead of the hard disk; The image data is stored in SD card in FAT32 file system, easily playbacked by processing software on Windows and Linux operating system; wireless transceiver module is put into use for wirelessly controlled.

  8. Test chamber for low-background IR focal plane testing

    NASA Technical Reports Server (NTRS)

    Staller, Craig; Capps, Richard W.; Butler, Douglas; Moss, Nancy; Norwood, Wynn

    1989-01-01

    A unique and versatile vacuum chamber has been designed for JPL's IR Focal Plane Technology Group. This chamber is equipped with multiple ports for cryogen and electrical vacuum feedthroughs, pumping units, vacuum gages, sources, and detector camera heads. The design incorporates a liquid-nitrogen-cooled optical table and radiation shield for low-background IR detector testing. Focal planes can be tested at temperatures ranging from 300 K to that of liquid helium. This paper describes the design and construction of this low-background IR focal plane test chamber and discusses some of its distinctive features. An analysis of the test chamber's performance is also presented.

  9. SPITZER'S VIEW ON AROMATIC AND ALIPHATIC HYDROCARBON EMISSION IN HERBIG Ae STARS

    SciTech Connect

    Acke, B.; Waters, L. B. F. M.; Bouwman, J.; Juhasz, A.; Henning, Th.; Van den Ancker, M. E.; Meeus, G.; Tielens, A. G. G. M.

    2010-07-20

    The chemistry of astronomical hydrocarbons, responsible for the well-known infrared emission features detected in a wide variety of targets, remains enigmatic. Here we focus on the group of young intermediate-mass Herbig Ae stars. We have analyzed the aliphatic and polycyclic aromatic hydrocarbon (PAH) emission features in the infrared spectra of a sample of 53 Herbig Ae stars, obtained with the Infrared Spectrograph aboard the Spitzer Space Telescope. We confirm that the PAH-to-stellar luminosity ratio is higher in targets with a flared dust disk. However, a few sources with a flattened dust disk still show relatively strong PAH emission. Since PAH molecules trace the gas disk, this indicates that gas disks may still be flared, while the dust disk has settled due to grain growth. There are indications that the strength of the 11.3 {mu}m feature also depends on dust disk structure, with flattened disks being less bright in this feature. We confirm that the CC bond features at 6.2 and 7.8 {mu}m shift to redder wavelengths with decreasing stellar effective temperature. Moreover, we show that this redshift is accompanied by a relative increase of aliphatic CH emission and a decrease of the aromatic 8.6 {mu}m CH feature strength. Cool stars in our sample are surrounded by hydrocarbons with a high aliphatic/aromatic CH ratio and a low aromatic CH/CC ratio, and vice versa for the hot stars. We conclude that, while the overall hydrocarbon emission strength depends on the dust disk's geometry, the relative differences seen in the IR emission features in disks around Herbig Ae stars are mainly due to chemical differences of the hydrocarbon molecules induced by the stellar UV field. Strong UV flux reduces the aliphatic component and emphasizes the spectral signature of the aromatic molecules in the IR spectra.

  10. ALMA and VLA observations of emission from the environment of Sgr A*

    NASA Astrophysics Data System (ADS)

    Yusef-Zadeh, F.; Schödel, R.; Wardle, M.; Bushouse, H.; Cotton, W.; Royster, M. J.; Kunneriath, D.; Roberts, D. A.; Gallego-Cano, E.

    2017-10-01

    We present 44 and 226 GHz observations of the Galactic Centre within 20 arcsec of Sgr A*. Millimetre continuum emission at 226 GHz is detected from eight stars that have previously been identified at near-IR and radio wavelengths. We also detect a 5.8 mJy source at 226 GHz coincident with the magnetar SGR J1745-29 located 2.39 arcsec SE of Sgr A* and identify a new 2.5 arcsec × 1.5 arcsec halo of mm emission centred on Sgr A*. The X-ray emission from this halo has been detected previously and is interpreted in terms of a radiatively inefficient accretion flow. The mm halo surrounds an EW linear feature that appears to arise from Sgr A* and coincides with the diffuse X-ray emission and a minimum in the near-IR extinction. We argue that the millimetre emission is produced by synchrotron emission from relativistic electrons in equipartition with an ˜1.5 mG magnetic field. The origin of this is unclear but its coexistence with hot gas supports scenarios in which the gas is produced by the interaction of winds either from the fast moving S-stars, the photoevaporation of low-mass YSO discs or by a jet-driven outflow from Sgr A*. The spatial anti-correlation of the X-ray, radio and mm emission from the halo and the low near-IR extinction provides a compelling evidence of an outflow sweeping up the interstellar material, creating a dust cavity within 2 arcsec of Sgr A*. Finally, the radio and mm counterparts to eight near-IR identified stars within ˜10 arcsec of Sgr A* provide accurate astrometry to determine the positional shift between the peak emission at 44 and 226 GHz.

  11. High-resolution radio emission from RCW 49/Westerlund 2

    NASA Astrophysics Data System (ADS)

    Benaglia, P.; Koribalski, B.; Peri, C. S.; Martí, J.; Sánchez-Sutil, J. R.; Dougherty, S. M.; Noriega-Crespo, A.

    2013-11-01

    Aims: The HII region RCW 49 and its ionizing cluster form an extensive, complex region that has been widely studied at infrared (IR) and optical wavelengths. The Molonglo 843 MHz and Australia Telescope Compact Array data at 1.4 and 2.4 GHz showed two shells. Recent high-resolution IR imaging revealed a complex dust structure and ongoing star formation. New high-bandwidth and high-resolution data of the RCW 49 field have been obtained to survey the radio emission at arcsec scale and investigate the small-scale features and nature of the HII region. Methods: Radio observations were collected with the new 2-GHz bandwidth receivers and the CABB correlator of the Australia Telescope Compact Array [ATCA], at 5.5 and 9.0 GHz. In addition, archival observations at 1.4 and 2.4 GHz have been re-reduced and re-analyzed in conjunction with observations in the optical, IR, X-ray, and gamma-ray regimes. Results: The new 2-GHz bandwidth data result in the most detailed radio continuum images of RCW 49 to date. The radio emission closely mimics the near-IR emission observed by Spitzer, showing pillars and filaments. The brightest continuum emission comes from the region known as the bridge. The overall flattish spectral index is typically consistent with a free-free emission mechanism. However, hints of nonthermal components are also present in the bridge. An interesting jet-like structure surrounded by a bubble feature whose nature is still unclear has been discovered close to the Westerlund 2 core. Two apparent bow shocks and a number of discrete sources have been detected as well in the surroundings of RCW 49. In addition, we also report on and discuss the possible detection of a hydrogen recombination line. Conclusions: The radio results support an association between the cm continuum and molecular emission. The detection of the radio recombination line kinematically favors a RCW 49 distance of 6-7 kpc. If the negative spectral indices measured at the bridge should be

  12. Nature of radio feature formed by re-started jet activity in 3C 84 and its relation with γ-ray emissions

    NASA Astrophysics Data System (ADS)

    Nagai, H.; Chida, H.; Kino, M.; Orienti, M.; D'Ammando, F.; Giovannini, G.; Hiura, K.

    2016-02-01

    Re-started jet activity occurred in the bright nearby radio source 3C 84 in about 2005. The re-started jet is forming a prominent component (namely C3) at the tip of jet. The component has showed an increase in radio flux density for more than 7 years while the radio spectrum remains optically thin. This suggests that the component is the head of a radio lobe including a hotspot where the particle acceleration occurs. Thus, 3C 84 is a unique laboratory to study the physical properties at the very early stage of radio source evolution. Another important aspect is that high energy and very high energy γ-ray emissions are detected from this source. The quest for the site of γ-ray emission is quite important to obtain a better understanding of γ-ray emission mechanisms in radio galaxies. In this paper, we review the observational results from very long baseline interferometry (VLBI) monitoring of 3C 84 reported in series of our previous papers. We argue the nature of re-started jet/radio lobe and its relation with high-energy emission.

  13. 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.

  14. Monitoring corneal hydration with a mid-infrared (IR) laser.

    PubMed

    Joshi, Abhijeet; Bennett, David B; Stafsudd, Oscar M

    2015-01-01

    A mid-infrared (IR) source at ∼ 3 μm radiation is used as a probe to measure hydration in porcine cornea. Since the Er(3+):YAG emission targets vibrational modes (around 3300 cm(-1)) in the H2O molecule, it is highly sensitive to changes in water content in the first ∼ 10 μm of the corneal tissue.

  15. 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.

  16. 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.

  17. 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.

  18. 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.

  19. 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.

  20. 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.

  1. New infrared observations of IRS1, IRS3 and the adjacent nebula in the OMC-2 cluster

    NASA Technical Reports Server (NTRS)

    Pendleton, Y.; Werner, M.; Capps, R.; Dinerstein, H. L.

    1984-01-01

    Near infrared reflection nebulae are often observed around embedded protostellar objects. New observations of the infrared cluster of low luminosity protostars in Orion Molecular Cloud 2 (OMC2) are reported. The asymmetric distribution of the extended emission seen about IRS1 is in fact another infrared reflection nebulae. Observations of near infrared polarimetry, photometry, and spectrophotometry were carried out.

  2. Oxide films state analysis by IR spectroscopy based on the simple oscillator approximation

    NASA Astrophysics Data System (ADS)

    Volkov, N. V.; Yakutkina, T. V.; Karpova, V. V.

    2017-05-01

    Stabilization of structure-phase state in a wide temperature range is one of the most important problems of improving properties of oxide compounds. As such, the search of new effective methods for obtaining metal oxides with desired physic-chemical, electro-physical and thermal properties and their control is important and relevant. The aim of this work is identification features state of the oxide films of some metals Be, Al, Fe, Cu, Zr on the metal surface of the polycrystalline samples by infrared spectroscopy. To identify the resonance emission bands the algorithm of IR-spectra processing was developed and realized on the basis of table processor EXCEL-2010, which allow revealing characteristic resonance bands successfully and identification of inorganic chemical compounds. In the frame of simple oscillator model, resonance frequencies of normal vibrations of water and some inorganic compounds: metal oxides - Be, Al, Fe, Cu, Zr were calculated and characteristic frequencies for different states (aggregate, deformation, phase) were specified. By means of IR-spectroscopy fundamental possibility of revealing oxides films on metal substrate features state is shown, that allow development and optimization of the technology for production of the oxide films with desired properties.

  3. DETECTION OF THE 3.3 {mu}m AROMATIC FEATURE IN THE SUPERNOVA REMNANT N49 WITH AKARI

    SciTech Connect

    Seok, Ji Yeon; Koo, Bon-Chul; Onaka, Takashi

    2012-01-10

    We present an infrared (IR) study of the supernova remnant (SNR) N49 in the Large Magellanic Cloud with the near-IR (NIR; 2.5-5 {mu}m) spectroscopic observations performed by AKARI. The observations were performed as a coarse spectral mapping to cover most of the bright region in the east, which enables us to compare the distribution of various line emissions and to examine their correlation. We detect the 3.3 {mu}m aromatic feature in the remnant, which is the first time the presence of the 3.3 {mu}m aromatic feature related to an SNR has been reported. In the line maps of the H{sub 2} 1-0 O(3), the 3.3 {mu}m feature, and the Br{alpha}, the distribution of the aromatic feature shows overall correlation with those of other emissions together with regional differences that reflect the local physical conditions. By comparing other archival imaging data at different wavelengths, the association of the aromatic emission with other ionic/molecular emissions is clarified. We examine the archival Spitzer Infrared Spectrograph data of N49 and find signatures of other polycyclic aromatic hydrocarbon (PAH) features at 6.2, 7.7, and 11.3 {mu}m corresponding to the 3.3 {mu}m aromatic feature. Based on the band ratios of the PAHs, we find that the PAHs in N49 are not only dominantly neutral, but they are also small in size. We discuss the origin of the PAH emission in N49 and conclude that the emission is either from the PAHs that have survived the shock or from the PAHs in the preshock gas that was heated by the radiative precursor.

  4. Radio and gamma ray evidence for a molecular-arm feature at 5 kpc from the galactic centre. [observing galactic longitude of CO emission

    NASA Technical Reports Server (NTRS)

    Solomon, P. M.; Stecker, F. W.

    1974-01-01

    Recent measurements of the galactic CO distribution as evidenced from 2.6 mm radio observations of the CO emission line intensity are correlated with the SAS-2 measurements of galactic gamma ray emission. Both distributions are indicative of a ring-shaped distribution or arm consisting of cool clouds of molecular hydrogen at a galactocentric distance of approximately 5 kpc. The mean density of H2 in this region is estimated to be between 1 and 5 cu cm. Both a galactic and extra-galactic origin of cosmic rays are consistent with the observations, although the presence of dynamical effects and increased star formation at 5 kpc in the dense molecular clouds may be connected with an increase in cosmic-ray production.

  5. MMW/IR beam combiner with graphene IR window for MMW/IR compact range compound test

    NASA Astrophysics Data System (ADS)

    Chen, Dong; Li, Yanhong; Pang, Xudong; Zhu, Weihua; Wang, Liquan; Liu, Zhigang; Wang, Tailei; Zhu, Shouzheng

    2017-06-01

    A millimeter wave (MMW)/infrared (IR) beam combiner with a graphene IR window for the MMW/IR compact range (CR) compound test is creatively proposed with comprehensive analysis and simulation. Graphene is used as the IR window material to transfer the IR feed signal behind a perforated MMW CR reflector for it has the unique property of high IR transmissivity and high MMW conductivity. This research shows that graphene IR windows have better IR transmissivity than conducting inductive mesh IR windows when the beam combiner meets the MMW CR test demanding. Graphene IR windows also show a better MMW test bandwidth than dielectric IR windows. Meanwhile, the graphene IR window MMW/IR beam combiner has a circular aperture test zone with which it is sufficient to test a cylindrical unit under test according to the requirement.

  6. Spitzer-IRS High-Resolution Spectroscopy of the 12 μm Seyfert Galaxies. II. Results for the Complete Data Set

    NASA Astrophysics Data System (ADS)

    Tommasin, Silvia; Spinoglio, Luigi; Malkan, Matthew A.; Fazio, Giovanni

    2010-02-01

    We present our Spitzer-Infrared Spectrometer (IRS) spectroscopic survey from 10 μm to 37 μm of the Seyfert galaxies of the 12 μm Galaxy Sample, collected in a high-resolution mode (R ~ 600). The new spectra of 61 galaxies, together with the data we already published, give us a total of 91 12 μm Seyfert galaxies observed, out of 112. We discuss the mid-IR emission lines and features of the Seyfert galaxies, using an improved active galactic nucleus (AGN) classification scheme: instead of adopting the usual classes of Seyfert 1's and Seyfert 2's, we use the spectropolarimetric data from the literature to divide the objects into categories "AGN 1" and "AGN 2," where AGN 1's include all broad-line objects, including the Seyfert 2's showing hidden broad lines in polarized light. The remaining category, AGN 2's, contains only Seyferts with no detectable broad lines in either direct or polarized spectroscopy. We present various mid-IR observables, such as ionization-sensitive and density-sensitive line ratios, the polycyclic aromatic hydrocarbon (PAH) 11.25 μm feature and the H2 S(1) rotational line equivalent widths (EWs), the (60-25 μm) spectral index, and the source extendedness at 19 μm, to characterize similarities and differences in the AGN populations, in terms of AGN dominance versus star formation dominance. We find that the mid-IR emission properties characterize all the AGN 1's objects as a single family, with strongly AGN-dominated spectra. In contrast, the AGN 2's can be divided into two groups, the first one with properties similar to the AGN 1's except without detected broad lines, and the second with properties similar to the non-Seyfert galaxies, such as LINERs or starburst galaxies. We computed a semianalytical model to estimate the AGN and the starburst contributions to the mid-IR galaxy emission at 19 μm. For 59 galaxies with appropriate data, we can separate the 19 μm emission into AGN and starburst components using the measured mid-IR

  7. 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.

  8. IR Optical Wave Guide

    DTIC Science & Technology

    1976-05-01

    thereby avoiding oxygen contamination. Oxygen contamination in the tip area during drawing did K ,j" not present a problem because of short exposure...increasing temperature upward through the reservoir region. The latter feature prevents convection in the glasses; thus, the fibers are pulled from...speed d.c. motor at surface rates ranging from 160 to 1460 cm/sec. Timing belt drives were utilized to prevent slippage. Surface velocities were measured

  9. Divergent Roles of IRS (Insulin Receptor Substrate) 1 and 2 in Liver and Skeletal Muscle.

    PubMed

    Eckstein, Sabine Sarah; Weigert, Cora; Lehmann, Rainer

    2017-01-01

    IRS1 and IRS2 are the most important representatives of the IRS protein family and critical nodes in insulin/IGF1-signaling. Although they are quite similar in their structural and functional features they show tissue-specific differences. In this review, we outline the functions of IRS1 and IRS2 in skeletal muscle and liver with regard to their importance for metabolism, growth and differentiation. Mechanisms contributing to IRS1 and IRS2 dysregulation in disease states as well as consequences thereof are discussed. IRS1 plays the dominant role in skeletal muscle. It is crucial for normal growth and differentiation of myofibers, insulin-dependent glucose uptake and glycogen synthesis. The presence of IRS2 in skeletal muscle is negligible for insulin-induced glucose uptake and the general role of IRS2 in muscle is still not fully understood. In liver IRS1 and IRS2 are important to mediate insulindependent regulation of glucose and lipid metabolism and complement each other in the diurnal regulation thereof. IRS1 in the liver is more important for signaling in the late refeeding period, whereas IRS2 signaling is mostly dominating in the period directly after food intake and during fasting. Importantly, the expression level of IRS1 and IRS2 is different within the liver lobule, which could be an explanation for the phenomenon of selective insulin resistance. Dysregulated muscular or hepatic abundance and/or phosphorylation status of IRS1 and IRS2 are important factors in the pathogenesis of insulin resistance, type 2 diabetes and muscle wasting. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.

  10. Lack of Arg972 polymorphism in the IRS1 gene in Parakanã Brazilian Indians.

    PubMed

    Bezerra, Rosângela M N; Chadid, Thiago T; Altemani, Claúdia M; Sales, Teresa S I; Menezes, Raimundo; Soares, Manoel C P; Saad, Sara T O; Saad, Mario J A

    2004-02-01

    Several polymorphisms in the insulin receptor substrate-1 (IRS1) gene have been reported in the last years. The most common IRS1 variant, a Gly --> Arg substitution at codon 972 (Arg972 IRS1), is more prevalent among subjects who have features of insulin resistance syndrome associated, or not, with type 2 diabetes in European populations. To determine whether the absence of IRS1 polymorphism is a more general characteristic of Paleo-Indian-derived populations, we examined the Arg972 IRS1 polymorphism in Parakanã Indians and found a lack of this polymorphism in the Parakanã population.

  11. The NASA Ames PAH IR Spectroscopic Database: A Demo of its Contents and Web Tools

    NASA Astrophysics Data System (ADS)

    Boersma, Christiaan; Sánchez de Armas, F.; Ricca, A.; Cami, J.; Peeters, E.; Mattioda, A. L.; Bauschlicher, C. W., Jr.; Allamandola, L. J.

    2009-01-01

    The features formerly known as the Unidentified Infrared (UIR) Emission Bands are now generally attributed to polycyclic aromatic hydrocarbons (PAHs). Exploitation of these features as astrophysical and astrochemical probes requires the IR properties of PAHs under interstellar conditions. To fulfill this need, we experimentally measured and theoretically computed the 2-2000 µm spectra of many PAHs over the past 18 years at NASA's Ames Research Center. Today's collection comprises about 600 theoretically computed and 60 laboratory measured spectra of PAHs in different forms. The molecules in the collection range in size from C10H8 to C130H28. For most of these, spectra are available for PAHs in their neutral and singly charged (+/-) states. In some cases, IR spectra of multiply charged species were also computed. The database includes pure PAHs; PAHs containing nitrogen (PANHs), oxygen, and silicon; PAHs with side groups; PAHs with extra hydrogens; and PAHs complexed with iron and magnesium. This collection of PAH spectra from 2 - 2000 µm has been assembled into a uniform database, which we will make publicly available on the web in early 2009. A WebGUI interface has been developed that can effectively interrogate the database using a variety of queries, such as formula, molecular name, charge, specific number of atoms, etc. Several molecules can be selected in such a process and one can obtain their 3-D structures, plot and co-add their spectra, adjust parameters such as the bandwidth, download their data and print graphs. The database can also be downloaded as a whole and IDL-routines are provided to interrogate it. This talk will present an overview of the contents and the web-GUI tools of the NASA Ames PAH IR Spectroscopic Database. Hands-on demonstrations will be available at the SOFIA Booth.

  12. Optical properties of PbIn6Te10 in the long-wave IR

    NASA Astrophysics Data System (ADS)

    Andreev, Yu M.; Badikov, V. V.; Ionin, A. A.; Kinyaevskiy, I. O.; Klimachev, Yu M.; Kotkov, A. A.; Lanskii, G. V.; Svetlichnyi, V. A.

    2016-12-01

    Optical properties of nonlinear PbIn6Te10 (PIT) crystal were studied for the first time within 30-1200 µm (0.2-15 THz) by FTIR and THz-TDS. It was found that PIT possesses the most attractive transparency features for efficient generation of long-wave mid-IR emission including 20-60 µm (5-15 THz) region by optical rectification. This crystal is also found useful for phase matched DFG generation into the long-wave THz region. In particular, by model study phase matched down-conversion of CO and CO2 laser lines into 130-1200 µm (0.3-2.3 THz) range is shown possible by ooe and eoe type of three wave interaction. Noncritical 90° phase matching for eoe type of interactions can be realized by selecting samples with specified composition.

  13. 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

  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; techni