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.

Infrared spectroscopy of dense clouds in the C-H stretch region - Methanol and 'diamonds'

NASA Technical Reports Server (NTRS)

Allamandola, L. J.; Sandford, S. A.; Tielens, A. G. G. M.; Herbst, T. M.

1992-01-01

The paper presents high spectral resolution studies in the 3100-2600/cm range of the protostars NGC 7538 IRS9, W33A, W3 IRS 5, and S140 IRS 1. Well-resolved absorption bands at about 2825/cm and 2880/cm were found superposed on the LF wing of the strong O-H stretch feature. The 2880/cm band, previously detected toward W33A, is also in the spectrum of NGC 7538 IRS 9. The relative strength of these two bands varies, showing that they are associated with two different carriers. The new band at about 2880/cm falls near the position of C-H stretching vibrations in tertiary carbon atoms. The strength of this feature, in combination with the lack of strong features associated with primary and secondary carbon atoms, suggests that the carrier of the new feature has a diamondlike structure. This new feature is tentatively attributed to interstellar 'diamonds'. The detection of this band in the spectra of all four dense molecular clouds suggests that the carrier is ubiquitous in dense clouds.

Redistribution of Lunar Polar Water to Mid-latitudes and Its Role in Forming an OH Veneer

NASA Technical Reports Server (NTRS)

Farrell, William M.; Hurley, D. M.; Hodges, R. R.; Killen, R. M.; Halekas, J. S.; Zimmerman, M. I.; Delory, G. T.

2013-01-01

We suggest that energization processes like ion sputtering and impact vaporization can eject/release polar water molecules residing within cold trapped regions with sufficient velocity to allow their redistribution to mid-latitudes. We consider the possibility that these polar-ejected molecules can contribution to the water/OH veneer observed as a 3 micrometer IR absorption feature at mid-latitudes by Chandrayaan-1, Cassini, and EPOXI. We find this source cannot fully account for the observed IR feature, but could be a low intensity additional source.

Quantitative IR microscopy and spectromics open the way to 3D digital pathology.

PubMed

Bobroff, Vladimir; Chen, Hsiang-Hsin; Delugin, Maylis; Javerzat, Sophie; Petibois, Cyril

2017-04-01

Currently, only mass-spectrometry (MS) microscopy brings a quantitative analysis of chemical contents of tissue samples in 3D. Here, the reconstruction of a 3D quantitative chemical images of a biological tissue by FTIR spectro-microscopy is reported. An automated curve-fitting method is developed to extract all intense absorption bands constituting IR spectra. This innovation benefits from three critical features: (1) the correction of raw IR spectra to make them quantitatively comparable; (2) the automated and iterative data treatment allowing to transfer the IR-absorption spectrum into a IR-band spectrum; (3) the reconstruction of an 3D IR-band matrix (x, y, z for voxel position and a 4 th dimension with all IR-band parameters). Spectromics, which is a new method for exploiting spectral data for tissue metadata reconstruction, is proposed to further translate the related chemical information in 3D, as biochemical and anatomical tissue parameters. An example is given with oxidative stress distribution and the reconstruction of blood vessels in tissues. The requirements of IR microscopy instrumentation to propose 3D digital histology as a clinical routine technology is briefly discussed. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

"CHON" particles: The interstellar component of cometary dust

NASA Technical Reports Server (NTRS)

Lien, David J.

1998-01-01

Interstellar dust is characterized by strong absorption in the ultraviolet and the mid-IR. Current models of interstellar dust are based on three chemically distinct components: a form of carbon (usually graphite), a silicate, and a blend of polycyclic aromatic hydrocarbons or other carbonaceous material. Previous work using effective medium theories to understand the optical properties of cometary dust suggested that an amalgam of materials could reproduce the observed interstellar and cometary dust features. Recently, Lawler and Brownlee (1992) re-analyzed the PIA and PUMA-1 data sets from the Giotto flyby of P/Halley and discovered that the so-called "CHON" particles were actually composed of a blend of carbon-bearing and silicon-bearing materials. Based on effective medium theories, the absorption spectrum of such a material would display the spectral features of each of the components - strong UV absorption from the carbonaceous component and strong absorption in the IR from the silicate component. To test this idea, vapor-deposited samples were created using two different deposition techniques: sputtering with an argon RF magnetron and deposition from an argon plasma torch. Two different compositions were tested: a blend of graphite and silica in a 7:1 ratio and an amalgam of materials whose approximate composition matches the "CHON"-silicate abundances for the uncompressed PIA data set of Lawler and Brownlee: graphite, iron oxide, magnesium oxide, ammonium sulfate, calcium carbonate, and silica in mass ratios of 6:4.3:4:2.2:1:9. The samples were finely ground and pressed into 2" diameter disks using a 40 ton press. In all, four different experiments were performed: one with each of the compositions (C:SiO and "CHON") in both the RF magnetron and the plasma torch chambers. The RF magnetron created a uniform dark thin film on the substrate surface, and the plasma torch created a coating of small (<100 micron) diameter grey particles. The spectra of all four samples show a strong, broad absorption feature at around 220 nm as well as a strong but narrower absorption peak near 10 microns. The RF magnetron sputtered samples showed some sub-structure in the UV, and the peak of the absorption was shifted toward longer wavelengths. The UV absorption in the plasma torch deposited samples have no sub-structure, and the peak absorption is very near 220 nm. Strong absorption near 9 microns is seen in the spectra from both sample preparation techniques, and is consistent with the IR spectra of some terrestrial silicates. Other features, particularly at 6.2 and 8.6 microns, are seen in the interstellar medium. A strong feature near 2 microns is due to absorbed water in the sample. Based on the results of these experiments, there is evidence that a material with a composition similar to that detected in "CHON" particles in the coma of P/Halley have a spectral signature which reproduces the main absorption features of interstellar dust. This suggests that the "CHON" particles could be the interstellar component of cometary dust.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Li, Cui-Ping; Nie, Li; College of Materials Science and Engineering, Nanjing Tech University, Nanjing 210009

A new salt [H{sub 2}DABCO][Pt(mnt){sub 2}]{sub 2} (1) (mnt{sup 2-}=maleonitriledithiolate and H{sub 2}DABCO{sup 2+} is diprotonated 1,4-diazabicyclo[2.2.2]octane) has been synthesized; its crystal structure, magnetic and near-IR absorption properties have been investigated. Two different [Pt(mnt){sub 2}]{sup -} anions form the strong π-dimers, labeled as Pt(1)-dimer and Pt(2)-dimer, with quite shorter Pt…Pt and S…S distances and molecular plane-to-plane distance (<3.5 Å) within a dimer. The [Pt(mnt){sub 2}]{sub 2}{sup 2-} π-dimers are connected through the cations in the strong H-bond manner to form three-dimensional H-bond supramolecular crystal. The salt shows weak paramagnetism in 1.99–300 K and this is due to the existence ofmore » strong antiferromagnetic coupling within a π-dimer. In addition, a small thermal hysteresis loop is observed at ca. 120 K, indicating that a phase transition probably occurs that is further confirmed by variable-temperature IR spectra. Another fascinating functionality of 1 is the intense near-IR absorption in the region of 750–2500 nm, and this near-IR absorption feature makes it to be a promising optical material. - Graphical abstract: A H-bond supramolecular crystal of [H{sub 2}DABCO][Pt(mnt){sub 2}]{sub 2} shows a magnetic phase transition at ca. 120 K with sizable thermal hysteresis loop and intense near-IR absorption in the region of 750–2500 nm.« less

Enhancing the sensitivity of mid-IR quantum cascade laser-based cavity-enhanced absorption spectroscopy using RF current perturbation.

PubMed

Manfred, Katherine M; Kirkbride, James M R; Ciaffoni, Luca; Peverall, Robert; Ritchie, Grant A D

2014-12-15

The sensitivity of mid-IR quantum cascade laser (QCL) off-axis cavity-enhanced absorption spectroscopy (CEAS), often limited by cavity mode structure and diffraction losses, was enhanced by applying a broadband RF noise to the laser current. A pump-probe measurement demonstrated that the addition of bandwidth-limited white noise effectively increased the laser linewidth, thereby reducing mode structure associated with CEAS. The broadband noise source offers a more sensitive, more robust alternative to applying single-frequency noise to the laser. Analysis of CEAS measurements of a CO(2) absorption feature at 1890  cm(-1) averaged over 100 ms yielded a minimum detectable absorption of 5.5×10(-3)  Hz(-1/2) in the presence of broadband RF perturbation, nearly a tenfold improvement over the unperturbed regime. The short acquisition time makes this technique suitable for breath applications requiring breath-by-breath gas concentration information.

Detection of the 2165 Inverse Centimeter (4.619 Micron) XCN Band in the Spectrum of L1551 IRS 5

NASA Technical Reports Server (NTRS)

Tegler, Stephen C.; Weintraub, David A.; Allamandola, Louis J.; Sandford, Scott A.; Rettig, Terrence W.; Campins, Humberto

1993-01-01

We report the detection of a broad absorption band at 2165 cm (4.619 microns) in the spectrum of L1551 IRS 5. New laboratory results over the 2200-2100 /cm wavenumber interval (4.55-4.76 microns), performed with realistic interstellar ice analogs, suggest that this feature is due to a CN-containing compound. We will refer to this compound as XCN. We also confirm the presence of frozen CO (both in nonpolar and polar matrices) through absorption bands at 2140 /cm (4.67 microns) and 2135 /cm (4.68 microns). The relative abundance of solid-state CO to frozen H2O is approx. 0.13 while the abundance of XCN seems comparable to that of frozen CO.

Analysis of fingerprints features of infrared spectra of various processed products of Radix Aconiti kusnezoffii

NASA Astrophysics Data System (ADS)

Tu-ya; Yang, Ping; Sun, Su-qin; Zhou, Qun; Bao, Xiao-hua; Noda, Isao

2010-06-01

Fourier-transform infrared spectroscopy (FTIR) and two-dimensional correlation infrared spectroscopy (2D-IR)) are employed to analyze various processed products and ether extracts of Radix Aconiti kusnezoffii. There is a resemblance among the spectra of different processed products. The major difference lies in the absorption peak at 1641 cm -1 in the IR spectra, which reflects the transformation of raw aconite to the processed products. There are distinctive differences in the absorption peaks in the range of 1800-1500 cm -1 in the second derivative spectra, which has better resolution, of different processed products. 2D-IR spectra, which elevate the resolution further, can present even more differences among the products in the range of 1800-800 cm -1. Analysis of ether extracts of various processed products proves that there are alcohols, esters, carboxylic acids or ketones in all of them. However, their contents in different samples have obvious differences. With the advantages of high resolution, high-speed and convenience, IR can quickly and precisely distinguish various processed products of Radix A. kusnezoffii, and can be applied to predict the tendency of transformation of the complicated chemical mixture systems under heat perturbation.

Tracers of Star Formation in the Near Infrared

NASA Astrophysics Data System (ADS)

Martins, L.; Ardila, A.; Gruenwald, R.; de Souza, R.

2010-04-01

Starburst features in the optical are nowadays well known, but the use of this knowledge is not always possible (e.g. objects heavily obscured). In this case the near-IR is of unprecedented value. Recent models show that TP-AGB stars should dominate the NIR spectra of populations 0.3 to 2 Gyr old. While the optical spectra is insensitive to the presence of these stars, the near-IR changes dramatically. Not only does the absolute flux in the near-IR is affected, but also peculiar absorption features appear. These features can be used as indicators of 1 Gyr stellar population. In this work we used the IRTF Spex to create the first empirical database of NIR spectra of carefully selected starbursts, to test for the first time and in a consistent way the new stellar population models that account for the TP-AGB. The methodology used is to do stellar population synthesis in the optical and in the NIR, and compare the predictions of both spectral regions. We also compare the strength of important features of the TP-AGB stars, like the CN (1.1 microns) and CO (2.3 microns) bands with optical diagnostics.

High-Resolution IR Absorption Spectroscopy of Polycyclic Aromatic Hydrocarbons in the 3-micrometers Region: Role of Periphery

NASA Technical Reports Server (NTRS)

Maltseva, Elena; Petrignani, Annemieke; Candian, Alessandra; Mackie, Cameron J.; Huang, Xinchuan; Lee, Timothy J.; Tielens, Alexander G. G. M.; Oomens, Jos; Buma, Wybren Jan

2017-01-01

In this work we report on high-resolution IR absorption studies that provide a detailed view on how the peripheral structure of irregular polycyclic aromatic hydrocarbons (PAHs) affects the shape and position of their 3-micrometers absorption band. To this purpose we present mass-selected, high-resolution absorption spectra of cold and isolated phenanthrene, pyrene, benz[a]antracene, chrysene, triphenylene, and perylene molecules in the 2950-3150 per cm range. The experimental spectra are compared with standard harmonic calculations, and anharmonic calculations using a modified version of the SPECTRO program that incorporates a Fermi resonance treatment utilizing intensity redistribution. We show that the 3-micrometers region is dominated by the effects of anharmonicity, resulting in many more bands than would have been expected in a purely harmonic approximation. Importantly, we find that anharmonic spectra as calculated by SPECTRO are in good agreement with the experimental spectra. Together with previously reported high-resolution spectra of linear acenes, the present spectra provide us with an extensive dataset of spectra of PAHs with a varying number of aromatic rings, with geometries that range from open to highly-condensed structures, and featuring CH groups in all possible edge configurations. We discuss the astrophysical implications of the comparison of these spectra on the interpretation of the appearance of the aromatic infrared 3-micrometers band, and on features such as the two-component emission character of this band and the 3-micrometers emission plateau.

High-resolution IR Absorption Spectroscopy of Polycyclic Aromatic Hydrocarbons in the 3 μm Region: Role of Periphery

NASA Astrophysics Data System (ADS)

Maltseva, Elena; Petrignani, Annemieke; Candian, Alessandra; Mackie, Cameron J.; Huang, Xinchuan; Lee, Timothy J.; Tielens, Alexander G. G. M.; Oomens, Jos; Buma, Wybren Jan

2016-11-01

In this work we report on high-resolution IR absorption studies that provide a detailed view on how the peripheral structure of irregular polycyclic aromatic hydrocarbons (PAHs) affects the shape and position of their 3 μm absorption band. For this purpose, we present mass-selected, high-resolution absorption spectra of cold and isolated phenanthrene, pyrene, benz[a]antracene, chrysene, triphenylene, and perylene molecules in the 2950-3150 cm-1 range. The experimental spectra are compared with standard harmonic calculations and anharmonic calculations using a modified version of the SPECTRO program that incorporates a Fermi resonance treatment utilizing intensity redistribution. We show that the 3 μm region is dominated by the effects of anharmonicity, resulting in many more bands than would have been expected in a purely harmonic approximation. Importantly, we find that anharmonic spectra as calculated by SPECTRO are in good agreement with the experimental spectra. Together with previously reported high-resolution spectra of linear acenes, the present spectra provide us with an extensive data set of spectra of PAHs with a varying number of aromatic rings, with geometries that range from open to highly condensed structures, and featuring CH groups in all possible edge configurations. We discuss the astrophysical implications of the comparison of these spectra on the interpretation of the appearance of the aromatic infrared 3 μm band, and on features such as the two-component emission character of this band and the 3 μm emission plateau.

Soft Lithographic Procedure for Producing Plastic Microfluidic Devices with View-ports Transparent to Visible and Infrared Light.

PubMed

Suryana, Mona; Shanmugarajah, Jegan V; Maniam, Sivakumar M; Grenci, Gianluca

2017-08-17

Infrared (IR) spectro-microscopy of living biological samples is hampered by the absorption of water in the mid-IR range and by the lack of suitable microfluidic devices. Here, a protocol for the fabrication of plastic microfluidic devices is demonstrated, where soft lithographic techniques are used to embed transparent Calcium Fluoride (CaF2) view-ports in connection with observation chamber(s). The method is based on a replica casting approach, where a polydimethylsiloxane (PDMS) mold is produced through standard lithographic procedures and then used as the template to produce a plastic device. The plastic device features ultraviolet/visible/infrared (UV/Vis/IR) -transparent windows made of CaF2 to allow for direct observation with visible and IR light. The advantages of the proposed method include: a reduced need for accessing a clean room micro-fabrication facility, multiple view-ports, an easy and versatile connection to an external pumping system through the plastic body, flexibility of the design, e.g., open/closed channels configuration, and the possibility to add sophisticated features such as nanoporous membranes.

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

Coherent control of optical absorption and the energy transfer pathway of an infrared quantum dot hybridized with a VO2 nanoparticle

NASA Astrophysics Data System (ADS)

Hatef, Ali; Zamani, Naser; Johnston, William

2017-04-01

We systematically investigate the optical response of a semiconductor quantum dot (QD) hybridized with a vanadium dioxide nanoparticle (VO2NP) in the infrared (IR) region. The VO2NP features a semiconductor to metal phase change characteristic below and above a critical temperature that leads to an abrupt change in the particle’s optical properties. This feature means that the QD-VO2NP hybrid system can support the coherent coupling of exciton-polaritons and exciton-plasmon polaritons in the semiconductor and metal phases of the VO2NP, respectively. In our calculations, the VO2NP phase transition is modelled with a filling fraction (f), representing the fraction of the VO2NP in the metallic phase. The phase transition is driven by the hybrid system’s interaction with a continuous wave (CW) IR laser field. In this paper, we show how control over the filling fraction results in the enhancement or suppression of the QD’s linear absorption. These variations in the QD absorption is due to dramatic changes in the effective local field experienced by the QD and the non-radiative energy transfer from the QD to the VO2NP. The presented results have the potential to be applied to the design of thermal sensors at the nanoscale.

HIGH-RESOLUTION IR ABSORPTION SPECTROSCOPY OF POLYCYCLIC AROMATIC HYDROCARBONS IN THE 3 μ m REGION: ROLE OF PERIPHERY

DOE Office of Scientific and Technical Information (OSTI.GOV)

Maltseva, Elena; Petrignani, Annemieke; Buma, Wybren Jan

2016-11-01

In this work we report on high-resolution IR absorption studies that provide a detailed view on how the peripheral structure of irregular polycyclic aromatic hydrocarbons (PAHs) affects the shape and position of their 3 μ m absorption band. For this purpose, we present mass-selected, high-resolution absorption spectra of cold and isolated phenanthrene, pyrene, benz[a]antracene, chrysene, triphenylene, and perylene molecules in the 2950–3150 cm{sup −1} range. The experimental spectra are compared with standard harmonic calculations and anharmonic calculations using a modified version of the SPECTRO program that incorporates a Fermi resonance treatment utilizing intensity redistribution. We show that the 3 μmore » m region is dominated by the effects of anharmonicity, resulting in many more bands than would have been expected in a purely harmonic approximation. Importantly, we find that anharmonic spectra as calculated by SPECTRO are in good agreement with the experimental spectra. Together with previously reported high-resolution spectra of linear acenes, the present spectra provide us with an extensive data set of spectra of PAHs with a varying number of aromatic rings, with geometries that range from open to highly condensed structures, and featuring CH groups in all possible edge configurations. We discuss the astrophysical implications of the comparison of these spectra on the interpretation of the appearance of the aromatic infrared 3 μ m band, and on features such as the two-component emission character of this band and the 3 μ m emission plateau.« less

How secondary school students conceptualize infrared radiation-matter interaction? Findings from a research study and implications for an instructional design

NASA Astrophysics Data System (ADS)

Isabel Hernández, Marıa; Rıos, Raquel; Pintó, Roser

2016-05-01

This study has been carried out within the REVIR scenario, which is a project promoting that secondary school students have access to a computerized laboratory at the Faculty of Education of our university and work in small groups during four hours with specific instructional material. One of the laboratory sessions included in the REVIR project deals with IR radiation-matter interaction, and is addressed to post-compulsory secondary students (16-18 year-old students). Within this framework, we have conducted a research study to analyse students' conceptualizations of the processes or mechanisms that take place in IR radiation-matter interaction (energy transfer, selective absorption), and its effects at a macroscopic level (temperature increase) and at a molecular level (vibration). For data collection, a question was posed to all students at the end of each REVIR session, asking students to relate what was described in an article about the application of an IR laser for acne treatment to what they had learnt throughout the session. The analysis of the 67 students' answers to that question revealed that many students explained the effects of the IR laser in vague terms, often repeating information included in the article, without explaining absorption of IR radiation in terms of energy. In consecutive versions of the instructional material, more oriented application questions were added after the article and explicit discussion around synthesis and exploratory (of students' previous ideas) questions was carried out during the session. From the analysis of 49 and 119 students' answers in consecutive later versions, we found that the introduction of these changes resulted in a greater number of students' descriptions in macroscopic and microscopic terms, and a lower number of answers simply repeating information extracted from the reading. Furthermore, more students explicitly explained absorption in terms of energy associated to IR light. Implications for the instructional design, in terms of critical features affecting people's abilities to transfer what they have learned, are discussed below.

Characteristics of the surface chemistry of linden pyrochar after removal of labile organic matter

NASA Astrophysics Data System (ADS)

Valeeva, A. A.; Smirnova, E. V.; Giniyatullin, K. G.; Vorobev, V. V.; Biktasheva, L. R.; Grachev, A. N.

2018-01-01

The changes of chemical properties of the pyrochar surface were studied in the laboratory experiment that simulated pedogenic transformation of pyrochar under the influence of soil biota. The native pyrochar samples were obtained by pyrolysis of linden wood residues at the temperature of 250°C, 450°C and 650°C. Their modified samples were obtained by removing an easily degradable pool of organic substances that can be used by microorganisms during the first months after application to the soil. In low-temperature linden pyrochar (250°C and 450°C) dominated carboxylic and phenolic surface groups, in high-temperature (650°C) - lactonic groups. After removal of readily decomposable organic substances the acidity of the phenolic and lactonic groups in pyrochar of low-temperature pyrolysis sharply decreased. Characteristic feature of all studied samples is the presence in IR spectra of absorption bands of gyroxyl, carbonyl, methylene groups and organosilicon polymers. The feature of IR spectra of linden pyrochar (250°C and 450°C) is the presence of absorption bands of the stretching vibrations of the tertiary alcohols and phenols C-O group.

Infrared Spectroscopy of Carbonaceous-chondrite Inclusions in the Kapoeta Meteorite: Discovery of Nanodiamonds with New Spectral Features and Astrophysical Implications

NASA Astrophysics Data System (ADS)

Abdu, Yassir A.; Hawthorne, Frank C.; Varela, Maria E.

2018-03-01

We report the finding of nanodiamonds, coexisting with amorphous carbon, in carbonaceous-chondrite (CC) material from the Kapoeta achondritic meteorite by Fourier-transform infrared (FTIR) spectroscopy and micro-Raman spectroscopy. In the C–H stretching region (3100–2600 cm‑1), the FTIR spectrum of the Kapoeta CC material (KBr pellet) shows bands attributable to aliphatic CH2 and CH3 groups, and is very similar to IR spectra of organic matter in carbonaceous chondrites and the diffuse interstellar medium. Nanodiamonds, as evidenced by micro-Raman spectroscopy, were found in a dark region (∼400 μm in size) in the KBr pellet. Micro-FTIR spectra collected from this region are dramatically different from the KBr-pellet spectrum, and their C–H stretching region is dominated by a strong and broad absorption band centered at ∼2886 cm‑1 (3.47 μm), very similar to that observed in IR absorption spectra of hydrocarbon dust in dense interstellar clouds. Micro-FTIR spectroscopy also indicates the presence of an aldehyde and a nitrile, and both of the molecules are ubiquitous in dense interstellar clouds. In addition, IR peaks in the 1500–800 cm‑1 region are also observed, which may be attributed to different levels of nitrogen aggregation in diamonds. This is the first evidence for the presence of the 3.47 μm interstellar IR band in meteorites. Our results further support the assignment of this band to tertiary CH groups on the surfaces of nanodiamonds. The presence of the above interstellar bands and the absence of shock features in the Kapoeta nanodiamonds, as indicated by Raman spectroscopy, suggest formation by a nebular-condensation process similar to chemical-vapor deposition.

The Electronic Structure and Spectra of Triphenylamines Functionalized by Phenylethynyl Groups

NASA Astrophysics Data System (ADS)

Baryshnikov, G. V.; Minaeva, V. A.; Minaev, B. F.; Grigoras, M.

2018-01-01

We study the features of the electronic structure and the IR, UV, and visible spectra of a series of triphenylamines substituted with phenylethynyl groups. The analysis is performed at the level of the density functional theory (DFT) and its nonstationary version in comparison with the experimental data of IR and electron spectroscopy. It is shown that, in the excited state, there is a change in the alternation of single, double, and triple bonds in accordance with the character of bonding and antibonding in the lowest vacant molecular orbital. The gradual introduction of additional phenylethynyl groups does not cause frequency shifts in the IR spectra of the molecules under study, but significantly affects the intensity of the corresponding IR bands. A similar effect is also observed in the electronic-absorption spectra of these compounds. This can be used for optical tuning of triphenylamines as promising materials for organic light-emitting diodes and solar cells.

Constraints on the OH-to-H Abundance Ratio in Infrared-bright Galaxies Derived from the Strength of the OH 35 μm Absorption Feature

NASA Astrophysics Data System (ADS)

Stone, Myra; Veilleux, Sylvain; González-Alfonso, Eduardo; Spoon, Henrik; Sturm, Eckhard

2018-02-01

We analyze Spitzer/InfraRed Spectrograph (IRS) observations of the OH 35 μm feature in 15 nearby (z ≲ 0.06) (ultra-)luminous infrared galaxies (U/LIRGs). All objects exhibit OH 35 μm purely in absorption, as expected. The small optical depth of this transition makes the strength of this feature a good indicator of the true OH column density. The measured OH 35 μm equivalent widths imply an average OH column density and a 1-σ standard deviation to the mean of {N}{OH}=1.31+/- 0.22× {10}17 cm‑2. This number is then compared with the hydrogen column density for a typical optical depth at 35 μm of ∼0.5 and gas-to-dust ratio of 125 to derive an OH-to-H abundance ratio of {X}{OH}=1.01+/- 0.15× {10}-6. This abundance ratio is formally a lower limit. It is consistent with the values generally assumed in the literature. The OH 35 μm line profiles predicted from published radiative transfer models constrained by observations of OH 65, 79, 84, and 119 μm in 5 objects (Mrk 231, Mrk 273, IRAS F05189-2524, IRAS F08572+3915, and IRAS F20551-4250) are also found to be consistent with the IRS OH 35 μm spectra.

Mid-infrared Study of Stones from the Sutters Mill Meteorite

NASA Technical Reports Server (NTRS)

Nuevo, Michel; Sandford, Scott A.; Flynn, George; Wirick, Sue

2013-01-01

The Sutter's Mill meteorite fell in northern California on April 22, 2012, and numerous pieces have been recovered and studied with several analytical techniques [1]. We present a Fourier-transform infrared (FTIR) spectroscopy analysis of fragments from several stones of the meteorite. Methods and analysis: Infrared spectra of samples SM2 and SM12 were recorded with a Nicolet iN10 MX FTIR microscope in the mid-IR range (4000-650/cm; spectral resolution 4/cm), while samples SM20 and SM30 were analyzed with a synchrotron-based Nicolet Continuum IR microscope in the same range. Samples were deposited on a clean glass slide, crushed with either a stainless steel roller tool or between 2 slides, and placed directly on the focal plane of the microscopes. Results: IR spectra of non-fusion crust samples show several absorption features associated with minerals such as olivines, phyllosilicates, carbonates (calcite and dolomite), and pyroxenes, as well as organics [2]. The carbonates display a main, broad band centered at 1433/cm, with additional bands at 2515/cm, 1797/cm, 882/cm, and 715/cm. Features associated with phyllosilicates include a symmetric Si-O stretching mode band centered at 1011/cm and several O-H stretching mode bands?a broad band centered at 3415/cm that is probably due to adsorbed H2O, and occasionally a much weaker, narrower feature centered near 3680/cm due to structural O-H. Features observed in the 2985-2855/cm range suggest the presence of aliphatic -CH3 and -CH2- groups. However, some of these bands show unusual relative intensities, mainly because of carbonate overtone bands that fall in the same spectral range, which can make the identification of C-H stretching bands problematic. The positions and relative strengths of the aliphatic -CH2- and -CH3 features, where they can be distinguished from overlapping carbonate bands, are consistent with those in interplanetary dust particles (IDPs) and Murchison. Finally, the absence of a strong C=O absorption feature near 1700/cm distinguishes the organics in the Sutter's Mill meteorite from that in most IDPs and in Murchison, but is consistent with the organic matter in Tagish Lake.

EXTINCTION AND POLYCYCLIC AROMATIC HYDROCARBON INTENSITY VARIATIONS ACROSS THE H II REGION IRAS 12063-6259

DOE Office of Scientific and Technical Information (OSTI.GOV)

Stock, D. J.; Peeters, E.; Otaguro, J. N.

The spatial variations in polycyclic aromatic hydrocarbon (PAH) band intensities are normally attributed to the physical conditions of the emitting PAHs, however in recent years it has been suggested that such variations are caused mainly by extinction. To resolve this question, we have obtained near-infrared (NIR), mid-infrared (MIR), and radio observations of the compact H II region IRAS 12063-6259. We use these data to construct multiple independent extinction maps and also to measure the main PAH features (6.2, 7.7, 8.6, and 11.2 {mu}m) in the MIR. Three extinction maps are derived: the first using the NIR hydrogen lines and casemore » B recombination theory; the second combining the NIR data with radio data; and the third making use of the Spitzer/IRS MIR observations to measure the 9.8 {mu}m silicate absorption feature using the Spoon method and PAHFIT (as the depth of this feature can be related to overall extinction). The silicate absorption over the bright, southern component of IRAS 12063-6259 is almost absent while the other methods find significant extinction. While such breakdowns of the relationship between the NIR extinction and the 9.8 {mu}m absorption have been observed in molecular clouds, they have never been observed for H II regions. We then compare the PAH intensity variations in the Spitzer/IRS data after dereddening to those found in the original data. It was found that in most cases, the PAH band intensity variations persist even after dereddening, implying that extinction is not the main cause of the PAH band intensity variations.« less

Study on IR Properties of Reduced Graphene Oxide

NASA Astrophysics Data System (ADS)

Ma, Deyue; Li, Xiaoxia; Guo, Yuxiang; Zeng, Yurun

2018-01-01

Firstly, the reduced graphene oxide was prepared by modified hummer method and characterized. Then, the complex refractive index of reduced graphene oxide in IR band was tested and its IR absorption and radiation properties were researched by correlated calculation. The results show that reduced graphene oxide prepared by hummer method are multilayered graphene with defects and functional groups on its surface. Its absorption in near and far IR bands is strong, but it’s weaker in middle IR band. At the IR atmosphere Window, its normal spectral emissivity decreases with wavelength increasing, and its total normal spectral emissivity in 3 ∼ 5μm and 8 ∼ 14μm are 0.75 and 0.625, respectively. Therefore, reduced graphene oxide can be used as IR absorption and coating materials and have a great potential in microwave and infrared compatible materials.

The Host Galaxies Of UV-selected AGNs At z 2-3

NASA Astrophysics Data System (ADS)

Hainline, Kevin; Shapley, A.; Greene, J.; Steidel, C.

2012-01-01

An important goal for studies of galaxy formation consists of tracing a direct evolutionary connection between the growth of supermassive black holes powering active galactic nuclei (AGNs) and the build-up of stellar mass in their host galaxies. In the local universe, AGNs are preferentially found in bulge-dominated galaxies, but the AGN demographics at earlier epochs are not as well understood. We present a rest-frame UV composite spectrum for a sample of 33 z 2-3 AGNs drawn from the UV-selected Lyman Break Galaxy (LBG) survey. This spectrum shows many emission and absorption features, such as HI Lyman-alpha, NV 1240, NIV] 1483, 1486, CIV 1548, 1550, HeII 1640, and CIII] 1907, 1909. Redshifted SiIV 1394 absorption provides evidence for outflowing high-ionization gas in these objects at speeds of 103 km/s. Finally, using optical, near-IR, and mid-IR photometry, which cover the rest-frame UV to near-IR portions of the galaxies' spectral energy distributions, we perform stellar population synthesis modeling of the sample. Based on these results, we explore the relationship in the host galaxy between AGN activity, maturity of the stellar population, and regulation of star formation.

The Rise of SN 2014J in the Nearby Galaxy M 82

NASA Technical Reports Server (NTRS)

A.Goobar; Johansson, J.; Amanullah, R.; Cao, Y.; Perley, D.A.; Kasliwal, M. M.; Ferreti, R.; Nugent, P. E.; Harris, C.; Cenko, S. B.

2014-01-01

We report on the discovery of SN 2014J in the nearby galaxy M 82. Given its proximity, it offers the best opportunity to date to study a thermonuclear supernova over a wide range of the electromagnetic spectrum. Optical, near-IR and mid-IR observations on the rising lightcurve, orchestrated by the intermediate Palomar Transient Factory (iPTF), show that SN 2014J is a spectroscopically normal Type Ia supernova, albeit exhibiting high-velocity features in its spectrum and heavily reddened by dust in the host galaxy. Our earliest detections start just hours after the fitted time of explosion. We use high-resolution optical spectroscopy to analyze the dense intervening material and do not detect any evolution in the resolved absorption features during the lightcurve rise. Similarly to other highly reddened Type Ia supernovae, a low value of total-to-selective extinction, R (sub V) less than or approximately equal to 2, provides the best match to our observations. We also study pre-explosion optical and near-IR images from HST with special emphasis on the sources nearest to the SN location.

Flux growth of Yb(6.6)Ir(6)Sn(16) having mixed-valent ytterbium.

PubMed

Peter, Sebastian C; Subbarao, Udumula; Rayaprol, Sudhindra; Martin, Joshua B; Balasubramanian, Mahalingam; Malliakas, Christos D; Kanatzidis, Mercouri G

2014-07-07

The compound Yb6.6Ir6Sn16 was obtained as single crystals in high yield from the reaction of Yb with Ir and Sn run in excess indium. Single-crystal X-ray diffraction analysis shows that Yb6.6Ir6Sn16 crystallizes in the tetragonal space group P42/nmc with a = b = 9.7105(7) Å and c = 13.7183(11) Å. The crystal structure is composed of a [Ir6Sn16] polyanionic network with cages in which the Yb atoms are embedded. The Yb sublattice features extensive vacancies on one crystallographic site. Magnetic susceptibility measurements on single crystals indicate Curie-Weiss law behavior <100 K with no magnetic ordering down to 2 K. The magnetic moment within the linear region (<100 K) is 3.21 μB/Yb, which is ∼70% of the expected value for a free Yb(3+) ion suggesting the presence of mixed-valent ytterbium atoms. X-ray absorption near edge spectroscopy confirms that Yb6.6Ir6Sn16 exhibits mixed valence. Resistivity and heat capacity measurements for Yb6.6Ir6Sn16 indicate non-Fermi liquid metallic behavior.

Sensitive photo-thermal response of graphene oxide for mid-infrared detection

NASA Astrophysics Data System (ADS)

Bae, Jung Jun; Yoon, Jung Hyun; Jeong, Sooyeon; Moon, Byoung Hee; Han, Joong Tark; Jeong, Hee Jin; Lee, Geon-Woong; Hwang, Ha Ryong; Lee, Young Hee; Jeong, Seung Yol; Lim, Seong Chu

2015-09-01

This study characterizes the effects of incident infrared (IR) radiation on the electrical conductivity of graphene oxide (GO) and examines its potential for mid-IR detection. Analysis of the mildly reduced GO (m-GO) transport mechanism near room temperature reveals variable range hopping (VRH) for the conduction of electrons. This VRH behavior causes the m-GO resistance to exhibit a strong temperature dependence, with a large negative temperature coefficient of resistance of approximately -2 to -4% K-1. In addition to this hopping transport, the presence of various oxygen-related functional groups within GO enhances the absorption of IR radiation significantly. These two GO material properties are synergically coupled and provoke a remarkable photothermal effect within this material; specifically, a large resistance drop is exhibited by m-GO in response to the increase in temperature caused by the IR absorption. The m-GO bolometer effect identified in this study is different from that exhibited in vanadium oxides, which require added gold-black films that function as IR absorbers owing to their limited IR absorption capability.This study characterizes the effects of incident infrared (IR) radiation on the electrical conductivity of graphene oxide (GO) and examines its potential for mid-IR detection. Analysis of the mildly reduced GO (m-GO) transport mechanism near room temperature reveals variable range hopping (VRH) for the conduction of electrons. This VRH behavior causes the m-GO resistance to exhibit a strong temperature dependence, with a large negative temperature coefficient of resistance of approximately -2 to -4% K-1. In addition to this hopping transport, the presence of various oxygen-related functional groups within GO enhances the absorption of IR radiation significantly. These two GO material properties are synergically coupled and provoke a remarkable photothermal effect within this material; specifically, a large resistance drop is exhibited by m-GO in response to the increase in temperature caused by the IR absorption. The m-GO bolometer effect identified in this study is different from that exhibited in vanadium oxides, which require added gold-black films that function as IR absorbers owing to their limited IR absorption capability. Electronic supplementary information (ESI) available. See DOI: 10.1039/c5nr04039f

Infrared absorption of methanethiol clusters (CH3SH)n, n = 2-5, recorded with a time-of-flight mass spectrometer using IR depletion and VUV ionization

NASA Astrophysics Data System (ADS)

Fu, Lung; Han, Hui-Ling; Lee, Yuan-Pern

2012-12-01

We investigated IR spectra in the CH- and SH-stretching regions of size-selected methanethiol clusters, (CH3SH)n with n = 2-5, in a pulsed supersonic jet using infrared (IR)-vacuum ultraviolet (VUV) ionization. VUV emission at 132.50 nm served as the source of ionization in a time-of-flight mass spectrometer. Clusters were dissociated with light from a tunable IR laser before ionization. The variations in intensity of methanethiol cluster ions (CH3SH)n+ were monitored as the IR laser light was tuned across the range 2470-3100 cm-1. In the SH-stretching region, the spectrum of (CH3SH)2 shows a weak band near 2601 cm-1, red-shifted only 7 cm-1 from that of the monomer. In contrast, all spectra of (CH3SH)n, n = 3-5, show a broad band near 2567 cm-1 with much greater intensity. In the CH-stretching region, absorption bands of (CH3SH)2 are located near 2865, 2890, 2944, and 3010 cm-1, red-shifted by 3-5 cm-1 from those of CH3SH. These red shifts increase slightly for larger clusters and bands near 2856, 2884, 2938, and 3005 cm-1 were observed for (CH3SH)5. These spectral results indicate that the S-H...S hydrogen bond plays an important role in clusters with n = 3-5, but not in (CH3SH)2, in agreement with theoretical predictions. The absence of a band near 2608 cm-1 that corresponds to absorption of the non-hydrogen-bonded SH moiety and the large width of observed feature near 2567 cm-1 indicate that the dominant stable structures of (CH3SH)n, n = 3-5, have a cyclic hydrogen-bonded framework.

Infrared absorption of methanol-water clusters (CH3OH)n(H2O), n = 1-4, recorded with the VUV-ionization/IR-depletion technique

NASA Astrophysics Data System (ADS)

Lee, Yu-Fang; Kelterer, Anne-Marie; Matisz, Gergely; Kunsági-Máté, Sándor; Chung, Chao-Yu; Lee, Yuan-Pern

2017-04-01

We recorded infrared (IR) spectra in the CH- and OH-stretching regions of size-selected clusters of methanol (M) with one water molecule (W), represented as MnW, n = 1-4, in a pulsed supersonic jet using the photoionization/IR-depletion technique. Vacuum ultraviolet emission at 118 nm served as the source of ionization in a time-of-flight mass spectrometer to detect clusters MnW as protonated forms Mn-1WH+. The variations in intensities of Mn-1WH+ were monitored as the wavelength of the IR laser light was tuned across the range 2700-3800 cm-1. IR spectra of size-selected clusters were obtained on processing of the observed action spectra of the related cluster-ions according to a mechanism that takes into account the production and loss of each cluster due to IR photodissociation. Spectra of methanol-water clusters in the OH region show significant variations as the number of methanol molecules increases, whereas those in the CH region are similar for all clusters. Scaled harmonic vibrational wavenumbers and relative IR intensities predicted with the M06-2X/aug-cc-pVTZ method for the methanol-water clusters are consistent with our experimental results. For dimers, absorption bands of a structure WM with H2O as a hydrogen-bond donor were observed at 3570, 3682, and 3722 cm-1, whereas weak bands of MW with methanol as a hydrogen-bond donor were observed at 3611 and 3753 cm-1. For M2W, the free OH band of H2O was observed at 3721 cm-1, whereas a broad feature was deconvoluted to three bands near 3425, 3472, and 3536 cm-1, corresponding to the three hydrogen-bonded OH-stretching modes in a cyclic structure. For M3W, the free OH shifted to 3715 cm-1, and the hydrogen-bonded OH-stretching bands became much broader, with a weak feature near 3179 cm-1 corresponding to the symmetric OH-stretching mode of a cyclic structure. For M4W, the observed spectrum agrees unsatisfactorily with predictions for the most stable cyclic structure, indicating significant contributions from branched isomers, which is distinctly different from M5 of which the cyclic form dominates.

Infrared absorption of methanol-water clusters (CH3OH)n(H2O), n = 1-4, recorded with the VUV-ionization/IR-depletion technique.

PubMed

Lee, Yu-Fang; Kelterer, Anne-Marie; Matisz, Gergely; Kunsági-Máté, Sándor; Chung, Chao-Yu; Lee, Yuan-Pern

2017-04-14

We recorded infrared (IR) spectra in the CH- and OH-stretching regions of size-selected clusters of methanol (M) with one water molecule (W), represented as M n W, n = 1-4, in a pulsed supersonic jet using the photoionization/IR-depletion technique. Vacuum ultraviolet emission at 118 nm served as the source of ionization in a time-of-flight mass spectrometer to detect clusters M n W as protonated forms M n-1 WH + . The variations in intensities of M n-1 WH + were monitored as the wavelength of the IR laser light was tuned across the range 2700-3800 cm -1 . IR spectra of size-selected clusters were obtained on processing of the observed action spectra of the related cluster-ions according to a mechanism that takes into account the production and loss of each cluster due to IR photodissociation. Spectra of methanol-water clusters in the OH region show significant variations as the number of methanol molecules increases, whereas those in the CH region are similar for all clusters. Scaled harmonic vibrational wavenumbers and relative IR intensities predicted with the M06-2X/aug-cc-pVTZ method for the methanol-water clusters are consistent with our experimental results. For dimers, absorption bands of a structure WM with H 2 O as a hydrogen-bond donor were observed at 3570, 3682, and 3722 cm -1 , whereas weak bands of MW with methanol as a hydrogen-bond donor were observed at 3611 and 3753 cm -1 . For M 2 W, the free OH band of H 2 O was observed at 3721 cm -1 , whereas a broad feature was deconvoluted to three bands near 3425, 3472, and 3536 cm -1 , corresponding to the three hydrogen-bonded OH-stretching modes in a cyclic structure. For M 3 W, the free OH shifted to 3715 cm -1 , and the hydrogen-bonded OH-stretching bands became much broader, with a weak feature near 3179 cm -1 corresponding to the symmetric OH-stretching mode of a cyclic structure. For M 4 W, the observed spectrum agrees unsatisfactorily with predictions for the most stable cyclic structure, indicating significant contributions from branched isomers, which is distinctly different from M 5 of which the cyclic form dominates.

External-Cavity Quantum Cascade Laser Spectroscopy for Mid-IR Transmission Measurements of Proteins in Aqueous Solution.

PubMed

Alcaráz, Mirta R; Schwaighofer, Andreas; Kristament, Christian; Ramer, Georg; Brandstetter, Markus; Goicoechea, Héctor; Lendl, Bernhard

2015-07-07

In this work, we report mid-IR transmission measurements of the protein amide I band in aqueous solution at large optical paths. A tunable external-cavity quantum cascade laser (EC-QCL) operated in pulsed mode at room temperature allowed one to apply a path length of up to 38 μm, which is four times larger than that applicable with conventional FT-IR spectrometers. To minimize temperature-induced variations caused by background absorption of the ν2-vibration of water (HOH-bending) overlapping with the amide I region, a highly stable temperature control unit with relative temperature stability within 0.005 °C was developed. An advanced data processing protocol was established to overcome fluctuations in the fine structure of the emission curve that are inherent to the employed EC-QCL due to its mechanical instabilities. To allow for wavenumber accuracy, a spectral calibration method has been elaborated to reference the acquired IR spectra to the absolute positions of the water vapor absorption bands. Employing this setup, characteristic spectral features of five well-studied proteins exhibiting different secondary structures could be measured at concentrations as low as 2.5 mg mL(-1). This concentration range could previously only be accessed by IR measurements in D2O. Mathematical evaluation of the spectral overlap and comparison of second derivative spectra confirm excellent agreement of the QCL transmission measurements with protein spectra acquired by FT-IR spectroscopy. This proves the potential of the applied setup to monitor secondary structure changes of proteins in aqueous solution at extended optical path lengths, which allow experiments in flow through configuration.

Spectroscopy for Industrial Applications: High-Temperature Processes

NASA Astrophysics Data System (ADS)

Fateev, Alexander; Grosch, Helge; Clausen, Sonnik; Barton, Emma J.; Yurchenko, Sergei N.; Tennyson, Jonathan

2014-06-01

The continuous development of the spectroscopic databases brings new perspectives in the environmental and industrial on-line process control, monitoring and stimulates further optical sensor developments. This is because no calibration gases are needed and, in general, temperature-dependent spectral absorption features gases of interest for a specific instrument can in principle be calculated by knowing only the gas temperature and pressure in the process under investigation/monitoring. The latest HITRAN-2012 database contains IR/UV spectral data for 47 molecules and it is still growing. However use of HITRAN is limited to low-temperature processes (< 400 K) and therefor can be used for absorption spectra calculations at limited temperature/pressure ranges. For higher temperatures, the HITEMP-2010 database is available. Only a few molecules CO2, H2O, CO and NO are those of interest for e.g. various combustion and astronomical applications are included. In the recent few years, several efforts towards a development of hot line lists have been made; those have been implemented in the latest HITRAN2012 database1. High-resolution absorption measurements of NH3 (IR, 0.1 cm-1) and phenol (UV, 0.019 nm) on a flow gas cell2 up to 800 K are presented. Molecules are of great interest in various high-temperature environments including exoplanets, combustion and gasification. Measured NH3 hot lines have been assigned and spectra have been compared with that obtained by calculations based on the BYTe hot line list1. High-temperature NH3 absorption spectra have been used in the analysis of in situ high-resolution IR absorption measurements on the producer gas in low-temperature gasification process on a large scale. High-resolution UV temperature-dependent absorption cross-sections of phenol are reported for the first time. All UV data have been calibrated by relevant GC/MS measurements. Use of the data is demonstrated by the analysis of in situ UV absorption measurements on a small-scale low-temperature gasifier. A comparison between in situ, gas extraction and conventional gas sampling measurements is presented. Overall the presentation shows an example of successful industrial and academic partnerships within the framework of national and international ongoing projects.

Nanoscale infrared (IR) spectroscopy and imaging of structural lipids in human stratum corneum using an atomic force microscope to directly detect absorbed light from a tunable IR laser source.

PubMed

Marcott, Curtis; Lo, Michael; Kjoller, Kevin; Domanov, Yegor; Balooch, Guive; Luengo, Gustavo S

2013-06-01

An atomic force microscope (AFM) and a tunable infrared (IR) laser source have been combined in a single instrument (AFM-IR) capable of producing ~200-nm spatial resolution IR spectra and absorption images. This new capability enables IR spectroscopic characterization of human stratum corneum at unprecendented levels. Samples of normal and delipidized stratum corneum were embedded, cross-sectioned and mounted on ZnSe prisms. A pulsed tunable IR laser source produces thermomechanical expansion upon absorption, which is detected through excitation of contact resonance modes in the AFM cantilever. In addition to reducing the total lipid content, the delipidization process damages the stratum corneum morphological structure. The delipidized stratum corneum shows substantially less long-chain CH2 -stretching IR absorption band intensity than normal skin. AFM-IR images that compare absorbances at 2930/cm (lipid) and 3290/cm (keratin) suggest that regions of higher lipid concentration are located at the perimeter of corneocytes in the normal stratum corneum. © 2013 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Absorption measurements of the second overtone band of NO in ambient and combustion gases with a 1.8-mum room-temperature diode laser.

PubMed

Sonnenfroh, D M; Allen, M G

1997-10-20

We describe the development of a room-temperature diode sensor for in situ monitoring of combustion-generated NO. The sensor is based on a near-IR diode laser operating near 1.8 mum, which probes isolated transitions in the second overtone (3, 0) absorption band of NO. Based on absorption cell data, the sensitivity for ambient atmospheric pressure conditions is of the order of 30 parts in 10(6) by volume for a meter path (ppmv-m), assuming a minimum measurable absorbance of 10(-5). Initial H(2) -air flame measurements are complicated by strong water vapor absorption features that constrain the available gain and dynamic range of the present detection system. Preliminary results suggest that detection limits in this environment of the order of 140 ppmv-m could be achieved with optimum baseline correction.

Absorption measurements of the second overtone band of NO in ambient and combustion gases with a 1.8- m room-temperature diode laser

NASA Astrophysics Data System (ADS)

Sonnenfroh, David M.; Allen, Mark G.

1997-10-01

We describe the development of a room-temperature diode sensor for in situ monitoring of combustion-generated NO. The sensor is based on a near-IR diode laser operating near 1.8 m, which probes isolated transitions in the second overtone (3,0) absorption band of NO. Based on absorption cell data, the sensitivity for ambient atmospheric pressure conditions is of the order of 30 parts in 10 6 by volume for a meter path (ppmv m), assuming a minimum measurable absorbance of 10 5 . Initial H 2 air flame measurements are complicated by strong water vapor absorption features that constrain the available gain and dynamic range of the present detection system. Preliminary results suggest that detection limits in this environment of the order of 140 ppmv m could be achieved with optimum baseline correction.

Probing the infrared counterparts of diffuse far-ultraviolet sources in the Galaxy

NASA Astrophysics Data System (ADS)

Saikia, Gautam; Shalima, P.; Gogoi, Rupjyoti; Pathak, Amit

2017-12-01

Recent availability of high quality infrared (IR) data for diffuse regions in the Galaxy and external galaxies have added to our understanding of interstellar dust. A comparison of ultraviolet (UV) and IR observations may be used to estimate absorption, scattering and thermal emission from interstellar dust. In this paper, we report IR and UV observations for selective diffuse sources in the Galaxy. Using archival mid-infrared (MIR) and far-infrared (FIR) observations from Spitzer Space Telescope, we look for counterparts of diffuse far-ultraviolet (FUV) sources observed by the Voyager, Far Ultraviolet Spectroscopic Explorer (FUSE) and Galaxy Evolution Explorer (GALEX) telescopes in the Galaxy. IR emission features at 8 μm are generally attributed to Polycyclic Aromatic Hydrocarbon (PAH) molecules, while emission at 24 μm are attributed to Very Small Grains (VSGs). The data presented here is unique and our study tries to establish a relation between various dust populations. By studying the FUV-IR correlations separately at low and high latitude locations, we have identified the grain component responsible for the diffuse FUV emission.

Time-Resolved IR-Absorption Spectroscopy of Hot-Electron Dynamics in Satellite and Upper Conduction Bands in GaP

NASA Technical Reports Server (NTRS)

Cavicchia, M. A.; Alfano, R. R.

1995-01-01

The relaxation dynamics of hot electrons in the X6 and X7 satellite and upper conduction bands in GaP was directly measured by femtosecond UV-pump-IR-probe absorption spectroscopy. From a fit to the induced IR-absorption spectra the dominant scattering mechanism giving rise to the absorption at early delay times was determined to be intervalley scattering of electrons out of the X7 upper conduction-band valley. For long delay times the dominant scattering mechanism is electron-hole scattering. Electron transport dynamics of the upper conduction band of GaP has been time resolved.

Optical properties of reduced graphene oxide and CuFe2O4 composites in the IR region

NASA Astrophysics Data System (ADS)

Ma, De-yue; Li, Xiao-xia; Guo, Yu-xiang; Zeng, Yu-run

2018-01-01

The complex refractive index of reduced graphene oxide and CuFe2O4 composites prepared by hydrothermal method was calculated using infrared Micro-reflective spectra and K-K relation, and the calculation errors were analyzed according to its IR transmission and spectral reflectivity calculated by Fresnel formula. And then normal emissivity of the composite in IR atmospheric window was calculated by means of Fresnel formula and modified refraction angle formula. The calculation accuracy was verified by comparing measured normal total emissivity with the calculated one. The results show that complex refractive index and normal emissivity calculated by the formulas have a high accuracy. It has been found that the composite has a good absorption and radiation characteristics in IR atmospheric window and a strong scattering ability in middle IR region by analyzing its extinction, absorption and radiation properties in IR region. Therefore, it may be used as IR absorption, extinction and radiation materials in some special fields.

Modifying infrared scattering effects of single yeast cells with plasmonic metal mesh

NASA Astrophysics Data System (ADS)

Malone, Marvin A.; Prakash, Suraj; Heer, Joseph M.; Corwin, Lloyd D.; Cilwa, Katherine E.; Coe, James V.

2010-11-01

The scattering effects in the infrared (IR) spectra of single, isolated bread yeast cells (Saccharomyces cerevisiae) on a ZnSe substrate and in metal microchannels have been probed by Fourier transform infrared imaging microspectroscopy. Absolute extinction [(3.4±0.6)×10-7 cm2 at 3178 cm-1], scattering, and absorption cross sections for a single yeast cell and a vibrational absorption spectrum have been determined by comparing it to the scattering properties of single, isolated, latex microspheres (polystyrene, 5.0 μm in diameter) on ZnSe, which are well modeled by the Mie scattering theory. Single yeast cells were then placed into the holes of the IR plasmonic mesh, i.e., metal films with arrays of subwavelength holes, yielding "scatter-free" IR absorption spectra, which have undistorted vibrational lineshapes and a rising generic IR absorption baseline. Absolute extinction, scattering, and absorption spectral profiles were determined for a single, ellipsoidal yeast cell to characterize the interplay of these effects.

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 forsterite formed. The forsterite crystal shapes (equant, b-platelets, c-platelets, b-columns - excluding a- and c-columns) derived from our modeling [17] of comet Hale- Bopp, compared to laboratory synthesis experiments [18], suggests that these crystals are high temperature condensates. By observing and modeling the crystalline features in comet ISON, we may constrain forsterite crystal shape(s) and link to their formation temperature(s) and environment(s).

Mid-Infrared Properties of OH Megamaser Host Galaxies. I. Spitzer IRS Low- and High-Resolution Spectroscopy

NASA Astrophysics Data System (ADS)

Willett, Kyle W.; Darling, Jeremy; Spoon, Henrik W. W.; Charmandaris, Vassilis; Armus, Lee

2011-03-01

We present mid-infrared spectra and photometry from the Infrared Spectrograph on the Spitzer Space Telescope for 51 OH megamasers (OHMs), along with 15 galaxies confirmed to have no megamaser emission above L OH = 102.3 L sun. The majority of galaxies display moderate-to-deep 9.7 μm amorphous silicate absorption, with OHM galaxies showing stronger average absorption and steeper 20-30 μm continuum emission than non-masing galaxies. Emission from multiple polycyclic aromatic hydrocarbons (PAHs), especially at 6.2, 7.7, and 11.3 μm, is detected in almost all systems. Fine-structure atomic emission (including [Ne II], [Ne III], [S III], and [S IV]) and multiple H2 rotational transitions are observed in more than 90% of the sample. A subset of galaxies show emission from rarer atomic lines, such as [Ne V], [O IV], and [Fe II]. Fifty percent of the OHMs show absorption from water ice and hydrogenated amorphous carbon grains, while absorption features from CO2, HCN, C2H2, and crystalline silicates are also seen in several OHMs. Column densities of OH derived from 34.6 μm OH absorption are similar to those derived from 1667 MHz OH absorption in non-masing galaxies, indicating that the abundance of masing molecules is similar for both samples. This data paper presents full mid-infrared spectra for each galaxy, along with measurements of line fluxes and equivalent widths, absorption feature depths, and spectral indices.

Collision-induced absorption in the region of the ν2 + ν3 band of carbon dioxide

NASA Astrophysics Data System (ADS)

Baranov, Yu. I.

2018-03-01

The IR absorption spectra of pure carbon dioxide in the region of the forbidden ν2 + ν3 vibrational transition at 3004 cm-1 have been recorded using a Fourier-transform spectrometer. A multipass-optical cell with the path length of 100 m was used in the study. The data were taken at room temperature of 294.8 K with a resolution of 0.02 cm-1 over the spectral region 2500-3500 cm-1. A sample pressures varied from 207 to 463 kPa (2.04-4.57 atm). The measured binary absorption coefficients provide the band integrated intensity value of (2.39 ± 0.04) ∗ 10-4 cm-2 amagat-2. The result is compared with those from previous works. The observed band profile features are discussed.

UNTANGLING THE NEAR-IR SPECTRAL FEATURES IN THE PROTOPLANETARY ENVIRONMENT OF KH 15D

DOE Office of Scientific and Technical Information (OSTI.GOV)

Arulanantham, Nicole A.; Herbst, William; Gilmore, Martha S.

2017-01-10

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 H{sub 2} emission features associated with the inner part of the jetmore » 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 μ m 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 M {sub J}, 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.« less

Composite Reflective Absorptive IR-Blocking Filters Embedded in Metamaterial Antireflection Coated Silicon

NASA Technical Reports Server (NTRS)

Munson, C. D.; Choi, S. K.; Coughlin, K. P.; McMahon, J. J.; Miller, K. H.; Page, L. A.; Wollack, E. J.

2017-01-01

Infrared (IR)-blocking filters are crucial for controlling the radiative loading on cryogenic systems and for optimizing the sensitivity of bolometric detectors in the far-IR. We present a new IR filter approach based on a combination of patterned frequency-selective structures on silicon and a thin (2575 micron thick) absorptive composite based on powdered reststrahlen absorbing materials. For a 300 K blackbody, this combination reflects approximately 50% of the incoming light and blocks greater than.99.8% of the total power with negligible thermal gradients and excellent low-frequency transmission. This allows a reduction in the IR thermal loading to negligible levels in a single cold filter. These composite filters are fabricated on silicon substrates, which provide excellent thermal transport laterally through the filter and ensure that the entire area of the absorptive filter stays near the bath temperature. A metamaterial antireflection coating cut into these substrates reduces in-band reflections to below 1%, and the in-band absorption of the powder mix is below 1% for signal bands below 750 GHz. This type of filter can be directly incorporated into silicon refractive optical elements.

Computed tomography measurement of gaseous fuel concentration by infrared laser light absorption

NASA Astrophysics Data System (ADS)

Kawazoe, Hiromitsu; Inagaki, Kazuhisa; Emi, Y.; Yoshino, Fumio

1997-11-01

A system to measure gaseous hydrocarbon distributions was devised, which is based on IR light absorption by C-H stretch mode of vibration and computed tomography method. It is called IR-CT method in the paper. Affection of laser light power fluctuation was diminished by monitoring source light intensity by the second IR light detector. Calibration test for methane fuel was carried out to convert spatial data of line absorption coefficient into quantitative methane concentration. This system was applied to three flow fields. The first is methane flow with lifted flame which is generated by a gourd-shaped fuel nozzle. Feasibility of the IR-CT method was confirmed through the measurement. The second application is combustion field with diffusion flame. Calibration to determine absorptivity was undertaken, and measured line absorption coefficient was converted spatial fuel concentration using corresponding temperature data. The last case is modeled in cylinder gas flow of internal combustion engine, where gaseous methane was led to the intake valve in steady flow state. The fuel gas flow simulates behavior of gaseous gasoline which is evaporated at intake valve tulip. Computed tomography measurement of inner flow is essentially difficult because of existence of surrounding wall. In this experiment, IR laser beam was led to planed portion by IR light fiber. It is found that fuel convection by airflow takes great part in air-fuel mixture formation and the developed IR-CT system to measure fuel concentration is useful to analyze air-fuel mixture formation process and to develop new combustors.

Experimental Determination of the Molar Absorption Coefficient of n-Hexane Adsorbed on High-Silica Zeolites.

PubMed

Gatti, Giorgio; Olivas Olivera, Diana F; Sacchetto, Vittoria; Cossi, Maurizio; Braschi, Ilaria; Marchese, Leonardo; Bisio, Chiara

2017-09-06

Determination of the molar absorption coefficients of the CH 3 bending mode at ν˜ =1380 cm -1 (ϵ 1380 ) of n-hexane adsorbed from the gas phase on two different dealuminated zeolites is derived by a combination of IR spectroscopy and microgravimetric analysis. High-silica zeolite Y (HSZ-Y) and zeolite ZSM-5 (with SiO 2 /Al 2 O 3 ratios of 200 and 280, respectively) with different textural and surface features are selected to evaluate the effect of the pore structure and architecture on the value of ϵ 1380 of the adsorbed n-hexane. Experimental data indicate that the molecule experiences a different adsorption environment inside zeolites; thus resulting in a significant change of the dipole moment and very different ϵ 1380 values: (0.278±0.018) cm μmol -1 for HSZ-Y and (0.491±0.032) cm μmol -1 for ZSM-5. Experimental data are also supported by computational modeling, which confirms the effect of different matrices on the IR absorption intensity. This study reveals that the use of probe molecules for quantitative measurements of surface sites has to be judiciously adopted, especially if adsorption occurs in the restricted spaces of microporous materials. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

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.

SPIRE Data Evaluation and Nuclear IR Fluorescence Processes.

DTIC Science & Technology

1982-11-30

so that all isotopes can be dealt with in a single run rather than a number of separate runs. At lower altitudes the radiance calculation needs to be...approximation can be inferred from the work of Neuendorffer (1982) on developing an analytic expression for the absorption of a single non-overlapping line...personnel by using prominent atmospheric infrared features such as the OH maximum, the HNO3 maximum, the CO3 4.3 um knee, etc. The azimuth however

INFRARED AND ULTRAVIOLET SPECTRA OF METHANE DILUTED IN SOLID NITROGEN AND IRRADIATED WITH ELECTRONS DURING DEPOSITION AT VARIOUS TEMPERATURES

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chin, Chih-Hao; Chen, Sian-Cong; Liu, Meng-Chen

We recorded the infrared and ultraviolet absorption spectra of CH{sub 4}:N{sub 2} matrix samples that underwent electron bombardment during deposition in the temperature range of 10–44 K. In contrast to a previous experiment on the IR spectroscopy of electron-bombarded icy samples, methyl and azide radicals became the main products upon electron bombardment during deposition; furthermore, reduced production of nitrile species was observed for deposition at 10 and 20 K. On the other hand, for deposition above 33 K, the observed bands of the radical species (such as methyl and azide) decreased, and bands of large nitriles appeared. This observation maymore » suggest that radical species easily diffuse and recombine to form more complex molecules in solid nitrogen at higher temperatures. Further measurements of similar samples at 10–33 K in the UV region revealed the intense band of azide radicals at 272.5 nm and weak, broad, overlapping features of methyl and azide radicals in the 225–197 nm region. For deposition at 44 K, only a broad feature centered at 219.4 nm was observed, and the possible carriers of nitrile species were proposed based on the corresponding IR spectrum and theoretical predictions of excitation energy. This band is similar to the observed absorption feature of Pluto’s surface recorded by the Hubble telescope in terms of both band position and bandwidth. Our findings therefore further support the suggestion that complex nitrile species may exist on the surface of Pluto.« less

FT-Raman, FT-IR and UV-visible spectral investigations and ab initio computations of anti-epileptic drug: Vigabatrin

NASA Astrophysics Data System (ADS)

Edwin, Bismi; Joe, I. Hubert

2013-10-01

Vibrational analysis of anti-epileptic drug vigabatrin, a structural GABA analog was carried out using NIR FT-Raman and FTIR spectroscopic techniques. The equilibrium geometry, various bonding features and harmonic vibrational wavenumbers were studied using density functional theory method. The detailed interpretation of the vibrational spectra has been carried out with the aid of VEDA.4 program. Vibrational spectra, natural bond orbital analysis and optimized molecular structure show clear evidence for the effect of electron charge transfer on the activity of the molecule. Predicted electronic absorption spectrum from TD-DFT calculation has been compared with the UV-vis spectrum. The Mulliken population analysis on atomic charges and the HOMO-LUMO energy were also calculated. Good consistency is found between the calculated results and experimental data for the electronic absorption as well as IR and Raman spectra. The blue-shifting of the Csbnd C stretching wavenumber reveals that the vinyl group is actively involved in the conjugation path. The NBO analysis confirms the occurrence of intramolecular hyperconjugative interactions resulting in ICT causing stabilization of the system.

Intercalation of IR absorber into layered double hydroxides: Preparation, thermal stability and selective IR absorption

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhu, Haifeng; Tang, Pinggui; Feng, Yongjun, E-mail: yjfeng@mail.buct.edu.cn

2012-03-15

Highlights: Black-Right-Pointing-Pointer PMIDA anions were intercalated into Mg{sub 2}Al-NO{sub 3} LDH by anion-exchange method. Black-Right-Pointing-Pointer The prepared material has highly selective IR absorption property in 9-11 {mu}m. Black-Right-Pointing-Pointer The obtained material has practical applications as heat-retaining additive. -- Abstract: N-phosphonomethyl aminodiacetic acid (PMIDA) was intercalated into the interlayer spacing of layered double hydroxides (LDH) by an anion-exchange method. The intercalated LDHs were characterized by various techniques such as powder X-ray diffraction (XRD), FT-IR spectroscopy, elemental analysis and simultaneous thermogravimetric and mass spectrometry (TG-MS) in details. The results show the formation of Mg{sub 2}Al-PMIDA LDH based on the expansion of d-spacingmore » from 0.89 nm to 1.22 nm and the disappearance of the characteristic IR absorption band at 1384 cm{sup -1} for NO{sub 3}{sup -} anions. The incorporation of Mg{sub 2}Al-PMIDA LDH into the low density polyethylene (LDPE) as an additive enhances the selectivity of IR absorption in the main wavelength region 9-11 {mu}m for radiant heat loss at night. Mg{sub 2}Al-PMIDA LDH as a heat-retaining additive has practical application in agricultural plastic films.« less

Displacement of polarons by vibrational modes in doped conjugated polymers

NASA Astrophysics Data System (ADS)

Anderson, M.; Ramanan, C.; Fontanesi, C.; Frick, A.; Surana, S.; Cheyns, D.; Furno, M.; Keller, T.; Allard, S.; Scherf, U.; Beljonne, D.; D'Avino, G.; von Hauff, E.; Da Como, E.

2017-10-01

Organic pi-conjugated polymers are deemed to be soft materials with strong electron-phonon coupling, which results in the formation of polarons, i.e., charge carriers dressed by self-localized distortion of the nuclei. Universal signatures for polarons are optical resonances below the band gap and intense vibrational modes (IVMs), both found in the infrared (IR) spectral region. Here, we study p -doped conjugated homo- and copolymers by combining first-principles modelling and optical spectroscopy from the far-IR to the visible. Polaronic IVMs are found to feature absorption intensities comparable to purely electronic transitions and, most remarkably, show only loose resemblance to the Raman or IR-active modes of the neutral polymer. The IVM frequency is dramatically scaled down (up to 50%) compared to the backbone carbon-stretching modes in the pristine polymers. The very large intensity of IVMs is associated with displacement of the excess positive charge along the backbone driven by specific vibrational modes. We propose a quantitative picture for the identification of these polaron shifting modes that solely based on structural information, directly correlates with their IR intensity. This finding finally discloses the elusive microscopic mechanism behind the huge IR intensity of IVMs in doped polymeric semiconductors.

Subwavelength engineered fiber-to-chip silicon-on-sapphire interconnects for mid-infrared applications (Conference Presentation)

NASA Astrophysics Data System (ADS)

Alonso-Ramos, Carlos; Han, Zhaohong; Le Roux, Xavier; Lin, Hongtao; Singh, Vivek; Lin, Pao Tai; Tan, Dawn; Cassan, Eric; Marris-Morini, Delphine; Vivien, Laurent; Wada, Kazumi; Hu, Juejun; Agarwal, Anuradha; Kimerling, Lionel C.

2016-05-01

The mid-Infrared wavelength range (2-20 µm), so-called fingerprint region, contains the very sharp vibrational and rotational resonances of many chemical and biological substances. Thereby, on-chip absorption-spectrometry-based sensors operating in the mid-Infrared (mid-IR) have the potential to perform high-precision, label-free, real-time detection of multiple target molecules within a single sensor, which makes them an ideal technology for the implementation of lab-on-a-chip devices. Benefiting from the great development realized in the telecom field, silicon photonics is poised to deliver ultra-compact efficient and cost-effective devices fabricated at mass scale. In addition, Si is transparent up to 8 µm wavelength, making it an ideal material for the implementation of high-performance mid-IR photonic circuits. The silicon-on-insulator (SOI) technology, typically used in telecom applications, relies on silicon dioxide as bottom insulator. Unfortunately, silicon dioxide absorbs light beyond 3.6 µm, limiting the usability range of the SOI platform for the mid-IR. Silicon-on-sapphire (SOS) has been proposed as an alternative solution that extends the operability region up to 6 µm (sapphire absorption), while providing a high-index contrast. In this context, surface grating couplers have been proved as an efficient means of injecting and extracting light from mid-IR SOS circuits that obviate the need of cleaving sapphire. However, grating couplers typically have a reduced bandwidth, compared with facet coupling solutions such as inverse or sub-wavelength tapers. This feature limits their feasibility for absorption spectroscopy applications that may require monitoring wide wavelength ranges. Interestingly, sub-wavelength engineering can be used to substantially improve grating coupler bandwidth, as demonstrated in devices operating at telecom wavelengths. Here, we report on the development of fiber-to-chip interconnects to ZrF4 optical fibers and integrated SOS circuits with 500 nm thick Si, operating around 3.8 µm wavelength. Results on facet coupling and sub-wavelength engineered grating coupler solutions in the mid-IR regime will be compared.

IR Absorption Coefficients for the Quantification of Water in Hydrous Ringwoodite

NASA Astrophysics Data System (ADS)

Thomas, Sylvia-Monique; Jacobsen, Steven D.; Bina, Craig R.; Smyth, Joseph R.; Frost, Daniel J.

2010-05-01

Raman spectroscopy, combined with the 'Comparator technique' has been developed to determine water contents ranging from a few wt ppm to wt% in glasses and nominally anhydrous minerals including garnets, olivine, and SiO2 polymorphs (Thomas et al. 2009). The routine is one promising example of quantification tools to determine mineral specific molar absorption coefficients (ɛ) for IR spectroscopy. Mineral specific absorption coefficients are required because general IR calibrations do not necessarily apply to minerals with water incorporated as hydroxyl point defects. Here we utilize the 'Comparator technique' to provide ɛ-values for a set of synthetic Fe-free (Fo100) and Fe-bearing (Fo90, Fo87, Fo83, Fo60) ringwoodites, as well as for γ-Mg2GeO4. Ringwoodite is considered one of the major phases of the Earth's lower transition zone (520-660 km depth) and the knowledge of its absolute water storage capacity is essential for modeling the Earth's deep water cycle. Samples were synthesized at variable P-T conditions in a multi-anvil press and cover a range of OH contents. Single-crystals were characterized using X-ray diffraction and IR spectroscopy. Mineral specific IR absorption coefficients were calculated from independently determined water contents from Raman spectroscopy. Unpolarized IR spectra of Mg-ringwoodite show broad absorption features in the OH region with band maxima at ~2350, 2538, 3130, 3172, 3598 and 3688 cm-1. In the spectra of Fe-bearing ringwoodite and γ-Mg2GeO4 the maxima of the main OH band are shifted to 3244 cm-1 (Fo60) and 3207 cm-1, respectively. For Mg-ringwoodite with the mean wavenumber (area-weighted average of the peak position) of 3170 cm-1 an ɛ-value of 191500 ± 38300 L cm-2/ molH2O was determined. For the ringwoodites with Fo90, Fo87 and Fo83 composition and the mean wavenumbers of 3229 cm-1, 3252 cm-1 and 3163 cm-1 values of 123600 ± 24700 L cm-2/ molH2O, 176300 ± 52900 L cm-2/ molH2O and 155000 ± 46500 L cm-2/ molH2O were computed. Our value for pure Mg-ringwoodite is in very good agreement with the value according to Libowitzky & Rossman (1997) and the absorption coefficient proposed by Balan et al. (2008), but is higher than the extrapolated value from Koch-Müller & Rhede (2010). However, in case of the sample with Fo60 composition water content and ɛ-value determined here are in excellent agreement with those calculated by Koch-Müller & Rhede (2010). Here, we will further discuss general IR calibrations and the dependence of ɛ on structure, composition and frequency for the (Mg,Fe)2SiO4 polymorphs in the mantle. We agree with the findings of Koch-Müller & Rhede (2010), which report that using the calibrations according to Paterson (1982) and Libowitzky & Rossman (1997) leads to a water content underestimation in case of Fe-rich (Fay-Fo60) samples. At this point this cannot be generalized for Mg-rich ringwoodite. References Thomas et al. (2009), Phys. Chem. Mineral., 36, 489-509. Libowitzky & Rossman (1997), Am. Mineral., 82, 1111-1115. Koch-Müller & Rhede (2010), Am. Mineral., in press. Paterson (1982), Bull. Mineral. (Paris), 105, 20-29.

Mid-infrared transmission spectra of crystalline and nanophase iron oxides/oxyhydroxides and implications for remote sensing of Mars

NASA Technical Reports Server (NTRS)

Bell, James F., III; Roush, Ted L.; Morris, Richard V.

1995-01-01

Ferric-iron-bearing materials play an important role in the interpretation of visible to near-IR Mars spectra, and they may play a similarly important role in the analysis of new mid-IR spacecraft spectral observations to be obtained over the next decade. We review existing data on mid-IR transmission spectra of ferric oxides/oxyhydroxides and present new transmission spectra for ferric-bearing materials spanning a wide range of mineralogy and crystallinity. These materials include 11 samples of well-crystallized ferric oxides (hematite, maghemite, and magnetite) and ferric oxyhydroxides (goethite, lepidocrocite). We also report the first transmission spectra for purely nanophase ferric oxide samples that have been shown to exhibit spectral similarities to Mars in the visible to near-IR and we compare these data to previous and new transmission spectra of terrestrial palagonites. Most of these samples show numerous, diagnostic absorption features in the mid-IR due to Fe(3+)-O(2-) vibrational transitions, structural and/or bound OH, and/or silicates. These data indicate that high spatial resolution, moderate spectral resolution mid-IR ground-based and spacecraft observations of Mars may be able to detect and uniquely discriminate among different ferric-iron-bearing phases on the Martian surface or in the airborne dust.

Mid-infrared transmission spectra of crystalline and nanophase iron oxides/oxyhydroxides and implications for remote sensing of Mars

NASA Technical Reports Server (NTRS)

Bell, James F., III; Roush, Ted L.; Morris, Richard V.

1995-01-01

Ferric-iron-bearing materials play an important role in the interpretation of visible to near-IR Mars spectra, and they may play a similarly important role in the analysis of new mid-IR spacecraft spectral observations to be obtained over the next decade. We review exisiting data on mid-IR transmission spectra of ferric oxides/oxyhydroxides and present new transmission spectra for ferric-bearing materials spanning a wide range of mineralogy and crystallinity. These materials include 11 samples of well-crystallized ferric oxides (hematite, maghemite, and magnetite) and ferric oxyhydroxides (goethite, lepidocrocite). We also report the first transmission spectra for purely nanophase ferric oxide samples that have been shown to exhibit spectral similarities to Mars in the visible to near-IR and we compare these data to previous and new transmission spectra of terrestial palagonites. Most of these samples show numerous, diagnostic absorption features in the mid-IR due to Fe(3+) - 0(2-) vibrational transitions, structural and/or bound OH, and/or silicates. These data indicate that high spatial resolution, moderate spectral resolution mid-IR ground-based and spacecraft observations of Mars may be able to detect and uniquely discriminate among different ferric-iron-bearing phases on the Martian surface or in the airborne dust.

Atmospheric pressure laser desorption/ionization using a 6-7 µm-band mid-infrared tunable laser and liquid water matrix.

PubMed

Hiraguchi, Ryuji; Hazama, Hisanao; Masuda, Katsuyoshi; Awazu, Kunio

2015-01-01

Due to the characteristic absorption peaks in the IR region, various molecules can be used as a matrix for infrared matrix-assisted laser desorption/ionization (IR-MALDI). Especially in the 6-7 µm-band IR region, solvents used as the mobile phase for liquid chromatography have absorption peaks that correspond to their functional groups, such as O-H, C=O, and CH3. Additionally, atmospheric pressure (AP) IR-MALDI, which is applicable to liquid-state samples, is a promising technique to directly analyze untreated samples. Herein we perform AP-IR-MALDI mass spectrometry of a peptide, angiotensin II, using a mid-IR tunable laser with a tunable wavelength range of 5.50-10.00 µm and several different matrices. The wavelength dependences of the ion signal intensity of [M + H](+) of the peptide are measured using a conventional solid matrix, α-cyano-4-hydroxycinnamic acid (CHCA) and a liquid matrix composed of CHCA and 3-aminoquinoline. Other than the O-H stretching and bending vibration modes, the characteristic absorption peaks are useful for AP-IR-MALDI. Peptide ions are also observed from an aqueous solution of the peptide without an additional matrix, and the highest peak intensity of [M + H](+) is at 6.00 µm, which is somewhat shorter than the absorption peak wavelength of liquid water corresponding to the O-H bending vibration mode. Moreover, long-lasting and stable ion signals are obtained from the aqueous solution. AP-IR-MALDI using a 6-7 µm-band IR tunable laser and solvents as the matrix may provide a novel on-line interface between liquid chromatography and mass spectrometry. Copyright © 2015 John Wiley & Sons, Ltd.

Design strategies to minimize the radiative efficiency of global warming molecules

PubMed Central

Bera, Partha P.; Francisco, Joseph S.; Lee, Timothy J.

2010-01-01

A strategy is devised to screen molecules based on their radiative efficiency. The methodology should be useful as one additional constraint when determining the best molecule to use for an industrial application. The strategy is based on the results of a recent study where we examined molecular properties of global warming molecules using ab initio electronic structure methods to determine which fundamental molecular properties are important in assessing the radiative efficiency of a molecule. Six classes of perfluorinated compounds are investigated. For similar numbers of fluorine atoms, their absorption of radiation in the IR window decreases according to perfluoroethers > perfluorothioethers ≈ sulfur/carbon compounds > perfluorocarbons > perfluoroolefins > carbon/nitrogen compounds. Perfluoroethers and hydrofluorethers are shown to possess a large absorption in the IR window due to (i) the C─O bonds are very polar, (ii) the C-O stretches fall within the IR window and have large IR intensity due to their polarity, and (iii) the IR intensity for C-F stretches in which the fluorine atom is bonded to the carbon that is bonded to the oxygen atom is enhanced due to a larger C─F bond polarity. Lengthening the carbon chain leads to a larger overall absorption in the IR window, though the IR intensity per bond is smaller. Finally, for a class of partially fluorinated compounds with a set number of electronegative atoms, the overall absorption in the IR window can vary significantly, as much as a factor of 2, depending on how the fluorine atoms are distributed within the molecule. PMID:20439762

IR Spectra of Different O2-Content Hemoglobin from Computational Study: Promising Detector of Hemoglobin Variant in Medical Diagnosis.

PubMed

Zhou, Su-Qin; Chen, Tu-Nan; Ji, Guang-Fu; Wang, En-Ren

2017-06-01

IR spectra of heme and different O 2 -content hemoglobin were studied by the quantum computation method at the molecule level. IR spectra of heme and different O 2 -content hemoglobin were quantificationally characterized from 0 to 100 THz. The IR spectra of oxy-heme and de-oxy-heme are obviously different at the frequency regions of 9.08-9.48, 38.38-39.78, 50.46-50.82, and 89.04-91.00 THz. At 24.72 THz, there exists the absorption peak for oxy-heme, whereas there is not the absorption peak for de-oxy-heme. Whether the heme contains Fe-O-O bond or not has the great influence on its IR spectra and vibration intensities of functional groups in the mid-infrared area. The IR adsorption peak shape changes hardly for different O 2 -content hemoglobin. However, there exist three frequency regions corresponding to the large change of IR adsorption intensities for containing-O 2 hemoglobin in comparison with de-oxy-hemoglobin, which are 11.08-15.93, 44.70-50.22, and 88.00-96.68 THz regions, respectively. The most differential values with IR intensity of different O 2 -content hemoglobin all exceed 1.0 × 10 4  L mol -1  cm -1 . With the increase of oxygen content, the absorption peak appears in the high-frequency region for the containing-O 2 hemoglobin in comparison with de-oxy-hemoglobin. The more the O 2 -content is, the greater the absorption peak is at the high-frequency region. The IR spectra of different O 2 -content hemoglobin are so obviously different in the mid-infrared region that it is very easy to distinguish the hemoglobin variant by means of IR spectra detector. IR spectra of hemoglobin from quantum computation can provide scientific basis and specific identification of hemoglobin variant resulting from different O 2 contents in medical diagnosis.

Hybridized orbital states in spin-orbit coupled 3 d -5 d double perovskites studied by x-ray absorption spectroscopy

NASA Astrophysics Data System (ADS)

Lee, Min-Cheol; Lee, Sanghyun; Won, C. J.; Lee, K. D.; Hur, N.; Chen, Jeng-Lung; Cho, Deok-Yong; Noh, T. W.

2018-03-01

We investigated the orbital hybridization mechanism in 3 d -5 d double perovskites (DPs) of La2CoIrO6 and La2CoPtO6 using x-ray absorption spectroscopy. It is clearly evidenced by O K -edge and Co K -edge x-ray absorption spectra that the Co 3 d orbitals hybridize not only with the half-filled Ir/Pt jeff states but also with the fully empty (unpolarized) Ir/Pt eg states in both DPs. The Co 3 d eg-Ir 5 d eg hybridization cannot contribute to the ferrimagnetic long-range order in La2CoIrO6 established by spin-selective Co 3 d t2 g-Ir 5 d jeff hybridization through the intermediate oxygen p state but could serve as an origin of paramagnetism. The strengths of such orbital hybridizations were found to be almost invariant to temperature, even far above the Curie temperature, implying persistent paramagnetism against the antiferromagnetic ordering in the spin-orbit entangled 3 d -5 d DPs.

Fourier Transform Infrared (FT-IR) Spectroscopy of Atmospheric Trace Gases HCl, NO and SO2

NASA Technical Reports Server (NTRS)

Haridass, C.; Aw-Musse, A.; Dowdye, E.; Bandyopadhyay, C.; Misra, P.; Okabe, H.

1998-01-01

Fourier Transform Infrared (FT-IR) spectral data have been recorded in the spectral region 400-4000/cm of hydrogen chloride and sulfur dioxide with I/cm resolution and of nitric oxide with 0.25 cm-i resolution, under quasi-static conditions, when the sample gas was passed through tubings of aluminum, copper, stainless steel and teflon. The absorbance was measured for the rotational lines of the fundamental bands of (1)H(35)Cl and (1)H(37)Cl for pressures in the range 100-1000 Torr and for the (14)N(16)O molecule in the range 100-300 Torr. The absorbance was also measured for individual rotational lines corresponding to the three modes of vibrations (upsilon(sub 1) - symmetric stretch, upsilon(sub 2) - symmetric bend, upsilon(sub 3) - anti-symmetric stretch) of the SO2 molecule in the pressure range 25-150 Torr. A graph of absorbance versus pressure was plotted for the observed rotational transitions of the three atmospherically significant molecules, and it was found that the absorbance was linearly proportional to the pressure range chosen, thereby validating Beer's law. The absorption cross-sections were determined from the graphical slopes for each rotational transition recorded for the HCl, NO and SO2 species. Qualitative and quantitative spectral changes in the FT-IR data will be discussed to identify and characterize various tubing materials with respect to their absorption features.

The Star-grazing Bodies in the HD 172555 System

NASA Astrophysics Data System (ADS)

Grady, C. A.; Brown, Alexander; Welsh, Barry; Roberge, Aki; Kamp, Inga; Rivière Marichalar, P.

2018-06-01

Kiefer et al. reported the detection of infalling Ca II absorption in HD 172555, a member of the β Pictoris Moving Group (βPMG). We obtained HST Space Telescope Imaging Spectrograph and Cosmic Origins Spectrograph spectroscopy of this star at 2 epochs separated by a week, and we report the discovery of infalling gas in resonant transitions of Si III and IV, C II and IV, and neutral atomic oxygen. Variable absorption is seen in the C II transitions and is optically thick, with covering factors which range between 58% and 68%, similar to features seen in β Pictoris. The O I spectral profile resembles that of C II, showing a strong low-velocity absorption to +50 km s‑1 in the single spectral segment obtained during orbital night, as well as what may be higher-velocity absorption. Studies of the mid-IR spectrum of this system have suggested the presence of silica. The O I absorption differs from that seen in Si III, suggesting that the neutral atomic oxygen does not originate in SiO dissociation products but in a more volatile parent molecule such as CO.

The Complete Transmission Spectrum of WASP-39b with a Precise Water Constraint

NASA Astrophysics Data System (ADS)

Wakeford, H. R.; Sing, D. K.; Deming, D.; Lewis, N. K.; Goyal, J.; Wilson, T. J.; Barstow, J.; Kataria, T.; Drummond, B.; Evans, T. M.; Carter, A. L.; Nikolov, N.; Knutson, H. A.; Ballester, G. E.; Mandell, A. M.

2018-01-01

WASP-39b is a hot Saturn-mass exoplanet with a predicted clear atmosphere based on observations in the optical and infrared. Here, we complete the transmission spectrum of the atmosphere with observations in the near-infrared (NIR) over three water absorption features with the Hubble Space Telescope (HST) Wide Field Camera 3 (WFC3) G102 (0.8–1.1 μm) and G141 (1.1–1.7 μm) spectroscopic grisms. We measure the predicted high-amplitude H2O feature centered at 1.4 μm and the smaller amplitude features at 0.95 and 1.2 μm, with a maximum water absorption amplitude of 2.4 planetary scale heights. We incorporate these new NIR measurements into previously published observational measurements to complete the transmission spectrum from 0.3 to 5 μm. From these observed water features, combined with features in the optical and IR, we retrieve a well constrained temperature T eq = 1030{}-20+30 K, and atmospheric metallicity {151}-46+48× solar, which is relatively high with respect to the currently established mass–metallicity trends. This new measurement in the Saturn-mass range hints at further diversity in the planet formation process relative to our solar system giants.

[Determination of the content of sulfur of coal by the infrared absorption method with high acccuracy].

PubMed

Wang, Hai-Feng; Lu, Hai; Li, Jia; Sun, Guo-Hua; Wang, Jun; Dai, Xin-Hua

2014-02-01

The present paper reported the differential scanning calorimetry-thermogravimetry curves and the infrared (IR) absorption spectrometry under the temperature program analyzed by the combined simultaneous thermal analysis-IR spectrometer. The gas products of coal were identified by the IR spectrometry. This paper emphasized on the combustion at high temperature-IR absorption method, a convenient and accurate method, which measures the content of sulfur in coal indirectly through the determination of the content of sulfur dioxide in the mixed gas products by IR absorption. It was demonstrated, when the instrument was calibrated by varied pure compounds containing sulfur and certified reference materials (CRMs) for coal, that there was a large deviation in the measured sulfur contents. It indicates that the difference in chemical speciations of sulfur between CRMs and the analyte results in a systematic error. The time-IR absorption curve was utilized to analyze the composition of sulfur at low temperatures and high temperatures and then the sulfur content of coal sample was determined by using a CRM for coal with a close composition of sulfur. Therefore, the systematic error due to the difference in chemical speciations of sulfur between the CRM and analyte was eliminated. On the other hand, in this combustion at high temperature-IR absorption method, the mass of CRM and analyte were adjusted to assure the sulfur mass equal and then the CRM and the analyte were measured alternately. This single-point calibration method reduced the effect of the drift of the IR detector and improved the repeatability of results, compared with the conventional multi-point calibration method using the calibration curves of signal intensity vs sulfur mass. The sulfur content results and their standard deviations of an anthracite coal and a bituminous coal with a low sulfur content determined by this modified method were 0.345% (0.004%) and 0.372% (0.008%), respectively. The uncertainty (U, k =2) of sulfur contents of two coal samples was evaluated to be 0.019% and 0.021%, respectively. Two main modifications, namely the calibration using the coal CRM with a similar composition of low-temperature sulfur and high temperature sulfur, and the single-point calibration alternating CRM and analyte, endow the combustion at high temperature-IR absorption method with an accuracy obviously better than that of the ASTM method. Therefore, this modified method has a well potential in the analysis of sulfur content.

Synthesis, spectral features and biological activity of some novel hetarylazo dyes derived from 6-amino-1,3-dimethyluracil

NASA Astrophysics Data System (ADS)

Yousefi, Hessamoddin; Yahyazadeh, Asieh; Yazdanbakhsh, Mohammad Reza; Rassa, Mehdi; Moradi-e-Rufchahi, Enayat O.'llah

2012-05-01

A series of hetarylazoaminouracil dyes were prepared by coupling of 6-amino-1,3-dimethyluracil with eight diazotized heterocyclic amines in nitrosyl sulphuric acid. The prepared azo dyes were characterized by UV-Vis, FT-IR, 13C NMR, 1H NMR spectroscopic techniques and elemental analysis. The solvatochromism of dyes was evaluated with respect to wavelength of maximum absorption (λmax) in seven solvents with different polarities: acetic acid, methanol, water, chloroform, acetonitrile, dimethyl sulfoxide and dimethyl formamide. The effects of acid, base and concentration of the dye on the visible absorption spectra were also reported. In addition, the antimicrobial activity of the synthesized dyes was evaluated on Escherichia coli, Bacillus subtilis, Micrococcus leuteus and Pseudomonas aeruginosa.

Time-Resolved O3 Chemical Chain Reaction Kinetics Via High-Resolution IR Laser Absorption Methods

NASA Technical Reports Server (NTRS)

Kulcke, Axel; Blackmon, Brad; Chapman, William B.; Kim, In Koo; Nesbitt, David J.

1998-01-01

Excimer laser photolysis in combination with time-resolved IR laser absorption detection of OH radicals has been used to study O3/OH(v = 0)/HO2 chain reaction kinetics at 298 K, (i.e.,(k(sub 1) is OH + 03 yields H02 + 02 and (k(sub 2) is H02 + 03 yields OH + 202). From time-resolved detection of OH radicals with high-resolution near IR laser absorption methods, the chain induction kinetics have been measured at up to an order of magnitude higher ozone concentrations ([03] less than or equal to 10(exp 17) molecules/cu cm) than accessible in previous studies. This greater dynamic range permits the full evolution of the chain induction, propagation, and termination process to be temporally isolated and measured in real time. An exact solution for time-dependent OH evolution under pseudo- first-order chain reaction conditions is presented, which correctly predicts new kinetic signatures not included in previous OH + 03 kinetic analyses. Specifically, the solutions predict an initial exponential loss (chain "induction") of the OH radical to a steady-state level ([OH](sub ss)), with this fast initial decay determined by the sum of both chain rate constants, k(sub ind) = k(sub 1) + k(sub 2). By monitoring the chain induction feature, this sum of the rate constants is determined to be k(sub ind) = 8.4(8) x 10(exp -14) cu cm/molecule/s for room temperature reagents. This is significantly higher than the values currently recommended for use in atmospheric models, but in excellent agreement with previous results from Ravishankara et al.

Calculation and Comparative Analysis of the IR Spectra of Homobrassinolide and (22S,23S)-Homobrassinolide

NASA Astrophysics Data System (ADS)

Andrianov, V. M.; Korolevich, M. V.

2015-09-01

Normal vibrational frequencies and absolute IR band intensities of the biologically active steroid phytohormones homobrassinolide and (22S,23S)-homobrassinolide were calculated in the framework of an original approach that combined classical analysis of normal modes using molecular mechanics with quantum-chemical estimation of the absolute intensities. IR absorption bands were interpreted based on a comparison of the experimental and theoretical absorption spectra. The impact of structural differences in the side chains of these molecules on the formation of their IR spectra in the region 1500-950 cm -1 was estimated.

Direct Observations of Clouds on Brown Dwarfs: A Spitzer Study of Extreme Cases

NASA Astrophysics Data System (ADS)

Burgasser, Adam; Cruz, Kelle; Cushing, Michael; Kirkpatrick, J. Davy; Looper, Dagny; Lowrance, Patrick; Marley, Mark; Saumon, Didier

2008-03-01

Clouds play a fundamental role in the emergent spectral energy distributions and observed variability of very low mass stars and brown dwarfs, yet hey have only been studied indirectly thus far. Recent indications of a broad silicate grain absorption feature in the 8-11 micron spectra of mid-type L dwarfs, and evidence that the strength of this absorption varies according to broad-band near-infrared color, may finally allow the first direct studies of clouds and condensate grain properties in brown dwarf atmospheres. We propose to observe a sample of 18 ``extreme'' L dwarfs - objects with unusually blue and red near-infrared colors - with IRAC and IRS to study the 8-11 micron feature in detail (including grain size distributions and bulk compositions), and to constrain advanced condensate cloud atmosphere models currently in development. Our program provides a unique examination of the general processes of cloud formation by focusing on the relatively warm photospheres of late-type brown dwarfs.

Infrared spectra and crystal chemistry of scapolites: implications for Martian mineralogy

USGS Publications Warehouse

Swayze, G.A.; Clark, R.N.

1990-01-01

Near-infrared and midinfrared spectra of a wide range of scapolite compositions were studied to determine the cause of the 2.36-??m features that have been correlated with similar features in the near-IR spectrum of Mars. We attribute the 2.36-??m features to vibrations caused by HCO-3 and HSO-4 in the anion sites of scapolite. The 2.36-??m absorption complex consists of four overlapping bands. The relative intensities of all four bands vary according to the HCO-3/HSO-4 ratio and disordered anion site occupancy. The positional disorder of HCO-3 and HSO4 in the low-symmetry anion site of scapolite gives the 2.36-??m band complex a unique spectral signature not likely to be duplicated in any other mineral. -from Authors

Prediction and Characterization of NaGaS2, A High Thermal Conductivity Mid-Infrared Nonlinear Optical Material for High-Power Laser Frequency Conversion.

PubMed

Hou, Dianwei; Nissimagoudar, Arun S; Bian, Qiang; Wu, Kui; Pan, Shilie; Li, Wu; Yang, Zhihua

2018-06-15

Infrared nonlinear optical (IR NLO) crystals are the major materials to widen the output range of solid-state lasers to mid- or far-infrared regions. The IR NLO crystals used in the middle IR region are still inadequate for high-power laser applications because of deleterious thermal effects (lensing and expansion), low laser-induced damage threshold, and two-photon absorption. Herein, the unbiased global minimum search method was used for the first time to search for IR NLO optical materials and ultimately found a new IR NLO material NaGaS 2 . It meets the stringent demands for IR NLO materials pumped by high-power laser with the highest thermal conductivity among common IR NLO materials able to avoid two-photon absorption, a classic nonlinear coefficient, and wide infrared transparency.

Infrared absorption spectra of molecular crystals: Possible evidence for small-polaron formation?

NASA Astrophysics Data System (ADS)

Pržulj, Željko; Čevizović, Dalibor; Zeković, Slobodan; Ivić, Zoran

2008-09-01

The temperature dependence of the position of the so-called anomalous band peaked at 1650cm in the IR-absorption spectrum of crystalline acetanilide (ACN) is theoretically investigated within the small-polaron theory. Its pronounced shift towards the position of the normal band is predicted with the rise of temperature. Interpretation of the IR-absorption spectra in terms of small-polaron model has been critically assessed on the basis of these results.

Formation and Destruction Processes of Interstellar Dust: From Organic Molecules to carbonaceous Grains

NASA Technical Reports Server (NTRS)

Salama, F.; Biennier, L.

2004-01-01

The study of the formation and destruction processes of cosmic dust is essential to understand and to quantify the budget of extraterrestrial organic molecules. interstellar dust presents a continuous size distribution from large molecules, radicals and ions to nanometer-sized particles to micron-sized grains. The lower end of the dust size distribution is thought to be responsible for the ubiquitous spectral features that are seen in emission in the IR (UIBs) and in absorption in the visible (DIBs). The higher end of the dust-size distribution is thought to be responsible for the continuum emission plateau that is seen in the IR and for the strong absorption seen in the interstellar UV extinction curve. All these spectral signatures are characteristic of cosmic organic materials that are ubiquitous and present in various forms from gas-phase molecules to solid-state grains. Although dust with all its components plays an important role in the evolution of interstellar chemistry and in the formation of organic molecules, little is known on the formation and destruction processes of dust. Recent space observations in the UV (HST) and in the IR (ISO) help place size constraints on the molecular component of carbonaceous IS dust and indicate that small (ie., subnanometer) PAHs cannot contribute significantly to the IS features in the UV and in the IR. Studies of large molecular and nano-sized IS dust analogs formed from PAH precursors have been performed in our laboratory under conditions that simulate diffuse ISM environments (the particles are cold -100 K vibrational energy, isolated in the gas phase and exposed to a high-energy discharge environment in a cold plasma). The species (molecules, molecular fragments, ions, nanoparticles, etc) formed in the pulsed discharge nozzle (PDN) plasma source are detected with a high-sensitivity cavity ring-down spectrometer (CRDS). We will present new experimental results that indicate that nanoparticles are generated in the plasma. From these unique measurements, we derive information on the nature, the size and the structure of interstellar dust particles, the growth and the destruction processes of IS dust and the resulting budget of extraterrestrial organic molecules.

Detecting infrared luminescence and non-chemical signaling of living cells: single cell mid-IR spectroscopy in cryogenic environments

NASA Astrophysics Data System (ADS)

Pereverzev, Sergey

2017-02-01

Many life-relevant interaction energies are in IR range, and it is reasonable to believe that some biochemical reactions inside cells can results in emission of IR photons. Cells can use this emission for non-chemical and non-electrical signaling. Detecting weak infrared radiation from live cells is complicated because of strong thermal radiation background and absorption of radiation by tissues. A microfluidic device with live cells inside a vacuum cryogenic environment should suppress this background, and thereby permit observation of live cell auto-luminescence or signaling in the IR regime. One can make IR-transparent windows not emitting in this range, so only the cell and a small amount of liquid around it will emit infrared radiation. Currently mid-IR spectroscopy of single cells requires the use of a synchrotron source to measure absorption or reflection spectra. Decreasing of thermal radiation background will allow absorption and reflection spectroscopy of cells without using synchrotron light. Moreover, cell auto-luminescence can be directly measured. The complete absence of thermal background radiation for cryogenically cooled samples allows the use IR photon-sensitive detectors and obtaining single molecule sensitivity in IR photo-luminescence measurements. Due to low photon energies, photo-luminescence measurements will be non-distractive for pressures samples. The technique described here is based upon US patent 9366574.

Determination of iridium in mafic rocks by atomic absorption

USGS Publications Warehouse

Grimaldi, F.S.; Schnepfe, M.M.

1970-01-01

Iridium is determined in mineralized mafic rocks by atomic absorption after fire-assay concentration into a gold bead. Interelement interferences in the atomic-absorption determination are removed and Ir sensitivity is increased by buffering the solutions with a mixture of copper and sodium sulphates. Substantial amounts of Ag, Al, Au, Bi, Ca, Cd, Co, Cr, Fe, Ho, Hg, K, La, Mg, Mn, Mo, Ni, Pb, Te, Ti, V, Y, Zn and platinum metals can be tolerated in the atomic-absorption determination. The sensitivity and detection limits are 3.2 and 0.25 ppm of Ir, respectively. ?? 1970.

Indirect Gas Species Monitoring Using Tunable Diode Lasers

DOEpatents

Von Drasek, William A.; Saucedo, Victor M.

2005-02-22

A method for indirect gas species monitoring based on measurements of selected gas species is disclosed. In situ absorption measurements of combustion species are used for process control and optimization. The gas species accessible by near or mid-IR techniques are limited to species that absorb in this spectral region. The absorption strength is selected to be strong enough for the required sensitivity and is selected to be isolated from neighboring absorption transitions. By coupling the gas measurement with a software sensor gas, species not accessible from the near or mid-IR absorption measurement can be predicted.

X-ray Absorption Spectroscopy Study of the Effect of Rh doping in Sr2IrO4

PubMed Central

Sohn, C. H.; Cho, Deok-Yong; Kuo, C.-T.; Sandilands, L. J.; Qi, T. F.; Cao, G.; Noh, T. W.

2016-01-01

We investigate the effect of Rh doping in Sr2IrO4 using X-ray absorption spectroscopy (XAS). We observed appearance of new electron-addition states with increasing Rh concentration (x in Sr2Ir1−xRhxO4) in accordance with the concept of hole doping. The intensity of the hole-induced state is however weak, suggesting weakness of charge transfer (CT) effect and Mott insulating ground states. Also, Ir Jeff = 1/2 upper Hubbard band shifts to lower energy as x increases up to x = 0.23. Combined with optical spectroscopy, these results suggest a hybridisation-related mechanism, in which Rh doping can weaken the (Ir Jeff = 1/2)–(O 2p) orbital hybridisation in the in-planar Rh-O-Ir bond networks. PMID:27025538

Mapping the amide I absorption in single bacteria and mammalian cells with resonant infrared nanospectroscopy

NASA Astrophysics Data System (ADS)

Baldassarre, L.; Giliberti, V.; Rosa, A.; Ortolani, M.; Bonamore, A.; Baiocco, P.; Kjoller, K.; Calvani, P.; Nucara, A.

2016-02-01

Infrared (IR) nanospectroscopy performed in conjunction with atomic force microscopy (AFM) is a novel, label-free spectroscopic technique that meets the increasing request for nano-imaging tools with chemical specificity in the field of life sciences. In the novel resonant version of AFM-IR, a mid-IR wavelength-tunable quantum cascade laser illuminates the sample below an AFM tip working in contact mode, and the repetition rate of the mid-IR pulses matches the cantilever mechanical resonance frequency. The AFM-IR signal is the amplitude of the cantilever oscillations driven by the thermal expansion of the sample after absorption of mid-IR radiation. Using purposely nanofabricated polymer samples, here we demonstrate that the AFM-IR signal increases linearly with the sample thickness t for t \\gt 50 nm, as expected from the thermal expansion model of the sample volume below the AFM tip. We then show the capability of the apparatus to derive information on the protein distribution in single cells through mapping of the AFM-IR signal related to the amide-I mid-IR absorption band at 1660 cm-1. In Escherichia Coli bacteria we see how the topography changes, observed when the cell hosts a protein over-expression plasmid, are correlated with the amide I signal intensity. In human HeLa cells we obtain evidence that the protein distribution in the cytoplasm and in the nucleus is uneven, with a lateral resolution better than 100 nm.

Discrete frequency infrared microspectroscopy and imaging with a tunable quantum cascade laser

PubMed Central

Kole, Matthew R.; Reddy, Rohith K.; Schulmerich, Matthew V.; Gelber, Matthew K.; Bhargava, Rohit

2012-01-01

Fourier-transform infrared imaging (FT-IR) is a well-established modality but requires the acquisition of a spectrum over a large bandwidth, even in cases where only a few spectral features may be of interest. Discrete frequency infrared (DF-IR) methods are now emerging in which a small number of measurements may provide all the analytical information needed. The DF-IR approach is enabled by the development of new sources integrating frequency selection, in particular of tunable, narrow-bandwidth sources with enough power at each wavelength to successfully make absorption measurements. Here, we describe a DF-IR imaging microscope that uses an external cavity quantum cascade laser (QCL) as a source. We present two configurations, one with an uncooled bolometer as a detector and another with a liquid nitrogen cooled Mercury Cadmium Telluride (MCT) detector and compare their performance to a commercial FT-IR imaging instrument. We examine the consequences of the coherent properties of the beam with respect to imaging and compare these observations to simulations. Additionally, we demonstrate that the use of a tunable laser source represents a distinct advantage over broadband sources when using a small aperture (narrower than the wavelength of light) to perform high-quality point mapping. The two advances highlight the potential application areas for these emerging sources in IR microscopy and imaging. PMID:23113653

Connecting the Interstellar Gas and Dust Properties in Distant Galaxies Using Quasar Absorption Systems

NASA Technical Reports Server (NTRS)

Aller, Monique C.; Dwek, Eliahu; Kulkarni, Varsha P.; York, Donald G.; Welty, Daniel E.; Vladilo, Giovanni; Som, Debopam; Lackey, Kyle; Dwek, Eli; Beiranvand, Nassim;

FT-Raman, FT-IR and UV-visible spectral investigations and ab initio computations of anti-epileptic drug: vigabatrin.

PubMed

Edwin, Bismi; Joe, I Hubert

2013-10-01

Vibrational analysis of anti-epileptic drug vigabatrin, a structural GABA analog was carried out using NIR FT-Raman and FTIR spectroscopic techniques. The equilibrium geometry, various bonding features and harmonic vibrational wavenumbers were studied using density functional theory method. The detailed interpretation of the vibrational spectra has been carried out with the aid of VEDA.4 program. Vibrational spectra, natural bond orbital analysis and optimized molecular structure show clear evidence for the effect of electron charge transfer on the activity of the molecule. Predicted electronic absorption spectrum from TD-DFT calculation has been compared with the UV-vis spectrum. The Mulliken population analysis on atomic charges and the HOMO-LUMO energy were also calculated. Good consistency is found between the calculated results and experimental data for the electronic absorption as well as IR and Raman spectra. The blue-shifting of the C-C stretching wavenumber reveals that the vinyl group is actively involved in the conjugation path. The NBO analysis confirms the occurrence of intramolecular hyperconjugative interactions resulting in ICT causing stabilization of the system. Copyright © 2013 Elsevier B.V. All rights reserved.

Analysis of fingerprints features of infrared spectra of various processed products of Rhizoma Coptidis and their different extracts

NASA Astrophysics Data System (ADS)

Xu, Beilei; Zhang, Guijun; Xu, Changhua; Sun, Suqin

2015-09-01

Fourier transform infrared spectroscopy (FT-IR) associated with second derivative infrared spectroscopy (SD-IR) and two-dimensional correlation infrared spectroscopy (2D-IR) are employed to analyze various processed products and different extracts of Rhizoma Coptidis. There is a shift of the peak of 1641 cm-1 of raw Rhizoma Coptidis after processed, which drifts to lower wave number. Peaks at 1508, 1387, 1363, 1332, 1274 and 1234 cm-1 barely change in most samples, except an obvious enhancement of these peaks after processed, suggesting that processed Rhizoma Coptidis may have higher content of berberine than raw material, which is corresponding to the results of correlation coefficients analysis. There are some differences in the absorption peaks in the range of 1800-1000 cm-1 in the SD-IR spectra, which have better resolution, of different processed products. 2D-IR spectra, which elevate the resolution further, can present more differences among the products in the range of 1300-800 cm-1 and 1800-1300 cm-1. Analysis of aqueous, ethanol and petroleum ether extracts of various processed products proves that there are distinctive differences of all auto-peaks in shapes and intensities in all of them. With the advantages of high resolution, high speed and convenience, FT-IR combined with 2D-IR can quickly and precisely distinguish various processed products of Rhizoma Coptidis and can be applied to predict the tendency of transformation of the complicated chemical mixture systems under heat perturbation.

TIME-DOMAIN SPECTROSCOPY OF A T TAURI STAR

NASA Astrophysics Data System (ADS)

Dupree, Andrea K.; Brickhouse, Nancy S.; Cranmer, Steven R.; Berlind, Perry L.; Strader, Jay; Smith, Graeme H.

2014-06-01

High resolution optical and near-infrared spectra of TW Hya, the nearest accreting T Tauri star, cover a decade and reveal the substantial changes in accretion and wind properties. Our spectra suggest that the broad near-IR, optical, and far-uv emission lines, centered on the star, originate in a turbulent post-shock region and can undergo scattering by the overlying stellar wind as well as absorption from infalling material. Stable absorption features appear in H-alpha, apparently caused by an accreting column silhouetted in the stellar wind. The free-fall velocity of material correlates inversely with the strength of the post-shock emission, consistent with a dipole accretion model. Terminal outflow velocities appear to be directly related to the amount of post-shock emission, giving evidence for an accretion-driven stellar wind.

The Cheshire-cat-like Behavior of 2nu(sub 3) Overtone of Co2 near 2.134 micron: NIR Lab Spectra of Solid CO2 in H2O and CH3OH

NASA Technical Reports Server (NTRS)

Bernstein, Max; Sandford, Scott; Cruikshank, Dale

2005-01-01

Infrared (IR) spectra have demonstrated that solid H2O is very common in the outer Solar System, and solid carbon dioxide (CO2) has been detected on icy satellites, comets, and planetismals throughout the outer Solar System. In such environments, CO2 and H2O must sometimes be mixed at a molecular level, changing their IR absorption features. In fact, the IR spectra of CO2-H2O mixtures are not equivalent to a linear combination of the spectra of the pure materials. Laboratory IR spectra of pure CO2 and H2O have been published but a lack of near-IR spectra of CO2-H2O mixtures has made the interpretation of outer Solar System spectra more difficult. We present near infrared (IR) spectra of CO2 in H2O and in CH3OH compared to that of pure solid CO2 and find significant differences. Peaks not present in either pure H2O or pure CO2 spectra become evident. First, the CO2 (2nu(sub 3)) overtone near 2.134 micron (4685/ cm) that is not seen in pure solid CO2 is prominent in the spectrum of a CO2/H2O = 25 mixture. Second, a 2.74 micron (3650/ cm) dangling OH feature of water (and a potentially related peak at 1.89 micron) appear in the spectra of CO2-H2O ice mixtures, but may not be specific to the presence of CO2. Other CO2 peaks display shifts in position and increased width because of intermolecular interactions with water. Changes in CO2 peak positions and profiles on warming of a CO2/H2O = 5 mixture are consistent with 'segregation' of the ice into nearly pure separate components. Absolute strengths for absorptions of CO2 in solid H2O are estimated. Similar results are observed for CO2 in solid CH3OH. Since the CO2 ( 2nu(sub 3)) overtone near 2.134 micron (4685/ cm) is not present in pure CO2 but prominent in mixtures it may be a good observational indicator of whether solid CO2 is a pure material or intimately mixed with other molecules. Significant changes in the near IR spectrum of solid CO2 in the presence of H2O and CH3OH means that the abundance of solid CO2 in the outer Solar System may have been under-estimated in those environments where solid CO2 and H2O or CH3OH are mixed.

Infrared spectroscopy of molecular submonolayers on surfaces by infrared scanning tunneling microscopy: tetramantane on Au111.

PubMed

Pechenezhskiy, Ivan V; Hong, Xiaoping; Nguyen, Giang D; Dahl, Jeremy E P; Carlson, Robert M K; Wang, Feng; Crommie, Michael F

2013-09-20

We have developed a new scanning-tunneling-microscopy-based spectroscopy technique to characterize infrared (IR) absorption of submonolayers of molecules on conducting crystals. The technique employs a scanning tunneling microscope as a precise detector to measure the expansion of a molecule-decorated crystal that is irradiated by IR light from a tunable laser source. Using this technique, we obtain the IR absorption spectra of [121]tetramantane and [123]tetramantane on Au(111). Significant differences between the IR spectra for these two isomers show the power of this new technique to differentiate chemical structures even when single-molecule-resolved scanning tunneling microscopy (STM) images look quite similar. Furthermore, the new technique was found to yield significantly better spectral resolution than STM-based inelastic electron tunneling spectroscopy, and to allow determination of optical absorption cross sections. Compared to IR spectroscopy of bulk tetramantane powders, infrared scanning tunneling microscopy (IRSTM) spectra reveal narrower and blueshifted vibrational peaks for an ordered tetramantane adlayer. Differences between bulk and surface tetramantane vibrational spectra are explained via molecule-molecule interactions.

Airborne pipeline leak detection: UV or IR?

NASA Astrophysics Data System (ADS)

Babin, François; Gravel, Jean-François; Allard, Martin

2016-05-01

This paper presents a study of different approaches to the measurement of the above ground vapor plume created by the spill caused by a small 0.1 l/min (or less) leak in an underground liquid petroleum pipeline. The scenarios are those for the measurement from an airborne platform. The usual approach is that of IR absorption, but in the case of liquid petroleum products, there are drawbacks that will be discussed, especially when using alkanes to detect a leak. The optical measurements studied include UV enhanced Raman lidar, UV fluorescence lidar and IR absorption path integrated lidars. The breadboards used for testing the different approaches will be described along with the set-ups for leak simulation. Although IR absorption would intuitively be the most sensitive, it is shown that UV-Raman could be an alternative. When using the very broad alkane signature in the IR, the varying ground spectral reflectance are a problem. It is also determined that integrated path measurements are preferred, the UV enhanced Raman measurements showing that the vapor plume stays very close to the ground.

Isolation of site-specific anharmonicities of individual water molecules in the I-·(H2O)2 complex using tag-free, isotopomer selective IR-IR double resonance

NASA Astrophysics Data System (ADS)

Yang, Nan; Duong, Chinh H.; Kelleher, Patrick J.; Johnson, Mark A.; McCoy, Anne B.

2017-12-01

We reveal the microscopic mechanics of iodide ion microhydration by recording the isotopomer-selective vibrational spectra of the I-·(H2O)·(D2O), I-·(HOD)·(D2O), and I-·(DOH)·(H2O) isotopologues using a new class of ion spectrometer that is optimized to carry out two-color, IR-IR photodissociation in a variety of pump-probe schemes. Using one of these, we record the linear absorption spectrum of a cryogenically cooled cluster without the use of a messenger ;tag;. In another protocol, we reveal the spectra of individual H2O and D2O molecules embedded in each of the two possible binding sites in the iodide dihydrate, as well as the bands due to individual OH and OD groups in each of the four local binding environments. Finally, we demonstrate how temperature dependent isotopic scrambling among the spectral features can be used to monitor the onset of large amplitude motion, heretofore inferred from changes in the envelope of the OH stretching vibrational manifold.

A first principle study for the adsorption and absorption of carbon atom and the CO dissociation on Ir(100) surface

NASA Astrophysics Data System (ADS)

Erikat, I. A.; Hamad, B. A.

2013-11-01

We employ density functional theory to examine the adsorption and absorption of carbon atom as well as the dissociation of carbon monoxide on Ir(100) surface. We find that carbon atoms bind strongly with Ir(100) surface and prefer the high coordination hollow site for all coverages. In the case of 0.75 ML coverage of carbon, we obtain a bridging metal structure due to the balance between Ir-C and Ir-Ir interactions. In the subsurface region, the carbon atom prefers the octahedral site of Ir(100) surface. We find large diffusion barrier for carbon atom into Ir(100) surface (2.70 eV) due to the strong bonding between carbon atom and Ir(100) surface, whereas we find a very small segregation barrier (0.22 eV) from subsurface to the surface. The minimum energy path and energy barrier for the dissociation of CO on Ir(100) surface are obtained by using climbing image nudge elastic band. The energy barrier of CO dissociation on Ir(100) surface is found to be 3.01 eV, which is appreciably larger than the association energy (1.61 eV) of this molecule.

A first principle study for the adsorption and absorption of carbon atom and the CO dissociation on Ir(100) surface.

PubMed

Erikat, I A; Hamad, B A

2013-11-07

We employ density functional theory to examine the adsorption and absorption of carbon atom as well as the dissociation of carbon monoxide on Ir(100) surface. We find that carbon atoms bind strongly with Ir(100) surface and prefer the high coordination hollow site for all coverages. In the case of 0.75 ML coverage of carbon, we obtain a bridging metal structure due to the balance between Ir-C and Ir-Ir interactions. In the subsurface region, the carbon atom prefers the octahedral site of Ir(100) surface. We find large diffusion barrier for carbon atom into Ir(100) surface (2.70 eV) due to the strong bonding between carbon atom and Ir(100) surface, whereas we find a very small segregation barrier (0.22 eV) from subsurface to the surface. The minimum energy path and energy barrier for the dissociation of CO on Ir(100) surface are obtained by using climbing image nudge elastic band. The energy barrier of CO dissociation on Ir(100) surface is found to be 3.01 eV, which is appreciably larger than the association energy (1.61 eV) of this molecule.

Masked red-emitting carbopyronine dyes with photosensitive 2-diazo-1-indanone caging group.

PubMed

Kolmakov, Kirill; Wurm, Christian; Sednev, Maksim V; Bossi, Mariano L; Belov, Vladimir N; Hell, Stefan W

2012-03-01

Caged near-IR emitting fluorescent dyes are in high demand in optical microscopy but up to now were unavailable. We discovered that the combination of a carbopyronine dye core and a photosensitive 2-diazo-1-indanone residue leads to masked near-IR emitting fluorescent dyes. Illumination of these caged dyes with either UV or visible light (λ < 420 nm) efficiently generates fluorescent compounds with absorption and emission at 635 nm and 660 nm, respectively. A high-yielding synthetic route with attractive possibilities for further dye design is described in detail. Good photostability, high contrast, and a large fluorescence quantum yield after uncaging are the most important features of the new compounds for non-invasive imaging in high-resolution optical microscopy. For use in immunolabelling the caged dyes were decorated with a (hydrophilic) linker and an (activated) carboxyl group.

The Infrared Spectrum of Matrix Isolated Aminoacetonitrile: A Precursor to the Amino Acid Glycine

NASA Technical Reports Server (NTRS)

Bernstein, Max P.; Bauschlicher, Charles W., Jr.; Sandford, Scott A.

2003-01-01

We present infrared (IR) spectral data from matrix isolation experiments and density functional theory calculations on the pre-biologically interesting molecule aminoacetonitrile, a precursor to glycine. We find that this nitrile has an unusually weak nitrile (C=N) stretch in the infrared, in contrast to expectations based on measurements and models of other nitriles under astrophysical conditions. The absence of an observable nitrile absorption feature in the infrared will make the IR search for this molecule considerably more difficult, and will raise estimates of upper limits on nitriles in interstellar and outer Solar System ices. This is also of relevance to assessing the formation routes of the amino acid glycine, since aminoacetonitrile is the putative precursor to glycine via the Strecker synthesis, the mechanism postulated to have produced the amino acids in meteorites.

Stellar occultation candidates from the guide star catalog. I - Saturn, 1991-1999

NASA Technical Reports Server (NTRS)

Bosh, A. S.; Mcdonald, S. W.

1992-01-01

A list of 203 potential occultations by Saturn and its ring of stars from the HST Guide Star Catalog (GSC) during the years 1991-1999 is presented. This list features many fainter candidates than do current occultation candidate lists for Saturn; these fainter stars can also provide a high signal-to-noise ratio if observed with a large telescope or in the IR where Saturn and its rings have absorption bands. The occultation circumstances are listed, as well as star information found in the GSC.

Thermal Pressure in Diffuse H2 Gas Measured by Herschel [C II] Emission and FUSE UV H2 Absorption

NASA Astrophysics Data System (ADS)

Velusamy, T.; Langer, W. D.; Goldsmith, P. F.; Pineda, J. L.

2017-04-01

UV absorption studies with the Far Ultraviolet Spectroscopic Explorer (FUSE) satellite have made important observations of H2 molecular gas in Galactic interstellar translucent and diffuse clouds. Observations of the 158 μm [C II] fine-structure line with Herschel trace the same H2 molecular gas in emission. We present [C II] observations along 27 lines of sight (LOSs) toward target stars of which 25 have FUSE H2 UV absorption. Two stars have only HST STIS C II λ2325 absorption data. We detect [C II] 158 μm emission features in all but one target LOS. For three target LOSs that are close to the Galactic plane, | {\\text{}}b| < 1°, we also present position-velocity maps of [C II] emission observed by Herschel Heterodyne Instrument in the Far Infrared (HIFI) in on-the-fly spectral-line mapping. We use the velocity-resolved [C II] spectra observed by the HIFI instrument toward the target LOSs observed by FUSE to identify [C II] velocity components associated with the H2 clouds. We analyze the observed velocity integrated [C II] spectral-line intensities in terms of the densities and thermal pressures in the H2 gas using the H2 column densities and temperatures measured by the UV absorption data. We present the H2 gas densities and thermal pressures for 26 target LOSs and from the [C II] intensities derive a mean thermal pressure in the range of ˜6100-7700 K cm-3 in diffuse H2 clouds. We discuss the thermal pressures and densities toward 14 targets, comparing them to results obtained using the UV absorption data for two other tracers C I and CO. Our results demonstrate the richness of the far-IR [C II] spectral data which is a valuable complement to the UV H2 absorption data for studying diffuse H2 molecular clouds. While the UV absorption is restricted to the directions of the target star, far-IR [C II] line emission offers an opportunity to employ velocity-resolved spectral-line mapping capability to study in detail the clouds’ spatial and velocity structures.

Frontiers in Chemical Physics

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bowlan, Pamela Renee

2016-05-02

These are slides dealing with frontiers in chemical physics. The following topics are covered: Time resolving chemistry with ultrashort pulses in the 0.1-40 THz spectral range; Example: Mid-infrared absorption spectrum of the intermediate state CH 2OO; Tracking reaction dynamics through changes in the spectra; Single-shot measurement of the mid-IR absorption dynamics; Applying 2D coherent mid-IR spectroscopy to learn more about transition states; Time resolving chemical reactions at a catalysis using mid-IR and THz pulses; Studying topological insulators requires a surface sensitive probe; Nonlinear phonon dynamics in Bi 2Se 3; THz-pump, SHG-probe as a surface sensitive coherent 2D spectroscopy; Nanometer andmore » femtosecond spatiotemporal resolution mid-IR spectroscopy; Coherent two-dimensional THz/mid-IR spectroscopy with 10nm spatial resolution; Pervoskite oxides as catalysts; Functionalized graphene for catalysis; Single-shot spatiotemporal measurements; Spatiotemporal pulse measurement; Intense, broad-band THz/mid-IR generation with organic crystals.« less

The composition of Martian aeolian sands: Thermal emissivity from Viking IRTM observations

NASA Technical Reports Server (NTRS)

Edgett, Kenneth S.; Christensen, Philip R.

1992-01-01

Aeolian sands provide excellent surfaces for the remote determination of the mineralogic composition of Martian materials, because such deposits consist of relatively well-sorted, uniform particle sizes and might consist of chemically unaltered, primary mineral grains derived from bedrock. Dark features on the floors of Martian craters are controlled by aeolian processes and many consist largely of unconsolidated, windblown sand. Measurement of the thermal emissivity of geologic materials provides a way to identify mid-infrared absorption bands, the strength and positions of which vary with mineral structure and composition. The Viking Infrared Thermal Mapper (IRTM) had four surface-sensing mid-IR bands, three of which, the 7, 9, and 11 micron channels, correspond to absorption features characteristic of carbonates, sialic, and mafic minerals, respectively. In this study, the highest quality IRTM data were constrained so as to avoid the effects of atmospheric dust, clouds, surface frosts, and particle size variations (the latter using data obtained between 7 and 9 H, and they were selected for dark intracrater features such that only data taken directly from the dark feature were used, so as to avoid thermal contributions from adjacent but unrelated materials. Three-point emissivity spectra of Martian dart intracrater features were compared with laboratory emission spectra of minerals and terrestrial aeolian sands convolved using the IRTM response function to the four IRTM spectral channels.

SimBAL: A Spectral Synthesis Approach to Analyzing Broad Absorption Line Quasar Spectra

NASA Astrophysics Data System (ADS)

Terndrup, Donald M.; Leighly, Karen; Gallagher, Sarah; Richards, Gordon T.

2017-01-01

Broad Absorption Line quasars (BALQSOs) show blueshifted absorption lines in their rest-UV spectra, indicating powerful winds emerging from the central engine. These winds are essential part of quasars: they can carry away angular momentum and thus facilitate accretion through a disk, they can distribute chemically-enriched gas through the intergalactic medium, and they may inject kinetic energy to the host galaxy, influencing its evolution. The traditional method of analyzing BALQSO spectra involves measuring myriad absorption lines, computing the inferred ionic column densities in each feature, and comparing with the output of photonionization models. This method is inefficient and does not handle line blending well. We introduce SimBAL, a spectral synthesis fitting method for BALQSOs, which compares synthetic spectra created from photoionization model results with continuum-normalized observed spectra using Bayesian model calibration. We find that we can obtain an excellent fit to the UV to near-IR spectrum of the low-redshift BALQSO SDSS J0850+4451, including lines from diverse ionization states such as PV, CIII*, SIII, Lyalpha, NV, SiIV, CIV, MgII, and HeI*.

Simulation of X-ray transient absorption for following vibrations in coherently ionized F2 molecules

NASA Astrophysics Data System (ADS)

Dutoi, Anthony D.; Leone, Stephen R.

2017-01-01

Femtosecond and attosecond X-ray transient absorption experiments are becoming increasingly sophisticated tools for probing nuclear dynamics. In this work, we explore and develop theoretical tools needed for interpretation of such spectra,in order to characterize the vibrational coherences that result from ionizing a molecule in a strong IR field. Ab initio data for F2 is combined with simulations of nuclear dynamics, in order to simulate time-resolved X-ray absorption spectra for vibrational wavepackets after coherent ionization at 0 K and at finite temperature. Dihalogens pose rather difficult electronic structure problems, and the issues encountered in this work will be reflective of those encountered with any core-valence excitation simulation when a bond is breaking. The simulations reveal a strong dependence of the X-ray absorption maximum on the locations of the vibrational wave packets. A Fourier transform of the simulated signal shows features at the overtone frequencies of both the neutral and the cation, which reflect spatial interferences of the vibrational eigenstates. This provides a direct path for implementing ultrafast X-ray spectroscopic methods to visualize coherent nuclear dynamics.

Spectral Anomalies in the 11 and 12 micron Region From the Mariner Mars 7 Infrared Spectrometer

NASA Technical Reports Server (NTRS)

Kirkland, Laurel E.; Herr, Kenneth C.

2000-01-01

Two hundred-forty infrared spectra acquired by the 1969 Mariner Mars 7 Infrared Spectrometer (IRS), spanning the wavelength region 1.8-14.4 micron (5550-690/cm), have recently been recovered and calibrated in both wavelength and intensity. An examination of these IRS spectra has revealed absorptions at 11.25 and 12.5 micron that have not previously been reported for Mars. A search of the literature and spectral data bases shows that materials that exhibit a doublet at 11.25 and 12.5 micron are rare. In this paper we examine potential causes for these features and include a detailed discussion of carbonates, goethite, CO2 ice, and water ice. CO2 ice and water ice measured in transmission do not exhibit bands that match those recorded at 11.25 and 12.5 micron for Mars, which indicates that CO2 or water ice clouds are not the source of these features. Since these bands show no clear correlation with atmospheric path length, they are most likely caused by a surface material. In the IRS database they appear to be exceptionally intense in the western part of the Hellas basin. Goethite exhibits bands that are a good spectral match, but confirming whether goethite causes the features will require additional studies of the 20-50 micron region. These studies will require laboratory measurements of weathering coatings and an examination of spectra recorded of Mars by the 1971 Mariner Mars Infrared Interferometer Spectrometer (IRIS; 5-50 micron 2000200/cm) and the 1996 Thermal Emission Spectrometer (TES; 6-50 micron 1667-200/cm).

Hyperspectral imaging using novel LWIR OPO for hazardous material detection and identification

NASA Astrophysics Data System (ADS)

Ruxton, Keith; Robertson, Gordon; Miller, Bill; Malcolm, Graeme P. A.; Maker, Gareth T.

2014-05-01

Current stand-off hyperspectral imaging detection solutions that operate in the mid-wave infrared (MWIR), nominally 2.5 - 5 μm spectral region, are limited by the number of absorption bands that can be addressed. This issue is most apparent when evaluating a scene with multiple absorbers with overlapping spectral features making accurate material identification challenging. This limitation can be overcome by moving to the long wave IR (LWIR) region, which is rich in characteristic absorption features, which can provide ample molecular information in order to perform presumptive identification relative to a spectral library. This work utilises an instrument platform to perform negative contrast imaging using a novel LWIR optical parametric oscillator (OPO) as the source. The OPO offers continuous tuning in the region 5.5 - 9.5 μm, which includes a number of molecular vibrations associated with the target material compositions. Scanning the scene of interest whilst sweeping the wavelength of the OPO emission will highlight the presence of a suspect material and by analysing the resulting absorption spectrum, presumptive identification is possible. This work presents a selection of initial results using the LWIR hyperspectral imaging platform on a range of white powder materials to highlight the benefit operating in the LWIR region compared to the MWIR.

DFT Calculation of IR Absorption Spectra for PCE-nH2O, TCE-nH2O, DCE-nH2O, VC-nH2O for Small and Water-Dominated Molecular Clusters

DTIC Science & Technology

2017-10-31

of isolated molecules and that of bulk systems. DFT calculated absorption spectra represent quantitative estimates that can be correlated with...spectra, can be correlated with the presence of these hydrocarbons (see reference [1]). Accordingly, the molecular structure and IR absorption spectra of...associated with different types of ambient molecules, e.g., H2O, in order to apply background subtraction or spectral-signature- correlation algorithms

Development of Detailed and Reduced Kinetics Mechanisms for Surrogates of Petroleum-Derived and Synthetic Jet Fuels

DTIC Science & Technology

2011-02-28

Meeting of Combustion, Atlanta, Georgia, paper 2A18, March 20-23, 2011. 9.2 Web Releases Sirjean, B., Dames, A., Sheen, D.A., You, X.-Q., Sung, C...was no significant interfering absorption or emission. IR diode laser absorption of CO2 and H2O: The recent commercial availability of DFB...distributed feedback) IR diode lasers in the wavelength vicinity of 2.5-2.7 microns has allowed the development of a new CO2 and H2O absorption diagnostics

Studies of solid carbon dioxide in interstellar ice analogs subject to thermal processing

NASA Astrophysics Data System (ADS)

White, Douglas W.

2010-09-01

Solid CO2 has been detected in many lines of sight in the interstellar medium from infrared observatories. Spectral profiles from space-based observatories have suggested that CO2 on icy grain mantles is mixed with other common molecules such as H2O and CH 3OH in interstellar regions and that thermal annealing has occurred. The vibrational mode at 658 cm-1 (15.2 mum) is suspected to be a powerful diagnostic tool as to the composition of species on icy grain mantles as well as thermal histories. However, previous studies have not systematically investigated ice composition and temperature. Laboratory spectra of interstellar ice analogs have been created in this study order to better understand the physical properties of solid CO2 in these interstellar environments. Existing databases of ice composition studies and effects of ice thermal history were updated in this study to include a more systematic approach. The 658 cm-1 (15.2 mum) bending mode feature of CO2 is examined here and the subsequent astrophysical implications stated. In the first set of experiments, 47 mixtures of H2O,CH3OH, andCO2 were slowly warmed and mid-infrared absorption spectra were recorded at 5K intervals. The second set of experiments involved examining the CO2 bending mode feature of 10 different CO2-containing ice mixtures at different temperatures where ice segregation was suspected. In these experiments, the ice mixtures were slowly heated to the desired temperature for increasing time intervals before cooling down and recording mid-IR absorption spectra. These studies may be used to analyze IR data from space-based observatories such as the Spitzer Space Telescope Infrared Spectrograph as well other future IR observations of the interstellar medium. Finally, mass spectroscopy measurements were taken from temperature programmed desorption (TPD) experiments performed on several binary mixtures of H2O + CO2 and CH 3OH + CO2. Physical properties such as desorption energy of CO2 can be determined from the TPD traces of these experiments. The work provided here addresses the physical properties of solid CO 2 thermally processed in ice mixtures in interstellar environments by laboratory simulations spectroscopically analyzed by mid-infrared absorption profiles and TPD.

Colors and Compositional Characteristics of Kuiper Belt Objects and Centaurs

NASA Astrophysics Data System (ADS)

Lederer, S. M.; Vilas, F.; Jarvis, K. S.; French, L.

2001-11-01

We present a study designed by Painter et al. (DPS 2000) to search for evidence of aqueous alteration in the surface material of solar system objects. Using VRI broadband photometry, we will search for the presence of the 0.7 um absorption feature (indicative of Fe-bearing hydrated silicates) in KBOs and Centaurs. Vilas (Icarus 111, 1994) found a strong correlation between the presence of the 0.7-um feature in low-albedo asteroids with solar-like colors and the 3-um water of hydration feature, indicative of phyllosilicates. Recent work by Howell et al. (LPSC, 2001) confirms that the presence of the 0.7 um feature in low-albedo asteroids definitely indicates the presence of the 3.0-um water of hydration absorption feature, suggesting the action of aqueous alteration in asteroids. In addition, Feierberg et al. (Icarus 63, 1985) showed that when the U - B color difference is > 0.12 in ECAS photometry, the 3.0-um absorption feature is often present in low albedo asteroids. Therefore, if the U-B color difference is > 0.12 and the 0.7-um feature is present in UBVRI reflectance photometry, water of hydration is implied in KBOs and Centaurs. We pursue these studies based on the mixed flat or steeply reddened photometry of these objects: Water ice has been identified in near-IR dark, flat spectra of some Centaurs, providing a source for the action of aqueous alteration. The complex collisional history proposed for these objects suggests a potential source of heating that would melt water ice, providing a mechanism for aqueous alteration to occur. Finally, we will use BVR photometry to determine the B-V and V-R colors, as has been done by Tegler and Romanishin (Nature, 407). We will compare our results with colors of KBOs and Centaurs published in the literature. This research was supported by the National Research Council and the NASA Planetary Astronomy Program.

Graphene-Based Platform for Infrared Near-Field Nanospectroscopy of Water and Biological Materials in an Aqueous Environment.

PubMed

Khatib, Omar; Wood, Joshua D; McLeod, Alexander S; Goldflam, Michael D; Wagner, Martin; Damhorst, Gregory L; Koepke, Justin C; Doidge, Gregory P; Rangarajan, Aniruddh; Bashir, Rashid; Pop, Eric; Lyding, Joseph W; Thiemens, Mark H; Keilmann, Fritz; Basov, D N

2015-08-25

Scattering scanning near-field optical microscopy (s-SNOM) has emerged as a powerful nanoscale spectroscopic tool capable of characterizing individual biomacromolecules and molecular materials. However, applications of scattering-based near-field techniques in the infrared (IR) to native biosystems still await a solution of how to implement the required aqueous environment. In this work, we demonstrate an IR-compatible liquid cell architecture that enables near-field imaging and nanospectroscopy by taking advantage of the unique properties of graphene. Large-area graphene acts as an impermeable monolayer barrier that allows for nano-IR inspection of underlying molecular materials in liquid. Here, we use s-SNOM to investigate the tobacco mosaic virus (TMV) in water underneath graphene. We resolve individual virus particles and register the amide I and II bands of TMV at ca. 1520 and 1660 cm(-1), respectively, using nanoscale Fourier transform infrared spectroscopy (nano-FTIR). We verify the presence of water in the graphene liquid cell by identifying a spectral feature associated with water absorption at 1610 cm(-1).

Broadband dye-sensitized upconverting nanocrystals enabled near-infrared planar perovskite solar cells

NASA Astrophysics Data System (ADS)

Lai, Xuesen; Li, Xitao; Lv, Xinding; Zheng, Yan-Zhen; Meng, Fanli; Tao, Xia

2017-12-01

Extending the spectral absorption of perovskite solar cells (PSCs) from visible into near-infrared (NIR) range is a promising strategy to minimize non-absorption loss of solar photons and enhance the cell photovoltaic performance. Herein, we report on for the first time a viable strategy of incorporating IR806 dye-sensitized upconversion nanocrystals (IR806-UCNCs) into planar PSC for broadband upconversion of NIR light (800-1000 nm) into perovskite absorber-responsive visible emissions. A smart trick is firstly adopted to prepare hydrophilic IR806-UCNCs via a NOBF4 assisted two-step ligand-exchange that allows incorporating with perovskite precursor for in-situ growth of upconverting planar perovskite film. Unlike typically reported upconverting nanoparticles with narrow NIR absorption, the as-prepared IR806-UCNCs are able to harvest NIR light broadly and then transfer the captured energy to the UCNCs for an efficient visible upconversion. The IR806-UCNCs-incorporated cell exhibits a power conversion efficiency of 17.49%, corresponding to 29% increment from that of the pristine cell (13.52%). This strategy provides a feasible way to enable the most efficient harvesting of NIR sunlight for solar cells and other optoelectric devices.

Spherically symmetric, expanding, non-LTE model atmospheres for novae during their early stages

NASA Technical Reports Server (NTRS)

Hauschildt, P. H.; Wehrse, R.; Starrfield, S.; Shaviv, G.

1992-01-01

In the continuum and line-blanketed models presented here, nova atmospheres are characterized by a very slow decrease of density with increasing radius. This feature leads to very large geometrical extensions so that there are large temperature differences between the inner and outer parts of the line-forming regions. The theoretical spectra show a large IR excess and a small Balmer jump which may be either in absorption or in emission. For the parameters considered (effective temperature of about 10 exp 4 K, L = 2 x 10 exp 4 solar luminosities, outer boundary density of about 3 x 10 exp -15 g cm exp -3, mass-loss rate of 10 exp -5 solar masses/yr), most lines are in absorption. The effects of changes in the abundances of the heavy elements on the emergent spectra are discussed. The strong unidentified features observed in ultraviolet spectra of novae are found in actuality to be regions of transparency within the Fe 'forest'. Ultraviolet spectra obtained from the IUE archives are displayed, and spectral synthesis of these spectra is done using the theoretical atmospheres.

Intrinsic Raman spectroscopy for quantitative biological spectroscopy Part II

PubMed Central

Bechtel, Kate L.; Shih, Wei-Chuan; Feld, Michael S.

2009-01-01

We demonstrate the effectiveness of intrinsic Raman spectroscopy (IRS) at reducing errors caused by absorption and scattering. Physical tissue models, solutions of varying absorption and scattering coefficients with known concentrations of Raman scatterers, are studied. We show significant improvement in prediction error by implementing IRS to predict concentrations of Raman scatterers using both ordinary least squares regression (OLS) and partial least squares regression (PLS). In particular, we show that IRS provides a robust calibration model that does not increase in error when applied to samples with optical properties outside the range of calibration. PMID:18711512

Effect of iron status on iron absorption in different habitual meals in young south Indian women.

PubMed

Kalasuramath, Suneeta; Kurpad, Anura V; Thankachan, Prashanth

2013-02-01

Iron deficiency (ID) affects a large number of women in India. An inverse relationship exists between iron (Fe) status and Fe absorption. Dietary inhibitory and enhancing factors exert a profound influence on bioavailability of Fe. Although the current recommended dietary allowance (RDA) for Fe is based on 8 per cent bioavailability, it is not clear if this holds good for the usual highly inhibitory Indian diet matrix. This study was aimed to determine Fe absorption from several habitually consumed south Indian food and to evaluate the interaction of Fe status with absorption. Four Fe absorption studies were performed on 60 apparently healthy young women, aged 18-35 years. Based on blood biochemistry, 45 of them were ID and 15 were iron replete (IR). The habitual meals assessed were rice, millet and wheat based meals in the ID subjects and rice based meal alone in the IR subjects. Each subject received the test meal labelled with 3 mg of ⁵⁷Fe and Fe absorption was measured based on erythrocyte incorporation of isotope label 14 days following administration. Mean fractional Fe absorption from the rice, wheat and millet based meals in the ID subjects were 8.3, 11.2 and 4.6 per cent, respectively. Fe absorption from the rice-based meals was 2.5 per cent in IR subjects. Fe absorption is dictated by Fe status from low bioavailability meals. Millet based meals have the lowest bioavailability, while the rice and wheat based meals had moderate to good bioavailability. In millet based meals, it is prudent to consider ways to improve Fe absorption.

Fast-response IR spatial light modulators with a polymer network liquid crystal

NASA Astrophysics Data System (ADS)

Peng, Fenglin; Chen, Haiwei; Tripathi, Suvagata; Twieg, Robert J.; Wu, Shin-Tson

2015-03-01

Liquid crystals (LC) have widespread applications for amplitude modulation (e.g. flat panel displays) and phase modulation (e.g. beam steering). For phase modulation, a 2π phase modulo is required. To extend the electro-optic application into infrared region (MWIR and LWIR), several key technical challenges have to be overcome: 1. low absorption loss, 2. high birefringence, 3. low operation voltage, and 4. fast response time. After three decades of extensive development, an increasing number of IR devices adopting LC technology have been demonstrated, such as liquid crystal waveguide, laser beam steering at 1.55μm and 10.6 μm, spatial light modulator in the MWIR (3~5μm) band, dynamic scene projectors for infrared seekers in the LWIR (8~12μm) band. However, several fundamental molecular vibration bands and overtones exist in the MWIR and LWIR regions, which contribute to high absorption coefficient and hinder its widespread application. Therefore, the inherent absorption loss becomes a major concern for IR devices. To suppress IR absorption, several approaches have been investigated: 1) Employing thin cell gap by choosing a high birefringence liquid crystal mixture; 2) Shifting the absorption bands outside the spectral region of interest by deuteration, fluorination and chlorination; 3) Reducing the overlap vibration bands by using shorter alkyl chain compounds. In this paper, we report some chlorinated LC compounds and mixtures with a low absorption loss in the near infrared and MWIR regions. To achieve fast response time, we have demonstrated a polymer network liquid crystal with 2π phase change at MWIR and response time less than 5 ms.

Infrared fluorescence from PAHs in the laboratory

NASA Technical Reports Server (NTRS)

Cherchneff, Isabelle; Barker, John R.

1989-01-01

Several celestial objects, including UV rich regions of planetary and reflection nebulae, stars, H II regions, and extragalactic sources, are characterized by the unidentified infrared emission bands (UIR bands). A few years ago, it was proposed that polycyclic aromatic hydrocarbon species (PAHs) are responsible for most of the UIR bands. This hypothesis is based on a spectrum analysis of the observed features. Comparisons of observed IR spectra with lab absorption spectra of PAHs support the PAH hypothesis. An example spectrum is represented, where the Orion Bar 3.3 micron spectrum is compared with the absorption frequencies of the PAHs Chrysene, Pyrene, and Coronene. The laser excited 3.3 micron emission spectrum is presented from a gas phase PAH (azulen). The infrared fluorescence theory (IRF) is briefly explained, followed by a description of the experimental apparatus, a report of the results, and discussion.

Pyroxene Spectroscopy: Effects of Major Element Composition on Near, Mid and Far-Infrared Spectra

NASA Technical Reports Server (NTRS)

Klima, R. L.; Pieters, C. M.; Dyar, M. D.

2005-01-01

Pyroxene is one of the most common minerals in both evolved and undifferentiated solid bodies of the solar system. Various compositions of pyroxene have been directly studied in meteorites and lunar samples and remotely observed by telescopic and orbital measurements of the moon, Mars, Mercury, and several classes of asteroids. Laboratory studies of pyroxene spectra have shown that absorption features diagnostic of pyroxene in both the near and mid infrared are composition dependent. The challenge for remote analyses has been to reduce the level of ambiguity to allow a quantitative assessment of mineral chemistry. This study focuses on the analysis of a comprehensive set of synthetic Ca-Fe-Mg pyroxenes from the visible through far-IR (0.3-50 m) to address the fundamental constraints of crystal structure on absorption.

Introducing cymantrene labels into scattering scanning near-field infrared microscopy.

PubMed

Kopf, Ilona; N'Dongo, Harmel W Peindy; Ballout, Fouad; Schatzschneider, Ulrich; Bründermann, Erik; Havenith, Martina

2012-11-07

In this paper we investigate metal-organic compounds as infrared (IR) active labels by scattering scanning near-field infrared microscopy (IR s-SNOM, often also abbreviated as s-SNIM) with a lateral resolution of 90 × 90 nm(2). Tailor-made IR spectroscopic probes based on cymantrene (CpMn(CO)(3) with Cp = η(5)-C(5)H(5)) conjugated to a cysteine-modified pseudoneurotensin (pNT-Cys-OH) peptide were prepared by automated microwave-assisted solid phase peptide synthesis (SPPS) and characterized by HPLC, ESI-MS and IR. Well-defined patterned self-assembled monolayers on a gold surface were prepared by microcontact printing of 1-octadecanethiol (ODT) followed by additional incubation in ethanolic solution of the cymantrene-peptide derivative. The self-assembled monolayers have been evidenced by infrared reflection absorption spectroscopy (IRRAS) and AFM. CO laser source radiation was tuned (1944, 1900, 1798 and 1658 cm(-1)) for imaging contrast with good matching correlation between spectroscopic and topographic patterns at specific characteristic metal carbonyl and amide bands (1944 cm(-1) (λ = 5.14 μm) and 1658 cm(-1) (λ = 6.03 μm)). Cymantrene probes provide an attractive method to tag a unique spectroscopic feature on any bio(macro)molecule. Introducing such probes into super-resolution IR s-SNOM will enable molecular tracking and distribution studies even in complex biological systems.

A dosimetric comparison of {sup 169}Yb versus {sup 192}Ir for HDR prostate brachytherapy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lymperopoulou, G.; Papagiannis, P.; Sakelliou, L.

2005-12-15

For the purpose of evaluating the use of {sup 169}Yb for prostate High Dose Rate brachytherapy (HDR), a hypothetical {sup 169}Yb source is assumed with the exact same design of the new microSelectron source replacing the {sup 192}Ir active core by pure {sup 169}Yb metal. Monte Carlo simulation is employed for the full dosimetric characterization of both sources and results are compared following the AAPM TG-43 dosimetric formalism. Monte Carlo calculated dosimetry results are incorporated in a commercially available treatment planning system (SWIFT{sup TM}), which features an inverse treatment planning option based on a multiobjective dose optimization engine. The qualitymore » of prostate HDR brachytherapy using the real {sup 192}Ir and hypothetical {sup 169}Yb source is compared in a comprehensive analysis of different prostate implants in terms of the multiobjective dose optimization solutions as well as treatment quality indices such as Dose Volume Histograms (DVH) and the Conformal Index (COIN). Given that scattering overcompensates for absorption in intermediate photon energies and distances in the range of interest to prostate HDR brachytherapy, {sup 169}Yb proves at least equivalent to {sup 192}Ir irrespective of prostate volume. This has to be evaluated in view of the shielding requirements for the {sup 169}Yb energies that are minimal relative to that for {sup 192}Ir.« less

Fourier transform infrared spectroscopy imaging of live epithelial cancer cells under non-aqueous media.

PubMed

Soh, JunYi; Chueng, Adeline; Adio, Aminat; Cooper, Alan J; Birch, Brian R; Lwaleed, Bashir A

2013-04-01

Fourier transform infrared (FT-IR) imaging is increasingly being applied to biomedical specimens, but strong IR absorption by water complicates live cell imaging. This study investigates the viability of adherent epithelial cells maintained for short periods under mineral oils in order to facilitate live cell spectroscopy using FT-IR with subsequent imaging. The MGH-U1 urothelial or CaCo2 colorectal cancer cell lines were grown on plastic surfaces or mid-range infrared transparent windows. Medium in established cultures was replaced with paraffin mineral oil, or Fluorolube, for up to 2 h, and viability assessed by supravital staining. Drug handling characteristics were also assessed. Imaging of preparations was attempted by reflectance and transmission using a Varian FT-IR microscope. Cells covered by mineral oil remained viable for 2 h, with recovery into normal medium possible. MTT ((3-(4,5-dimethylthlazol-2-yl)-2,5-diphenyl tetrazolium) conversion to crystalline formazan and differential patterns of drug uptake were maintained. The combination of a calcium fluoride substrate, Fluorolube oil, and transmission optics proved best for spectroscopy. Spectral features were used to obtain images of live cells. The viability of cells overlaid with IR transparent oils was assessed as part of a technique to optimise conditions for FT-IR imaging. Images of untreated cells were obtained using both reflectance and transmission. This represents an effective means of imaging live cells by IR spectroscopy, and also means that imaging is not necessarily a terminal event. It also increases options for producing images based on real-time biochemistry in a range of in vitro experimental and 'optical biopsy' contexts.

Versatile mid-infrared frequency-comb referenced sub-Doppler spectrometer

NASA Astrophysics Data System (ADS)

Gambetta, A.; Vicentini, E.; Coluccelli, N.; Wang, Y.; Fernandez, T. T.; Maddaloni, P.; De Natale, P.; Castrillo, A.; Gianfrani, L.; Laporta, P.; Galzerano, G.

2018-04-01

We present a mid-IR high-precision spectrometer capable of performing accurate Doppler-free measurements with absolute calibration of the optical axis and high signal-to-noise ratio. The system is based on a widely tunable mid-IR offset-free frequency comb and a Quantum-Cascade-Laser (QCL). The QCL emission frequency is offset locked to one of the comb teeth to provide absolute-frequency calibration, spectral-narrowing, and accurate fine frequency tuning. Both the comb repetition frequency and QCL-comb offset frequency can be modulated to provide, respectively, slow- and fast-frequency-calibrated scanning capabilities. The characterisation of the spectrometer is demonstrated by recording sub-Doppler saturated absorption features of the CHF3 molecule at around 8.6 μm with a maximum signal-to-noise ratio of ˜7 × 103 in 10 s integration time, frequency-resolution of 160 kHz, and accuracy of less than 10 kHz.

Detecting the building blocks of aromatics

NASA Astrophysics Data System (ADS)

Joblin, Christine; Cernicharo, José

2018-01-01

Interstellar clouds are sites of active organic chemistry (1). Many small, gasphase molecules are found in the dark parts of the clouds that are protected from ultraviolet (UV) photons, but these molecules photodissociate in the external layers of the cloud that are exposed to stellar radiation (see the photo). These irradiated regions are populated by large polycyclic aromatic hydrocarbons (PAHs) with characteristic infrared (IR) emission features. These large aromatics are expected to form from benzene (C6H6), which is, however, difficult to detect because it does not have a permanent dipole moment and can only be detected via its IR absorption transitions against a strong background source (2). On page 202 of this issue, McGuire et al. (3) report the detection of benzonitrile (c-C6H5CN) with radio telescopes. Benzonitrile likely forms in the reaction of CN with benzene; from its observation, it is therefore possible to estimate the abundance of benzene itself.

3D metamaterial absorber for attomole molecular detection (Conference Presentation)

NASA Astrophysics Data System (ADS)

Tanaka, Takuo; Ishikawa, Atsushi

2016-09-01

3D Metamaterial absorber was used for a background-suppressed surface-enhanced molecular detection technique. By utilizing the resonant coupling of plasmonic modes of a metamaterial absorber and infrared (IR) vibrational modes of a self-assembled monolayer (SAM), attomole level molecular sensitivity was experimentally demonstrated. IR absorption spectroscopy of molecular vibrations is of importance in chemical, material, medical science and so on, since it provides essential information of the molecular structure, composition, and orientation. In the vibrational spectroscopic techniques, in addition to the weak signals from the molecules, strong background degrades the signal-to-noise ratio, and suppression of the background is crucial for the further improvement of the sensitivity. Here, we demonstrate low-background resonant Surface enhanced IR absorption (SEIRA) by using the metamaterial IR absorber that offers significant background suppression as well as plasmonic enhancement. The fabricated metamaterial consisted of 1D array of Au micro-ribbons on a thick Au film separated by a transparent gap layer made of MgF2. The surface structures were designed to exhibit an anomalous IR absorption at 3000 cm-1, which spectrally overlapped with C-H stretching vibrational modes. 16-Mercaptohexadecanoic acid (16-MHDA) was used as a test molecule, which formed a 2-nm thick SAM with their thiol head-group chemisorbed on the Au surface. In the FTIR measurements, the symmetric and asymmetric C-H stretching modes were clearly observed as reflection peaks within a broad plasmonic absorption of the metamaterial.

Application of Fourier transform infrared (FT-IR) spectroscopy in determination of microalgal compositions.

PubMed

Meng, Yingying; Yao, Changhong; Xue, Song; Yang, Haibo

2014-01-01

Fourier transform infrared spectroscopy (FT-IR) was applied in algal strain screening and monitoring cell composition dynamics in a marine microalga Isochrysis zhangjiangensis during algal cultivation. The content of lipid, carbohydrate and protein of samples determined by traditional methods had validated the accuracy of FT-IR method. For algal screening, the band absorption ratios of lipid/amide I and carbo/amide I from FT-IR measurements allowed for the selection of Isochrysis sp. and Tetraselmis subcordiformis as the most potential lipid and carbohydrate producers, respectively. The cell composition dynamics of I. zhangjiangensis measured by FT-IR revealed the diversion of carbon allocation from protein to carbohydrate and neutral lipid when nitrogen-replete cells were subjected to nitrogen limitation. The carbo/amide I band absorption ratio had also been demonstrated to depict physiological status under nutrient stress in T. subcordiformis. FT-IR serves as a tool for the simultaneous measurement of lipid, carbohydrate, and protein content in cell. Copyright © 2013 Elsevier Ltd. All rights reserved.

Early-stage young stellar objects in the Small Magellanic Cloud

NASA Astrophysics Data System (ADS)

Oliveira, J. M.; van Loon, J. Th.; Sloan, G. C.; Sewiło, M.; Kraemer, K. E.; Wood, P. R.; Indebetouw, R.; Filipović, M. D.; Crawford, E. J.; Wong, G. F.; Hora, J. L.; Meixner, M.; Robitaille, T. P.; Shiao, B.; Simon, J. D.

2013-02-01

We present new observations of 34 young stellar object (YSO) candidates in the Small Magellanic Cloud (SMC). The photometric selection required sources to be bright at 24 and 70 μm (to exclude evolved stars and galaxies). The anchor of the analysis is a set of Spitzer Infrared Spectrograph (IRS) spectra, supplemented by ground-based 3-5 μm spectra, Spitzer Infrared Array Camera and Multiband Imaging Photometer for Spitzer photometry, near-infrared (IR) imaging and photometry, optical spectroscopy and radio data. The sources' spectral energy distributions and spectral indices are consistent with embedded YSOs; prominent silicate absorption is observed in the spectra of at least 10 sources, silicate emission is observed towards four sources. Polycyclic aromatic hydrocarbon (PAH) emission is detected towards all but two sources. Based on band ratios (in particular the strength of the 11.3-μm and the weakness of the 8.6-μm bands) PAH emission towards SMC YSOs is dominated by predominantly small neutral grains. Ice absorption is observed towards 14 sources in the SMC. The comparison of H2O and CO2 ice column densities for SMC, Large Magellanic Cloud and Galactic samples suggests that there is a significant H2O column density threshold for the detection of CO2 ice. This supports the scenario proposed by Oliveira et al., where the reduced shielding in metal-poor environments depletes the H2O column density in the outer regions of the YSO envelopes. No CO ice is detected towards the SMC sources. Emission due to pure rotational 0-0 transitions of molecular hydrogen is detected towards the majority of SMC sources, allowing us to estimate rotational temperatures and H2 column densities. All but one source are spectroscopically confirmed as SMC YSOs. Based on the presence of ice absorption, silicate emission or absorption and PAH emission, the sources are classified and placed in an evolutionary sequence. Of the 33 YSOs identified in the SMC, 30 sources populate different stages of massive stellar evolution. The presence of ice- and/or silicate-absorption features indicates sources in the early embedded stages; as a source evolves, a compact H ii region starts to emerge, and at the later stages the source's IR spectrum is completely dominated by PAH and fine-structure emission. The remaining three sources are classified as intermediate-mass YSOs with a thick dusty disc and a tenuous envelope still present. We propose one of the SMC sources is a D-type symbiotic system, based on the presence of Raman, H and He emission lines in the optical spectrum, and silicate emission in the IRS spectrum. This would be the first dust-rich symbiotic system identified in the SMC.

Methods and apparatus for mid-infrared sensing

DOEpatents

Lin, Pao Tai; Cai, Yan; Agarwal, Anuradha Murthy; Kimerling, Lionel C.

2015-06-02

A chip-scale, air-clad semiconductor pedestal waveguide can be used as a mid-infrared (mid-IR) sensor capable of in situ monitoring of organic solvents and other analytes. The sensor uses evanescent coupling from a silicon or germanium waveguide, which is highly transparent in the mid-IR portion of the electromagnetic spectrum, to probe the absorption spectrum of fluid surrounding the waveguide. Launching a mid-IR beam into the waveguide exposed to a particular analyte causes attenuation of the evanescent wave's spectral components due to absorption by carbon, oxygen, hydrogen, and/or nitrogen bonds in the surrounding fluid. Detecting these changes at the waveguide's output provides an indication of the type and concentration of one or more compounds in the surrounding fluid. If desired, the sensor may be integrated onto a silicon substrate with a mid-IR light source and a mid-IR detector to form a chip-based spectrometer.

Upconversion excitations in Pr3+-doped BaY2F8 crystal

NASA Astrophysics Data System (ADS)

Piramidowicz, R.; Mahiou, R.; Boutinaud, P.; Malinowski, M.

2011-09-01

We report the orange-to-blue and infrared-(IR)-to-blue wavelengths upconversion luminescence in Pr3+:BaY2F8 crystals. Mechanism of the orange light upconversion into blue 3P0 state emission was confirmed to be energy transfer between two Pr3+ ions in the 1D2 state. IR-to-blue upconversion has only been observed under two different color IR pumping. The first resonant step was the 3H4→1G4 ground state absorption transition, and the second resonant transition was the excited state absorption from the 1G4 to 1I6 and 3PJ levels. A comparison of the efficiency of the IR-to-blue upconversion in several praseodymium activated host is presented and discussed. A model of the IR pumped upconversion praseodymium blue laser is presented and the population inversion conditions are calculated.

Electrochemical and in situ spectroscopic studies of materials of relevance to energy storage and electrocatalysis

NASA Astrophysics Data System (ADS)

Mo, Yibo

In situ X-ray absorption (XAS), surface enhanced Raman spectroscopy (SERS) and rotating ring disk electrode techniques have been employed for the characterization of materials of relevance to electrochemical energy storage and electrocatalysis. In particular, analysis of in situ Ir LIII-edge extended X-ray absorption fine structure (EXAFS) of IrO2 films electrodeposited on Au substrates yielded Ir-O bond lengths decreasing in the sequence 2.02, 1.97 and 1.93 A, for Ir3+, Ir4+ and Ir5+ sites, respectively. Although features consistent with the presence of crystalline IrO2 in the highly hydrated films were found from in situ SERS, the lack of intense shells in the FT of the EXAFS function beyond the nearest oxygen neighbors indicates that the films by and large do not display long range order. In similar studies, the Fourier transform of the k3-weighted Ru K-edge EXAFS of electrodeposited RuO2 films recorded in situ were characterized by two shells attributed to Ru-O and Ru-Ru interactions at 1.94(1) and 3.12(2) A, in agreement with results obtained ex situ for Ru4+ in hydrous RuO2, whereas films in the reduced state yielded a single Ru-O interaction shell at 2.02(1) A. Extensions of these in situ XAS to the study of electrocatalysts for the nitrite reduction made it possible to identify and characterize the electronic and structural properties of a nitrosyl iron porphyrin adduct adsorbed on an electrode surface via the analysis of Fe K-edge XAS data. The effects of Se and S ad-atoms on the electrocatalytic activity of Pt electrodes have been examined using RRDE techniques. In acid, within a rather narrow range of coverages, both S- and Se-modified Pt surfaces promote the 2-electron reduction of dioxygen to hydrogen peroxide at ca. 100% faradaic efficiency over a wide potential region. Also developed were methods for immobilizing unsupported dispersed high area Pt particles a glassy carbon (GC) disk of a rotating Pt(ring)/GC(disk) electrode assembly allowing electrochemical measurements to be performed under forced convection with only minimal losses of Pt from the surface.

Helium broadened propane absorption cross sections in the far-IR

NASA Astrophysics Data System (ADS)

Wong, A.; Billinghurst, B.; Bernath, P. F.

2017-09-01

Infrared absorption spectra for pure and He broadened propane have been recorded in the far-IR region (650-1300 cm-1) at the Canadian Light Source (CLS) facility using either the synchrotron or internal glowbar source depending on the required resolution. The measurements were made for 4 temperatures in the range 202-292 K and for 3 pressures of He broadening gas up to 100 Torr. Infrared absorption cross sections are derived from the spectra and the integrated cross sections are within 10 % of the corresponding values from the Pacific Northwest National Laboratory (PNNL) for all temperatures and pressures.

Impact and radiation influence on solid hydrocarbon transformation and structuring (by IR-spectroscopy)

NASA Astrophysics Data System (ADS)

Kovaleva, O.

2009-04-01

Solid hydrocarbons (bitumens)-typical specimens of natural organic minerals-are one of the most essential objects of petroleum geology and at the same time-one of the least investigated objects of organic mineralogy. Moreover they can be treated as admissible analogs of meteorite carbonaceous materials. According to terrestrial analog of meteoritic organic matter it's possible to estimate the chemical structure of extraterrestrial matter. Further investigation of impact force and radiation influence on the bitumen chemical structure change will make it possible to connect them with extraterrestrial organic matter. This work represents the research of impact influence on the processes of transformation and structuring of asphaltite and changes in the molecular structure of solid bitumens constituting the carbonization series (asphaltite--kerite--anthraxolite), which were subjected to the impact of high radiation doses (10 and 100 Mrad) by infrared spectroscopy (IRS). In percussion experiments peak pressure varied from 10 to 63.4 GPa; temperature - from the first tens degrees to several hundreds degrees Celsius. The radiation experiment was performed in the Arzamas-16 Federal Nuclear Center in line with conditions described in [1]. Asphaltite, which sustained shock load from 17.3 to 23 GPa, didn't undergo considerable changes in its element composition. Though their IR-spectra differ from the spectrum of initial asphaltite by heightened intensity of absorption bands of aromatic groups, as well as by insignificant rise of heterogroups and condensed structures oscillation strength. At the same time the intensity of aliphatic (СН2 and СН3) groups absorption hasn't changed. Probably there've just been the carbon and hydrogen atomic rearrangement. However, shock load up to 26.7 GPa leads to asphaltite transformation into the albertite. There've been observed the intensity decrease of aliphatic groups on its IR-spectrum. Under growth of shock load up to 60 GPa bitumen has lost essential part of aliphatic, hetero-groups. Relative intensity of absorption bands of aromatic groups has dramatically increased. By nature and intensity of absorption bands this spectrum looks more similar to the impsonite/lower anthraxolite. A pressure of 60 GPa has lead to further matter carbonization. IR-spectra of these specimens have weak absorption bands and are mostly presented by aromatic structures. They've become similar to middle/high anthraxolite. A pressure of more than 60 GPa (with kamacite) has resulted in dramatic coalification of the material. The details have completely vanished in their spectra and they've grown similar with graphite. It should be noted that these specimens have been taken from the lower parts of ampoules. At the same time it has been established that IR-spectra of specimens from the upper parts are indicative of less coalification. Their spectra illustrate absorption bands of aliphatic, aromatic, and hetero-groups. They look similar to impsonite. Gamma radiation of up to 10 Mrad on slightly metamorphosed solid bitumens of the asphaltite category substantially changed their molecular structures. In addition to the predominance of aliphatic components, the content of condensed structures is also increased in the molecular structures. The increase in the share of aliphatic groups (as compared with natural samples) is probably explained by the fact that alkyl radicals, which occur in the structure and/or form by radiation processes, interact to form aliphatic products with both higher and lower molecular masses. This process is accompanied by the significant loss of heterofunctional groups, because they are usually less resistant to radiation than hydrocarbons. The loss of the functional group is one of the main processes that accompany their radiation. An increase in radiation dose up to 100 Mrad results in further notable changes of the asphaltite molecular structure, which are reflected by the substantial loss of some aliphatic, aromatic, condensed, and heterofunctional groups. According to these spectral characteristics, the substance becomes similar to natural lower anthraxolites. The IR spectra of kerites subjected to radiation of up to 10 and 100 Mrad appeared to be generally identical to each other in terms of the set and intensity of absorption bands. However, in addition to areas with the aromatic structure, some segments with the aliphatic structure (CH2 and CH3 groups) are also present in kerite subjected to radiation of up to 10 Mrad. These groups probably occur inside benzene rings or replace marginal hydrocarbon cycles. Consequently, this element may enter the structure of cyclic and aromatic compounds as a "stitcher." In addition, oxygen-bearing groups of the C--O type are also present, although in insignificant quantities. It can be assumed that radioactive decay breaks down C--C bonds and produces C--O structures due to the linkage with oxygen atoms or the detachment of the hydrogen atom nearest to the functional group.It should be noted that natural kerites represent a complex combination of planar polycyclic and linear (aliphatic) areas with different degrees of their structure ordering [2]; i.e., they contain substantially more aromatic fragments than asphaltites. The content of C=C oscillation groups in the benzene ring is probably retained owing to the high radiation resistance of benzene in the IR spectra of kerites subjected to radiation. In general, the structure of radiated kerites demonstrates features typical of natural high anthraxolies. Absorption bands disappear as a result of the increase in the carbon content in the bitumen structure and the consequent increase in the share of aromatic rings. Therefore, the IR spectra of anthraxolites after the radiation impact become similar to those of graphites, although the IR spectra of anthraxolites subjected to radiation of up to 10 Mrad still demonstrate weak absorption bands characteristic of the benzene ring. Thus it might be supposed that if solid bitumens can be extraterrestrial matter analog (asteroids) than it might be probable that the formation of the whole spectrum of solid bitumens from kerite-like to antraxolite-like can be the result of impact events on asteroids. The results show that, in addition to temperature and impact, radiation can also affect the process of coalification. Using carbonization of the asphaltite--kerite--anthraxolite series as an example, we have established that traces of the influence of high-energy radiation on a substance are reflected in the modification of its structure and the appearance of features similar to those of graphite. 1. N. P. Yushkin, Vestn. Inst. Geol., No. 9, 2 (1999) [in Russian]. 2. V. G. Melkov and A. M. Sergeeva. Role of Solid Carbonaceous Substances in the Formation of Endogenic Uranium Mineralization. (Nedra, Moscow, 1990) [in Russian]. ACKNOWLEDGMENTS I am grateful to V.V. Nazarov (VNIIEF) for the radiation treatment of bitumens and A.V. Andreev (EKO MVD RK) for the analysis of IR spectra. I'd like to thank A.V. Korochantsev for specimens kindly put at my disposal. This work was carried out within the framework of the Program of the RAS "Origin and Evolution of the Biosphere" with the financial support of the NSH-1014.2008.5, the RFBR (project no. 06-05-64755-а).

Design and Performance Assessment of a Stable Astigmatic Herriott Cell for Trace Gas Measurements on Airborne Platforms

NASA Technical Reports Server (NTRS)

Dyroff, Christoph; Fried, Alan; Richter, Dirk; Walega, James G.; Zahniser, Mark S.; McManus, J. Barry

2005-01-01

The present paper discusses a new, more stable, astigmatic Herriott cell employing carbon fiber stabilizing rods. Laboratory tests using a near-IR absorption feature of CO at 1564.168-nm revealed a factor of two improvement in measurement stability compared with the present commercial design when the sampling pressure was changed by +/-2 Torr around 50 Torr. This new cell should significantly enhance our efforts to measure trace gases employing pathlengths of 100 to 200-meters on airborne platforms with minimum detectable line center absorbances of less than 10(exp -6).

Synthesis temperature effect on the structural features and optical absorption of Zn(1-x)Co(x)Al2O4 oxides.

PubMed

Gaudon, M; Apheceixborde, A; Ménétrier, M; Le Nestour, A; Demourgues, A

2009-10-05

Zinc/cobalt aluminates with spinel-type structure were prepared by a polymeric route, leading to a pure phase with controlled grain size. The prepared pigments were characterized by powder X-ray diffraction Rietveld analyses in order to determine structural features, scanning electron microscopy for morphological investigation, helium pycnometry and (27)Al MAS NMR in order to highlight the occurrence of defects inside the structure, and UV-visible-near-IR spectroscopy to identify electronic transitions responsible for the compounds' color. The green-blue coloration of these pigments is known to be dependent on the sample thermal history. Here, for the first time, the Zn(1-x)Co(x)Al(2)O(4) color is newly interpreted. The pigment is green once synthesized at low temperature (i.e., with diminution of the pigment grain size); this variation was attributed to the appearance of a new absorption band located at about 500 nm, linked to a complex network feature involving Co ions in octahedral sites as well as oxygen and cationic vacancies. Hence, this work shows the possibility of easily getting a nonstoichiometric network with an abnormal cationic distribution from "chimie douce" processes with moderate synthesis temperature, and so various colorations for the same composition.

Infrared observations and laboratory simulations of interstellar CH_4_ and SO_2_.

NASA Astrophysics Data System (ADS)

Boogert, A. C. A.; Schutte, W. A.; Helmich, F. P.; Tielens, A. G. G. M.; Wooden, D. H.

1997-02-01

Interstellar CH_4_ may consume a fair amount of the carbon budget in dense molecular clouds, but probably less than CO, CH_3_OH, and CO_2_. However, it can only be observed at wavelength regions in the infrared that are heavily affected by the earth atmosphere. With new space and airborne missions (e.g. ISO, SOFIA) in mind we have studied the near infrared absorption spectra of solid and gaseous CH_4_. We obtained laboratory spectra of the ν_4_ deformation mode (1302cm^-1^, 7.68μm) of solid CH_4_ in astrophysically relevant mixtures. We found that the peak position and width of this absorption band vary strongly as a function of molecular environment, compared to temperature and particle shape effects. Hence, observations of this feature will provide a powerful probe of the molecular composition of interstellar ices. Also the gas phase CH_4_ ro-vibrational spectrum of the same band has been calculated. Using observed physical conditions around the protostar W 33A, we show that unresolved gaseous CH_4_ lines are detectable (at the 2-5% level) at a resolution R>1000, when the column density N>=10^16^ cm^-2^. An astrophysically relevant molecule with a very strong transition in the same wavelength regime, is SO_2_. We studied the ν _3_ asymmetric stretching mode (1319 cm^-1^, 7.58 μm) of solid SO_2_ in several mixtures, revealing that the peak position, width and detailed profile of this band are very sensitive to the molecular environment. Besides probing the composition of ice mantles, observations of solid SO_2_ will provide important information on the sulfur budget locked up in grain mantles, which is currently poorly known. We compare the laboratory and calculated spectra of CH_4_ and SO_2_ with previously published ground based spectra and new airborne observations of young stellar objects in the 7-8μm region. W 33A, NGC 7538 : IRS1 and IRS9 show a feature near 7.68μm that is consistent with absorption by solid CH_4_ or the Q-branch of gaseous CH_4_. The column density of solid CH_4_ would be 0.3-4% of solid H_2_O, indicating that solid CH_4_ consumes 0.5+/-0.3% of the cosmic carbon abundance. A gaseous origin would imply a column density of at least this amount, being highly dependent on the assumed temperature of the absorbing gas. A second absorption feature is detected toward W 33A and NGC 7538 : IRS1 at 7.58 μm. The peak position and width of this feature are consistent with the ν_3_ mode of solid SO_2_ in a matrix of solid CH_3_OH or pure SO_2_. The derived column density is 0.1-1% of solid H_2_O, indicating that solid SO_2_ locks up 0.6-6% of the cosmic sulfur abundance. This study shows that 7-8μm spectroscopy of dense molecular clouds, using new airborne and space-based platforms, will provide valuable information on the composition of icy grain mantles and molecular cloud chemistry.

[IR study on a series of tungsten clusters].

PubMed

Yu, R; Chen, J; Lu, S

2000-10-01

In this paper, the IR study on a series of tungsten clusters which contain a [W2S4]2+ or [W2MM'S4]4+ (M,M'=Cu,Ag) core is reported. According to the results of X-ray structural analysis and the IR spectra of the clusters, some characteristic IR absorptions of the clusters were assigned. The study of IR spectra of these clusters shows that the variation of structure can reflect on the IR spectra significantly.

Mid-IR absorption sensing of heavy water using a silicon-on-sapphire waveguide.

PubMed

Singh, Neetesh; Casas-Bedoya, Alvaro; Hudson, Darren D; Read, Andrew; Mägi, Eric; Eggleton, Benjamin J

2016-12-15

We demonstrate a compact silicon-on-sapphire (SOS) strip waveguide sensor for mid-IR absorption spectroscopy. This device can be used for gas and liquid sensing, especially to detect chemically similar molecules and precisely characterize extremely absorptive liquids that are difficult to detect by conventional infrared transmission techniques. We reliably measure concentrations up to 0.25% of heavy water (D₂O) in a D₂O-H₂O mixture at its maximum absorption band at around 4 μm. This complementary metal-oxide-semiconductor (CMOS) compatible SOS D₂O sensor is promising for applications such as measuring body fat content or detection of coolant leakage in nuclear reactors.

Parylene supported 20um*20um uncooled thermoelectric infrared detector with high fill factor

NASA Astrophysics Data System (ADS)

Modarres-Zadeh, Mohammad J.; Carpenter, Zachary S.; Rockley, Mark G.; Abdolvand, Reza

2012-06-01

Presented is a novel design for an uncooled surface-micromachined thermoelectric (TE) infrared (IR) detector. The detector features a P-doped polysilicon/Nichrome (Cr20-Ni80) thermocouple, which is embedded into a thin layer of Parylene-N to provide structural support. The low thermal conductivity (~0.1W/m.K), chemical resistance, and ease of deposition/patterning of Parylene-N make it an excellent choice of material for use in MEMS thermal detectors. This detector also features an umbrella-like IR absorber composed of a three layer stack of NiCr/SiN/NiCr to optimize IR absorption. The total device area is 20 um * 20 um per pixel with an absorber area of ~19 um * 19 um resulting in a fill factor of 90%. At room temperature, a DC responsivity of ~170V/W with a rise time of less than 8 ms is measured from the fabricated devices in vacuum when viewing a 500K blackbody without any concentrating optics. The dominant source of noise in thermoelectric IR detectors is typically Johnson noise when the detectors are operating in an open circuit condition. The fabricated detectors have resistances about 85KOhm which results in Johnson noise of about 38nV/Hz^0.5. The D* is calculated to be 9 * 106 cm*Hz0.5/ W. Preliminary finite element analysis indicates that the thermal conduction from the hot junction to the substrate through the TE wires is dominant ( GTE >> Gparylene) considering the fabricated dimensions of the parylene film and the TE wires. Thus, by further reducing the size of the TE wires, GTE can be decreased and hence, responsivity can be improved while the parylene film sustains the structural integrity of the cell.

Research on simulated infrared image utility evaluation using deep representation

NASA Astrophysics Data System (ADS)

Zhang, Ruiheng; Mu, Chengpo; Yang, Yu; Xu, Lixin

2018-01-01

Infrared (IR) image simulation is an important data source for various target recognition systems. However, whether simulated IR images could be used as training data for classifiers depends on the features of fidelity and authenticity of simulated IR images. For evaluation of IR image features, a deep-representation-based algorithm is proposed. Being different from conventional methods, which usually adopt a priori knowledge or manually designed feature, the proposed method can extract essential features and quantitatively evaluate the utility of simulated IR images. First, for data preparation, we employ our IR image simulation system to generate large amounts of IR images. Then, we present the evaluation model of simulated IR image, for which an end-to-end IR feature extraction and target detection model based on deep convolutional neural network is designed. At last, the experiments illustrate that our proposed method outperforms other verification algorithms in evaluating simulated IR images. Cross-validation, variable proportion mixed data validation, and simulation process contrast experiments are carried out to evaluate the utility and objectivity of the images generated by our simulation system. The optimum mixing ratio between simulated and real data is 0.2≤γ≤0.3, which is an effective data augmentation method for real IR images.

Mid-Infrared Study of Samples from Multiple Stones from the Sutters Mill Meteorite

NASA Technical Reports Server (NTRS)

Sandford, S. A.; Nuevo, M.; Flynn, G. J.; Wirick, S.

2013-01-01

The Sutter's Mill meteorite fell in N. California on April 22, 2012 and numerous pieces have been recovered and studied. We present Fourier transform infrared (FTIR) spectra of fragments from several stones of the meteorite. Methods and analysis: Infrared spectra of the samples were recorded with a Nicolet iN10 MX FTIR microscope in the mid-IR range (4000-675/cm; spectral resolution 4/cm). All samples were deposited on a clean glass slide, crushed with a stainless steel roller tool, and placed directly on the focal plane of the microscope. IR spectra were collected by averaging 128 scans. Results: Preliminary IR spectra of the non-fusion crust samples show mineral compositions that are dominated by phyllosilicates, carbonates, or mixtures of both [2]. The carbonates display a dominant, broad band centered at 1433/cm, with additional bands at 2515/cm, 1797/cm, 882/cm, and 715/cm). Features associated with phyllosilicates include a symmetric Si-O stretching mode band centered at 1011/cm and several O-H stretching mode bands. The O-H shows up in two forms (1) a broadband centered at 3415/cm that is probably largely due to adsorbed H2O and (2) a much weaker, narrower feature centered near 3680/cm due to structural -OH. Features observed in the 2985-2855/cm range suggest the presence of aliphatic -CH3 and -CH2- groups. The relative intensities of the bands in this range are somewhat unusual. Typically, the asymmetric aliphatic CH stretching bands are stronger than the symmetric stretching bands, but in this case the reverse is true. This unusual pattern is well matched by the aliphatic features seen in the spectrum of a terrestrial calcite (CaCO3) standard. This observation, and the fact that the strength of the carbonate and aliphatic bands seem to correlate, suggest the organics are associated with the carbonates. Conclusions: IR spectra of samples from the Sutter's Mill meteorite show absorption features associated with carbonates, phyllosilicates, and organics. Both the unusual band profile of the aliphatic C-H stretching mode bands and their correlation with the strength of the carbonate bands suggests the organics and the carbonates are associated in some manner.

The Role of Exotic Molecules In Model Exoplanet Spectra

NASA Astrophysics Data System (ADS)

Chang, Caroline; Iyer, Nandini; Morley, Caroline; Fortney, Jonathan J.

2016-01-01

We present the absorption signatures of 21 elemental and molecular species normally found in observed planetary spectra. Fifty model exoplanet spectra that span temperatures from 400 to 2000 K, gravities from 100 to 1000 m/s2, and are 0.3-3 times solar metallicity composition are obtained by converting the pressure-temperature profiles through publicly available radiative transfer code (DISORT), assuming chemical equilibrium conditions. We explore the dependency of an individual specie's effect on a spectrum in the near-IR by removing its equilibrium abundance or enriching the specie's abundance. While testing for the individual effect of each species, it is found that the temperature is a key property for identifying absorption features in this diverse set of model spectra. Strong and abundant absorbers such as CO and CH4 are not as prevalent in high temperature models over 1200 K as H2O at 0.9-2.2 and 2.3-4.1 microns. In addition, we investigate the vertical mixing and disequilibrium of CO and CH4 and find features of these carbon species at 3.3-4.2 and 4.3-5.0 microns across all models. Trace species such as NH3 and Na exhibit prevalent signatures in cold planets (~400-800 K) at the 1-1.1, 1.3-1.5, and 1.6-1.8 micron ranges. A consistent PH3 feature is identified for 400 K spectra at 4-4.8 microns. In our hot model spectra with temperatures greater than 1400 K, TiO shows more significant absorption features than VO, suggesting that these molecules potentially play separate roles in determining thermal inversions. Hydrocarbons such as C2H2 with abundances higher than 10-4 exhibit prevalent absorption features at ~4.2-4.5 microns, indicating that photochemical reactions may be needed to further enrich these abundances. A table of these signatures at their respective temperatures, gravities, and metallicities is presented here. This research presented here was conducted by high-school students under the auspices of the University of California Santa Cruz's Science Internship Program.

Metamaterial absorber for molecular detection and identification (Conference Presentation)

NASA Astrophysics Data System (ADS)

Tanaka, Takuo

2017-03-01

Metamaterial absorber was used for a background-suppressed surface-enhanced molecular detection technique. By utilizing the resonant coupling between plasmonic modes of a metamaterial absorber and infrared (IR) vibrational modes of a self-assembled monolayer (SAM), attomole level molecular sensitivity was experimentally demonstrated. IR absorption spectroscopy of molecular vibrations is of importance in chemical, material, medical science and so on, since it provides essential information of the molecular structure, composition, and orientation. In the vibrational spectroscopic techniques, in addition to the weak signals from the molecules, strong background degrades the signal-to-noise ratio, and suppression of the background is crucial for the further improvement of the sensitivity. Here, we demonstrate low-background resonant Surface enhanced IR absorption (SEIRA) by using the metamaterial IR absorber that offers significant background suppression as well as plasmonic enhancement. By using mask-less laser lithography technique, metamaterial absorber which consisted of 1D array of Au micro-ribbons on a thick Au film separated by a transparent gap layer made of MgF2 was fabricated. This metamaterial structure was designed to exhibit an anomalous IR absorption at 3000 cm-1, which spectrally overlapped with C-H stretching vibrational modes. 16-Mercaptohexadecanoic acid (16-MHDA) was used as a test molecule, which formed a 2-nm thick SAM with their thiol head-group chemisorbed on the Au surface. In the FTIR measurements, the symmetric and asymmetric C-H stretching modes were clearly observed as reflection peaks within a broad plasmonic absorption of the metamaterial, and 1.8 attomole molecular sensitivity was experimentally demonstrated.

The nuclear near-infrared spectral properties of nearby galaxies

NASA Astrophysics Data System (ADS)

Mason, Rachel; Ardila, Alberto; Martins, Lucimara; Riffel, Rogerio; Gonzalez-Martin, Omaira; Ramos Almeida, Christina; Ruschel Dutra, Daniel; Ho, Luis C.; Thanjavur, Karun; Flohic, Helene; Alonso-Herrero, Almudena; Lira, Paulina; McDermid, Richard; Riffel, Rogemar A.; Schiavon, Ricardo P.; Winge, Claudia; Perlman, Eric S.; Hoenig, Michael D.

2015-01-01

We present spectra of the nuclear regions of 50 nearby (D = 1 - 92 Mpc, median = 20 Mpc) galaxies of morphological types E to Sm. The spectra, obtained with the Gemini Near-IR Spectrograph on the Gemini North telescope, cover a wavelength range of approximately 0.85-2.5 μm at R˜1300-1800. There is evidence that most of the galaxies host an active galactic nucleus (AGN), but the range of AGN luminosities (log (L2-10 keV [erg s-1]) = 37.0-43.2) in the sample means that the spectra display a wide variety of features. Some nuclei, especially the Seyferts, exhibit a rich emission-line spectrum. Other objects, in particular the type 2 Low Ionisation Nuclear Emission Region galaxies, show just a few, weak emission lines, allowing a detailed view of the underlying stellar population. These spectra display numerous absorption features sensitive to the stellar initial mass function, as well as molecular bands arising in cool stars, and many other atomic absorption lines. We compare the spectra of subsets of galaxies known to be characterised by intermediate-age and old stellar populations, and find clear differences in their absorption lines and continuum shapes. We also examine the effect of atmospheric water vapor on the signal-to-noise ratio achieved in regions between the conventional NIR atmospheric windows, of potential interest to those planning observations of redshifted emission lines or other features affected by telluric H2O. Further exploitation of this data set is in progress, and the reduced spectra and data reduction tools are made available to the community.

The mid-infrared transmission spectra of Antarctic ureilites

NASA Technical Reports Server (NTRS)

Sandford, Scott A.

1993-01-01

The mid-IR (4000-450/cm; 2.5-22.2 microns) transmission spectra of seven Antarctic ureilites and 10 Antarctic H-5 ordinary chondrites are presented. The ureilite spectra show a number of absorption bands, the strongest of which is a wide, complex feature centered near 1000/cm (10 microns) due to Si-O stretching vibrations in silicates. The profiles and positions of the substructure in this feature indicate that Mg-rich olivines and pyroxenes are the main silicates responsible. The relative abundances of these two minerals, as inferred from the spectra, show substantial variation from meteorite to meteorite, but generally indicate olivine is the most abundant (olivine:pyroxene = 60:40 to 95:5). Both the predominance of olivine and the variable olivine-to-pyroxene ratio are consistent with the known composition and heterogeneity of ureilites. The H-5 ordinary chondrites spanned a range of weathering classes and were used to provide a means of addressing the extent to which the ureilite spectra may have been altered by weathering processes. It was found that, while weathering of these meteorites produces some weak bands due to the formation of small amounts of carbonates and hydrates, the profile of the main silicate feature has been little affected by Antarctic exposure in the meteorites studied here. The mid-IR ureilite spectra provide an additional means of testing potential asteroidal parent bodies for the ureilites.

Influence of polarity of solvents on IR absorption and Raman spectra of ascorbic acid

NASA Astrophysics Data System (ADS)

Kutsenko, S. A.; Danyaeva, Y. S.; Maximova, S. V.

2018-04-01

The results of numerical calculations of IR absorption and Raman spectra of ascorbic acid in polar and nonpolar solutions are presented. The dependence of the change in the total energy and the dipole moment of the molecule on the characteristics of the solvents was investigated using the two solvation models. Spectral bands and the corresponding structural groups of the molecule are found, the characteristics of which are most vulnerable to solvents.

Time-domain calculations of the polarized Raman spectra, the transient infrared absorption anisotropy, and the extent of delocalization of the OH stretching mode of liquid water.

PubMed

Torii, Hajime

2006-08-03

The polarized Raman spectrum and the time dependence of the transient infrared (TRIR) absorption anisotropy are calculated for the OH stretching mode of liquid water (neat liquid H2O) by using time-domain formulations, which include the effects of both the diagonal frequency modulations (of individual oscillators) induced by the interactions between the dipole derivatives and the intermolecular electric field, and the off-diagonal (intermolecular) vibrational coupling described by the transition dipole coupling (TDC) mechanism. The IR spectrum of neat liquid H2O and the TRIR anisotropy of a liquid mixture of H2O/HDO/D2O are also calculated. It is shown that the calculated features of these optical signals, including the temperature dependence of the polarized Raman and IR spectra, are in reasonable agreement with the experimental results, indicating that the frequency separation between the isotropic and anisotropic components of the polarized Raman spectrum and the rapid decay (approximately 0.1 ps) of the TRIR anisotropy of the OH stretching mode of neat liquid H2O are mainly controlled by the resonant intermolecular vibrational coupling described by the TDC mechanism. Comparing with the time evolution of vibrational excitations, it is suggested that the TRIR anisotropy decays in the time needed for the initially localized vibrational excitations to delocalize over a few oscillators. It is also shown that the enhancement of the dipole derivatives by the interactions with surrounding molecules is an important factor in generating the spectral profiles of the OH stretching Raman band. The time-domain behavior of the molecular motions that affect the spectroscopic features is discussed.

Mushroom plasmonic metamaterial infrared absorbers

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ogawa, Shinpei, E-mail: Ogawa.Shimpei@eb.MitsubishiElectric.co.jp; Fujisawa, Daisuke; Hata, Hisatoshi

2015-01-26

There has been a considerable amount of interest in the development of various types of electromagnetic wave absorbers for use in different wavelength ranges. In particular, infrared (IR) absorbers with wavelength selectivity can be applied to advanced uncooled IR sensors, which would be capable of identifying objects through their radiation spectrum. In the present study, mushroom plasmonic metamaterial absorbers (MPMAs) for the IR wavelength region were designed and fabricated. The MPMAs consist of a periodic array of thin metal micropatches connected to a thin metal plate with narrow silicon (Si) posts. A Si post height of 200 nm was achieved bymore » isotropic XeF{sub 2} etching of a thin Si layer sandwiched between metal plates. This fabrication procedure is relatively simple and is consistent with complementary metal oxide semiconductor technology. The absorption spectra of the fabricated MPMAs were experimentally measured. In addition, theoretical calculations of their absorption properties were conducted using rigorous coupled wave analysis. Both the calculated and measured absorbance results demonstrated that these MPMAs can realize strong selective absorption at wavelengths beyond the period of the array by varying the micropatch width. Absorbance values greater than 90% were achieved. Dual- or single-mode absorption can also be selected by varying the width of the Si posts. Pixel structures using such MPMAs could be used as high responsivity, high resolution and fast uncooled IR sensors.« less

A Group Increment Scheme for Infrared Absorption Intensities of Greenhouse Gases

NASA Technical Reports Server (NTRS)

Kokkila, Sara I.; Bera, Partha P.; Francisco, Joseph S.; Lee, Timothy J.

2012-01-01

A molecule's absorption in the atmospheric infrared (IR) window (IRW) is an indicator of its efficiency as a greenhouse gas. A model for estimating the absorption of a fluorinated molecule within the IRW was developed to assess its radiative impact. This model will be useful in comparing different hydrofluorocarbons and hydrofluoroethers contribution to global warming. The absorption of radiation by greenhouse gases, in particular hydrofluoroethers and hydrofluorocarbons, was investigated using ab initio quantum mechanical methods. Least squares regression techniques were used to create a model based on this data. The placement and number of fluorines in the molecule were found to affect the absorption in the IR window and were incorporated into the model. Several group increment models are discussed. An additive model based on one-carbon groups is found to work satisfactorily in predicting the ab initio calculated vibrational intensities.

Coupling Molecular Modeling to the Traditional "IR-ID" Exercise in the Introductory Organic Chemistry Laboratory

ERIC Educational Resources Information Center

Stokes-Huby, Heather; Vitale, Dale E.

2007-01-01

This exercise integrates the infrared unknown identification ("IR-ID") experiment common to most organic laboratory syllabi with computer molecular modeling. In this modification students are still required to identify unknown compounds from their IR spectra, but must additionally match some of the absorptions with computed frequencies they…

Randomized structured triglycerides increase lymphatic absorption of tocopherol and retinol compared with the equivalent physical mixture in a rat model of fat malabsorption.

PubMed

Tso, P; Lee, T; DeMichele, S J

2001-08-01

Previously we demonstrated that the digestion, absorption and lymphatic transport of lipid and key essential fatty acids (EFA) from randomly interesterified fish oil/medium-chain structured triglycerides (STG) were significantly higher than an equivalent physical mixture (PM) in a normal lymph fistula rat model and in a rat model of lipid malabsorption caused by ischemia/reperfusion (I/R) injury. The goals of this study were to further explore the potential absorptive benefits of STG by comparing the intestinal absorption and lymphatic transport of tocopherol and retinol when delivered gastrically with either STG or PM under normal conditions and after I/R injury to the small bowel. Food-deprived male Sprague-Dawley rats were randomly assigned to two treatments (sham controls or I/R). Under halothane anesthesia, the superior mesenteric artery (SMA) was occluded for 20 min and then reperfused in I/R rats. The SMA was isolated but not occluded in control rats. In both groups, the mesenteric lymph duct was cannulated and a gastric tube was inserted. Each treatment group received 1 mL of the fish oil/MCT STG or PM (7 rats/group) along with (14)C-alpha-tocopherol and (3)H-retinol through the gastric tube followed by an infusion of PBS at 3 mL/h for 8 h. Lymph was collected hourly for 8 h. Under steady-state conditions, the amount of (14)C-alpha-tocopherol and (3)H-retinol transported into lymph was significantly higher in the STG-fed rats compared with those fed PM in both control and I/R groups. In addition, control and I/R rats given STG had earlier steady-state outputs of (14)C-alpha-tocopherol and (3)H-retinol and maintained approximately 30% higher outputs in lymph throughout the 8-h lymph collection period compared with rats given the PM. We conclude that STG provides the opportunity to potentiate improved absorption of fat-soluble vitamins under normal and malabsorptive states.

In situ observation of carbon nanotube layer growth on microbolometers with substrates at ambient temperature

NASA Astrophysics Data System (ADS)

Svatoš, Vojtěch; Gablech, Imrich; Ilic, B. Robert; Pekárek, Jan; Neužil, Pavel

2018-03-01

Carbon nanotubes (CNTs) have near unity infrared (IR) absorption efficiency, making them extremely attractive for IR imaging devices. Since CNT growth occurs at elevated temperatures, the integration of CNTs with IR imaging devices is challenging and has not yet been achieved. Here, we show a strategy for implementing CNTs as IR absorbers using differential heating of thermally isolated microbolometer membranes in a C2H2 environment. During the process, CNTs were catalytically grown on the surface of a locally heated membrane, while the substrate was maintained at an ambient temperature. CNT growth was monitored in situ in real time using optical microscopy. During growth, we measured the intensity of light emission and the reflected light from the heated microbolometer. Our measurements of bolometer performance show that the CNT layer on the surface of the microbolometer membrane increases the IR response by a factor of (2.3 ± 0.1) (mean ± one standard deviation of the least-squares fit parameters). This work opens the door to integrating near unity IR absorption, CNT-based, IR absorbers with hybrid complementary metal-oxide-semiconductor focal plane array architectures.

Onco-hematological diagnostics by IR spectroscopy

NASA Astrophysics Data System (ADS)

Darchuk, Sergey D.; Korovina, Larisa A.; Sizov, Fiodor F.; Bebeshko, Vladimir G.

1998-10-01

Application of the infrared (IR) spectroscopy to early medical onco-hematological diagnostics, in particular to leukemia, is described. Leukemia is characterized by the orthophosphates acid (soluble) forms (HPO42-) accumulation in bone apatites. Bone hydroxyapatite contains predominantly basic PO43- nonsoluble orthophosphate. At the same time condensed forms of pyrophosphates (e.g., CaH2P3O7) in bones and especially in dried urine were found by the analysis of IR absorption spectra of persons with leukemia. It was show that the dried urine infrared quantitative absorption spectra investigations of phosphates contents make it possible to trace the dynamics of these elements contents during the leukemia progression and can serve for onco-hematological diagnostics at early stage of leukemia.

Optimization of silicon waveguides for gas detection application at mid-IR wavelengths

NASA Astrophysics Data System (ADS)

Butt, M. A.; Kozlova, E. S.

2018-04-01

There are several trace gases such as N2O, CO, CO2, NO, H2O, NO2, NH3, CH4 etc. which have their absorption peaks in Mid-IR spectrum These gases strongly absorb in the mid-IR > 2.5 μm spectral region due to their fundamental rotational and vibrational transitions. In this work, we modelled and optimized three different kinds of waveguides such as rib, strip and slot based on silicon platform to obtain maximum evanescent field ratio. These waveguides are designed at 3.39 μm and 4.67 μm which correspond to the absorption line of methane (CH4) and carbon monoxide (CO) respectively.

The interstellar C-H stretching band near 3.4 microns - Constraints on the composition of organic material in the diffuse interstellar medium

NASA Technical Reports Server (NTRS)

Sandford, S. A.; Allamandola, L. J.; Tielens, A. G. G. M.; Pendleton, Y.; Sellgren, K.

1991-01-01

The composition and history of dust in the diffuse ISM was studied using 3600-2700/cm absorption spectra of objects which have widely varying amounts of visual extinctions along different lines of sight. The 3300/cm and 2950/cm features are attributed to O-H and C-H stretching vibrations, respectively. The O-H feature in OH 32.8-0.3 is suggestive of circumstellar water ice and is probably not due to material in the diffuse ISM. The features in the 3100-2700/cm region are attributed either to C-H vibrations or to M stars. The spectra of the latter show a series of narrow features in this region that are identified with photospheric OH. Objects in which these bands are seen include OH 01-477, T629-5, and the Galactic center source IRS 7. The C-H stretch feature of diffuse ISM dust has subpeaks which fall within 5/cm of C-H stretching vibrations in the -CH2- and -CH3 groups of saturated aliphatic hydrocarbons.

Laser Infrared Desorption Spectroscopy to Detect Complex Organic Molecules on Icy Planetary Surfaces

NASA Technical Reports Server (NTRS)

Sollit, Luke S.; Beegle, Luther W.

2008-01-01

Laser Desorption-Infrared Spectroscopy (LD-IR) uses an IR laser pulse to desorb surface materials while a spectrometer measures the emission spectrum of the desorbed materials (Figure 1). In this example, laser desorption operates by having the incident laser energy absorbed by near surface material (10 microns in depth). This desorption produces a plume that exists in an excited state at elevated temperatures. A natural analog for this phenomenon can be observed when comets approach the sun and become active and individual molecular emission spectra can be observed in the IR [1,2,3,4,5]. When this occurs in comets, the same species that initially emit radiation down to the ground state are free to absorb it, reducing the amount of detectable emission features. The nature of our technique results in absorption not occurring, because the laser pulse could easily be moved away form the initial desorption plume, and still have better spatial resolution then reflectance spectroscopy. In reflectance spectroscopy, trace components have a relatively weak signal when compared to the entire active nature of the surface. With LDIR, the emission spectrum is used to identify and analyze surface materials.

Advances in data processing for open-path Fourier transform infrared spectrometry of greenhouse gases.

PubMed

Shao, Limin; Griffiths, Peter R; Leytem, April B

2010-10-01

The automated quantification of three greenhouse gases, ammonia, methane, and nitrous oxide, in the vicinity of a large dairy farm by open-path Fourier transform infrared (OP/FT-IR) spectrometry at intervals of 5 min is demonstrated. Spectral pretreatment, including the automated detection and correction of the effect of interrupting the infrared beam, is by a moving object, and the automated correction for the nonlinear detector response is applied to the measured interferograms. Two ways of obtaining quantitative data from OP/FT-IR data are described. The first, which is installed in a recently acquired commercial OP/FT-IR spectrometer, is based on classical least-squares (CLS) regression, and the second is based on partial least-squares (PLS) regression. It is shown that CLS regression only gives accurate results if the absorption features of the analytes are located in very short spectral intervals where lines due to atmospheric water vapor are absent or very weak; of the three analytes examined, only ammonia fell into this category. On the other hand, PLS regression works allowed what appeared to be accurate results to be obtained for all three analytes.

Invisible ink mark detection in the visible spectrum using absorption difference.

PubMed

Lee, Joong; Kong, Seong G; Kang, Tae-Yi; Kim, Byounghyun; Jeon, Oc-Yeub

2014-03-01

One of popular techniques in gambling fraud involves the use of invisible ink marks printed on the back surface of playing cards. Such covert patterns are transparent in the visible spectrum and therefore invisible to unaided human eyes. Invisible patterns can be made visible with ultraviolet (UV) illumination or a CCD camera installed with an infrared (IR) filter depending on the type of ink materials used. Cheating gamers often wear contact lenses or eyeglasses made of IR or UV filters to recognize the secret marks on the playing cards. This paper presents an image processing technique to reveal invisible ink patterns in the visible spectrum without the aid of special equipment such as UV lighting or IR filters. A printed invisible ink pattern leaves a thin coating on the surface with different refractive index for different wavelengths of light, which results in color dispersion or absorption difference. The proposed method finds the differences of color components caused by absorption difference to detect invisible ink patterns on the surface. Experiment results show that the proposed scheme is effective for both UV-active and IR-active invisible ink materials. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.

Photothermal microfluidic cantilever deflection spectroscopy reflecting clustering mechanism of ethanol water mixtures

NASA Astrophysics Data System (ADS)

Ghoraishi, Maryam; Hawk, John; Thundat, Thomas

Aqueous mixture of alcohol is a typical prototype for biomolecules, micelle formation, and structural stability of proteins. Therefore, Short chain alcohols such as EtOH have been used as a simple model for understanding of more complex aqueous biomolecules. Here we study vibrational energy peaks of EtOH water binary mixtures using micromechanical calorimetric spectroscopy using bimaterial microfluidic cantilevers (BMC). The IR spectra of EtOH-water are experimentally collected employing a BMC as concentration of EtOH changes from 20-100 wt%. As concentration of EtOH varies in the mixture, considerable shifts in the wavenumber at IR absorption peak maxima are reported. The experimentally measured shifts in the wavenumber at IR absorption peak maxima are related to changes in dipole moment (μ) of EtOH at different concentration. The relationship between IR absorption wavenumber for both anti and gauche conformers of EtOH, and inverse dipole moment, 1/ μ, of EtOH at different concentrations follows a power law dependence. Our technique offers a platform to investigate dipole effect on molecular vibrations of mixtures in confined picoliter volumes, previously unexplored with other analytical techniques due to limitations of volume under study.

High-pressure insulator-to-metal transition in Sr3Ir2O7 studied by x-ray absorption spectroscopy

NASA Astrophysics Data System (ADS)

Donnerer, C.; Sala, M. Moretti; Pascarelli, S.; Rosa, A. D.; Andreev, S. N.; Mazurenko, V. V.; Irifune, T.; Hunter, E. C.; Perry, R. S.; McMorrow, D. F.

2018-01-01

High-pressure x-ray absorption spectroscopy was performed at the Ir L3 and L2 absorption edges of Sr3Ir2O7 . The branching ratio of white-line intensities continuously decreases with pressure, reflecting a reduction in the angular part of the expectation value of the spin-orbit coupling operator, 〈L .S 〉 . Up to the high-pressure structural transition at 53 GPa, this behavior can be explained within a single-ion model, where pressure increases the strength of the cubic crystal field, which suppresses the spin-orbit induced hybridization of Jeff=3 /2 and eg levels. We observe a further reduction of the branching ratio above the structural transition, which cannot be explained within a single-ion model of spin-orbit coupling and cubic crystal fields. This change in 〈L .S 〉 in the high-pressure, metallic phase of Sr3Ir2O7 could arise from noncubic crystal fields or a bandwidth-driven hybridization of Jeff=1 /2 ,3 /2 states and suggests that the electronic ground state significantly deviates from the Jeff=1 /2 limit.

Single-crystal films of a combination of materials (co-crystal) involving DAST and IR-125 for electro-optic applications

NASA Astrophysics Data System (ADS)

Narayanan, A.; Titus, J.; Rajagopalan, H.; Vippa, P.; Thakur, M.

2006-03-01

Single-crystal film of DAST (4'-dimethylamino-N-methyl-4-stilbazolium tosylate) has been shown [1] to have exceptionally large electro-optic coefficients (r11 ˜ 770 pm/V at 633 nm). In this report, single crystal film of a combination of materials (co-crystal) involving DAST and a dye molecule IR-125 will be discussed. Modified shear method was used to prepare the co-crystal films. The film has been characterized using polarized optical microscopy, optical absorption spectroscopy and x-ray diffraction. The optical absorption spectrum has two major bands: one at about 350--600 nm corresponding to DAST and the other at about 600-900 nm corresponding to IR-125. The x-ray diffraction results show peaks involving the presence of DAST and IR-125 within the co-crystal film. Since the co-crystal has strong absorption at longer wavelengths it is expected to show higher electro-optic coefficients at longer wavelengths. Preliminary measurements at 1.55 μm indicate a high electro-optic coefficient of the co-crystal film. [1] Swamy, Kutty, Titus, Khatavkar, Thakur, Appl. Phys. Lett. 2004, 85, 4025; Kutty, Thakur, Appl. Phys. Lett. 2005, 87, 191111.

Blue emitting undecaplatinum clusters

NASA Astrophysics Data System (ADS)

Chakraborty, Indranath; Bhuin, Radha Gobinda; Bhat, Shridevi; Pradeep, T.

2014-07-01

A blue luminescent 11-atom platinum cluster showing step-like optical features and the absence of plasmon absorption was synthesized. The cluster was purified using high performance liquid chromatography (HPLC). Electrospray ionization (ESI) and matrix assisted laser desorption ionization (MALDI) mass spectrometry (MS) suggest a composition, Pt11(BBS)8, which was confirmed by a range of other experimental tools. The cluster is highly stable and compatible with many organic solvents.A blue luminescent 11-atom platinum cluster showing step-like optical features and the absence of plasmon absorption was synthesized. The cluster was purified using high performance liquid chromatography (HPLC). Electrospray ionization (ESI) and matrix assisted laser desorption ionization (MALDI) mass spectrometry (MS) suggest a composition, Pt11(BBS)8, which was confirmed by a range of other experimental tools. The cluster is highly stable and compatible with many organic solvents. Electronic supplementary information (ESI) available: Details of experimental procedures, instrumentation, chromatogram of the crude cluster; SEM/EDAX, DLS, PXRD, TEM, FT-IR, and XPS of the isolated Pt11 cluster; UV/Vis, MALDI MS and SEM/EDAX of isolated 2 and 3; and 195Pt NMR of the K2PtCl6 standard. See DOI: 10.1039/c4nr02778g

Laser-Based Remote Sensing of Explosives by a Differential Absorption and Scattering Method

NASA Astrophysics Data System (ADS)

Ayrapetyan, V. S.

2018-01-01

A multifunctional IR parametric laser system is developed and tested for remote detection and identification of atmospheric gases, including explosive and chemically aggressive substances. Calculations and experimental studies of remote determination of the spectroscopic parameters of the best known explosive substances TNT, RDX, and PETN are carried out. The feasibility of high sensitivity detection ( 1 ppm) of these substances with the aid of a multifunctional IR parametric light source by differential absorption and scattering is demonstrated.

Development of a Novel Simplified PBPK Absorption Model to Explain the Higher Relative Bioavailability of the OROS® Formulation of Oxybutynin.

PubMed

Olivares-Morales, Andrés; Ghosh, Avijit; Aarons, Leon; Rostami-Hodjegan, Amin

2016-11-01

A new minimal Segmented Transit and Absorption model (mSAT) model has been recently proposed and combined with intrinsic intestinal effective permeability (P eff,int ) to predict the regional gastrointestinal (GI) absorption (f abs ) of several drugs. Herein, this model was extended and applied for the prediction of oral bioavailability and pharmacokinetics of oxybutynin and its enantiomers to provide a mechanistic explanation of the higher relative bioavailability observed for oxybutynin's modified-release OROS® formulation compared to its immediate-release (IR) counterpart. The expansion of the model involved the incorporation of mechanistic equations for the prediction of release, transit, dissolution, permeation and first-pass metabolism. The predicted pharmacokinetics of oxybutynin enantiomers after oral administration for both the IR and OROS® formulations were in close agreement with the observed data. The predicted absolute bioavailability for the IR formulation was within 5% of the observed value, and the model adequately predicted the higher relative bioavailability observed for the OROS® formulation vs. the IR counterpart. From the model predictions, it can be noticed that the higher bioavailability observed for the OROS® formulation was mainly attributable to differences in the intestinal availability (F G ) rather than due to a higher colonic f abs , thus confirming previous hypotheses. The predicted f abs was almost 70% lower for the OROS® formulation compared to the IR formulation, whereas the F G was almost eightfold higher than in the IR formulation. These results provide further support to the hypothesis of an increased F G as the main factor responsible for the higher bioavailability of oxybutynin's OROS® formulation vs. the IR.

Microstructures as IR-sensors with Staphylococcus aureus bacteria

NASA Astrophysics Data System (ADS)

Baikova, T. V.; Danilov, P. A.; Gonchukov, S. A.; Yermachenko, V. M.; Ionin, A. A.; Khmelnitskii, R. A.; Kudryashov, S. I.; Nguyen, T. T. H.; Rudenko, A. A.; Saraeva, I. N.; Svistunova, T. S.; Zayarny, D. A.

2017-09-01

Using a micro-hole grating in a supported silver film as a laser-fabricated novel optical platform for surface-enhanced IR absoprtion/reflection spectroscopy, characteristic absorption bands of Staphylococcus aureus, especially - its buried carotenoid fragments - were detected in FT-IR spectra with 10-fold analytical enhancement, paving the way to spectral express-identification of the pathogenic microorganisms.

Insulin Resistance in Nondiabetic Peritoneal Dialysis Patients: Associations with Body Composition, Peritoneal Transport, and Peritoneal Glucose Absorption.

PubMed

Bernardo, Ana Paula; Oliveira, Jose C; Santos, Olivia; Carvalho, Maria J; Cabrita, Antonio; Rodrigues, Anabela

2015-12-07

Insulin resistance has been associated with cardiovascular disease in peritoneal dialysis patients. Few studies have addressed the impact of fast transport status or dialysis prescription on insulin resistance. The aim of this study was to test whether insulin resistance is associated with obesity parameters, peritoneal transport rate, and glucose absorption. Insulin resistance was evaluated with homeostasis model assessment method (HOMA-IR), additionally corrected by adiponectin (HOMA-AD). Enrolled patients were prevalent nondiabetics attending at Santo António Hospital Peritoneal Dialysis Unit, who were free of hospitalization or infectious events in the previous 3 months (51 patients aged 50.4 ± 15.9 years, 59% women). Leptin, adiponectin, insulin-like growth factor-binding protein 1 (IGFBP-1), and daily glucose absorption were also measured. Lean tissue index, fat tissue index (FTI), and relative fat mass (rel.FM) were assessed using multifrequency bioimpedance. Patients were categorized according to dialysate to plasma creatinine ratio at 4 hours, 3.86% peritoneal equilibration test, and obesity parameters. Obesity was present in 49% of patients according to rel.FM. HOMA-IR correlated better with FTI than with body mass index. Significant correlations were found in obese, but not in nonobese patients, between HOMA-IR and leptin, leptin/adiponectin ratio (LAR), and IGFBP-1. HOMA-IR correlated with HOMA-AD, but did not correlate with glucose absorption or transport rate. There were no significant differences in insulin resistance indices, glucose absorption, and body composition parameters between fast and nonfast transporters. A total of 18 patients (35.3%) who had insulin resistance presented with higher LAR and rel.FM (7.3 [12.3, interquartile range] versus 0.7 [1.4, interquartile range], P<0.001, and 39.4 ± 10.1% versus 27.2 ± 11.5%, P=0.002, respectively), lower IGFBP-1 (8.2 ± 7.2 versus 21.0 ± 16.3 ng/ml, P=0.002), but similar glucose absorption and small-solute transport compared with patients without insulin resistance. FTI and LAR were independent correlates of HOMA-IR in multivariate analysis adjusted for glucose absorption and small-solute transport (r=0.82, P<0.001). Insulin resistance in nondiabetic peritoneal dialysis patients is associated with obesity and LAR independent of glucose absorption and small-solute transport status. Fast transport status was not associated with higher likelihood of obesity or insulin resistance. Copyright © 2015 by the American Society of Nephrology.

Mie-type scattering and non-Beer-Lambert absorption behavior of human cells in infrared microspectroscopy.

PubMed

Mohlenhoff, Brian; Romeo, Melissa; Diem, Max; Wood, Bayden R

2005-05-01

We report infrared microspectral features of nuclei in a completely inactive and contracted (pyknotic) state, and of nuclei of actively dividing cells. For pyknotic nuclei, the very high local concentration of DNA leads to opaqueness of the chromatin and, consequently, the absence of DNA signals in the IR spectra of very small nuclei. However, these nuclei can be detected by their scattering properties, which can be described by the Mie theory of scattering from dielectric spheres. This scattering depends on the size of the nucleus; consequently, quite different scattering cross-sections are calculated and observed for pyknotic and mitotic nuclei.

Intensity of the /R/Q sub zero branch in the nu-9 fundamental of ethane. [laboratory spectra for Jupiter and Saturn IR observations

NASA Technical Reports Server (NTRS)

Tokunaga, A.; Varanasi, P.

1976-01-01

Recent observations of Jupiter and Saturn at 12 microns have shown strong emission in the nu-9 fundamental of ethane. In order to derive the abundance of ethane from the planetary observations, the absolute intensity of the (R)Q sub zero branch of the nu-9 fundamental was measured, yielding a value of 0.74 plus or minus 0.09/sq cm/atm at 300 K. In order to study the absorption features of the nu-9 fundamental, the computed rotational structure of the band was compared with the laboratory spectrum.

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.

Luminescence and photoinduced absorption in ytterbium-doped optical fibres

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rybaltovsky, A A; Aleshkina, S S; Likhachev, M E

2011-12-31

Photochemical reactions induced in the glass network of an ytterbium-doped fibre core by IR laser pumping and UV irradiation have been investigated by analysing absorption and luminescence spectra. We have performed comparative studies of the photoinduced absorption and luminescence spectra of fibre preforms differing in core glass composition: Al{sub 2}O{sub 3} : SiO{sub 2}, Al{sub 2}O{sub 3} : Yb{sub 2}O{sub 3} : SiO{sub 2}, and P{sub 2}O{sub 5} : Yb{sub 2}O{sub 3} : SiO{sub 2}. The UV absorption spectra of unirradiated preform core samples show strong bands peaking at 5.1 and 6.5 eV, whose excitation plays a key role inmore » photoinduced colour centre generation in the glass network. 'Direct' UV excitation of the 5.1- and 6.5-eV absorption bands at 244 and 193 nm leads to the reduction of some of the Yb{sup 3+} ions to Yb{sup 2+}. The photodarkening of ytterbium-doped fibres by IR pumping is shown to result from oxygen hole centre generation. A phenomenological model is proposed for the IR-pumping-induced photodarkening of ytterbium-doped fibres. The model predicts that colour centre generation in the core glass network and the associated absorption in the visible range result from a cooperative effect involving simultaneous excitation of a cluster composed of several closely spaced Yb{sup 3+} ions.« less

Carbon monoxide recombination dynamics in truncated hemoglobins studied with visible-pump midIR-probe spectroscopy.

PubMed

Lapini, Andrea; Di Donato, Mariangela; Patrizi, Barbara; Marcelli, Agnese; Lima, Manuela; Righini, Roberto; Foggi, Paolo; Sciamanna, Natascia; Boffi, Alberto

2012-08-02

Carbon monoxide recombination dynamics upon photodissociation with visible light has been characterized by means of ultrafast visible-pump/MidIR probe spectroscopy for the truncated hemoglobins from Thermobifida fusca and Bacillus subtilis. Photodissociation has been induced by exciting the sample at two different wavelengths: 400 nm, corresponding to the heme absorption in the B-band, and 550 nm, in the Q-bands. The bleached iron-CO coordination band located at 1850-1950 cm(-1) and the free CO absorption band in the region 2050-2200 cm(-1) have been observed by probe pulses tuned in the appropriate infrared region. The kinetic traces measured at 1850-1950 cm(-1) reveal multiexponential subnanosecond dynamics that have been interpreted as arising from fast geminate recombination of the photolyzed CO. A compared analysis of the crystal structure of the two proteins reveals a similar structure of their distal heme pocket, which contains conserved polar and aromatic amino acid residues closely interacting with the iron ligand. Although fast geminate recombination is observed in both proteins, several kinetic differences can be evidenced, which can be interpreted in terms of a different structural flexibility of the corresponding heme distal pockets. The analysis of the free CO band-shape and of its dynamic evolution brings out novel features about the nature of the docking site inside the protein cavity.

Erythritol reduces small intestinal glucose absorption, increases muscle glucose uptake, improves glucose metabolic enzymes activities and increases expression of Glut-4 and IRS-1 in type 2 diabetic rats.

PubMed

Chukwuma, Chika Ifeanyi; Mopuri, Ramgopal; Nagiah, Savania; Chuturgoon, Anil Amichund; Islam, Md Shahidul

2017-08-02

Studies have reported that erythritol, a low or non-glycemic sugar alcohol possesses anti-hyperglycemic and anti-diabetic potentials but the underlying mode of actions is not clear. This study investigated the underlying mode of actions behind the anti-hyperglycemic and anti-diabetic potentials of erythritol using different experimental models (experiment 1, 2 and 3). Experiment 1 examined the effects of increasing concentrations (2.5-20%) of erythritol on glucose absorption and uptake in isolated rat jejunum and psoas muscle, respectively. Experiments 2 and 3 examined the effects of a single oral dose of erythritol (1 g/kg bw) on intestinal glucose absorption, gastric emptying and postprandial blood glucose increase, glucose tolerance, serum insulin level, muscle/liver hexokinase and liver glucose-6 phosphatase activities, liver and muscle glycogen contents and mRNA and protein expression of muscle Glut-4 and IRS-1 in normal and type 2 diabetic animals. Experiment 1 revealed that erythritol dose dependently enhanced muscle glucose ex vivo. Experiment 2 demonstrated that erythritol feeding delayed gastric emptying and reduced small intestinal glucose absorption as well as postprandial blood glucose rise, especially in diabetic animals. Experiment 3 showed that erythritol feeding improved glucose tolerance, muscle/liver hexokinase and liver glucose-6 phosphatase activities, glycogen storage and also modulated expression of muscle Glut-4 and IRS-1 in diabetic animals. Data suggest that erythritol may exert anti-hyperglycemic effects not only via reducing small intestinal glucose absorption, but also by increasing muscle glucose uptake, improving glucose metabolic enzymes activity and modulating muscle Glut-4 and IRS-1 mRNA and protein expression. Hence, erythritol may be a useful dietary supplement for managing hyperglycemia, particularly for T2D.

ERTS-1 observes algal blooms in Lake Erie and Utah Lake

NASA Technical Reports Server (NTRS)

Strong, A. E.

1973-01-01

During late summer when the surface waters of Lake Erie reach their maximum temperature an algal bloom is likely to develop. Such phenomena have been noticed on other shallow lakes using ERTS-1 and characterize eutrophic conditions. The concentration of the algae into long streamers provides additional information on surface circulations. To augment the ERTS-1 MSS data of Lake Erie an aircraft was flown to provide correlative thermal-IR and additional multiband photographs. The algal bloom is highly absorptive in the visible wavelengths but reverses contrast with the surrounding water in the near-IR bands. The absorption of shortwave energy heats the dark brown algal mass, providing a hot surface target for the thermal-IR scanner.

Quantum Chemical Design Guidelines for Absorption and Emission Color Tuning of fac-Ir(ppy)₃ Complexes.

PubMed

Natori, Yoshiki; Kitagawa, Yasutaka; Aoki, Shogo; Teramoto, Rena; Tada, Hayato; Era, Iori; Nakano, Masayoshi

2018-03-05

The fac -Ir(ppy)₃ complex, where ppy denotes 2-phenylpyridine, is one of the well-known luminescent metal complexes having a high quantum yield. However, there have been no specific molecular design guidelines for color tuning. For example, it is still unclear how its optical properties are changed when changing substitution groups of ligands. Therefore, in this study, differences in the electronic structures and optical properties among several substituted fac -Ir(ppy)₃ derivatives are examined in detail by density functional theory (DFT) and time-dependent DFT (TD-DFT) calculations. On the basis of those results, we present rational design guidelines for absorption and emission color tuning by modifying the species of substituents and their substitution positions.

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sargent, B. A.; Forrest, W.; Watson, Dan M.

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 seenmore » 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.« less

Infrared evanescent field sensing with quantum cascade lasers and planar silver halide waveguides.

PubMed

Charlton, Christy; Katzir, Abraham; Mizaikoff, Boris

2005-07-15

We demonstrate the first midinfrared evanescent field absorption measurements with an InGaAs/AlInAs/InP distributed feedback (DFB) quantum cascade laser (QCL) light source operated at room temperature coupled to a free-standing, thin-film, planar, silver halide waveguide. Two different analytes, each matched to the emission frequency of a QCL, were investigated to verify the potential of this technique. The emission of a 1650 cm(-1) QCL overlaps with the amide absorption band of urea, which was deposited from methanol solution, forming urea crystals at the waveguide surface after solvent evaporation. Solid urea was detected down to 80.7 microg of precipitate at the waveguide surface. The emission frequency of a 974 cm(-1) QCL overlaps with the CH3-C absorption feature of acetic anhydride. Solutions of acetic anhydride in acetonitrile have been detected down to a volume of 0.01 microL (10.8 microg) of acetic anhydride solution after deposition at the planar waveguide (PWG) surface. Free-standing, thin-film, planar, silver halide waveguides were produced by press-tapering heated, cylindrical, silver halide fiber segments to create waveguides with a thickness of 300-190 microm, a width of 3 mm, and a length of 35 mm. In addition, Fourier transform infrared (FT-IR) evanescent field absorption measurements with planar silver halide waveguides and transmission absorption QCL measurements verify the obtained results.

A Search for Variation in the Surface Mineralogical Composition of J VI Himalia

NASA Astrophysics Data System (ADS)

Jarvis, K. S.; Vilas, F.; Larson, S. M.; Gaffey, M. J.

1996-09-01

Diverse spectral data exist for Jupiter's moon J VI Himalia. The overall spectral shape suggests that it has the same mineralogical composition as a C-class asteroid, lending credibility to the theory that Himalia was a C-class asteroid that formed in or near the main asteroid belt and was ejected and captured into orbit around Jupiter. Using an algorithm developed earlier, ECAS photometry (Tholen and Zellner, 1984) of Himalia taken on one date only have tested positively for the presence of a 0.7- mu m feature attributed to an Fe(2+) -> Fe(3+) charge transfer transition in oxidized iron in phyllosilicates. The presence of this feature was confirmed by narrowband spectrophotometry obtained on one date in April, 1995. Narrowband spectrophotometry of Luu (1991) does not cover the full spectral range defined by the 0.7-mu m absorption feature, but is in good agreement with the ECAS photometry. However, no 3.0-mu m water of hydration absorption feature was observed in IR radiometry (A. S., Rivkin, per. comm.). Correlation between the 0.7-mu m feature and the 3.0-mu m feature has been demonstrated in spectra of low-albedo asteroids, and suggests that it should be present. A rough rotational period for Himalia of 9.2 - 9.8 hrs is known. Himalia could represent the junction of two different compositional units, produced when an impact fragmented Himalia's parent body. The presence of iron-bearing phyllosilicates on part of Himalia's surface supports the hypothesis that Himalia is a captured C-class asteroid. Rotationally-resolved spectra of Himalia could confirm a variation in composition; we have started a program to collect these data.

Electrochemical Dissolution of Iridium and Iridium Oxide Particles in Acidic Media: Transmission Electron Microscopy, Electrochemical Flow Cell Coupled to Inductively Coupled Plasma Mass Spectrometry, and X-ray Absorption Spectroscopy Study.

PubMed

Jovanovič, Primož; Hodnik, Nejc; Ruiz-Zepeda, Francisco; Arčon, Iztok; Jozinović, Barbara; Zorko, Milena; Bele, Marjan; Šala, Martin; Šelih, Vid Simon; Hočevar, Samo; Gaberšček, Miran

2017-09-13

Iridium-based particles, regarded as the most promising proton exchange membrane electrolyzer electrocatalysts, were investigated by transmission electron microscopy and by coupling of an electrochemical flow cell (EFC) with online inductively coupled plasma mass spectrometry. Additionally, studies using a thin-film rotating disc electrode, identical location transmission and scanning electron microscopy, as well as X-ray absorption spectroscopy have been performed. Extremely sensitive online time-and potential-resolved electrochemical dissolution profiles revealed that Ir particles dissolve well below oxygen evolution reaction (OER) potentials, presumably induced by Ir surface oxidation and reduction processes, also referred to as transient dissolution. Overall, thermally prepared rutile-type IrO 2 particles are substantially more stable and less active in comparison to as-prepared metallic and electrochemically pretreated (E-Ir) analogues. Interestingly, under OER-relevant conditions, E-Ir particles exhibit superior stability and activity owing to the altered corrosion mechanism, where the formation of unstable Ir(>IV) species is hindered. Due to the enhanced and lasting OER performance, electrochemically pre-oxidized E-Ir particles may be considered as the electrocatalyst of choice for an improved low-temperature electrochemical hydrogen production device, namely a proton exchange membrane electrolyzer.

Identification of crystalline structures in jet-cooled acetylene large clusters studied by two-dimensional correlation infrared spectroscopy

NASA Astrophysics Data System (ADS)

Matsumoto, Yoshiteru; Yoshiura, Ryuto; Honma, Kenji

2017-07-01

We investigated the crystalline structures of jet-cooled acetylene (C2H2) large clusters by laser spectroscopy and chemometrics. The CH stretching vibrations of the C2H2 large clusters were observed by infrared (IR) cavity ringdown spectroscopy. The IR spectra of C2H2 clusters were measured under the conditions of various concentrations of C2H2/He mixture gas for supersonic jets. Upon increasing the gas concentration from 1% to 10%, we observed a rapid intensity enhancement for a band in the IR spectra. The strong dependence of the intensity on the gas concentration indicates that the band was assigned to CH stretching vibrations of the large clusters. An analysis of the IR spectra by two-dimensional correlation spectroscopy revealed that the IR absorption due to the C2H2 large cluster is decomposed into two CH stretching vibrations. The vibrational frequencies of the two bands are almost equivalent to the IR absorption of the pure- and poly-crystalline orthorhombic structures in the aerosol particles. The characteristic temperature behavior of the IR spectra implies the existence of the other large cluster, which is discussed in terms of the phase transition of a bulk crystal.

Vibrational spectra and structures of neutral Si(m)C(n) clusters (m + n = 6): sequential doping of silicon clusters with carbon atoms.

PubMed

Savoca, Marco; Lagutschenkov, Anita; Langer, Judith; Harding, Dan J; Fielicke, André; Dopfer, Otto

2013-02-14

Vibrational spectra of mixed silicon carbide clusters Si(m)C(n) with m + n = 6 in the gas phase are obtained by resonant infrared-vacuum-ultraviolet two-color ionization (IR-UV2CI for n ≤ 2) and density functional theory (DFT) calculations. Si(m)C(n) clusters are produced in a laser vaporization source, in which the silicon plasma reacts with methane. Subsequently, they are irradiated with tunable IR light from an IR free electron laser before they are ionized with UV photons from an F(2) laser. Resonant absorption of one or more IR photons leads to an enhanced ionization efficiency for Si(m)C(n) and provides the size-specific IR spectra. IR spectra measured for Si(6), Si(5)C, and Si(4)C(2) are assigned to their most stable isomers by comparison with calculated linear absorption spectra. The preferred Si(m)C(n) structures with m + n = 6 illustrate the systematic transition from chain-like geometries for bare C(6) to three-dimensional structures for bare Si(6). In contrast to bulk SiC, carbon atom segregation is observed already for the smallest n (n = 2).

An overview on the research of Sr2IrO4-based system probed by X-ray absorption spectroscopy

NASA Astrophysics Data System (ADS)

Cheng, Jie; Zhu, Chaomin; Ma, Jingyuan; Wang, Yu; Liu, Shengli

2018-03-01

Investigations of materials with 5d transition metal ions have opened up new paradigms in condensed-matter physics because of their large spin-orbit coupling (SOC) interactions. The typical compound is Sr2IrO4, which attracted much attention due to its similarities to the parent compound of high-Tc cuprate superconductor La2CuO4. Theoretical calculations predicted that the unconventional superconductivity can occur in carrier doped-Sr2IrO4 system. Until now, hundreds of experimental methods were devoted to investigate the carrier doping effect on Sr2IrO4. Synchrotron radiation-based X-ray absorption spectroscopy (XAS) made great contributions to the local lattice and electronic structure, and also the intimate relationship between the local structure and physical properties induced by carrier doping. The aim of this review is a short introduction to the progress of research on Sr2IrO4-based system probed by the unique technique — XAS, including the strength of the SOC, valence changes upon doping and even local lattice structure with atomic level for this Sr2IrO4-based family.

Laboratory IR Detection of H2O, CO2 in Ion-Irradiated Ices Relevant to Europa

NASA Technical Reports Server (NTRS)

Moore, Marla H.; Hudson, R. L.

1999-01-01

Hydrogen peroxide has been identified on Europa (Carlson et al. 1999) based in part on the 3.50 micron absorption feature observed in Galileo NIMS spectra. The observed feature was fitted with laboratory reflectance spectra of H2O + H2O2. Since condensed phase molecules on Europa (H2O, CO2, SO2, and H2O2) are bombarded with a significant flux of energetic particles (H(+), O(n+), S(n+) and e-), we examined the proton irradiation of H2O at 80 K and the conditions for the IR detection of H2O2 near 3.5 microns. Contrary to expectations, H2O2 was not detected if pure H2O ice was irradiated at 80 K. This was an unexpected result since, H2O2 was detected if pure H2O was irradiated at 18 K. We find, however, that if H2O ice contains either O2 or CO2 then H2O2 is detected after irradiation at 80 K (Moore and Hudson, 1999). The source of O2 for the H2O ice on Europa could come from surface interactions with the tenuous oxygen atmosphere, or from the bombardment of the surface by O(n+).

Analysis of 2D THz-Raman spectroscopy using a non-Markovian Brownian oscillator model with nonlinear system-bath interactions.

PubMed

Ikeda, Tatsushi; Ito, Hironobu; Tanimura, Yoshitaka

2015-06-07

We explore and describe the roles of inter-molecular vibrations employing a Brownian oscillator (BO) model with linear-linear (LL) and square-linear (SL) system-bath interactions, which we use to analyze two-dimensional (2D) THz-Raman spectra obtained by means of molecular dynamics (MD) simulations. In addition to linear infrared absorption (1D IR), we calculated 2D Raman-THz-THz, THz-Raman-THz, and THz-THz-Raman signals for liquid formamide, water, and methanol using an equilibrium non-equilibrium hybrid MD simulation. The calculated 1D IR and 2D THz-Raman signals are compared with results obtained from the LL+SL BO model applied through use of hierarchal Fokker-Planck equations with non-perturbative and non-Markovian noise. We find that all of the qualitative features of the 2D profiles of the signals obtained from the MD simulations are reproduced with the LL+SL BO model, indicating that this model captures the essential features of the inter-molecular motion. We analyze the fitted 2D profiles in terms of anharmonicity, nonlinear polarizability, and dephasing time. The origins of the echo peaks of the librational motion and the elongated peaks parallel to the probe direction are elucidated using optical Liouville paths.

Detection and monitoring of H2O and CO2 ice clouds on Mars

USGS Publications Warehouse

Bell, J.F.; Calvin, W.M.; Ockert-Bell, M. E.; Crisp, D.; Pollack, James B.; Spencer, J.

1996-01-01

We have developed an observational scheme for the detection and discrimination of Mars atmospheric H2O and CO2 clouds using ground-based instruments in the near infrared. We report the results of our cloud detection and characterization study using Mars near IR images obtained during the 1990 and 1993 oppositions. We focused on specific wavelengths that have the potential, based on previous laboratory studies of H2O and CO2 ices, of yielding the greatest degree of cloud detectability and compositional discriminability. We have detected and mapped absorption features at some of these wavelengths in both the northern and southern polar regions of Mars. Compositional information on the nature of these absorption features was derived from comparisons with laboratory ice spectra and with a simplified radiative transfer model of a CO2 ice cloud overlying a bright surface. Our results indicate that both H2O and CO2 ices can be detected and distinguished in the polar hood clouds. The region near 3.00 ??m is most useful for the detection of water ice clouds because there is a strong H2O ice absorption at this wavelength but only a weak CO2 ice band. The region near 3.33 ??m is most useful for the detection of CO2 ice clouds because there is a strong, relatively narrow CO2 ice band at this wavelength but only broad "continuum" H2O ice absorption. Weaker features near 2.30 ??m could arise from CO2 ice at coarse grain sizes, or surface/dust minerals. Narrow features near 2.00 ??m, which could potentially be very diagnostic of CO2 ice clouds, suffer from contamination by Mars atmospheric CO2 absorptions and are difficult to interpret because of the rather poor knowledge of surface elevation at high latitudes. These results indicate that future ground-based, Earth-orbital, and spacecraft studies over a more extended span of the seasonal cycle should yield substantial information on the style and timing of volatile transport on Mars, as well as a more detailed understanding of the role of CO2 condensation in the polar heat budget. Copyright 1996 by the American Geophysical Union.

CO Adsorption on Reconstructed Ir(100) Surfaces from UHV to mbar Pressure: A LEED, TPD, and PM-IRAS Study

PubMed Central

2016-01-01

Clean and stable surface modifications of an iridium (100) single crystal, i.e., the (1 × 1) phase, the (5 × 1) reconstruction, and the oxygen-terminated (2 × 1)-O surface, were prepared and characterized by low energy electron diffraction (LEED), temperature-programmed desorption (TPD), infrared reflection absorption spectroscopy (IRAS) and polarization modulation IRAS (PM-IRAS). The adsorption of CO in UHV and at elevated (mbar) pressure/temperature was followed both ex situ and in situ on all three surface modifications, with a focus on mbar pressures of CO. The Ir(1 × 1) surface exhibited c(4 × 2)/c(2 × 2) and c(6 × 2) CO structures under low pressure conditions, and remained stable up to 100 mbar and 700 K. For the (2 × 1)-O reconstruction CO adsorption induced a structural change from (2 × 1)-O to (1 × 1), as confirmed by LEED, TPD, and IR. For Ir (2 × 1)-O TPD indicated that CO reacted with surface oxygen forming CO2. The (5 × 1) reconstruction featured a reversible and dynamic behavior upon CO adsorption, with a local lifting of the reconstruction to (1 × 1). After CO desorption, the (5 × 1) structure was restored. All three reconstructions exhibited CO adsorption with on-top geometry, as evidenced by IR. With increasing CO exposure the resonances shifted to higher wavenumber, due to adsorbate–adsorbate and adsorbate–substrate interactions. The largest wavenumber shift (from 2057 to 2100 cm–1) was observed for Ir(5 × 1) upon CO dosing from 1 L to 100 mbar. PMID:27257467

Investigation of silicate mineral sanidine by vibrational and NMR spectroscopic methods

NASA Astrophysics Data System (ADS)

Anbalagan, G.; Sankari, G.; Ponnusamy, S.; kumar, R. Thilak; Gunasekaran, S.

2009-10-01

Sanidine, a variety of feldspar minerals has been investigated through optical absorption, vibrational (IR and Raman), EPR and NMR spectroscopic techniques. The principal reflections occurring at the d-spacings, 3.2892, 3.2431, 2.9022 and 2.6041 Å confirm the presence of sanidine structure in the mineral. Sanidine shows five prominent characteristic infrared absorption bands in the region 1200-950, 770-720, 590-540 and 650-640 cm -1. The Raman spectrum shows the strongest band at 512 cm -1 characteristic of the feldspar structure, which contains four membered rings of tetrahedra. The UV-vis-NIR absorption spectrum had strong absorption features at 6757, 5780 and 5181 cm -1 due to the combination of fundamental OH- stretching. The bands at 11236 and 8196 cm -1and the strong, well-defined band at (30303 cm -1 attest the presence of Fe 2+ and Fe 3+, respectively, in the sample. The signals at g = 4.3 and 3.7 are interpreted in terms of Fe 3+ at two distinct tetrahedral positions Tl and T2 of the monoclinic crystal structure The 29Si NMR spectrum shows two peaks at -97 and -101 ppm corresponding to T2 and T1, respectively, and one peak in 27Al NMR for Al(IV).

Investigation of silicate mineral sanidine by vibrational and NMR spectroscopic methods.

PubMed

Anbalagan, G; Sankari, G; Ponnusamy, S; Kumar, R Thilak; Gunasekaran, S

2009-10-01

Sanidine, a variety of feldspar minerals has been investigated through optical absorption, vibrational (IR and Raman), EPR and NMR spectroscopic techniques. The principal reflections occurring at the d-spacings, 3.2892, 3.2431, 2.9022 and 2.6041 A confirm the presence of sanidine structure in the mineral. Sanidine shows five prominent characteristic infrared absorption bands in the region 1200-950, 770-720, 590-540 and 650-640 cm(-1). The Raman spectrum shows the strongest band at 512 cm(-1) characteristic of the feldspar structure, which contains four membered rings of tetrahedra. The UV-vis-NIR absorption spectrum had strong absorption features at 6757, 5780 and 5181 cm(-1) due to the combination of fundamental OH- stretching. The bands at 11236 and 8196 cm(-1)and the strong, well-defined band at (30303 cm(-1) attest the presence of Fe(2+) and Fe(3+), respectively, in the sample. The signals at g = 4.3 and 3.7 are interpreted in terms of Fe(3+) at two distinct tetrahedral positions Tl and T2 of the monoclinic crystal structure The (29)Si NMR spectrum shows two peaks at -97 and -101 ppm corresponding to T2 and T1, respectively, and one peak in (27)Al NMR for Al(IV).

Comparative analysis of high-performance infrared avalanche InxGa1-xAsyP1-y and Hg1-xCdxTe heterophotodiodes

NASA Astrophysics Data System (ADS)

Kholodnov, Viacheslav; Drugova, Albina; Nikitin, Mikhail; Chekanova, Galina

2012-10-01

Technology of infrared (IR) avalanche photodiodes (APDs) gradually moves from simple single element APD to 2D focal plane arrays (FPA). Spectral covering of APDs is expanded continuously from classic 1.3 μm to longer wavelengths due to using of narrow-gap semiconductor materials like Hg1-xCdxTe. APDs are of great interest to developers and manufacturers of different optical communication, measuring and 3D reconstruction thermal imaging systems. Major IR detector materials for manufacturing of high-performance APDs became heteroepitaxial structures InxGa1-xAsyP1-y and Hg1-xCdxTe. Progress in IR APD technology was achieved through serious improvement in material growing techniques enabling forming of multilayer heterostuctures with separate absorption and multiplication regions (SAM). Today SAM-APD design can be implemented both on InxGa1-xAsyP1-y and Hg1-xCdxTe multilayer heteroepitaxial structures. To create the best performance optimal design avalanche heterophotodiode (AHPD) it is necessary to carry out a detailed theoretical analysis of basic features of generation, avalanche breakdown and multiplication of charge carriers in proper heterostructure. Optimization of AHPD properties requires comprehensive estimation of AHPD's pixel performance depending on pixel's multi-layer structure design, layers doping, distribution of electric field in the structure and operating temperature. Objective of the present article is to compare some features of 1.55 μm SAM-AHPDs based on InxGa1-xAsyP1-y and Hg1-xCdxTe.

Looking for the Coldest Atmospheres: a Search for Planetary Mass Companions around T and Y Brown Dwarfs

NASA Astrophysics Data System (ADS)

Fontanive, Clemence

2017-08-01

We propose to obtain WFC3/IR imaging of the very coolest brown dwarfs (T < 800 K) to search for substellar and planetary-mass companions to these objects. Companions discovered by this program would likely be analogues of the 250 K brown dwarf WISE 0855 and would provide vital benchmark objects for theoretical models, closing the gap in mass and temperature between brown dwarfs and planets. Finding such an object as a member of a binary system would be even more valuable as it would allow for the measurement of dynamical masses. We recently placed the first constraints to date on the binary frequency for brown dwarfs with spectral types >T8. This program will triple our current sample size, a requirement in order to confirm our current results and compare substellar binary properties for various spectral type and age populations. The WFC3/IR plate will allow us to probe near equal-mass binaries down to separations of 0.2 (2-3 AU for the typical distances of our targets). True cool companions should show strong absorption around 1.4 um as a result of the deep water absorption band observed at that wavelength in substellar spectra. We therefore propose observations in the WFC3 F127M and F139M filters which will allow us to robustly identify bona fide candidates and distinguish them from background stars based on this spectral feature. Most of our targets lack suitable NGS AO guide stars or LGS AO tip-tilt stars to be observed with ground-based telescopes, and the 1.4 um water band is often unobservable from the ground due to telluric water absorption. WFC3 on HST is thus the only instrument suitable for these observations.

Novel transmucosal absorption enhancers obtained by aminoalkylation of chitosan.

PubMed

Zambito, Ylenia; Uccello-Barretta, Gloria; Zaino, Chiara; Balzano, Federica; Di Colo, Giacomo

2006-12-01

Literature data suggest that quaternized chitosans have a transmucosal drug absorption enhancing property depending on their MW, quaternization degree and other structural features. With the purpose of preparing novel effective promoters, a chitosan (Ch) from crab shell (ChC; viscometric MW, 800 kDa; deacetylation: 90%, IR; 84%, NMR) and one from shrimp shell (ChS; viscometric MW, 590 kDa; deacetylation: 90%, IR; 82%, NMR) were reacted with 2-diethylaminoethyl chloride (DEAE-Cl) and novel derivatives containing different percentages of pendant quaternary ammonium groups were obtained. NMR analysis, based on HSQC, COSY, TOCSY and ROESY maps, indicated that three partially substituted N,O-[N,N-diethylaminomethyl(diethyldimethylene ammonium)(n)]methyl chitosans, coded N(+)-ChS-2 (degree of substitution, DS=40%; n=1.6), N(+)-ChS-4 (DS=132%; n=2.5), and N(+)-ChC-4 (DS=85%; n=1.7) resulted from the reaction, depending on whether the DEAE-Cl/Ch repeating unit molar ratio, was 2:1 or 4:1. The effects of the derivatives on the permeability of rhodamine 123 (Rh-123), hydrophobic, marker of the transcellular absorption route, and of fluorescein sodium (NaFlu), polar, marker of the paracellular route, across excised porcine cheek epithelium were assessed, using Franz type diffusion cells. Rh-123 permeability was enhanced by N(+)-ChS-4 (enhancement ratio, ER=8.4) and by N(+)-ChC-4 (ER=3.9), whereas N(+)-ChS-2 was ineffective. NaFlu permeability was enhanced by N(+)-ChS-2 (ER=7.2), N(+)-ChS-4 (ER=7.4) and N(+)-ChC-4 (ER=6.6). In conclusion, the three derivatives, whichever their DS, promote paracellular transport, while transcellular transport is substantially accelerated only by the most substituted one.

Spectroscopy of PAHs with carbon side chains

NASA Astrophysics Data System (ADS)

Rouille, G.; Steglich, M.; Carpentier, Y.; Huisken, F.; Henning, T.

2011-05-01

The presence of polycyclic aromatic hydrocarbons (PAHs) in space has been inferred ever since sp ecific infrared emission bands were interpreted as their collective fingerprint. In parallel, it has been admitted that the famous diffuse interstellar bands (DIBs), which are absorption features observed in the visible wavelength range, are bands belonging to the electronic spectra of free-flying interstellar molecules yet to be identified. As neutral PAHs of medium and large sizes exhibit absorption bands in the range where the DIBs are found, these molecules, which also fulfill other criteria, have been proposed as potential carriers. Studies of small PAHs in solutions have shown that adding an ethynyl side chain (--CCH) to their structure causes their electronic transitions to shift toward longer wavelengths. This fact, added to the observations of interstellar polyynyl radicals, motivated our current research project on PAHs carrying polyynyl side chains. In a first stage, we are measuring the electronic spectra of small PAHs and of their ethynyl and butadiynyl (--CCCCH) derivatives at cryogenic temperatures in rare gas matrices. Then, measurements will be carried out in supersonic jets, providing us with spectra obtained under conditions relevant to the study of free-flying interstellar molecules. The results of IR absorption measurements will be included in our set of new data. As a complement to our laboratory study on the substituted PAHs, quantum chemical calculations are carried out to interprete and simulate their IR and vibronic spectra. We use the density functional theory approach and its time-dependent extension for calculating the electronic ground states and the electronically excited states, respectively. Through the analysis of the new data, it will be determined whether PAHs carrying polyynyl side chains can play a role in interstellar phenomena. The latest results of this on-going project will be presented.

Photoacoustic Experimental System to Confirm Infrared Absorption Due to Greenhouse Gases

ERIC Educational Resources Information Center

Kaneko, Fumitoshi; Monjushiro, Hideaki; Nishiyama, Masayoshi; Kasai, Toshio; Harris, Harold H.

2010-01-01

An experimental system for detecting infrared absorption using the photoacoustic (PA) effect is described. It is aimed for use at high-school level to illustrate the difference in infrared (IR) absorption among the gases contained in the atmosphere in connection with the greenhouse effect. The experimental system can be built with readily…

Collecting Quality Infrared Spectra from Microscopic Samples of Suspicious Powders in a Sealed Cell.

PubMed

Kammrath, Brooke W; Leary, Pauline E; Reffner, John A

2017-03-01

The infrared (IR) microspectroscopical analysis of samples within a sealed-cell containing barium fluoride is a critical need when identifying toxic agents or suspicious powders of unidentified composition. The dispersive nature of barium fluoride is well understood and experimental conditions can be easily adjusted during reflection-absorption measurements to account for differences in focus between the visible and IR regions of the spectrum. In most instances, the ability to collect a viable spectrum is possible when using the sealed cell regardless of whether visible or IR focus is optimized. However, when IR focus is optimized, it is possible to collect useful data from even smaller samples. This is important when a minimal sample is available for analysis or the desire to minimize risk of sample exposure is important. While the use of barium fluoride introduces dispersion effects that are unavoidable, it is possible to adjust instrument settings when collecting IR spectra in the reflection-absorption mode to compensate for dispersion and minimize impact on the quality of the sample spectrum.

IR absorption and surface-enhanced Raman spectra of the isoquinoline alkaloid berberine

NASA Astrophysics Data System (ADS)

Strekal', N. D.; Motevich, I. G.; Nowicky, J. W.; Maskevich, S. A.

2007-01-01

We present the IR absorption and surface-enhanced Raman scattering (SERS) spectra of the isoquinoline alkaloid berberine adsorbed on a silver hydrosol and on the surface of a silver electrode for different potentials. Based on quantum chemical calculations, for the first time we have assigned the vibrations in the berberine molecule according to vibrational mode. The effect of the potential of the silver electrode on the geometry of sorption of the molecule on the surface is considered, assuming a short-range mechanism for enhancement of Raman scattering.

Broad band nonlinear optical absorption measurements of the laser dye IR26 using white light continuum Z-scan

NASA Astrophysics Data System (ADS)

Dey, Soumyodeep; Bongu, Sudhakara Reddy; Bisht, Prem Ballabh

2017-03-01

We study the nonlinear optical response of a standard dye IR26 using the Z-scan technique, but with the white light continuum. The continuum source of wavelength from 450 nm to 1650 nm has been generated from the photonic crystal fiber on pumping with 772 nm of Ti:Sapphire oscillator. The use of broadband incident pulse enables us to probe saturable absorption (SA) and reverse saturable absorption (RSA) over the large spectral range with a single Z-scan measurement. The system shows SA in the resonant region while it turns to RSA in the non-resonant regions. The low saturation intensity of the dye can be explained based on the simultaneous excitation from ground states to various higher energy levels with the help of composite energy level diagram. The cumulative effects of excited state absorption and thermal induced nonlinear optical effects are responsible for the observed RSA.

Simultaneous Multiwavelength Variability Characterization of the Free-floating Planetary-mass Object PSO J318.5‑22

NASA Astrophysics Data System (ADS)

Biller, Beth A.; Vos, Johanna; Buenzli, Esther; Allers, Katelyn; Bonnefoy, Mickaël; Charnay, Benjamin; Bézard, Bruno; Allard, France; Homeier, Derek; Bonavita, Mariangela; Brandner, Wolfgang; Crossfield, Ian; Dupuy, Trent; Henning, Thomas; Kopytova, Taisiya; Liu, Michael C.; Manjavacas, Elena; Schlieder, Joshua

2018-02-01

We present simultaneous Hubble Space Telescope (HST) WFC3+Spitzer IRAC variability monitoring for the highly variable young (∼20 Myr) planetary-mass object PSO J318.5‑22. Our simultaneous HST + Spitzer observations covered approximately two rotation periods with Spitzer and most of a rotation period with the HST. We derive a period of 8.6 ± 0.1 hr from the Spitzer light curve. Combining this period with the measured v\\sin i for this object, we find an inclination of 56.°2 ± 8.°1. We measure peak-to-trough variability amplitudes of 3.4% ± 0.1% for Spitzer Channel 2 and 4.4%–5.8% (typical 68% confidence errors of ∼0.3%) in the near-IR bands (1.07–1.67 μm) covered by the WFC3 G141 prism—the mid-IR variability amplitude for PSO J318.5‑22 is one of the highest variability amplitudes measured in the mid-IR for any brown dwarf or planetary-mass object. Additionally, we detect phase offsets ranging from 200° to 210° (typical error of ∼4°) between synthesized near-IR light curves and the Spitzer mid-IR light curve, likely indicating depth-dependent longitudinal atmospheric structure in this atmosphere. The detection of similar variability amplitudes in wide spectral bands relative to absorption features suggests that the driver of the variability may be inhomogeneous clouds (perhaps a patchy haze layer over thick clouds), as opposed to hot spots or compositional inhomogeneities at the top-of-atmosphere level.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Thomas, Sylvia -Monique; Wilson, Kathryn; Koch-Muller, Monika

Majoritic garnet, characterized by an excess of silicon (>3 Si per formula unit), is considered one of the major phases of the Earth’s transition zone from 410-660 km depth. Quantifying the H 2O content of nominally anhydrous mantle minerals is necessary to evaluate their water storage capacity from experiments and modeling the Earth’s deep water cycle. We present mineral-specific infrared absorption coefficients for the purpose of quantifying the amount of water incorporated into majorite as hydroxyl point defects. A suite of majoritic garnet samples with varying proportions of Si, Fe, Al, Cr and H 2O was synthesized at conditions ofmore » 18-19 GPa and 1500-1800°C. Single-crystals were characterized using X-ray diffraction, electron microprobe analysis, secondary Ion Mass spectrometry (SIMS), IR, Raman and Mössbauer spectroscopy. We utilize SIMS and Raman spectroscopy in combination with IR spectroscopy to provide IR absorption coefficients for water in majoritic garnets with the general mineral formula (Mg,Fe) 3(Si,Mg,Fe,Al,Cr) 2[SiO4] 3. Furthermore, the IR absorption coefficient for majoritic garnet in the OH stretching region is frequency-dependent and ranges from 10 470 ± 3100 Lmol-1cm-2 to 23 400 ± 2300 Lmol -1cm -2.« less

Quantification of water in majoritic garnet

DOE PAGES

Thomas, Sylvia -Monique; Wilson, Kathryn; Koch-Muller, Monika; ...

2015-05-01

Majoritic garnet, characterized by an excess of silicon (>3 Si per formula unit), is considered one of the major phases of the Earth’s transition zone from 410-660 km depth. Quantifying the H 2O content of nominally anhydrous mantle minerals is necessary to evaluate their water storage capacity from experiments and modeling the Earth’s deep water cycle. We present mineral-specific infrared absorption coefficients for the purpose of quantifying the amount of water incorporated into majorite as hydroxyl point defects. A suite of majoritic garnet samples with varying proportions of Si, Fe, Al, Cr and H 2O was synthesized at conditions ofmore » 18-19 GPa and 1500-1800°C. Single-crystals were characterized using X-ray diffraction, electron microprobe analysis, secondary Ion Mass spectrometry (SIMS), IR, Raman and Mössbauer spectroscopy. We utilize SIMS and Raman spectroscopy in combination with IR spectroscopy to provide IR absorption coefficients for water in majoritic garnets with the general mineral formula (Mg,Fe) 3(Si,Mg,Fe,Al,Cr) 2[SiO4] 3. Furthermore, the IR absorption coefficient for majoritic garnet in the OH stretching region is frequency-dependent and ranges from 10 470 ± 3100 Lmol-1cm-2 to 23 400 ± 2300 Lmol -1cm -2.« less

Infrared Camera System for Visualization of IR-Absorbing Gas Leaks

NASA Technical Reports Server (NTRS)

Youngquist, Robert; Immer, Christopher; Cox, Robert

2010-01-01

Leak detection and location remain a common problem in NASA and industry, where gas leaks can create hazardous conditions if not quickly detected and corrected. In order to help rectify this problem, this design equips an infrared (IR) camera with the means to make gas leaks of IR-absorbing gases more visible for leak detection and location. By comparing the output of two IR cameras (or two pictures from the same camera under essentially identical conditions and very closely spaced in time) on a pixel-by-pixel basis, one can cancel out all but the desired variations that correspond to the IR absorption of the gas of interest. This can be simply done by absorbing the IR lines that correspond to the gas of interest from the radiation received by one of the cameras by the intervention of a filter that removes the particular wavelength of interest from the "reference" picture. This can be done most sensitively with a gas filter (filled with the gas of interest) placed in front of the IR detector array, or (less sensitively) by use of a suitable line filter in the same location. This arrangement would then be balanced against the unfiltered "measurement" picture, which will have variations from IR absorption from the gas of interest. By suitable processing of the signals from each pixel in the two IR pictures, the user can display only the differences in the signals. Either a difference or a ratio output of the two signals is feasible. From a gas concentration viewpoint, the ratio could be processed to show the column depth of the gas leak. If a variation in the background IR light intensity is present in the field of view, then large changes in the difference signal will occur for the same gas column concentration between the background and the camera. By ratioing the outputs, the same signal ratio is obtained for both high- and low-background signals, even though the low-signal areas may have greater noise content due to their smaller signal strength. Thus, one embodiment would use a ratioed output signal to better represent the gas column concentration. An alternative approach uses a simpler multiplication of the filtered signal to make the filtered signal equal to the unfiltered signal at most locations, followed by a subtraction to remove all but the wavelength-specific absorption in the unfiltered sample. This signal processing can also reveal the net difference signal representing the leaking gas absorption, and allow rapid leak location, but signal intensity would not relate solely to gas absorption, as raw signal intensity would also affect the displayed signal. A second design choice is whether to use one camera with two images closely spaced in time, or two cameras with essentially the same view and time. The figure shows the two-camera version. This choice involves many tradeoffs that are not apparent until some detailed testing is done. In short, the tradeoffs involve the temporal changes in the field picture versus the pixel sensitivity curves and frame alignment differences with two cameras, and which system would lead to the smaller variations from the uncontrolled variables.

Biotransformation and toxicokinetics of the insect repellent IR3535® in male and female human subjects after dermal exposure.

PubMed

Broschard, Thomas H; Bohlmann, Anja M; Konietzny, Stefan; Schauer, Ute M D; Dekant, Wolfgang

2013-04-26

The absorption and excretion of the insect repellent IR3535(®) was studied in human subjects (five males and five females) after dermal application of approx. 3g of a formulation containing 20% IR3535(®), i.e. the amounts of IR3535(®) applied were between 1.94 and 3.4 mmol/person (418-731 mg/person). Blood and urinary concentrations of IR3535(®) and its only metabolite, IR3535(®)-free acid, were determined over time. In plasma, concentrations of the parent compound IR3535(®) were at or below the limit of quantification (0.037 μmol/L). IR3535(®)-free acid peaked in plasma samples 2-6h after dermal application. Cmax mean values were 5.7 μmol/L in males, 3.0 μmol/L in females and 4.2 μmol/L in all volunteers. Mean AUC values were 41.6, 24.5 and 33.9 μmolL(-1)h in males, females and all subjects, respectively. In urine samples from all human subjects, both IR3535(®) and IR3535(®)-free acid were detectable, however, only very small amounts of IR3535(®) were found. Concentrations of IR3535(®)-free acid were several thousand-fold higher than the parent compound and peaked at the first two sampling points (4h and 8h after dermal application). Overall, IR3535(®) and IR3535(®)-free acid excreted with urine over 48 h representing 13.3 ± 3.05% of the dose applied. Since IR3535(®) is rapidly and extensively metabolized, and IR3535(®)-free acid has a low molecular weight and high water solubility, it is expected that urinary excretion of IR3535(®)-free acid and IR3535(®) represents the total extent of absorption of IR3535(®) in humans. Based on the results of this study, the skin penetration rate of IR3535(®) is 13.3% in humans after dermal application. Copyright © 2013 Elsevier Ireland Ltd. All rights reserved.

Fabrication and characterization of a water-free mid-infrared fluorotellurite glass.

PubMed

Lin, Aoxiang; Ryasnyanskiy, Aleksandr; Toulouse, Jean

2011-03-01

Using a physical and chemical dehydration technique and a high-pressure, ultradry O2 atmosphere in a semiclosed steel-chamber furnace, we fabricated a group of fluorotellurite glasses with a composition of (90-x)TeO2-xZnF2-10Na2O (mol.%, x=0-30). For x=30, no OH absorption was observed in the range of 0.38-6.1 μm. This is the first report of a water-free mid-IR fluorotellurite glass, to our knowledge, offering the common advantages of a robust oxide glass and an IR-transparent fluoride one. Besides optimized linear transmittance and absorption, the nonlinear refractive indices and Raman gain coefficients are reduced. These results are discussed in the context of mid-IR high-power laser generation and transmission.

Effects of alkyl spacer group length on Vis-NIR absorption behavior in FTC-like guest-host EO polymers

NASA Astrophysics Data System (ADS)

Barto, Richard R., Jr.; Bedworth, Peter V.; Epstein, Joseph A.; Ermer, Susan P.; Taylor, Rebecca E.; Frank, Curtis W.

2003-07-01

Spectral absorption behavior of a series of FTC-like dyes of varying shape incorporated into amorphous polycarbonate (APC) is characterized by photothermal deflection spectroscopy. Previous Monte Carlo calculations by Dalton and Robinson predict a strong dependence of the macroscopic nonlinear optical susceptibility on the chromophore waist:length aspect ratio in electric field-poled films. This dependence arises from London interactions between chromophores, which are expected to influence the absorption characteristics of the composite both by changing the local polarity of the medium and through dipole interactions. It is expected that these interactions will play a role in the absorption characteristics of unpoled films as well. Of particular interest are the spectral characteristics of the red edge of the main dye electronic absorption peak, and the fine structure in the near-IR, dominated by overtones of fundamental C-H stretching and bending modes. The spectral structure in these key regions can be influenced by inter- and intramolecular interactions and conformational changes in the dye. The near-IR structure, in turn, will dictate absorption loss in optical devices prepared from these materials at key transmission wavelengths (1.3 and 1.55 um). In this study, a homologous series of spacer lengths, ranging from ethyl to hexyl, attached to an FTC-like NLO chromophore, LMCO-46M, is characterized by a combination of photothermal deflection spectroscopy (PDS) and UV-Vis spectroscopy to examine the effects of the molecular environment on near-IR loss at 1090 nm, 1300 nm and 1550 nm.

Particle agglomerated 3-d nanostructures for photon absorption

NASA Astrophysics Data System (ADS)

Sivayoganathan, Mugunthan

The main objective of this thesis is to investigate the photon absorption properties of particle agglomerated 3-D structures that are synthesized through femtosecond laser ablation of solids. The size and morphology of these particle agglomerated 3-D structures, which can be tailored through adjusting laser parameters, determine the photon absorption property. A systematic theoretical and experimental study was performed to identify the effect of lasers on the size of the formed particles. The literature survey showed that the amount of supersaturation influences the growth rate as well as the nucleation rate of vapour condensed nanoparticles. Based on this theory, a mechanism was formed to explain the control of laser parameters over the size of formed particles. Further, a theoretical explanation was proposed from the experimental results for the transition of particle size distribution modals. These proposed mechanisms and explanations show the variation in particle size in the particle agglomerated 3-D nanostructures with laser parameters. The effect of laser parameters on the formed ring size was studied. Based on the previous studies, a mechanism was proposed for the formation of ring nanoclusters. The laser pulse intensity dependent ponderomotive force was the key force to define the formation of ring nanoclusters. Then the effect of laser parameters on ring size was studied. Structures fabricated on several materials such as graphite, aluminosilicate ceramic, zinc ingot, gold, and titanium were analyzed to show the influence of material properties, laser parameters, and the environmental conditions on the size of ring formed. The studies performed on the structures showed a minimum absorption of 0.75 A.U. in the bandwidth from UV to IR. The absorption spectrum is much wider compared to existing nanomaterials, such as silicon nanostructures and titanium dioxide nanostructures. To the best of the author's knowledge, it is a very competitive absorption rate when compared with the previous nanostructures used in photovoltaic conversion. Several features of nanostructures contribute to the enhancement of this light absorption. The special feature of the structure is that ease to fabricate and modify the properties by varying the laser parameters could make it competitive among other nanostructures available for solar cells.

Attosecond XUV absorption spectroscopy of doubly excited states in helium atoms dressed by a time-delayed femtosecond infrared laser

NASA Astrophysics Data System (ADS)

Yang, Z. Q.; Ye, D. F.; Ding, Thomas; Pfeifer, Thomas; Fu, L. B.

2015-01-01

In the present paper, we investigate the time-resolved transient absorption spectroscopy of doubly excited states of helium atoms by solving the time-dependent two-electron Schrödinger equation numerically based on a one-dimensional model. The helium atoms are subjected to an extreme ultraviolet (XUV) attosecond pulse and a time-delayed infrared (IR) few-cycle laser pulse. A superposition of doubly excited states populated by the XUV pulse is identified, which interferes with the direct ionization pathway leading to Fano resonance profiles in the photoabsorption spectrum. In the presence of an IR laser, however, the Fano line profiles are strongly modified: A shifting, splitting, and broadening of the original absorption lines is observed when the XUV attosecond pulse and infrared few-cycle laser pulse overlap in time, which is in good agreement with recent experimental results. At certain time delays, we observe symmetric Lorentz, inverted Fano profiles, and even negative absorption cross sections indicating that the XUV light can be amplified during the interaction with atoms. We further prove that the above pictures are general for different doubly excited states by suitably varying the frequency of the IR field to coherently couple the corresponding states.

Time-resolved diode laser infrared absorption spectroscopy of the nascent HCl in the infrared laser chemistry of 1,2-dichloro-1,1-difluoroethane

NASA Astrophysics Data System (ADS)

Dietrich, Peter; Quack, Martin; Seyfang, George

1990-04-01

The IR multiphoton excitation and the frequency, fluence and intensity dependence of the IR-laser chemical yields of CF 2ClCH 2Cl have been studied in the fluence range of 1 to 10 J cm -2 yielding a steady-state constant k(st)/ I=0.74×10 6 s -1 MW -1 cm 2 which is approximately independent of intensity. Time-resolved IR absorption spectroscopy with diode laser sources has been used to observe the nascent HCl during the first few 100 ns indicating a population inversion between the levels ν=1, J=4 and ν=2, J=5. At low reactant pressures ( p⩽10 Pa) the time-resolved measurement gives a steady-state rate constant consistent with the theoretical result adjusted to the static yield measurements. The capability of state-selective and time-resolved IR spectroscopy is thus demonstrated, giving real-time determinations of rate constants.

Review of Canadian Light Source facilities for biological applications

NASA Astrophysics Data System (ADS)

Grochulski, Pawel; Fodje, Michel; Labiuk, Shaun; Wysokinski, Tomasz W.; Belev, George; Korbas, Malgorzata; Rosendahl, Scott M.

2017-11-01

The newly-created Biological and Life Sciences Department at the Canadian Light Source (CLS) encompasses four sets of beamlines devoted to biological studies ranging in scope from the atomic scale to cells, tissues and whole organisms. The Canadian Macromolecular Crystallography Facility (CMCF) consists of two beamlines devoted primarily to crystallographic studies of proteins and other macromolecules. The Mid-Infrared Spectromicroscopy (Mid-IR) beamline focusses on using infrared energy to obtain biochemical, structural and dynamical information about biological systems. The Bio-Medical Imaging and Therapy (BMIT) facility consists of two beamlines devoted to advanced imaging and X-ray therapy techniques. The Biological X-ray Absorption Spectroscopy (BioXAS) facility is being commissioned and houses three beamlines devoted to X-ray absorption spectroscopy and multi-mode X-ray fluorescence imaging. Together, these beamlines provide CLS Users with a powerful array of techniques to study today's most pressing biological questions. We describe these beamlines along with their current powerful features and envisioned future capabilities.

Development of integrated platform based on chalcogenides for sensing applications in the mid-infrared

NASA Astrophysics Data System (ADS)

Gutierrez-Arroyo, Aldo; Bodiou, Loïc.; Lemaitre, Jonathan; Baudet, Emeline; Baillieul, Marion; Hardy, Isabelle; Caillaud, Celine; Colas, Florent; Boukerma, Kada; Rinnert, Emmanuel; Michel, Karine; Bureau, Bruno; Nazabal, Virginie; Charrier, Joël.

2018-03-01

Mid-Infrared (mid-IR) spectral range, spanning from 2 μm to 20 μm, is ideal for chemical sensing using spectroscopy thanks to the presence of vibrational absorption bands of many liquid and gas substances in this wavelength range. Indeed, mid-IR spectroscopy allows simultaneous qualitative and quantitative analysis by, respectively, identifying molecules from their spectral signature and relating the concentrations of different chemical agents to their absorption coefficient according to Beer-Lambert law. In the last years, photonic integrated sensors based on mid-IR spectroscopy have emerged as a cheap, accurate, and compact solution that would enable continuous real-time on-site diagnostics and monitoring of molecular species without the need to collect samples for off-site measurements. Here, we report the design, processing and characterization of a photonic integrated transducer based on selenide ridge waveguides. Evanescent wave detection of chemical substances in liquid phase (isopropyl alcohol, C3H8O, and acetic acid, C2H4O2, both dissolved in cyclohexane) is presented using their absorption at a wavelength of 7.7 μm.

4-Cyano-α-methyl-l-phenylalanine as a spectroscopic marker for the investigation of peptaibiotic-membrane interactions.

PubMed

De Zotti, Marta; Bobone, Sara; Bortolotti, Annalisa; Longo, Edoardo; Biondi, Barbara; Peggion, Cristina; Formaggio, Fernando; Toniolo, Claudio; Dalla Bona, Andrea; Kaptein, Bernard; Stella, Lorenzo

2015-04-01

Two analogs of the ten-amino acid residue, membrane-active lipopeptaibiotic trichogin GA IV, mono-labeled with 4-cyano-α-methyl-L-phenylalanine, a potentially useful fluorescence and IR absorption probe of the local microenvironment, were synthesized by the solid-phase methodology and conformationally characterized. The single modification was incorporated either at the N-terminus (position 1) or near the C-terminus (position 8) of the peptide main chain. In both cases, the replaced amino acid was the equally helicogenic α-aminoisobutyric acid (Aib) residue. We performed a solution conformational analysis by use of FT-IR absorption, CD, and 2D-NMR spectroscopies. The results indicate that both labeled analogs essentially maintain the overall helical propensity of the naturally occurring lipopeptaibiotic. Peptide-membrane interactions were assessed by fluorescence and ATR-IR absorption techniques. Analogies and differences between the two peptides were highlighted. Taken together, our data confirm literature results that some of the spectroscopic parameters of the 4-cyanobenzyl chromophore are sensitive markers of the local microenvironment. Copyright © 2015 Verlag Helvetica Chimica Acta AG, Zürich.

Spectroscopic, cyclic voltammetric and biological studies of transition metal complexes with mixed nitrogen-sulphur (NS) donor macrocyclic ligand derived from thiosemicarbazide

NASA Astrophysics Data System (ADS)

Chandra, Sulekh; Gupta, Lokesh Kumar; Sangeetika

2005-11-01

The complexation of new mixed thia-aza-oxa macrocycle viz., 2,12-dithio-5,9,14,18-tetraoxo-7,16-dithia-1,3,4,10,11,13-hexaazacyclooctadecane containing thiosemicarba-zone unit with a series of transition metals Co(II), Ni(II) and Cu(II) has been investigated, by different spectroscopic techniques. The structural features of the ligand have been studied by EI-mass, 1H NMR and IR spectral techniques. Elemental analyses, magnetic moment susceptibility, molar conductance, IR, electronic, and EPR spectral studies characterized the complexes. Electronic absorption and IR spectra of the complexes indicate octahedral geometry for chloro, nitrato, thiocyanato or acetato complexes. The dimeric and neutral nature of the sulphato complexes are confirmed from magnetic susceptibility and low conductance values. Electronic spectra suggests square-planar geometry for all sulphato complexes. The redox behaviour was studied by cyclic voltammetry, show metal-centered reduction processes for all complexes. The complexes of copper show both oxidation and reduction process. The redox potentials depend on the conformation of central atom in the macrocyclic complexes. Newly synthesized macrocyclic ligand and its transition metal complexes show markedly growth inhibitory activity against pathogenic bacterias and plant pathogenic fungi under study. Most of the complexes have higher activity than that of the metal free ligand.

NIR integral field spectroscopy of high mass young stellar objects

NASA Astrophysics Data System (ADS)

Murakawa, K.; Lumsden, S. L.; Oudmaijer, R. D.; Davies, B.; Hoare, M. G.

2013-03-01

We present K-band Integral Field Spectroscopy of six high mass young stellar objects (IRAS~18151-1208, AFGL~2136, S106~IRS4, V645 Cyg, IRAS~19065+0526, and G082.5682+ 00.4040) obtained using the adaptive optics assisted NIFS instrument mounted on the Gemini North telescope. The targets are chosen from the Red MSX Source survey led by University of Leeds. The data show the spectral features of Brγ, H2, and gas phase CO emissions and absorptions with a spectral resolution of R ≈ 5500, which allow a three-dimensional spectro-astrometric analysis of the line emissions. We discuss the results of the ionized jets and winds, and rotating CO torus.

Improving an Empirical Formula for the Absorption of Sound in the Sea

DTIC Science & Technology

2008-05-01

Onderwater propagatie Advanced acoustic modelling Auteur (s) ir. C.A.M van Moll Programmanummer Projectnummer dr. M.A. Ainslie V512 032.11648 ing. J...versus calculated absorption .................................................................... 9 3 Inverse theory ...45 7.1 Statistical theory

New High-Resolution Absorption Cross-Section Measurements of HCFC-142B in the Mid-Ir

NASA Astrophysics Data System (ADS)

Le Bris, Karine; Strong, Kimberly; Melo, Stella

2009-06-01

HCFC-142b (1-chloro-1,1-difluoroethane) is a temporary substitute for ozone-depleting chlorofluorocarbons (CFCs). However, due to its high absorption cross-sections in the mid-IR, HCFC-142b is also a highly potent greenhouse gas, now detectable from space by satellite missions. So far, the accuracy of the retrieval has been limited by the lack of reference data in a range of temperatures compatible with atmospheric observations. We present new absorption cross section measurements of HCFC-142b at high-resolution (0.02 cm^{-1}) from 223 K to 283 K in the 600 cm^{-1}- 4000 cm^{-1} spectral window. The composite spectra are calculated for each temperature from a set of acquisitions at different pressures by Fourier transform spectroscopy.

Detection of accreting gas toward HD 45677: A newly recognized, Herbig Be proto-planetary system

NASA Technical Reports Server (NTRS)

Grady, C. A.; Bjorkman, K. S.; Shepherd, D.; Schulte-Ladbeck, R. E.; Perez, M. R.; Dewinter, D.; The, P. S.

1993-01-01

We report detection of high velocity, accreting gas toward the Be star with IR excess and bipolar nebula, HD 45677. High velocity (+200 to +400 km/s), variable column density gas is visible in all IUE spectra from 1979-1992 in transitions of Si II, C II, Al III, Fe III, Si IV, and C IV. Low-velocity absorption profiles from low oscillator-strength transitions of Si II, Fe II, and Zn II exhibit double-peaked absorption profiles similar to those previously reported in optical spectra of FU Orionis objects. The UV absorption data, together with previously reported analyses of the IR excess and polarization of this object, suggest that HD 45677 is a massive, Herbig Be star with an actively accreting circumstellar, proto-planetary disk.

Family of BODIPY Photocages Cleaved by Single Photons of Visible/Near-Infrared Light.

PubMed

Peterson, Julie A; Wijesooriya, Chamari; Gehrmann, Elizabeth J; Mahoney, Kaitlyn M; Goswami, Pratik P; Albright, Toshia R; Syed, Aleem; Dutton, Andrew S; Smith, Emily A; Winter, Arthur H

2018-06-13

Photocages are light-sensitive chemical protecting groups that provide external control over when, where, and how much of a biological substrate is activated in cells using targeted light irradiation. Regrettably, most popular photocages (e.g., o-nitrobenzyl groups) absorb cell-damaging ultraviolet wavelengths. A challenge with achieving longer wavelength bond-breaking photochemistry is that long-wavelength-absorbing chromophores have shorter excited-state lifetimes and diminished excited-state energies. However, here we report the synthesis of a family of BODIPY-derived photocages with tunable absorptions across the visible/near-infrared that release chemical cargo under irradiation. Derivatives with appended styryl groups feature absorptions above 700 nm, yielding photocages cleaved with the highest known wavelengths of light via a direct single-photon-release mechanism. Photorelease with red light is demonstrated in living HeLa cells, Drosophila S2 cells, and bovine GM07373 cells upon ∼5 min irradiation. No cytotoxicity is observed at 20 μM photocage concentration using the trypan blue exclusion assay. Improved B-alkylated derivatives feature improved quantum efficiencies of photorelease ∼20-fold larger, on par with the popular o-nitrobenzyl photocages (εΦ = 50-100 M -1 cm -1 ), but absorbing red/near-IR light in the biological window instead of UV light.

SN 1994I in M51 and the nature of type Ibc supernovae

NASA Technical Reports Server (NTRS)

Wheeler, J. C.; Harkness, R. P.; Clocchiatti, A.; Benetti, S.; Brotherton, M. S.; Depoy, D. L.; Elias, J.

1994-01-01

Early spectra of SN 1994I in M51 (NGC 5194) are presented along with arguments that is a member of the class of helium-poor Type Ic supernovae. The issue of H and He in the spectra of Type Ib and Ic events is reexamined with the conclusion that Type Ib eject substantially less H than even transition events like SN 1993J and that Type Ic eject substantially less He than Type Ib and their optical spectra are consistent with no H or He. Type Ic show and absorption of the Si II lambda 6355 blend that characterizes Type Ia. This feature requires only a solar abundance of Si. Some Type Ic show an absorption that is probably C II lambda 6580. IR spectra are presented of SN 1990W which show the line of He I lambda 10830. The strength of this feature and the rather slow decay of the late time light curve suggest that this event could be better classified as a Type Ib. Even if trace abundances of H are present in Type Ib and of He in Type Ic the spectral differences still imply a distinctly different evolution for the progenitors of Type Ib from Type Ic and events like SN 1993J.

Observations of J002E3: Possible Discovery of an Apollo Rocket Body

NASA Astrophysics Data System (ADS)

Jorgensen, K.; Rivkin, A.; Binzel, R.; Whitely, R.; Hergenrother, C.; Chodas, P.; Chesley, S.; Vilas, F.

2003-05-01

In early September 2002, spectral and photometric observations of J002E3 were made at IRTF and Mt. Biglow in an effort to determine whether the object was an asteroid or a human-made. Early observations yielded a possible spin-rate and orientation. Additional spectral observations were completed in May 2003 at the Air Force Maui Optical Supercomputing (AMOS) site. Through the modeling of common spacecraft materials, the observations of J002E3 show a strong correlation of absorption features to a combination of human-made materials including white paint, black paint, and aluminum. Absorption features in the near IR show a strong correlation with paint containing a titanium-oxide semiconductor. Using the material model and the orbital information, it was concluded that J002E3 is a human-made object from an Apollo rocket upperstage, most likely Apollo 12. In addition, the J002E3 observations were compared to spectral observations of other rocket bodies launched during a similar time and the results agree well. Results from the observations and modeling will be presented. This work has been a collaboration of governmental agencies, education institutions, and amateur astronomers. Funding agencies include National Research Council, NASA JSC, MIT, University of Arizona, and JPL.

Near-Infrared Spectrophotometry of Phobos and Deimos

NASA Technical Reports Server (NTRS)

Rivkin, A. S.; Brown, R. H.; Trilling, D. E.; Bell, J. F., III; Plassmann, J. H.

2002-01-01

We have observed the leading and trailing hemispheres of Phobos from 1.65 to 3.5 microns and Deimos from 1.65 to 3.12 microns near opposition. We find the trailing hemisphere of Phobos to be brighter than its leading hemisphere by 0.24 +/- 0.06 magnitude at 1.65 microns and brighter than Deimos by 0.98 +/- 0.07 magnitude at 1.65 microns. We see no difference larger than observational uncertainties in spectral slope between the leading and trailing hemispheres when the spectra are normalized to 1.65 microns. We find no 3-microns absorption feature due to hydrated minerals on either hemisphere to a level of approx. 5 - 10% on Phobos and approx. 20% on Deimos. When the infrared data are joined to visible and near-IR data obtained by previous workers, our data suggest the leading (Stickney-dominated) side of Phobos is best matched by T-class asteroids. The spectral slope of the trailing side of Phobos and leading side of Deimos are bracketed by the D-class asteroids. The best laboratory spectral matches to these parts of Phobos are mature lunar soils and heated carbonaceous chondrites. The lack of 3-microns absorption features on either side of Phobos argues against the presence of a large interior reservoir of water ice according to current models of Phobos' interior.

Near-Infrared Spectrophotometry of Phobos and Deimos

NASA Technical Reports Server (NTRS)

Rivkin, A. S.; Brown, R. H.; Trilling, D. E.; Bell, J. F., III; Plassmann, J. H.

2002-01-01

We have observed the leading and trailing hemispheres of Phobos from 1.65 to 3.5 microns and Deimos from 1.65 to 3.12 microns near opposition. We find the trailing hemisphere of Phobos to be brighter than its leading hemisphere by 0.24 +/- 0.06 magnitude at 1.65 microns and brighter than Deimos by 0.98 +/- 0.07 magnitude at 1.65 microns. We see no difference larger than observational uncertainties in spectral slope between the leading and trailing hemispheres when the spectra are normalized to 1.65 microns. We find no 3-micron absorption feature due to hydrated minerals on either hemisphere to a level of approx. 5-10% on Phobos and approx. 20% on Deimos. When the infrared data are joined to visible and near-IR data obtained by previous workers, our data suggest the leading (Stickney-dominated) side of Phobos is best matched by T-class asteroids. The spectral slope of the trailing side of Phobos and leading side of Deimos are bracketed by the D-class asteroids. The best laboratory spectral matches to these parts of Phobos are mature lunar soils and heated carbonaceous chondrites. The lack of 3-micron absorption features on either side of Phobos argues against the presence of a large interior reservoir of water ice according to current models of Phobos' interior.

Thermally Resilient, Broadband Optical Absorber from UV to IR Derived from Carbon Nanostructures

NASA Technical Reports Server (NTRS)

Kaul, Anupama B.; Coles, James B.

2012-01-01

Optical absorber coatings have been developed from carbon-based paints, metal blacks, or glassy carbon. However, such materials are not truly black and have poor absorption characteristics at longer wavelengths. The blackness of such coatings is important to increase the accuracy of calibration targets used in radiometric imaging spectrometers since blackbody cavities are prohibitively large in size. Such coatings are also useful potentially for thermal detectors, where a broadband absorber is desired. Au-black has been a commonly used broadband optical absorber, but it is very fragile and can easily be damaged by heat and mechanical vibration. An optically efficient, thermally rugged absorber could also be beneficial for thermal solar cell applications for energy harnessing, particularly in the 350-2,500 nm spectral window. It has been demonstrated that arrays of vertically oriented carbon nanotubes (CNTs), specifically multi-walled-carbon- nanotubes (MWCNTs), are an exceptional optical absorber over a broad range of wavelengths well into the infrared (IR). The reflectance of such arrays is 100x lower compared to conventional black materials, such as Au black in the spectral window of 350-2,500 nm. Total hemispherical measurements revealed a reflectance of approximately equal to 1.7% at lambda approximately equal to 1 micrometer, and at longer wavelengths into the infrared (IR), the specular reflectance was approximately equal to 2.4% at lambda approximately equal to 7 micrometers. The previously synthesized CNTs for optical absorber applications were formed using water-assisted thermal chemical vapor deposition (CVD), which yields CNT lengths in excess of 100's of microns. Vertical alignment, deemed to be a critical feature in enabling the high optical absorption from CNT arrays, occurs primarily via the crowding effect with thermal CVD synthesized CNTs, which is generally not effective in aligning CNTs with lengths less than 10 m. Here it has been shown that the electric field inherent in a plasma yields vertically aligned CNTs at small length scales (less than 10 m), which still exhibit broadband, and high-efficiency optical absorption characteristics from the ultraviolet (UV) to IR. A thin and yet highly absorbing coating is extremely valuable for detector applications for radiometry in order to enhance sensitivity. A plasma-based process also increases the potential of forming the optical absorbers at lower synthesis temperatures in the future, increasing the prospects of integrating the absorbers with flexible substrates for low-cost solar cell applications, for example.

Structure of Protoplanetary Environments

NASA Technical Reports Server (NTRS)

Simon, Michal

2000-01-01

Our research focused on the structure and composition of the disks in the T Tau and Haro 6-10 multiple star systems and on the nature of the 'infrared companions' that these systems contain. This work has resulted in two papers, one on T Tau, presently under review at the Astrophysical Journal, and the other, on Haro 6-10, about to be submitted to Astronomy and Astrophysics. In the paper 'Evidence for Extinction and Accretion Variability in T Tau S' by Tracy L. Beck, L. Prato, and M. Simon, we present angularly resolved spectra of T Tau N (the visible star) and T Tau S (the infrared companion, IRC) in the three micrometer water ice-feature and the K-band. Most of the water ice absorption lies along the line of sight to T Tau S, confirming it is seen through stronger obscuration. A decrease in the ice-band absorption toward T Tau S between 12/98 and 1/00, significant, at the two-sigma level, was associated with an increase in its near IR flux. Bracket gamma emission is detected in T Tau N and S, and H2 (2.12 micrometer) emission only toward T Tau S, consistent with previous studies of IRCs. Our results suggest that the near IR variability of T Tau S is probably caused by both variations in accretion rate and extinction. Our paper on Haro 6-10, 'The Near IR and Ice Band Variability of Haro, 6-10' by Ch. Leinert, T.L. Beck, S. Ligori, M. Simon, J. Woitas, and R.R. Howell, represents a fusion of originally independent efforts at the Max Planck Institut fur Astronomie (Heidelberg) and Stony Brook. Our combined observations demonstrate that both Haro 6-10 S (the visible star) and Haro 6-10 N (the IRC) vary significantly in near IR flux on time scales as short as a month. The substantial decrease of Haro 6-10 S in the last four years carries the photometric signature of increased extinction. However, a comparable K-band flux increase of the IRC is associated with a dimming at H so cannot be explained by lower extinction. Absorption in the 3.1 micrometer ice band was always greater toward the IRC during our observations indicating a large amount of obscuring material. We detect variable extinction in the ice-band toward Haro 6-10 S and the IRC, significant at the 3.5-sigma and 2.0-sigma levels, respectively.

Formation and infrared absorption of protonated naphthalenes (1-C10H9+ and 2-C10H9+) and their neutral counterparts in solid para-hydrogen.

PubMed

Bahou, Mohammed; Wu, Yu-Jong; Lee, Yuan-Pern

2013-02-14

Protonated naphthalene (C(10)H(9)(+)) and its neutral counterparts (hydronaphthyl radicals, C(10)H(9)) are important intermediates in the reactions of aromatic compounds and in understanding the unidentified infrared (IR) emissions from interstellar media. We report the IR spectra of 1-C(10)H(9)(+), 2-C(10)H(9)(+), 1-C(10)H(9), and 2-C(10)H(9) trapped in solid para-hydrogen (p-H(2)); the latter three are new. These species were produced upon electron bombardment of a mixture of naphthalene (C(10)H(8)) and p-H(2) during matrix deposition. The intensities of IR features of 1-C(10)H(9)(+) decreased after the matrix was maintained in darkness for 19 h, whereas those of 1-C(10)H(9) and 2-C(10)H(9) increased. Irradiation of this matrix sample with light at 365 nm diminished lines of 1-C(10)H(9)(+) and 2-C(10)H(9) and enhanced lines of 1-C(10)H(9) and 2-C(10)H(9)(+); the latter species was unstable and converted to 1-C(10)H(9)(+) in less than 30 min and 2-C(10)H(9) was converted to 1-C(10)H(9) at 365 nm. Observed wavenumbers and relative intensities of these species agree satisfactorily with the anharmonic vibrational wavenumbers and IR intensities predicted with the B3PW91/6-311++G(2d,2p) method. Compared with spectra recorded previously with IR photodissociation of Ar-tagged C(10)H(9)(+) or IR multiphoton dissociation of C(10)H(9)(+), our method has the advantages of producing high-resolution IR spectra with a wide spectral coverage, true IR intensity and excellent ratio of signal to noise; both protonated species and their neutral counterparts are produced with little interference from other fragments. With these advantages, the IR spectra of 1-C(10)H(9)(+), 2-C(10)H(9)(+), 1-C(10)H(9), and 2-C(10)H(9) are here clearly characterized.

Spectroscopic (FT-IR, FT-Raman, UV absorption, 1H and 13C NMR) and theoretical (in B3LYP/6-311++G** level) studies on alkali metal salts of caffeic acid.

PubMed

Świsłocka, Renata

2013-01-01

The effect of some metals on the electronic system of benzoic and nicotinic acids has recently been investigated by IR, Raman and UV spectroscopy [1-3]. Benzoic and nicotinic acids are regarded model systems representing a wide group of aromatic ligands which are incorporated into enzymes. In this work the FT-IR (in solid state and in solution), FT-Raman, UV absorption and (1)H and (13)C NMR spectra of caffeic acid (3,4-dihydroxycinnamic acid) and its salts with lithium, sodium, potassium, rubidium and caesium were registered, assigned and analyzed. The effect of alkali metals on the electronic system of ligands was discussed. Studies of differences in the number and position of bands from the IR, Raman, UV absorption spectra and chemical shifts from NMR spectra allowed to conclude on the distribution of electronic charge in the molecules, the delocalization energy of π electrons and the reactivity of ligands in metal complexes. Optimized geometrical structures of studied compounds were calculated by B3LYP method using 6-311++G** basis set. Bond lengths, angles and dipole moments for the optimized structures of caffeic acid and lithium, sodium, potassium caffeinates were also calculated. The theoretical wavenumbers and intensities of IR spectra were obtained. The calculated parameters were compared to the experimental characteristics of investigated compounds. Microbial activity of studied compounds was tested against Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus and Proteus vulgaris. Copyright © 2012 Elsevier B.V. All rights reserved.

Integrated J- and H-band spectra of globular clusters in the LMC: implications for stellar population models and galaxy age dating

NASA Astrophysics Data System (ADS)

Lyubenova, M.; Kuntschner, H.; Rejkuba, M.; Silva, D. R.; Kissler-Patig, M.; Tacconi-Garman, L. E.

2012-07-01

Context. The rest-frame near-IR spectra of intermediate age (1-2 Gyr) stellar populations are dominated by carbon based absorption features offering a wealth of information. Yet, spectral libraries that include the near-IR wavelength range do not sample a sufficiently broad range of ages and metallicities to allow for accurate calibration of stellar population models and thus the interpretation of the observations. Aims: In this paper we investigate the integrated J- and H-band spectra of six intermediate age and old globular clusters in the Large Magellanic Cloud (LMC). Methods: The observations for six clusters were obtained with the SINFONI integral field spectrograph at the ESO VLT Yepun telescope, covering the J (1.09-1.41 μm) and H-band (1.43-1.86 μm) spectral range. The spectral resolution is 6.7 Å in J and 6.6 Å in H-band (FWHM). The observations were made in natural seeing, covering the central 24″ × 24″ of each cluster and in addition sampling the brightest eight red giant branch and asymptotic giant branch (AGB) star candidates within the clusters' tidal radii. Targeted clusters cover the ages of ~1.3 Gyr (NGC 1806, NGC 2162), 2 Gyr (NGC 2173) and ~13 Gyr (NGC 1754, NGC 2005, NGC 2019). Results.H-band C2 and K-band 12CO (2-0) feature strengths for the LMC globular clusters are compared to the models of Maraston (2005). C2 is reasonably well reproduced by the models at all ages, while 12CO (2-0) shows good agreement for older (age ≥ 2 Gyr) populations, but the younger (1.3 Gyr) globular clusters do not follow the models. We argue that this is due to the fact that the empirical calibration of the models relies on only a few Milky Way carbon star spectra, which show different 12CO (2-0) index strengths than the LMC stars. The C2 absorption feature strength correlates strongly with age. It is present essentially only in populations that have 1-2 Gyr old stars, while its value is consistent with zero for older populations. The distinct spectral energy distribution observed for the intermediate age globular clusters in the J- and H-bands agrees well with the model predictions of Maraston for the contribution from the thermally pulsing AGB phase. Conclusions: In this pilot project we present an empirical library of six LMC globular cluster integrated near-IR spectra that are useful for testing stellar population models in this wavelength regime. We show that the H-band C2 absorption feature and the J-, H-band spectral shape can be used as an age indicator for intermediate age stellar populations in integrated spectra of star clusters and galaxies. Based on observation collected at the ESO Paranal La Silla Observatory, Chile, Prog. ID 078.B-0205.Table 2 is available in electronic form at http://www.aanda.orgJ- and H-spectra are only available at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/543/A75

Infrared hyperspectral imaging for chemical vapour detection

NASA Astrophysics Data System (ADS)

Ruxton, K.; Robertson, G.; Miller, W.; Malcolm, G. P. A.; Maker, G. T.; Howle, C. R.

2012-10-01

Active hyperspectral imaging is a valuable tool in a wide range of applications. One such area is the detection and identification of chemicals, especially toxic chemical warfare agents, through analysis of the resulting absorption spectrum. This work presents a selection of results from a prototype midwave infrared (MWIR) hyperspectral imaging instrument that has successfully been used for compound detection at a range of standoff distances. Active hyperspectral imaging utilises a broadly tunable laser source to illuminate the scene with light at a range of wavelengths. While there are a number of illumination methods, the chosen configuration illuminates the scene by raster scanning the laser beam using a pair of galvanometric mirrors. The resulting backscattered light from the scene is collected by the same mirrors and focussed onto a suitable single-point detector, where the image is constructed pixel by pixel. The imaging instrument that was developed in this work is based around an IR optical parametric oscillator (OPO) source with broad tunability, operating in the 2.6 to 3.7 μm (MWIR) and 1.5 to 1.8 μm (shortwave IR, SWIR) spectral regions. The MWIR beam was primarily used as it addressed the fundamental absorption features of the target compounds compared to the overtone and combination bands in the SWIR region, which can be less intense by more than an order of magnitude. We show that a prototype NCI instrument was able to locate hydrocarbon materials at distances up to 15 metres.

Non-Destructive and Discriminating Identification of Illegal Drugs by Transient Absorption Spectroscopy in the Visible and Near-IR Wavelength Range

NASA Astrophysics Data System (ADS)

Sato, Chie; Furube, Akihiro; Katoh, Ryuzi; Nonaka, Hidehiko; Inoue, Hiroyuki

2008-11-01

We have tested the possibility of identifying illegal drugs by means of nanosecond transient absorption spectroscopy with a 10-ns UV-laser pulse for the excitation light and visible-to-near-IR light for the probe light. We measured the transient absorption spectra of acetonitrile solutions of d-methamphetamine, dl-3,4-methylenedioxymethamphetamine hydrochloride (MDMA), and dl-N-methyl-1-(1,3-benzodioxol-5-yl)-2-butanamine hydrochloride (MBDB), which are illegal drugs widely consumed in Japan. Transient absorption signals of these drugs were observed between 400 and 950 nm, a range in which they are transparent in the ground state. By analyzing the spectra in terms of exponential and Gaussian functions, we could identify the drugs and discriminate them from chemical substances having similar structures. We propose that transient absorption spectroscopy will be a useful, non-destructive method of inspecting for illegal drugs, especially when they are dissolved in liquids. Such a method may even be used for drugs packed in opaque materials if it is further extended to utilize intense femtosecond laser pulses.

Chemically Resolved Imaging of Biological Cells and Thin Films by Infrared Scanning Near-Field Optical Microscopy

PubMed Central

Cricenti, Antonio; Generosi, Renato; Luce, Marco; Perfetti, Paolo; Margaritondo, Giorgio; Talley, David; Sanghera, Jas S.; Aggarwal, Ishwar D.; Tolk, Norman H.; Congiu-Castellano, Agostina; Rizzo, Mark A.; Piston, David W.

2003-01-01

The infrared (IR) absorption of a biological system can potentially report on fundamentally important microchemical properties. For example, molecular IR profiles are known to change during increases in metabolic flux, protein phosphorylation, or proteolytic cleavage. However, practical implementation of intracellular IR imaging has been problematic because the diffraction limit of conventional infrared microscopy results in low spatial resolution. We have overcome this limitation by using an IR spectroscopic version of scanning near-field optical microscopy (SNOM), in conjunction with a tunable free-electron laser source. The results presented here clearly reveal different chemical constituents in thin films and biological cells. The space distribution of specific chemical species was obtained by taking SNOM images at IR wavelengths (λ) corresponding to stretch absorption bands of common biochemical bonds, such as the amide bond. In our SNOM implementation, this chemical sensitivity is combined with a lateral resolution of 0.1 μm (≈λ/70), well below the diffraction limit of standard infrared microscopy. The potential applications of this approach touch virtually every aspect of the life sciences and medical research, as well as problems in materials science, chemistry, physics, and environmental research. PMID:14507733

Discovery of a dual active galactic nucleus with ˜8 kpc separation

NASA Astrophysics Data System (ADS)

Ellison, Sara L.; Secrest, Nathan J.; Mendel, J. Trevor; Satyapal, Shobita; Simard, Luc

2017-09-01

Targeted searches for dual active galactic nuclei (AGNs), with separations 1-10 kpc, have yielded relatively few successes. A recent pilot survey by Satyapal et al. has demonstrated that mid-infrared (mid-IR) pre-selection has the potential to significantly improve the success rate for dual AGN confirmation in late stage galaxy mergers. In this Letter, we combine mid-IR selection with spatially resolved optical AGN diagnostics from the Mapping Nearby Galaxies at Apache Point Observatory survey to identify a candidate dual AGN in the late stage major galaxy merger SDSS J140737.17+442856.2 at z = 0.143. The nature of the dual AGN is confirmed with Chandra X-ray observations that identify two hard X-ray point sources with intrinsic (corrected for absorption) 2-10 keV luminosities of 4 × 1041 and 3.5 × 1043 erg s-1 separated by 8.3 kpc. The neutral hydrogen absorption (˜1022 cm-2) towards the two AGNs is lower than in duals selected solely on their mid-IR colours, indicating that strategies that combine optical and mid-IR diagnostics may complement techniques that identify the highly obscured dual phase, such as at high X-ray energies or mid-IR only.

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.

Absorption coefficients and frequency shifts measurement in the spectral range of 1071.88-1084.62 cm-1 vs. pressure for chlorodifluoromethane (CHClF2) using tunable CW CO2 laser

NASA Astrophysics Data System (ADS)

Al-Hawat, Sharif

2013-02-01

Infrared (IR) absorption in the spectral range of (1071.88-1084.62 cm-1) vs. pressure in chlorodifluoromethane (CFC-22, F-22, and CHClF2) was studied using a tunable continuous wave (CW) CO2 laser radiation on 9R branch lines with a maximum output power of about 2.12 W, provided with an absorber cell located outside the laser cavity. The absorption coefficients were determined vs. the gas pressure between 0.2 mbar and 170 mbar at lines from 9R branch for CFC-22. The frequency shifts of the absorption lines of CFC-22 in relative to the central frequencies of laser lines were calculated vs. the pressure on the basis of these absorption coefficients. The chosen lines were selected according to IR spectrum of the studied gas given by HITRAN cross section database. So the absorption was achieved for CFC-22 at the spectral lines of 9R branch situated from 9R (10) to 9R (30) emitted by a tunable CW CO2 laser. The absorption cross sections of CFC-22 determined in this work were compared with the relevant data given by HITRAN cross section database and a reasonable agreement was observed.

Diode laser absorption sensors for gas-dynamic and combustion flows

NASA Technical Reports Server (NTRS)

Allen, M. G.

1998-01-01

Recent advances in room-temperature, near-IR and visible diode laser sources for tele-communication, high-speed computer networks, and optical data storage applications are enabling a new generation of gas-dynamic and combustion-flow sensors based on laser absorption spectroscopy. In addition to conventional species concentration and density measurements, spectroscopic techniques for temperature, velocity, pressure and mass flux have been demonstrated in laboratory, industrial and technical flows. Combined with fibreoptic distribution networks and ultrasensitive detection strategies, compact and portable sensors are now appearing for a variety of applications. In many cases, the superior spectroscopic quality of the new laser sources compared with earlier cryogenic, mid-IR devices is allowing increased sensitivity of trace species measurements, high-precision spectroscopy of major gas constituents, and stable, autonomous measurement systems. The purpose of this article is to review recent progress in this field and suggest likely directions for future research and development. The various laser-source technologies are briefly reviewed as they relate to sensor applications. Basic theory for laser absorption measurements of gas-dynamic properties is reviewed and special detection strategies for the weak near-IR and visible absorption spectra are described. Typical sensor configurations are described and compared for various application scenarios, ranging from laboratory research to automated field and airborne packages. Recent applications of gas-dynamic sensors for air flows and fluxes of trace atmospheric species are presented. Applications of gas-dynamic and combustion sensors to research and development of high-speed flows aeropropulsion engines, and combustion emissions monitoring are presented in detail, along with emerging flow control systems based on these new sensors. Finally, technology in nonlinear frequency conversion, UV laser materials, room-temperature mid-IR materials and broadly tunable multisection devices is reviewed to suggest new sensor possibilities.

A comparative study of CO adsorption on tetrahexahedral Pt nanocrystals and interrelated Pt single crystal electrodes by using cyclic voltammetry and in situ FTIR spectroscopy.

PubMed

Liu, Hai-Xia; Tian, Na; Ye, Jin-Yu; Lu, Bang-An; Ren, Jie; Huangfu, Zhi-Chao; Zhou, Zhi-You; Sun, Shi-Gang

2014-01-01

This study focuses on CO adsorption at tetrahexahedral Pt nanocrystals (THH Pt NCs) by using cyclic voltammetry and in situ FTIR spectroscopy. Since the electrochemically prepared THH Pt NCs in this study are enclosed by {730} facets which could be considered by a subfacet configuration of 2{210} + {310}, we have also studied CO adsorption on the interrelated Pt(310) and Pt(210) single crystal electrodes as a comparison. Cyclic voltammetry results demonstrated that CO adsorbs dominantly on the (100) sites of THH Pt NCs at low CO coverage (θ(CO)≤ 0.135), while on both (100) and (110) sites at higher CO coverage. On ordered Pt(310) and Pt(210), i.e. they were flame annealed and then cooled in H(2) + Ar, CO adsorption also illustrates relative priority on (100) sites at low CO coverage; while at high CO coverage or on oxygen-disordered Pt(310) and Pt(210) when they were cooled in air after flame annealing, the adsorption of CO presents a weak preference on (100) sites of Pt(310) and even no preference at all on (100) sites of Pt(210). In situ FTIR spectroscopic studies illustrated that CO adsorption on THH Pt NCs yields anomalous infrared effects (AIREs), which are depicted by the Fano-like IR feature on a dense distribution (60 μm(-2)) and the enhancement of abnormal IR absorption on a sparse distribution (22 μm(-2)) of THH Pt NCs on glassy carbon substrate. Systematic investigation of CO coverage dependence of IR features revealed that, on THH Pt NCs, the IR band center (ν(COL)) of linearly bonded CO (COL) is rapidly shifted to higher wavenumbers along with the increase of CO coverage to 0.184, yielding a fast linear increase rate with a high slope (dν(COL)/dθ(IR)(CO) = 219 cm(-1)); when θ > 0.184, the increase of ν(COL) with θCO slows down and deviates drastically from linearity. In contrast, the ν(COL) on the ordered Pt(310) electrode maintains a linear increase with θ(IR)(CO) for the whole range of θ(IR)(CO) variation, and gives a much smaller increase rate of slope 74.3 cm(-1). The significant differences in CO adsorption behavior on THH Pt NCs and on interrelated Pt single crystal planes demonstrated clearly the unique properties of nanoparticles enclosed by high-index facets.

Identification of Uranium Minerals in Natural U-Bearing Rocks Using Infrared Reflectance Spectroscopy.

PubMed

Beiswenger, Toya N; Gallagher, Neal B; Myers, Tanya L; Szecsody, James E; Tonkyn, Russell G; Su, Yin-Fong; Sweet, Lucas E; Lewallen, Tricia A; Johnson, Timothy J

2018-02-01

The identification of minerals, including uranium-bearing species, is often a labor-intensive process using X-ray diffraction (XRD), fluorescence, or other solid-phase or wet chemical techniques. While handheld XRD and fluorescence instruments can aid in field applications, handheld infrared (IR) reflectance spectrometers can now also be used in industrial or field environments, with rapid, nondestructive identification possible via analysis of the solid's reflectance spectrum providing information not found in other techniques. In this paper, we report the use of laboratory methods that measure the IR hemispherical reflectance of solids using an integrating sphere and have applied it to the identification of mineral mixtures (i.e., rocks), with widely varying percentages of uranium mineral content. We then apply classical least squares (CLS) and multivariate curve resolution (MCR) methods to better discriminate the minerals (along with two pure uranium chemicals U 3 O 8 and UO 2 ) against many common natural and anthropogenic background materials (e.g., silica sand, asphalt, calcite, K-feldspar) with good success. Ground truth as to mineral content was attained primarily by XRD. Identification is facile and specific, both for samples that are pure or are partially composed of uranium (e.g., boltwoodite, tyuyamunite, etc.) or non-uranium minerals. The characteristic IR bands generate unique (or class-specific) bands, typically arising from similar chemical moieties or functional groups in the minerals: uranyls, phosphates, silicates, etc. In some cases, the chemical groups that provide spectral discrimination in the longwave IR reflectance by generating upward-going (reststrahlen) bands can provide discrimination in the midwave and shortwave IR via downward-going absorption features, i.e., weaker overtone or combination bands arising from the same chemical moieties.

Spectroscopic Properties of B2O3-PbO-Nd2O3 Glasses

NASA Astrophysics Data System (ADS)

Simon, V.; Ardelean, I.; Milea, I.; Peteanu, M.; Simon, S.

Samples belonging to xNd2O3(100-x) [2B2O3·PbO] glass system, with 0≤ x≤ 40 mol%, are investigated by IR and UV-VIS spectroscopies in order to obtain evidence for the influence of Nd2O3 on the local order from 2B2O3·PbO glass matrix. Besides the IR absorption bands characteristic to lead and boron arrangements, typical absorption lines of Nd3+ ions around 4000 cm-1 and 6000 cm-1 are recorded. The 6000 cm-1 band appears only for the samples with x≥25 mol% Nd2O3. The split of some UV-VIS absorption bands arising from transitions of neodymium ions in doublet lines as well as the shift of the absorption bands as the Nd2O3 content increases denote the influence of the lead-borate matrix on the radiative transitions of the lanthanide ion.

Fab MOR03268 triggers absorption shift of a diagnostic dye via packaging in a solvent-shielded Fab dimer interface.

PubMed

Hillig, Roman C; Urlinger, Stefanie; Fanghänel, Jörg; Brocks, Bodo; Haenel, Cornelia; Stark, Yvonne; Sülzle, Detlev; Svergun, Dmitri I; Baesler, Siegfried; Malawski, Guido; Moosmayer, Dieter; Menrad, Andreas; Schirner, Michael; Licha, Kai

2008-03-14

Molecular interactions between near-IR fluorescent probes and specific antibodies may be exploited to generate novel smart probes for diagnostic imaging. Using a new phage display technology, we developed such antibody Fab fragments with subnanomolar binding affinity for tetrasulfocyanine, a near-IR in vivo imaging agent. Unexpectedly, some Fabs induced redshifts of the dye absorption peak of up to 44 nm. This is the largest shift reported for a biological system so far. Crystal structure determination and absorption spectroscopy in the crystal in combination with microcalorimetry and small-angle X-ray scattering in solution revealed that the redshift is triggered by formation of a Fab dimer, with tetrasulfocyanine being buried in a fully closed protein cavity within the dimer interface. The derived principle of shifting the absorption peak of a symmetric dye via packaging within a Fab dimer interface may be transferred to other diagnostic fluorophores, opening the way towards smart imaging probes that change their wavelength upon interaction with an antibody.

The Hydrogen Content of a Rocky Earth-Size Exoplanet

NASA Astrophysics Data System (ADS)

Berta-Thompson, Zach

2016-10-01

The composition of a terrestrial planet's atmosphere results from a complex interplay of accretion, escape, and outgassing. We have little data on how such processes proceed for planets around stars other than our Sun. The warm, Earth-size planet GJ1132b transits a late M dwarf and offers a unique opportunity for studying the atmospheric composition of a rocky exoplanet. Thanks to this transiting planet's proximity (12pc) and large transit depth (0.3%), possible scenarios for GJ1132b's atmospheric transmission spectrum can be observed with the Hubble Space Telescope. Here, we propose to use WFC3/IR to observe five transits of GJ1132b, to search for absorption features from a cloud-free, hydrogen-rich atmosphere. Such an atmosphere could potentially arise from late outgassing of volatiles from the planetary interior. The detection of molecular absorption in GJ1132b's atmosphere is an important step toward the long-term goal of characterizing the atmospheres of cooler habitable planets, and GJ1132b is a favorable target for JWST observations. The results of this Hubble/WFC3 investigation would inform the optimal strategy to observe GJ1132b with JWST. If we detect deep absorption features with WFC3, JWST should observe GJ1132b across its entire wavelength range. If we do not, JWST may first need to focus more intensely on smaller individual wavelength windows. This planet provides the first chance for WFC3 to study the atmosphere of an exoplanet that almost resembles terrestrial worlds in our own Solar System.

Characterizing the thermal distributions of warm molecular hydrogen in protoplanetary disks

NASA Astrophysics Data System (ADS)

Hoadley, Keri; France, Kevin

2016-01-01

Probing the surviving molecular gas within the inner regions of protoplanetary disks (PPDs) around T Tauri stars (1 - 10 Myr) provides insight into the conditions in which planet formation and migration occurs while the gas disk is still present. Recent studies done by Hoadley et al. 2015 and Banzatti & Pontipoddan 2015 suggest that gas in the inner disks of PPDs appear to "respond" to the loss of small dust grains with evolving PPD stage, and IR-CO emission may either be thermally or photo-excited by stellar UV radiation, depending on PPD evolutionary stage. Because far-UV H2 emission lines are dominantly photo-excited by stellar HI-Lyman alpha photons, we observe H2 absorption features against the stellar Lyman alpha wings in a large sample of PPDs at various evolutionary stages. We aim to characterize whether the inner disk H2 environment is in thermal equilibrium at various stages of PPD evolution. We use a sophisticated first-principles approach to fitting multiple absorption features along the red- and blue-wings of the observed stellar Lyman alpha profiles to extract column density estimates of H2 along the line of sight to the target. We find that the high kinetic energy H2 observed in absorption against the LyA wing may be described as a part of the thermal distribution with high kinetic temperature - a potential indication of an inner disk molecular hazy "envelope" around the cooler bulk disk. Ongoing research may help determine the state of the gas and whether it evolves with disk evolutionary stage.

The Discovery of a Low-Mass Binary Companion to HD130948

NASA Astrophysics Data System (ADS)

Potter, D. E.; Cushing, M. C.; Neuhauser, R.

2003-10-01

We report the discovery of a low mass binary companion to the nearby (17.9 pc) main sequence star HD130948 (HR5534, HIP 72567) using the Hokupa'a adaptive optics instrument mounted on the Gemini North 8 meter telescope. Both companions have the same common proper motion as the primary star as seen over a 4 month baseline. The JHK' photometry of the companions, when placed on a near-IR color-magnitude diagram and compared with theoretical models places them at the bottom of the M-dwarf sequence. Preliminary near IR spectra have been obtained with SpeX mounted on the NASA IRTF 3 meter telescope are consistent with the photometric results and show carbon monoxide bandheads and water absorption features indicative of an early L-late M spectral type. The X-ray activity and Lithium abundance of the primary star indicate that the system is probably less than 1 Gyr old. Assuming a young age, these objects are less than 80 Mjupiter. With further astrometric observations carried out over an estimated orbital period of 10-20 years, a dynamical mass will be obtained.

The anharmonic quartic force field infrared spectra of three polycyclic aromatic hydrocarbons: Naphthalene, anthracene, and tetracene.

PubMed

Mackie, Cameron J; Candian, Alessandra; Huang, Xinchuan; Maltseva, Elena; Petrignani, Annemieke; Oomens, Jos; Buma, Wybren Jan; Lee, Timothy J; Tielens, Alexander G G M

2015-12-14

Current efforts to characterize and study interstellar polycyclic aromatic hydrocarbons (PAHs) rely heavily on theoretically predicted infrared (IR) spectra. Generally, such studies use the scaled harmonic frequencies for band positions and double harmonic approximation for intensities of species, and then compare these calculated spectra with experimental spectra obtained under matrix isolation conditions. High-resolution gas-phase experimental spectroscopic studies have recently revealed that the double harmonic approximation is not sufficient for reliable spectra prediction. In this paper, we present the anharmonic theoretical spectra of three PAHs: naphthalene, anthracene, and tetracene, computed with a locally modified version of the SPECTRO program using Cartesian derivatives transformed from Gaussian 09 normal coordinate force constants. Proper treatments of Fermi resonances lead to an impressive improvement on the agreement between the observed and theoretical spectra, especially in the C-H stretching region. All major IR absorption features in the full-scale matrix-isolated spectra, the high-temperature gas-phase spectra, and the most recent high-resolution gas-phase spectra obtained under supersonically cooled molecular beam conditions in the CH-stretching region are assigned.

The anharmonic quartic force field infrared spectra of three polycyclic aromatic hydrocarbons: Naphthalene, anthracene, and tetracene

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mackie, Cameron J., E-mail: mackie@strw.leidenuniv.nl; Candian, Alessandra; Tielens, Alexander G. G. M.

2015-12-14

Current efforts to characterize and study interstellar polycyclic aromatic hydrocarbons (PAHs) rely heavily on theoretically predicted infrared (IR) spectra. Generally, such studies use the scaled harmonic frequencies for band positions and double harmonic approximation for intensities of species, and then compare these calculated spectra with experimental spectra obtained under matrix isolation conditions. High-resolution gas-phase experimental spectroscopic studies have recently revealed that the double harmonic approximation is not sufficient for reliable spectra prediction. In this paper, we present the anharmonic theoretical spectra of three PAHs: naphthalene, anthracene, and tetracene, computed with a locally modified version of the SPECTRO program using Cartesianmore » derivatives transformed from Gaussian 09 normal coordinate force constants. Proper treatments of Fermi resonances lead to an impressive improvement on the agreement between the observed and theoretical spectra, especially in the C–H stretching region. All major IR absorption features in the full-scale matrix-isolated spectra, the high-temperature gas-phase spectra, and the most recent high-resolution gas-phase spectra obtained under supersonically cooled molecular beam conditions in the CH-stretching region are assigned.« less

Recent progress of quantum cascade laser research from 3 to 12  μm at the Center for Quantum Devices [Invited].

PubMed

Razeghi, Manijeh; Zhou, Wenjia; Slivken, Steven; Lu, Quan-Yong; Wu, Donghai; McClintock, Ryan

2017-11-01

The quantum cascade laser (QCL) is becoming the leading laser source in the mid-infrared (mid-IR) range, which contains two atmospheric transmission windows and many molecular fingerprint absorption features. Since its first demonstration in 1994, the QCL has undergone tremendous development in terms of the output power, wall plug efficiency, wavelength coverage, tunability and beam quality. At the Center for Quantum Devices, we have demonstrated high-power continuous wave operation of QCLs covering a wide wavelength range from 3 to 12 μm, with power output up to 5.1 W at room temperature. Recent research has resulted in power scaling in pulsed mode with up to 203 W output, electrically tunable QCLs based on monolithic sampled grating design, heterogeneous QCLs with a broad spectral gain, broadly tunable on-chip beam-combined QCLs, QCL-based mid-IR frequency combs, and fundamental mode surface emitting quantum cascade ring lasers. The developed QCLs will be the basis for a number of next-generation spectroscopy and sensing systems.

Multispectral near-IR reflectance imaging of simulated early occlusal lesions: Variation of lesion contrast with lesion depth and severity

PubMed Central

Simon, Jacob C.; Chan, Kenneth H.; Darling, Cynthia L.; Fried, Daniel

2014-01-01

Background and Objectives Early demineralization appears with high contrast at near-IR wavelengths due to a ten to twenty fold difference in the magnitude of light scattering between sound and demineralized enamel. Water absorption in the near-IR has a significant effect on the lesion contrast and the highest contrast has been measured in spectral regions with higher water absorption. The purpose of this study was to determine how the lesion contrast changes with lesion severity and depth for different spectral regions in the near-IR and compare that range of contrast with visible reflectance and fluorescence. Materials and Methods Forty-four human molars were used in this in vitro study. Teeth were painted with an acid-resistant varnish, leaving a 4×4 mm window on the occlusal surface of each tooth exposed for demineralization. Artificial lesions were produced in the unprotected windows after 12–48 hr exposure to a demineralizing solution at pH-4.5. Near-IR reflectance images were acquired over several near-IR spectral distributions, visible light reflectance, and fluorescence with 405-nm excitation and detection at wavelengths greater than 500-nm. Crossed polarizers were used for reflectance measurements to reduce interference from specular reflectance. Cross polarization optical coherence tomography (CP-OCT) was used to non-destructively assess the depth and severity of demineralization in each sample window. Matching two dimensional CP-OCT images of the lesion depth and integrated reflectivity were compared with the reflectance and fluorescence images to determine how accurately the variation in the lesion contrast represents the variation in the lesion severity. Results Artificial lesions appear more uniform on tooth surfaces exposed to an acid challenge at visible wavelengths than they do in the near-IR. Measurements of the lesion depth and severity using CP-OCT show that the lesion severity varies markedly across the sample windows and that the lesion contrast in the visible does not accurately reflect the large variation in the lesion severity. Reflectance measurements at certain near-IR wavelengths more accurately reflect variation in the depth and severity of the lesions. Conclusion The results of the study suggest that near-IR reflectance measurements at longer wavelengths coincident with higher water absorption are better suited for imaging early caries lesions. PMID:24375543

Early Salt Stress Effects on the Changes in Chemical Composition in Leaves of Ice Plant and Arabidopsis. A Fourier Transform Infrared Spectroscopy Study1

PubMed Central

Yang, Jyisy; Yen, Hungchen E.

2002-01-01

A technique based on Fourier transform infrared (FT-IR) spectrometry was developed to detect the corresponding changes in chemical composition associated with the rapid changes in sodium and water content in 200 mm NaCl-stressed halophyte ice plants (Mesembryanthemum crystallinum). The changes in glycophyte Arabidopsis stressed with 50 mm NaCl were also examined for comparison. The obtained IR spectra were further processed by deconvolution and curve fitting to examine the chemical nature of the responding sources in the leaves. Using three stages of ice plant leaves, absorption bands corresponding to carbohydrates, cell wall pectin, and proteins were identified, with distinct IR spectra representing each developmental stage. Within 48 h of mild salt stress, the absorption band intensities in the fingerprint region increased continuously in both plants, suggesting that the carbon assimilation was not affected at the early stage of stress. The intensities of ester and amide I absorption bands decreased slightly in Arabidopsis but increased in ice plant, suggesting that the cell expansion and protein synthesis ceased in Arabidopsis but continued in ice plant. In both plants, the shift in amide I absorption band was observed hourly after salt stress, indicating a rapid conformational change of cellular proteins. Analyses of the ratio between major and minor amide I absorption band revealed that ice plant was able to maintain a higher-ordered form of proteins under stress. Furthermore, the changes in protein conformation showed a positive correlation to the leaf sodium contents in ice plant, but not in Arabidopsis. PMID:12376666

On formation mechanism of Pd-Ir bimetallic nanoparticles through thermal decomposition of [Pd(NH3)4][IrCl6

NASA Astrophysics Data System (ADS)

Asanova, Tatyana I.; Asanov, Igor P.; Kim, Min-Gyu; Gerasimov, Evgeny Yu.; Zadesenets, Andrey V.; Plyusnin, Pavel E.; Korenev, Sergey V.

2013-10-01

The formation mechanism of Pd-Ir nanoparticles during thermal decomposition of double complex salt [Pd(NH3)4][IrCl6] has been studied by in situ X-ray absorption (XAFS) and photoelectron (XPS) spectroscopies. The changes in the structure of the Pd and Ir closest to the surroundings and chemical states of Pd, Ir, Cl, and N atoms were traced in the range from room temperature to 420 °C in inert atmosphere. It was established that the thermal decomposition process is carried out in 5 steps. The Pd-Ir nanoparticles are formed in pyramidal/rounded Pd-rich (10-200 nm) and dendrite Ir-rich (10-50 nm) solid solutions. A d charge depletion at Ir site and a gain at Pd, as well as the intra-atomic charge redistribution between the outer d and s and p electrons of both Ir and Pd in Pd-Ir nanoparticles, were found to occur.

PECASE: Multi-Spectral Photon Detection in Polymer/Nanoparticle Composites-Toward IR Photodectors and Solar Cells Applicable to Unmanned Vehicles

DTIC Science & Technology

2016-03-31

in Polymer/Nanoparticle Composites-Toward IR Photodectors and Solar Cells Applicable to Sb. GRANT NUMBER Unmanned Vehicles N00014-1 0-1-0481 Sc...photodetectors and solar cells deposited by RIR-MAPLE, and developing a simulation tool for optoelectronic device performance that accounts for RIR...MAPLE film properties. 1S. SUBJECT TERMS Hybrid nanocomposites, MAPLE, RIR-MAPLE, intraband absorption, mid-IR photodetectors, organic solar cells

Ytterbium-porphyrins as a new class of the luminescent labels

NASA Astrophysics Data System (ADS)

Tsvirko, M.; Korovin, Yu; Rusakova, N.

2007-08-01

New complexes of ytterbium with asymmetric porphyrins containing substituents in β-positions and hydrophobic meso-(monophenyl-p-oxypropyl)triphenylporphyrin (OPP) were obtained and characterized by elemental analysis, IR, UV-Vis absorption and luminescence spectroscopy. Electronic absorption, luminescence and luminescence excitation spectra of these complexes were studied at 295 K in DMF solutions and in the water-lecithin medium. The 4f-luminescence of ytterbium-porphyrins in the near infrared (IR) spectral region (λmax = 980 nm) is observed under excitation in Soret band (400-430 nm). The effect of substituent in porphyrin macroring on the 4f-luminescent properties was also investigated. The conjugates of these compounds with protein molecules - bovine serum albumin (BSA) were investigated as well. These compounds are interesting at the initial stage of diagnostics of tumor tissues as IR-luminescent probes due to their spectral-luminescent characteristics and some biochemical properties.

Insulation Resistance and Leakage Currents in Low-Voltage Ceramic Capacitors with Cracks

NASA Technical Reports Server (NTRS)

Teverovsky, Alexander A.

2014-01-01

Measurement of insulation resistance (IR) in multilayer ceramic capacitors (MLCCs) is considered a screening technique that ensures the dielectric is defect-free. This work analyzes the effectiveness of this technique for revealing cracks in ceramic capacitors. It is shown that absorption currents prevail over the intrinsic leakage currents during standard IR measurements at room temperature. Absorption currents, and consequently IR, have a weak temperature dependence, increase linearly with voltage (before saturation), and are not sensitive to the presence of mechanical defects. In contrary, intrinsic leakage currents increase super-linearly with voltage and exponentially with temperature (activation energy is in the range from 0.6 eV to 1.1 eV). Leakage currents associated with the presence of cracks have a weaker dependence on temperature and voltage compared to the intrinsic leakage currents. For this reason, intrinsic leakage currents prevail at high temperatures and voltages, thus masking the presence of defects.

Exchange field effect in the crystal-field ground state of Ce M Al 4 Si 2

DOE PAGES

Chen, K.; Strigari, F.; Sundermann, M.; ...

2016-09-06

The crystal-field ground-state wave functions of the tetragonal, magnetically ordering Kondo lattice materials CeMAl 4Si 2 (M = Rh, Ir, and Pt) are determined in this paper with low-temperature linearly polarized soft-x-ray absorption spectroscopy, and estimates for the crystal-field splittings are given from the temperature evolution of the linear dichroism. Values for the dominant exchange field in the magnetically ordered phases can be obtained from fitting the influence of magnetic order on the linear dichroism. The direction of the required exchange field is || c for the antiferromagnetic Rh and Ir compounds, with the corresponding strength of the order ofmore » λ ex ≈ 6 meV (65 K). Finally and furthermore, the presence of Kondo screening in the Rh and Ir compound is demonstrated on the basis of the absorption due to f 0 in the initial state.« less

Insulation Resistance and Leakage Currents in Low-Voltage Ceramic Capacitors with Cracks

NASA Technical Reports Server (NTRS)

Teverovsky, Alexander A.

2016-01-01

Measurement of insulation resistance (IR) in multilayer ceramic capacitors (MLCCs) is considered a screening technique that ensures the dielectric is defect-free. This work analyzes the effectiveness of this technique for revealing cracks in ceramic capacitors. It is shown that absorption currents prevail over the intrinsic leakage currents during standard IR measurements at room temperature. Absorption currents, and consequently IR, have a weak temperature dependence, increase linearly with voltage (before saturation), and are not sensitive to the presence of mechanical defects. In contrary, intrinsic leakage currents increase super-linearly with voltage and exponentially with temperature (activation energy is in the range from 0.6 eV to 1.1 eV). Leakage currents associated with the presence of cracks have a weaker dependence on temperature and voltage compared to the intrinsic leakage currents. For this reason, intrinsic leakage currents prevail at high temperatures and voltages, thus masking the presence of defects.

Simple model of a photoacoustic system as a CR circuit

NASA Astrophysics Data System (ADS)

Fukuhara, Akiko; Kaneko, Fumitoshi; Ogawa, Naohisa

2012-05-01

We introduce the photoacoustic educational system (PAES), by which we can identify which gas causes the greenhouse effect in a classroom (Kaneko et al 2010 J. Chem. Educ. 87 202-4). PAES is an experimental system in which a pulse of infrared (IR) is absorbed into gas as internal energy, an oscillation of pressure (sound) appears, and then we can measure the absorptance of IR by the strength of sound. In this paper, we construct a simple mathematical model for PAES which is equivalent to the CR circuit. The energy absorption of an IR pulse into gas corresponds to the charge of a condenser and the heat diffusion to the outside corresponds to the energy dissipation by electric resistance. We analyse the experimental results by using this simple model, and check its validity. Although the model is simple, it explains phenomena occurring in PAES and can be a good educational resource.

Mid-infrared study of stones from the Sutter's Mill meteorite

NASA Astrophysics Data System (ADS)

Nuevo, Michel; Sandford, Scott A.; Flynn, George J.; Wirick, Susan

2014-11-01

The Sutter's Mill meteorite fell in northern California on April 22, 2012. Several fragments of the meteorite were recovered, some of them shortly after the fall, others several days later after a heavy rainstorm. In this work, we analyzed several samples of four fragments―SM2, SM12, SM20, and SM30―from the Sutter's Mill meteorite with two infrared (IR) microscopes operating in the 4000-650 cm-1 (2.5-15.4 μm) range. Spectra show absorption features associated with minerals such as olivines, phyllosilicates, carbonates, and possibly pyroxenes, as well as organics. Spectra of specific minerals vary from one particle to another within a given stone, and even within a single particle, indicating a nonuniform mineral composition. Infrared features associated with aliphatic CH2 and CH3 groups associated with organics are also seen in several spectra. However, the presence of organics in the samples studied is not clear because these features overlap with carbonate overtone bands. Finally, other samples collected within days after the rainstorm show evidence for bacterial terrestrial contamination, which indicates how quickly meteorites can be contaminated on such small scales.

Diffusivity of the interstitial hydrogen shallow donor in In2O3

NASA Astrophysics Data System (ADS)

Qin, Ying; Weiser, Philip; Villalta, Karla; Stavola, Michael; Fowler, W. Beall; Biaggio, Ivan; Boatner, Lynn

2018-04-01

Hydrogen has been found to be an n-type dopant in In2O3 that gives rise to unintentional conductivity. An infrared (IR) absorption line observed at 3306 cm-1 has been assigned to the Hi+ center. Two types of experiments have been performed to determine the diffusivity of Hi+ in In2O3 from its IR absorption spectra. (i) At temperatures near 700 K, the O-H line at 3306 cm-1 has been used to determine the diffusivity of Hi+ from its in-diffusion and out-diffusion behaviors. (ii) At temperatures near 160 K, stress has been used to produce a preferential alignment of the Hi+ center that has been detected in IR absorption experiments made with polarized light. With the help of theory, the kinetics with which a stress-induced alignment can be produced yield the time constant for a single jump of the Hi+ center and also the diffusivity of Hi+ near 160 K. The combination of the diffusivity of Hi+ found near 700 K by mass-transport measurements and that found near 160 K from the time constant for a single Hi+ jump determines the diffusivity for Hi+ over eleven decades!

Acceptors in bulk and nanoscale ZnO

NASA Astrophysics Data System (ADS)

McCluskey, M. D.

2012-02-01

Zinc oxide (ZnO) is a semiconductor that emits bright UV light, with little wasted heat. This intrinsic feature makes it a promising material for energy-efficient white lighting, nano-lasers, and other optical applications. For devices to be competitive, however, it is necessary to develop reliable p-type doping. Although substitutional nitrogen has been considered as a potential p-type dopant for ZnO, theoretical and experimental work indicates that nitrogen is a deep acceptor and will not lead to p-type conductivity. This talk will highlight recent experiments on ZnO:N at low temperatures. A red/near-IR photoluminescence (PL) band is correlated with the presence of deep nitrogen acceptors. PL excitation (PLE) measurements show an absorption threshold of 2.26 eV, in good agreement with theory. Magnetic resonance experiments provide further evidence for this assignment. The results of these studies seem to rule out group-V elements as shallow acceptors in ZnO, contradicting numerous reports in the literature. If these acceptors do not work as advertised, is there a viable alternative? Optical studies on ZnO nanocrystals show some intriguing leads. At liquid-helium temperatures, a series of sharp IR absorption peaks arise from an unknown acceptor impurity. The data are consistent with a hydrogenic acceptor 0.46 eV above the valence band edge. While this binding energy is still too deep for many practical applications, it represents a significant improvement over the ˜ 1.3 eV binding energy for nitrogen acceptors. Nanocrystals present another twist. Due to their high surface-to-volume ratio, surface states are especially important. Specifically, electron-hole recombination at the surface give rises to a red luminescence band. From our PL and IR experiments, we have developed a ``unified'' model that attempts to explain acceptor and surface states in ZnO nanocrystals. This model could provide a useful framework for designing future nanoscale ZnO devices.

Methods of editing cloud and atmospheric layer affected pixels from satellite data

NASA Technical Reports Server (NTRS)

Nixon, P. R. (Principal Investigator); Wiegand, C. L.; Richardson, A. J.; Johnson, M. P.

1981-01-01

Plotted transects made from south Texas daytime HCMM data show the effect of subvisible cirrus (SCI) clouds in the emissive (IR) band but the effect is unnoticable in the reflective (VIS) band. The depression of satellite indicated temperatures ws greatest in the center of SCi streamers and tapered off at the edges. Pixels of uncontaminated land and water features in the HCMM test area shared identical VIS and IR digital count combinations with other pixels representing similar features. A minimum of 0.015 percent repeats of identical VIS-IR combinations are characteristic of land and water features in a scene of 30 percent cloud cover. This increases to 0.021 percent of more when the scene is clear. Pixels having shared VIS-IR combinations less than these amounts are considered to be cloud contaminated in the cluster screening method. About twenty percent of SCi was machine indistinguishable from land features in two dimensional spectral space (VIS vs IR).

Changes in the IR Spectra of Aqueous Solutions of Alkali Metal Chlorides during Crystallization

NASA Astrophysics Data System (ADS)

Koroleva, A. V.; Matveev, V. K.; Koroleva, L. A.; Pentin, Yu. A.

2018-02-01

The IR spectra of aqueous solutions of sodium chloride and rubidium chloride with the same concentration of 0.1 M upon freezing are studied in the middle IR region. The changes that occur in the absorption bands of the bending ν2, compound ν2 + νL, and stretching (ν1, 2ν2, and ν3) vibrations of water molecules with gradual crystallization of the solutions are studied. The obtained spectra of crystallized solutions are compared to the IR spectrum of ice Ih. Analysis allows conclusions about the structure of the investigated frozen crystallized solutions.

LASER APPLICATIONS AND OTHER TOPICS IN QUANTUM ELECTRONICS: Matrix laser IR-visible image converter

NASA Astrophysics Data System (ADS)

Lipatov, N. I.; Biryukov, A. S.

2006-04-01

A new type of a focal matrix IR-visible image converter is proposed. The pixel IR detectors of the matrix are tunable microcavities of VCSEL (vertical-cavity surface emitting laser) semiconductor microstructures. The image conversion is performed due to the displacements of highly reflecting cavity mirrors caused by thermoelastic stresses in their microsuspensions appearing upon absorption of IR radiation. Analysis of the possibilities of the converter shows that its sensitivity is 10-3-10-2 K and the time response is 10-4-10-3 s. These characteristics determine the practical application of the converter.

Enhanced spectroscopic gas sensors using in-situ grown carbon nanotubes

DOE Office of Scientific and Technical Information (OSTI.GOV)

De Luca, A.; Cole, M. T.; Milne, W. I.

2015-05-11

In this letter, we present a fully complementary-metal-oxide-semiconductor (CMOS) compatible microelectromechanical system thermopile infrared (IR) detector employing vertically aligned multi-walled carbon nanotubes (CNT) as an advanced nano-engineered radiation absorbing material. The detector was fabricated using a commercial silicon-on-insulator (SOI) process with tungsten metallization, comprising a silicon thermopile and a tungsten resistive micro-heater, both embedded within a dielectric membrane formed by a deep-reactive ion etch following CMOS processing. In-situ CNT growth on the device was achieved by direct thermal chemical vapour deposition using the integrated micro-heater as a micro-reactor. The growth of the CNT absorption layer was verified through scanning electronmore » microscopy, transmission electron microscopy, and Raman spectroscopy. The functional effects of the nanostructured ad-layer were assessed by comparing CNT-coated thermopiles to uncoated thermopiles. Fourier transform IR spectroscopy showed that the radiation absorbing properties of the CNT adlayer significantly enhanced the absorptivity, compared with the uncoated thermopile, across the IR spectrum (3 μm–15.5 μm). This led to a four-fold amplification of the detected infrared signal (4.26 μm) in a CO{sub 2} non-dispersive-IR gas sensor system. The presence of the CNT layer was shown not to degrade the robustness of the uncoated devices, whilst the 50% modulation depth of the detector was only marginally reduced by 1.5 Hz. Moreover, we find that the 50% normalized absorption angular profile is subsequently more collimated by 8°. Our results demonstrate the viability of a CNT-based SOI CMOS IR sensor for low cost air quality monitoring.« less

Possible near-IR channels for remote sensing precipitable water vapor from geostationary satellite platforms

NASA Technical Reports Server (NTRS)

Gao, B.-C.; Goetz, A. F. H.; Westwater, Ed R.; Conel, J. E.; Green, R. O.

1993-01-01

Remote sensing of troposheric water vapor profiles from current geostationary weather satellites is made using a few broadband infrared (IR) channels in the 6-13 micron region. Uncertainties greater than 20% exist in derived water vapor values just above the surface from the IR emission measurements. In this paper, we propose three near-IR channels, one within the 0.94-micron water vapor band absorption region, and the other two in nearby atmospheric windows, for remote sensing of precipitable water vapor over land areas, excluding lakes and rivers, during daytime from future geostationary satellite platforms. The physical principles are as follows. The reflectance of most surface targets varies approximately linearly with wavelength near 1 micron. The solar radiation on the sun-surface-sensor ray path is attenuated by atmospheric water vapor. The ratio of the radiance from the absorption channel with the radiances from the two window channels removes the surface reflectance effects and yields approximately the mean atmospheric water vapor transmittance of the absorption channel. The integrated water vapor amount from ground to space can be obtained with a precision of better than 5% from the mean transmittance. Because surface reflectances vary slowly with time, temporal variation of precipitable water vapor can be determined reliably. High spatial resolution, precipitable water vapor images are derived from spectral data collected by the Airborne Visable-Infrared Imaging Spectrometer, which measures solar radiation reflected by the surface in the 0.4-2.5 micron region in 10-nm channels and has a ground instantaneous field of view of 20 m from its platform on an ER-2 aircraft at 20 km. The proposed near-IR reflectance technique would complement the IR emission techniques for remote sensing of water vapor profiles from geostationary satellite platforms, especially in the boundary layer where most of the water vapor is located.

Diatoms in comets

NASA Technical Reports Server (NTRS)

Hoover, R.; Hoyle, F.; Wallis, M. K.; Wickramasinghe, N. C.

1986-01-01

The fossil record of the microscopic algae classified as diatoms suggests they were injected to earth at the Cretaceous boundary. Not only could diatoms remain viable in the cometary environment, but also many species might replicate in illuminated surface layers or early interior layers of cometary ice. Presumably they reached the solar system on an interstellar comet as an already-evolved assemblage of organisms. Diatoms might cause color changes to comet nuclei while their outgassing decays and revives around highly elliptical orbits. Just as for interstellar absorption, high-resolution IR observations are capable of distinguishing whether the 10-micron feature arises from siliceous diatom material or mineral silicates. The 10-30-micron band and the UV 220-nm region can also provide evidence of biological material.

LINE IDENTIFICATIONS OF TYPE I SUPERNOVAE: ON THE DETECTION OF Si II FOR THESE HYDROGEN-POOR EVENTS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Parrent, J. T.; Milisavljevic, D.; Soderberg, A. M.

2016-03-20

Here we revisit line identifications of type I supernovae (SNe I) and highlight trace amounts of unburned hydrogen as an important free parameter for the composition of the progenitor. Most one-dimensional stripped-envelope models of supernovae indicate that observed features near 6000–6400 Å in type I spectra are due to more than Si ii λ6355. However, while an interpretation of conspicuous Si ii λ6355 can approximate 6150 Å absorption features for all SNe Ia during the first month of free expansion, similar identifications applied to 6250 Å features of SNe Ib and Ic have not been as successful. When the corresponding synthetic spectra aremore » compared with high-quality timeseries observations, the computed spectra are frequently too blue in wavelength. Some improvement can be achieved with Fe ii lines that contribute redward of 6150 Å; however, the computed spectra either remain too blue or the spectrum only reaches a fair agreement when the rise-time to peak brightness of the model conflicts with observations by a factor of two. This degree of disagreement brings into question the proposed explosion scenario. Similarly, a detection of strong Si ii λ6355 in the spectra of broadlined Ic and super-luminous events of type I/R is less convincing despite numerous model spectra used to show otherwise. Alternatively, we suggest 6000–6400 Å features are possibly influenced by either trace amounts of hydrogen or blueshifted absorption and emission in Hα, the latter being an effect which is frequently observed in the spectra of hydrogen-rich, SNe II.« less

Physical conditions in broad and associated narrow absorption-line systems toward APM 08279+5255

NASA Astrophysics Data System (ADS)

Srianand, R.; Petitjean, P.

2000-05-01

Results of a careful analysis of the absorption systems with z_abs =~ z_em seen toward the bright, z_em ~ 3.91, gravitationally lensed quasar APM 08279+5255 are presented. Two of the narrow-line systems, at z_abs = 3.8931 and z_abs = 3.9135, show absorptions from singly ionized species with weak or no N v and O vi absorptions at the same redshift. Absorption due to fine structure transitions of C ii and S ii i (excitation energies corresponding to, respectively, 156mu m and 34mu m) are detected at z_abs = 3.8931. Excitation by IR radiation is favored as the column density ratios are consistent with the shape of APM 08279+5255 IR spectrum. The low-ionization state of the system favors a picture where the cloud is closer to the IR source than to the UV source, supporting the idea that the extension of the IR source is larger than ~ 200 pc. The absence of fine structure lines at z_abs = 3.9135 suggests that the gas responsible for this system is farther away from the IR source. Abundances are ~ 0.01 and 1 Zsun at z_abs = 3.913 and 3.8931 and aluminum could be over-abundant with respect to silicon and carbon by at least a factor of two and five. All this suggests that whereas the z_abs = 3.8931 system is probably located within 200 pc from the QSO and ejected at a velocity larger than 1000 km s-1, the z_abs = 3.9135 system is farther away and part of the host-galaxy. Several narrow-line systems have strong absorption lines due to C iv, O vi and N v and very low neutral hydrogen optical depths. This probably implies metallicities Z>= Z_sun although firm conclusion cannot be drawn as the exact value depends strongly on the shape of the ionizing spectrum. The C iv broad absorption has a complex structure with mini-BALs (width <= 1000 km s-1) and narrow components superposed on a continuous absorption of smaller optical depth. The continuous absorption is much stronger in O vi indicating that the corresponding gas-component is of higher ionization than the other components in the flow and that absorption structures in the BAL-flow are mainly due to density inhomogeneities. There is a tendency for mini-BALs to have different covering factors for different species. It is shown that a few of the absorbing clouds do not cover all the three QSO images, especially we conclude that the z_abs = 3.712 system covers only image C. Finally we identify narrow components within the BAL-flow with velocity separations within 5 km s-1 of the O vi, N v and S ii v doublet splittings suggesting that line driven radiative acceleration is an important process to explain the out-flow. Based on observations collected at the W.M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California and the National Aeronautics and Space Administration. The Observatory was made possible by the generous financial support of the W.M. Keck Foundation.

AFM-IR: Technology and Applications in Nanoscale Infrared Spectroscopy and Chemical Imaging.

PubMed

Dazzi, Alexandre; Prater, Craig B

2016-12-13

Atomic force microscopy-based infrared spectroscopy (AFM-IR) is a rapidly emerging technique that provides chemical analysis and compositional mapping with spatial resolution far below conventional optical diffraction limits. AFM-IR works by using the tip of an AFM probe to locally detect thermal expansion in a sample resulting from absorption of infrared radiation. AFM-IR thus can provide the spatial resolution of AFM in combination with the chemical analysis and compositional imaging capabilities of infrared spectroscopy. This article briefly reviews the development and underlying technology of AFM-IR, including recent advances, and then surveys a wide range of applications and investigations using AFM-IR. AFM-IR applications that will be discussed include those in polymers, life sciences, photonics, solar cells, semiconductors, pharmaceuticals, and cultural heritage. In the Supporting Information , the authors provide a theoretical section that reviews the physics underlying the AFM-IR measurement and detection mechanisms.

FDTD modeling of solar energy absorption in silicon branched nanowires.

PubMed

Lundgren, Christin; Lopez, Rene; Redwing, Joan; Melde, Kathleen

2013-05-06

Thin film nanostructured photovoltaic cells are increasing in efficiency and decreasing the cost of solar energy. FDTD modeling of branched nanowire 'forests' are shown to have improved optical absorption in the visible and near-IR spectra over nanowire arrays alone, with a factor of 5 enhancement available at 1000 nm. Alternate BNW tree configurations are presented, achieving a maximum absorption of over 95% at 500 nm.

THE MID-INFRARED EXTINCTION LAW AND ITS VARIATION IN THE COALSACK NEBULA

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wang Shu; Gao Jian; Jiang, B. W.

In recent years, the wavelength dependence of interstellar extinction from the ultraviolet (UV) to the near- and mid-infrared (IR) has been studied extensively. Although it is well established that the UV/optical extinction law varies significantly among the different lines of sight, it is not clear how IR extinction varies among various environments. In this work, using the color-excess method and taking red giants as the extinction tracer, we determine interstellar extinction A{sub {lambda}} in the four Spitzer/IRAC bands in [3.6], [4.5], [5.8], [8.0] {mu}m (relative to A{sub K{sub s}}, extinction in the Two Micron All Sky Survey (2MASS) K{sub s}more » band at 2.16 {mu}m) of the Coalsack nebula, a nearby starless dark cloud, based on the data obtained from the 2MASS and Spitzer/GLIMPSE surveys. We select five individual regions across the nebula that span a wide variety of physical conditions ranging from diffuse and translucent to dense environments, as traced by the visual extinction, the Spitzer/MIPS 24 {mu}m emission, and CO emission. We find that A{sub {lambda}}/A{sub K{sub s}}, mid-IR extinction relative to A{sub K{sub s}}, decreases from diffuse to dense environments, which may be explained in terms of ineffective dust growth in dense regions. The mean extinction (relative to A{sub K{sub s}}) is calculated for the four IRAC bands as well and exhibits a flat mid-IR extinction law consistent with previous determinations for other regions. Extinction in the IRAC 4.5 {mu}m band is anomalously high, much higher than that of the other three IRAC bands, and cannot be explained in terms of CO and CO{sub 2} ice. Mid-IR extinction in the four IRAC bands has also been derived for four representative regions in the Coalsack Globule 2, which respectively exhibit strong ice absorption, moderate or weak ice absorption, and very weak or no ice absorption. The derived mid-IR extinction curves are all flat, with A{sub {lambda}}/A{sub K{sub s}} increasing with the decrease of the 3.1 {mu}m H{sub 2}O ice absorption optical depth {tau}{sub ice}.« less

[Determination of Carbaryl in Rice by Using FT Far-IR and THz-TDS Techniques].

PubMed

Sun, Tong; Zhang, Zhuo-yong; Xiang, Yu-hong; Zhu, Ruo-hua

2016-02-01

Determination of carbaryl in rice by using Fourier transform far-infrared (FT- Far-IR) and terahertz time-domain spectroscopy (THz-TDS) combined with chemometrics was studied and the spectral characteristics of carbaryl in terahertz region was investigated. Samples were prepared by mixing carbaryl at different amounts with rice powder, and then a 13 mm diameter, and about 1 mm thick pellet with polyethylene (PE) as matrix was compressed under the pressure of 5-7 tons. Terahertz time domain spectra of the pellets were measured at 0.5~1.5 THz, and the absorption spectra at 1.6. 3 THz were acquired with Fourier transform far-IR spectroscopy. The method of sample preparation is so simple that it does not need separation and enrichment. The absorption peaks in the frequency range of 1.8-6.3 THz have been found at 3.2 and 5.2 THz by Far-IR. There are several weak absorption peaks in the range of 0.5-1.5 THz by THz-TDS. These two kinds of characteristic absorption spectra were randomly divided into calibration set and prediction set by leave-N-out cross-validation, respectively. Finally, the partial least squares regression (PLSR) method was used to establish two quantitative analysis models. The root mean square error (RMSECV), the root mean square errors of prediction (RMSEP) and the correlation coefficient of the prediction are used as a basis for the model of performance evaluation. For the R,, a higher value is better; for the RMSEC and RMSEP, lower is better. The obtained results demonstrated that the predictive accuracy of. the two models with PLSR method were satisfactory. For the FT-Far-IR model, the correlation between actual and predicted values of prediction samples (Rv) was 0.99. The root mean square error of prediction set (RMSEP) was 0.008 6, and for calibration set (RMSECV) was 0.007 7. For the THz-TDS model, R. was 0. 98, RMSEP was 0.004 4, and RMSECV was 0.002 5. Results proved that the technology of FT-Far-IR and THz- TDS can be a feasible tool for quantitative determination of carbaryl in rice. This paper provides a new method for the quantitative determination pesticide in other grain samples.

The Far Infrared Lines of OH as Molecular Cloud Diagnostics

NASA Technical Reports Server (NTRS)

Smith, Howard A.

2004-01-01

Future IR missions should give some priority to high resolution spectroscopic observations of the set of far-IR transitions of OH. There are 15 far-IR lines arising between the lowest eight rotational levels of OH, and ISO detected nine of them. Furthermore, ISO found the OH lines, sometimes in emission and sometimes in absorption, in a wide variety of galactic and extragalactic objects ranging from AGB stars to molecular clouds to active galactic nuclei and ultra-luminous IR galaxies. The ISO/LWS Fabry-Perot resolved the 119 m doublet line in a few of the strong sources. This set of OH lines provides a uniquely important diagnostic for many reasons: the lines span a wide wavelength range (28.9 m to 163.2 m); the transitions have fast radiative rates; the abundance of the species is relatively high; the IR continuum plays an important role as a pump; the contribution from shocks is relatively minor; and, not least, the powerful centimeter-wave radiation from OH allows comparison with radio and VLBI datasets. The problem is that the large number of sensitive free parameters, and the large optical depths of the strongest lines, make modeling the full set a difficult job. The SWAS montecarlo radiative transfer code has been used to analyze the ISO/LWS spectra of a number of objects with good success, including in both the lines and the FIR continuum; the DUSTY radiative transfer code was used to insure a self-consistent continuum. Other far IR lines including those from H2O, CO, and [OI] are also in the code. The OH lines all show features which future FIR spectrometers should be able to resolve, and which will enable further refinements in the details of each cloud's structure. Some examples are given, including the case of S140, for which independent SWAS data found evidence for bulk flows.

Resolution of Site-Specific Conformational Heterogeneity in Proline-Rich Molecular Recognition by Src Homology 3 Domains.

PubMed

Horness, Rachel E; Basom, Edward J; Mayer, John P; Thielges, Megan C

2016-02-03

Conformational heterogeneity and dynamics are increasingly evoked in models of protein molecular recognition but are challenging to experimentally characterize. Here we combine the inherent temporal resolution of infrared (IR) spectroscopy with the spatial resolution afforded by selective incorporation of carbon-deuterium (C-D) bonds, which provide frequency-resolved absorptions within a protein IR spectrum, to characterize the molecular recognition of the Src homology 3 (SH3) domain of the yeast protein Sho1 with its cognate proline-rich (PR) sequence of Pbs2. The IR absorptions of C-D bonds introduced at residues along a peptide of the Pbs2 PR sequence report on the changes in the local environments upon binding to the SH3 domain. Interestingly, upon forming the complex the IR spectra of the peptides labeled with C-D bonds at either of the two conserved prolines of the PXXP consensus recognition sequence show more absorptions than there are C-D bonds, providing evidence for the population of multiple states. In contrast, the NMR spectra of the peptides labeled with (13)C at the same residues show only single resonances, indicating rapid interconversion on the NMR time scale. Thus, the data suggest that the SH3 domain recognizes its cognate peptide with a component of induced fit molecular recognition involving the adoption of multiples states, which have previously gone undetected due to interconversion between the populated states that is too fast to resolve using conventional methods.

High-Resolution Near-Infrared Speckle Interferometry and Radiative Transfer Modeling of the OH/IR Star OH 26.5+0.6

NASA Astrophysics Data System (ADS)

Driebe, T.; Riechers, D.; Balega, Y. Y.; Hofmann, K.-H.; Men'shchikov, A. B.; Weigelt, G.

We present near-infrared speckle interferometry of the OH/IR star OH 26.5+0.6 in the K' band obtained with the 6m telescope of the Special Astrophysical Observatory (SAO) in Oct. 2003. At a wavelength of λ = 2.13 μm the diffraction-limited resolution of 74 mas was attained. The reconstructed visibility reveals a spherically symmetric, circumstellar dust shell (CDS) surrounding the central star. In accordance with the deep silicate absorption feature in the spectral energy distribution (SED), the drop of the visibility function to a value of 0.36 at the cutoff frequency indicates a rather large optical depth of the CDS. To determine the structure and the properties of the CDS of OH 26.5+0.6, radiative transfer calculations using the code DUSTY[3] were performed to simultaneously model its visibility and the SED. Since OH 26.5+0.6 is highly variable, the observational data taken into consideration for the modeling correspond to different phases of the object's variability cycle. As in the case of another OH/IR star, OH 104.9+2.4 (see [5] and Riechers et al., this volume), we used these observational constraints at different epochs to derive several physical parameters of the central star and the CDS of OH 26.5+0.6 as a function of phase

Spectral identification of geological units on the surface of Mars related to the presence of silicates from Earth-based near-infrared telescopic charge-coupled device imaging

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pinet, P.; Chevrel, S.

1990-08-30

During the September 1988 Mars opposition, the authors obtained new high spatial (100-150 km) and spectral ({Delta}{lambda}/{lambda} = 1%) resolution near-IR telescopic charge-coupled device images of Mars from Pic-du-Midi Observatory. These images allow the association of spectral units with morphologic surface units on Mars, especially within the dark regions which exhibit much greater variability than the bright regions. Mineralogical interpretation of the data leads to a global description of the surface state of alteration consistent with the spatial distribution of bright and dark regions, with the bright regions being more altered than the dark. Within the less altered regions, Fe{supmore » 2+} crystal field absorption bands are detected, indicative of the presence of mafic minerals (Opx, Cpx, O1) in agreement with a likely crustal basaltic composition. The most conspicuous Fe{sup 2+} absorption features are clearly related to the volcanic regions of the Syrtis Major Shield and Hesperia Planum unit. The strongest observed absorptions due to olivine and clinopyroxene are spatially associated with the restricted central caldera complex of Nili-Meroe Paterae (within Syrtis Major) and the Tyrrhena Patera unit (within Hesperia Planum) and indicate an ultramafic composition.« less

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 forsterite crystal shapes (equant, b-platelets, c-platelets, b-colums - excluding a- and c-columns) derived from our modeling [17] of comet Hale-Bopp, compared to laboratory synthesis experiments [18], suggests that these crystals are high temperature condensates. By observing and modeling the crystalline features in comet ISON, we may constrain forsterite crystal shape(s) and link to their formation temperature(s) and environment(s). References: [1] Campins, H., Ryan, E.V. 1989. ApJ, 341, 1059 [2] Crovisier, J., et al. 1997. Science, 275, 1904 [3] Wooden, D.H., et al. 1999. ApJ, 517, 1034 [4] Wooden, D.H., et al. 2004. ApJL, 612, L77 [5] Harker, D.E., et al. 2002. ApJ, 580, 579 [6] --. 2004, ApJ, 615, 1081 [7] Lisse, C.M., et al. 2006. Icarus 195, 941-944. [8] Lisse, C.M., et.al. 2007. Icarus 191, 223-240. [9] Kelley, M.S., et al. 2010, LPSC, 41, #2375 [10] Harker, D.E., et al. 2011, AJ, 141, 26 [11] Draine, B.T., & Flatau, P.J. 1994, J. Opt. Soc. Am. A, 11, 1491 [12] Draine, B.T., & Flatau, P.J. 2008, J. Opt. Soc. Am. A, 25, 2693 [13] Fabian, D., et al., 2001, A&A, 378, 228 [14] Tamanai, A., et al. 2006. ApJ, 648, L147 [15] Tamanai, A., et al. 2009. ASP Conf. Ser., 414, 438 [16] Koike, C., et al. 2010. ApJ, 709, 983 [17] Lindsay, S.S., et al. 2013, ApJ, 766, 54 [18] Tsuchiyama, A. 1998. Mineralogical J., 20, 59 [19] Kobatake, H., et al., 2008. Icarus, 198, 208 [20] Takigawa, A., et al.. 2009. ApJL, 707, L97

High-performance mushroom plasmonic metamaterial absorbers for infrared polarimetric imaging

NASA Astrophysics Data System (ADS)

Ogawa, Shinpei; Fujisawa, Daisuke; Hata, Hisatoshi; Uetsuki, Mitsuharu; Kuboyama, Takafumi; Kimata, Masafumi

2017-02-01

Infrared (IR) polarimetric imaging is a promising approach to enhance object recognition with conventional IR imaging for applications such as artificial object recognition from the natural environment and facial recognition. However, typical infrared polarimetric imaging requires the attachment of polarizers to an IR camera or sensor, which leads to high cost and lower performance caused by their own IR radiation. We have developed asymmetric mushroom plasmonic metamaterial absorbers (A-MPMAs) to address this challenge. The A-MPMAs have an all-Al construction that consists of micropatches and a reflector layer connected with hollow rectangular posts. The asymmetric-shaped micropatches lead to strong polarization-selective IR absorption due to localized surface plasmon resonance at the micropatches. The operating wavelength region can be controlled mainly by the micropatch and the hollow rectangular post size. AMPMAs are complicated three-dimensional structures, the fabrication of which is challenging. Hollow rectangular post structures are introduced to enable simple fabrication using conventional surface micromachining techniques, such as sacrificial layer etching, with no degradation of the optical properties. The A-MPMAs have a smaller thermal mass than metal-insulator-metal based metamaterials and no influence of the strong non-linear dispersion relation of the insulator materials constant, which produces a gap in the wavelength region and additional absorption insensitive to polarization. A-MPMAs are therefore promising candidates for uncooled IR polarimetric image sensors in terms of both their optical properties and ease of fabrication. The results presented here are expected to contribute to the development of highperformance polarimetric uncooled IR image sensors that do not require polarizers.

HIFI Spectroscopy of H2O Submillimeter Lines in Nuclei of Actively Star-forming Galaxies

NASA Astrophysics Data System (ADS)

Liu, L.; Weiß, A.; Perez-Beaupuits, J. P.; Güsten, R.; Liu, D.; Gao, Y.; Menten, K. M.; van der Werf, P.; Israel, F. P.; Harris, A.; Martin-Pintado, J.; Requena-Torres, M. A.; Stutzki, J.

2017-09-01

We present a systematic survey of multiple velocity-resolved H2O spectra using Herschel/Heterodyne Instrument for the Far Infrared (HIFI) toward nine nearby actively star-forming galaxies. The ground-state and low-excitation lines (E up ≤ 130 K) show profiles with emission and absorption blended together, while absorption-free medium-excitation lines (130 K ≤ E up ≤ 350 K) typically display line shapes similar to CO. We analyze the HIFI observation together with archival SPIRE/PACS H2O data using a state-of-the-art 3D radiative transfer code that includes the interaction between continuum and line emission. The water excitation models are combined with information on the dust and CO spectral line energy distribution to determine the physical structure of the interstellar medium (ISM). We identify two ISM components that are common to all galaxies: a warm ({T}{dust}˜ 40{--}70 K), dense (n({{H}})˜ {10}5{--}{10}6 {{cm}}-3) phase that dominates the emission of medium-excitation H2O lines. This gas phase also dominates the far-IR emission and the CO intensities for {J}{up}> 8. In addition, a cold ({T}{dust}˜ 20{--}30 K), dense (n({{H}})˜ {10}4{--}{10}5 {{cm}}-3), more extended phase is present. It outputs the emission in the low-excitation H2O lines and typically also produces the prominent line absorption features. For the two ULIRGs in our sample (Arp 220 and Mrk 231) an even hotter and more compact (R s ≤ 100 pc) region is present, which is possibly linked to AGN activity. We find that collisions dominate the water excitation in the cold gas and for lines with {E}{up}≤slant 300 K and {E}{up}≤slant 800 K in the warm and hot component, respectively. Higher-energy levels are mainly excited by IR pumping.

The design and application of a multi-band IR imager

NASA Astrophysics Data System (ADS)

Li, Lijuan

2018-02-01

Multi-band IR imaging system has many applications in security, national defense, petroleum and gas industry, etc. So the relevant technologies are getting more and more attention in rent years. As we know, when used in missile warning and missile seeker systems, multi-band IR imaging technology has the advantage of high target recognition capability and low false alarm rate if suitable spectral bands are selected. Compared with traditional single band IR imager, multi-band IR imager can make use of spectral features in addition to space and time domain features to discriminate target from background clutters and decoys. So, one of the key work is to select the right spectral bands in which the feature difference between target and false target is evident and is well utilized. Multi-band IR imager is a useful instrument to collect multi-band IR images of target, backgrounds and decoys for spectral band selection study at low cost and with adjustable parameters and property compared with commercial imaging spectrometer. In this paper, a multi-band IR imaging system is developed which is suitable to collect 4 spectral band images of various scenes at every turn and can be expanded to other short-wave and mid-wave IR spectral bands combination by changing filter groups. The multi-band IR imaging system consists of a broad band optical system, a cryogenic InSb large array detector, a spinning filter wheel and electronic processing system. The multi-band IR imaging system's performance is tested in real data collection experiments.

Confirming Planetary Mass Candidate Companions in Ophiuchus

NASA Astrophysics Data System (ADS)

Fontanive, Clemence

2016-10-01

We propose for follow-up observations to confirm common proper motion for two candidate planetary mass companions, identified as part of our GO 12944 (PI Allers) search for companions to the youngest ( 0.5 Myr) brown dwarfs in the nearby Ophiuchus star-forming region. If confirmed to be co-moving, these would be among the lowest mass planetary mass companions imaged to date, with estimated masses <5 Jupiter Masses and would be vital benchmark objects for evolutionary models at these young ages. With our multi-band optical and IR photometric approach based on the SpT-Q relation seen for Ophiuchus brown dwarfs (Allers in prep.), we have already estimated the spectral type of our candidate companions. This approach distinguishes substellar objects from background interlopers based on the strength of the 1.4 um water feature robustly observed in MLTY objects but not in reddened background stars - both our candidates show clear evidence of absorption at 1.4 um. If confirmed, these candidate companions would significantly increase the census of young planetary mass companions around extremely young brown dwarfs. These candidate companions are too faint to be observed with ground-based laser guide star adaptive optics (LGS AO) nor is the 1.4 um water feature observable from the ground for such faint objects due to telluric absorption, thus HST is the only telescope in the world suitable for these observations.

Spectroscopic Confirmation of Five Galaxy Clusters at z > 1.25 in the 2500 deg^2 SPT-SZ Survey

NASA Astrophysics Data System (ADS)

Khullar, Gourav; Bleem, Lindsey; Bayliss, Matthew; Gladders, Michael; South Pole Telescope (SPT) Collaboration

2018-06-01

We present spectroscopic confirmation of 5 galaxy clusters at 1.25 < z < 1.5, discovered in the 2500 deg2 South Pole Telescope Sunyaev-Zel’dovich (SPT-SZ) survey. These clusters, taken from a nearly redshift-independent mass-limited sample of clusters, have multi-wavelength follow-up imaging data from the X-ray to the near-IR, and currently form the most homogenous massive high-redshift cluster sample in existence. We briefly describe the analysis pipeline used on the low S/N spectra of these faint galaxies, and describing the multiple techniques used to extract robust redshifts from a combination of absorption-line (Ca II H&K doublet - λλ3934,3968Å) and emission-line ([OII] λλ3727,3729Å) spectral features. We present several ensemble analyses of cluster member galaxies that demonstrate the reliability of the measured redshifts. We also identify modest [OII] emission and pronounced CN and Hδ absorption in a composite stacked spectrum of 28 low S/N passive galaxy spectra with redshifts derived primarily from Ca II H&K features. This work increases the number of spectroscopically-confirmed SPT-SZ galaxy clusters at z > 1.25 from 2 to 7, further demonstrating the efficacy of SZ selection for the highest redshift massive clusters, and enabling further detailed study of these confirmed systems.

Molecular spectroscopy of CH Cygni in the 1998-2000 active phas

NASA Astrophysics Data System (ADS)

Kotnik-Karuza, D.; Jurdana-Sepic, R.; Majlinger, Z.

The subject of this study is the very peculiar symbiotic binary CH Cygni, in particular the physical conditions in the photosphere of its cool component. The latter has been classified as an M late type giant due to its spectral appearance in the optical and near IR spectral region during quiescent and active phases. Several consecutive spectra obtained with different exposure times covering the region lambda 4800-9000 A were obtained on 24/25 November 1999 which means that they belong to the 1998-2000 active phase. We have concentrated our investigations on the TiO absorption bands which are the most outstanding feature in these spectra. The bands, some of which give evidence of a partly resolved rotational structure, have been identified as members of the alpha, gamma, gamma prim, beta, delta, phi and epsilon band systems. Measurement of the band head relative intensities and some other features in their structure have led to determination of temperatures of the coolest layers in the red giant's photosphere.

Far-UV, visible, and near-IR reflectance spectra of frosts of H2O, CO2, NH3 and SO2

NASA Technical Reports Server (NTRS)

Hapke, B.; Wells, E.; Wagner, J.; Partlow, W.

1981-01-01

Measurements in the 0.1-2.5 micron range are presented for the reflectance spectra of the frosts of several volatiles pertinent to the study of comet nuclei. The frost spectra have distinctive features permitting their identification by spectroscopic reflectance remote sensing, notably in the far UV. It is found that: (1) H2O has a minimum at 0.16 microns and a maximum at 0.13 microns; (2) CO2 has minima near 0.21, 0.18 and 0.125 microns, with maxima at 0.19, 0.135 and 0.120 microns; (3) NH3 is bright at wavelengths longer than 0.21 microns, where reflectance drops to a value of only a few per cent at shorter wavelengths; (4) SO2 has a sharp drop at 0.32 microns, with a minimum at 0.18 microns and a maximum at 0.13 microns. The features in the frost spectra largely correspond to absorption line bands in the gas phase.

Mars - Remote spectral identification of H2O frost and mineral hydrate

NASA Technical Reports Server (NTRS)

Huguenin, R. L.; Clark, R. N.; Mccord, T. B.

1978-01-01

A reflectance spectrum (0.62-2.6 microns) of Mars (integral disk) is obtained using a newly developed IR spectrometer at the 2.25 m telescope on Mauna Kea, Hawaii. Details of the instrument, observations, and data reduction are presented. Several distinct absorption features are evident that were apparently caused by H2O, but the positions and intensities of the features are quite unusual. In summary, the regolith is probably not as desiccated and dehydrated as the full disk reflectance spectrum and Viking soil analyses would suggest. The surface materials become desiccated and dehydrated as a result of solar UV effects and because of the relative adsorption and desorption rates during the strong diurnal cycling. There may be significant amounts of H2O at depth, and in the Solis Lacus region the H2O reservoir may extend to within a few centimeters of the surface. The Solis Lacus region may therefore be an important target for future Mars landing or sample return mission.

The mid-IR Absorption Cross Sections of α- and β-NAT (HNO3 · 3H2O) in the range 170 to 185 K and of metastable NAD (HNO3 · 2H2O) in the range 172 to 182 K

NASA Astrophysics Data System (ADS)

Iannarelli, R.; Rossi, M. J.

2015-11-01

Growth and Fourier transform infrared (FTIR) absorption in transmission of the title nitric acid hydrates have been performed in a stirred flow reactor (SFR) under tight control of the H2O and HNO3 deposition conditions affording a closed mass balance of the binary mixture. The gas and condensed phases have been simultaneously monitored using residual gas mass spectrometry and FTIR absorption spectroscopy, respectively. Barrierless nucleation of the metastable phases of both α-NAT (nitric acid trihydrate) and NAD (nitric acid dihydrate) has been observed when HNO3 was admitted to the SFR in the presence of a macroscopic thin film of pure H2O ice of typically 1 µm thickness. The stable β-NAT phase was spontaneously formed from the precursor α-NAT phase through irreversible thermal rearrangement beginning at 185 K. This facile growth scheme of nitric acid hydrates requires the presence of H2O ice at thicknesses in excess of approximately hundred nanometers. Absolute absorption cross sections in the mid-IR spectral range (700-4000 cm-1) of all three title compounds have been obtained after spectral subtraction of excess pure ice at temperatures characteristic of the upper troposphere/lower stratosphere. Prominent IR absorption frequencies correspond to the antisymmetric nitrate stretch vibration (ν3(NO3-)) in the range 1300 to 1420 cm-1 and the bands of hydrated protons in the range 1670 to 1850 cm-1 in addition to the antisymmetric O-H stretch vibration of bound H2O in the range 3380 to 3430 cm-1 for NAT.

Mid-wave infrared hyperspectral imaging of unknown chemical warfare agents

NASA Astrophysics Data System (ADS)

Clewes, Rhea J.; Howle, Chris R.; Guicheteau, Jason; Emge, Darren; Ruxton, Keith; Robertson, Gordon; Miller, William; Malcolm, Graeme; Maker, Gareth T.

2013-05-01

The ability of a stand-off chemical detector to distinguish two different chemical warfare agents is demonstrated in this paper. Using Negative Contrast Imaging, based upon IR absorption spectroscopy, we were able to detect 1 μl of VX, sulfur mustard and water on a subset of representative surfaces. These experiments were performed at a range of 1.3 metres and an angle of 45° to the surface. The technique employed utilises a Q-switched intracavity MgO:PPLN crystal that generated 1.4 - 1.8 μm (shortwave) and 2.6 - 3.6 μm (midwave) infrared radiation (SWIR and MWIR, respectively). The MgO:PPLN crystal has a fanned grating design which, via translation through a 1064 nm pump beam, enables tuning through the SWIR and MWIR wavelength ranges. The SWIR and MWIR beams are guided across a scene via a pair of raster scanned mirrors allowing detection of absorption features within these spectral regions. This investigation exploited MWIR signatures, as they provided sufficient molecular information to distinguish between toxic and benign chemicals in these proof-of-concept experiments.

The detection of high-velocity outflows from M8E-IR

NASA Technical Reports Server (NTRS)

Mitchell, George F.; Allen, Mark; Beer, Reinhard; Dekany, Richard; Huntress, Wesley

1988-01-01

A high-resolution (0.059/cm) M band (4.6 micron) spectrum of the embedded young stellar object M8E-IR is presented and discussed. The spectrum shows strong absorption to large blueshifts in the rotational lines of the fundamental vibrational band, v = 1-0, of CO. The absorption is interpreted as being due to gas near to, and flowing from, the central object. The outflowing gas is warm (95-330 K) and consists of discrete velocity components with the very high velocities of 90, 130, 150, and 160 km/s. On the basis of a simple model, it is estimated that the observed outflows are less than 100 yr old.

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

PubMed Central

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

2013-01-01

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

Infrared Spectroscopy in Cancer Diagnosis and Chemotherapy Monitoring

NASA Astrophysics Data System (ADS)

Tolstorozhev, G. B.; Bel'kov, M. V.; Skornyakov, I. V.; Butra, V. A.; Pekhnyo, V. I.; Kozachkova, A. N.; Tsarik, N. I.; Kutsenko, I. P.; Sharykina, N. I.

2014-07-01

We demonstrate that IR spectroscopic analysis can be used in diagnosis and chemotherapy monitoring for cancers of various organs at the molecular level. We used Fourier transform IR spectroscopy to study human breast and thyroid tumor tissues which were removed during surgery. The characteristic frequencies of C = O stretching vibrations in the IR spectra of tissues of pathological foci were compared with data from histological examination. In the IR spectra of healthy tissues or for benign tumors, the most intense absorption bands ν(C = O) are located in the interval 1675-1650 cm-1. When malignant neoplasms are present in the organs, the intensity of the bands in this range of the spectrum is reduced, while the intensities of the absorption bands in the 1710-1680 cm-1 interval increase. We also studied lung tissue for mice of the C57B1/6 line for healthy tissue and after implantation of B-16 melanoma tumor. The IR spectra of healthy mouse lung tissue and mouse lung tissue with B-16 melanoma metastases in the region of the C = O stretching vibrations display the same differences. We found that when lung malignancy was treated with the optimal dose of a synthesized drug based on palladium complexes of methylenediphosphonic acid, the spectroscopic signs of the presence of metastases in the lungs disappear, and the IR spectrum of the lung tissue after treatment practically coincides with the spectrum of healthy lung tissue.

Infrared molecular emissions from comets

NASA Technical Reports Server (NTRS)

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

1983-01-01

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

Olivine Composition of the Mars Trojan 5261 Eureka: Spitzer IRS Data

NASA Technical Reports Server (NTRS)

Lim, L. F.; Burt, B. J.; Emery, J. P.; Mueller, M.; Rivkin, A. S.; Trilling, D.

2011-01-01

The largest Mars trojan, 5261 Eureka, is one of two prototype "Sa" asteroids in the Bus-Demeo taxonomy. Analysis of its visible/near-IR spectrum led to the conclusion that it might represent either an angritic analog or an olivine-rich composition such as an R chondrite. Spitzer IRS data (5-30 micrometers) have enabled us to resolve this ambiguity. The thermal-IR spectrum exhibits strong olivine reststrahlen features consistent with a composition of approximately equals Fo60-70. Laboratory spectra of R chondrites, brachinites, and chassignites are dominated by similar features.

A SYSTEMATIC SEARCH FOR THE SPECTRA WITH FEATURES OF CRYSTALLINE SILICATES IN THE SPITZER IRS ENHANCED PRODUCTS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chen, Rui; Luo, Ali; Liu, Jiaming

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. Themore » 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.« less

A far wing line shape theory and its application to the water continuum absorption in the infrared region. I

NASA Technical Reports Server (NTRS)

Ma, Q.; Tipping, R. H.

1991-01-01

The present theory for the continuous absorption that is due to the far-wing contribution of allowed lines is based on the quasistatic approximation for the far wing limit and the binary collision approximation of one absorber molecule and one bath molecule. The validity of the theory is discussed, and numerical results of the water-continuum absorption in the IR region are presented for comparison with experimental data. Good agreement is obtained for both the magnitude and temperature dependence of the absorption coefficients.

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

NASA Technical Reports Server (NTRS)

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

1989-01-01

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

The HITRAN2016 molecular spectroscopic database

NASA Astrophysics Data System (ADS)

Gordon, I. E.; Rothman, L. S.; Hill, C.; Kochanov, R. V.; Tan, Y.; Bernath, P. F.; Birk, M.; Boudon, V.; Campargue, A.; Chance, K. V.; Drouin, B. J.; Flaud, J.-M.; Gamache, R. R.; Hodges, J. T.; Jacquemart, D.; Perevalov, V. I.; Perrin, A.; Shine, K. P.; Smith, M.-A. H.; Tennyson, J.; Toon, G. C.; Tran, H.; Tyuterev, V. G.; Barbe, A.; Császár, A. G.; Devi, V. M.; Furtenbacher, T.; Harrison, J. J.; Hartmann, J.-M.; Jolly, A.; Johnson, T. J.; Karman, T.; Kleiner, I.; Kyuberis, A. A.; Loos, J.; Lyulin, O. M.; Massie, S. T.; Mikhailenko, S. N.; Moazzen-Ahmadi, N.; Müller, H. S. P.; Naumenko, O. V.; Nikitin, A. V.; Polyansky, O. L.; Rey, M.; Rotger, M.; Sharpe, S. W.; Sung, K.; Starikova, E.; Tashkun, S. A.; Auwera, J. Vander; Wagner, G.; Wilzewski, J.; Wcisło, P.; Yu, S.; Zak, E. J.

2017-12-01

This paper describes the contents of the 2016 edition of the HITRAN molecular spectroscopic compilation. The new edition replaces the previous HITRAN edition of 2012 and its updates during the intervening years. The HITRAN molecular absorption compilation is composed of five major components: the traditional line-by-line spectroscopic parameters required for high-resolution radiative-transfer codes, infrared absorption cross-sections for molecules not yet amenable to representation in a line-by-line form, collision-induced absorption data, aerosol indices of refraction, and general tables such as partition sums that apply globally to the data. The new HITRAN is greatly extended in terms of accuracy, spectral coverage, additional absorption phenomena, added line-shape formalisms, and validity. Moreover, molecules, isotopologues, and perturbing gases have been added that address the issues of atmospheres beyond the Earth. Of considerable note, experimental IR cross-sections for almost 300 additional molecules important in different areas of atmospheric science have been added to the database. The compilation can be accessed through www.hitran.org. Most of the HITRAN data have now been cast into an underlying relational database structure that offers many advantages over the long-standing sequential text-based structure. The new structure empowers the user in many ways. It enables the incorporation of an extended set of fundamental parameters per transition, sophisticated line-shape formalisms, easy user-defined output formats, and very convenient searching, filtering, and plotting of data. A powerful application programming interface making use of structured query language (SQL) features for higher-level applications of HITRAN is also provided.

Interstellar PAH Analogs in the Laboratory: Comparison with Astronomical Data

NASA Technical Reports Server (NTRS)

Salama, Farid

2005-01-01

Polycyclic Aromatic Hydrocarbons (PAHs) are an important and ubiquitous component of carbon-bearing materials in space. PAHs are the best-known candidates to account for the IR emission bands (UIR bands) and PAH spectral features are now being used as new probes of the ISM. PAHs are also thought to be among the carriers of the diffuse interstellar absorption bands (DIBs). In the model dealing with the interstellar spectral features, PAHs are present as a mixture of radicals, ions and neutral species. PAH ionization states reflect the ionization balance of the medium while PAH size, composition, and structure reflect the energetic and chemical history of the medium. A major challenge for laboratory astrophysics is to reproduce (in a realistic way) the physical conditions that exist in the emission and/or absorption interstellar zones. An extensive laboratory program has been developed at NASA Ames to assess the physical and chemical properties of PAHs in such environments and to describe how they influence the radiation and energy balance in space and the interstellar chemistry. In particular, laboratory experiments provide measurements of the spectral characteristics of interstellar PAH analogs from the ultraviolet and visible range to the infrared range for comparison with astronomical data. This paper will focus on the recent progress made in the laboratory to measure the direct absorption spectra of neutral and ionized PAHs in the near-UV and visible range. Intrinsic band profiles and band positions of cold gas-phase PAHs can now be measured with high-sensitivity spectroscopy and directly compared to the astronomical data. Preliminary conclusions from the comparison of the laboratory data with astronomical observations will also be presented.

Comprehensive Experimental and Computational Spectroscopic Study of Hexacyanoferrate Complexes in Water: From Infrared to X-ray Wavelengths.

PubMed

Ross, Matthew; Andersen, Amity; Fox, Zachary W; Zhang, Yu; Hong, Kiryong; Lee, Jae-Hyuk; Cordones, Amy; March, Anne Marie; Doumy, Gilles; Southworth, Stephen H; Marcus, Matthew A; Schoenlein, Robert W; Mukamel, Shaul; Govind, Niranjan; Khalil, Munira

2018-05-17

We present a joint experimental and computational study of the hexacyanoferrate aqueous complexes at equilibrium in the 250 meV to 7.15 keV regime. The experiments and the computations include the vibrational spectroscopy of the cyanide ligands, the valence electronic absorption spectra, and Fe 1s core hole spectra using element-specific-resonant X-ray absorption and emission techniques. Density functional theory-based quantum mechanics/molecular mechanics molecular dynamics simulations are performed to generate explicit solute-solvent configurations, which serve as inputs for the spectroscopy calculations of the experiments spanning the IR to X-ray wavelengths. The spectroscopy simulations are performed at the same level of theory across this large energy window, which allows for a systematic comparison of the effects of explicit solute-solvent interactions in the vibrational, valence electronic, and core-level spectra of hexacyanoferrate complexes in water. Although the spectroscopy of hexacyanoferrate complexes in solution has been the subject of several studies, most of the previous works have focused on a narrow energy window and have not accounted for explicit solute-solvent interactions in their spectroscopy simulations. In this work, we focus our analysis on identifying how the local solvation environment around the hexacyanoferrate complexes influences the intensity and line shape of specific spectroscopic features in the UV/vis, X-ray absorption, and valence-to-core X-ray emission spectra. The identification of these features and their relationship to solute-solvent interactions is important because hexacyanoferrate complexes serve as model systems for understanding the photochemistry and photophysics of a large class of Fe(II) and Fe(III) complexes in solution.

Combined fluorescence, reflectance, and ground measurements of a stressed Norway spruce forest for forest damage assessment

NASA Technical Reports Server (NTRS)

Banninger, C.

1991-01-01

The detection and monitoring of stress and damage in forested areas is of utmost importance to forest managers for planning purposes. Remote sensing are the most suitable means to obtain this information. This requires that remote sensing data employed in a forest survey be properly chosen and utilized for their ability to measure canopy spectral features directly related to key tree and canopy properties that are indicators of forest health and vitality. Plant reflectance in the visible to short wave IR regions (400 to 2500 nm) provides information on its biochemical, biophysical, and morphological make up, whereas plant fluorescence in the 400 to 750 nm region is more indicative of the capacity and functioning of its photosynthetic apparatus. A measure of both these spectral properties can be used to provide an accurate assessment of stress and damage within the forest canopy. Foliar chlorophyll and nitrogen are essential biochemical constituents required for the proper functioning and maintenance of a plant's biological processes. Chlorophyll-a is the prime reactive center for photosynthesis, by which a plant converts CO2 and H2O into necessary plant products. Nitrogen forms an important component of the amino-acids, enzymes, proteins, alkaloids, and cyanogenic compounds that make up a plant, including its pigments. Both chlorophyll and nitrogen have characteristic absorption features in the visible to short wave IR region. By measuring the wavelength position and depth of these features and the fluorescence response of the foliage, the health and vitality of a canopy can be ascertained. Examples for a stressed Norway spruce forest in south-eastern Austria are presented.

Diffusivity of the interstitial hydrogen shallow donor in In 2 O 3

DOE Office of Scientific and Technical Information (OSTI.GOV)

Qin, Ying; Weiser, Philip; Villalta, Karla

Hydrogen has been found to be an n-type dopant in In2O3 that gives rise to unintentional conductivity. An infrared (IR) absorption line observed at 3306 cm-1 has been assigned to the Hi+ center. Two types of experiments have been performed to determine the diffusivity of Hi+ in In2O3 from its IR absorption spectra. (i) At temperatures near 700 K, the O-H line at 3306 cm-1 has been used to determine the diffusivity of Hi+ from its in-diffusion and out-diffusion behavior. (ii) At temperatures near 160 K, stress has been used to produce a preferential alignment of the Hi+ center thatmore » has been detected in IR absorption experiments made with polarized light. With the help of theory, the kinetics with which a stress-induced alignment can be produced yield the time constant for a single jump of the Hi+ center and also the diffusivity of Hi+ near 160 K. The combination of the diffusivity of Hi+ found near 700 K by mass-transport measurements along with the diffusivity found near 160 K from the time constant for a single Hi+ jump determines the diffusivity for Hi+ over eleven decades!« less

Robust infrared-shielding coating films prepared using perhydropolysilazane and hydrophobized indium tin oxide nanoparticles with tuned surface plasmon resonance.

PubMed

Katagiri, Kiyofumi; Takabatake, Ryuichi; Inumaru, Kei

2013-10-23

Robust infrared (IR)-shielding coating films were prepared by dispersing indium tin oxide (ITO) nanoparticles (NPs) in a silica matrix. Hydrophobized ITO NPs were synthesized via a liquid phase process. The surface plasmon resonance (SPR) absorption of the ITO NPs could be tuned by varying the concentration of Sn doping from 3 to 30 mol %. The shortest SPR wavelength and strongest SPR absorption were obtained for the ITO NPs doped with 10% Sn because they possessed the highest electron carrier density. Coating films composed of a continuous silica matrix homogeneously dispersed with ITO NPs were obtained using perhydropolysilazane (PHPS) as a precursor. PHPS was completely converted to silica by exposure to the vapor from aqueous ammonia at 50 °C. The prepared coating films can efficiently shield IR radiation even though they are more than 80% transparent in the visible range. The coating film with the greatest IR-shielding ability completely blocked IR light at wavelengths longer than 1400 nm. The pencil hardness of this coating film was 9H at a load of 750 g, which is sufficiently robust for applications such as automotive glass.

Optical properties of graphene, silicene, germanene, and stanene from IR to far UV - A first principles study

NASA Astrophysics Data System (ADS)

John, Rita; Merlin, Benita

2017-11-01

This study offers an analysis of optical properties of Graphene and its 2D analogues: Silicene, Germanene, and Stanene with the help of band structures based on Density Functional Theory. The complex dielectric function and complex refractive index are calculated in both parallel (||) and perpendicular (⊥) polarization directions of the electromagnetic field. From these calculated values, optical observables like absorption, reflection, optical conductivity, and electron loss function have been studied. The optical response of all materials is shifted from ultraviolet (UV) to infrared (IR) from graphene to stanene; Graphene is more into UV region and other materials in the IR and visible regions. The intensity of absorption is maximum for stanene. The real part of dielectric function reveals the existence of plasma frequency in the || polarization direction indicating the metal to dielectric transition except for graphene. Study on refractive index clearly displays the birefringence characteristics of all materials. Reflectivity is enhanced in the mid IR and visible regions when light is polarized in the || direction. The in-depth investigations arrive at fine results which would enable the prediction of their potential applications in the optical and optoelectronic industries.

Strategic modulation of the photonic properties of conjugated organometallic Pt-Ir polymers exhibiting hybrid CT-excited states.

PubMed

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

2015-04-01

Polymer 6, ([trans-Pt(PBu3 )2 (C≡C)2 ]-[Ir(dFMeppy)2 (N^N)](PF6 ))n , (([Pt]-[Ir](PF6 ))n ; N^N = 5,5'-disubstituted-2,2'-bipyridyl; dFMeppy = 2-(2,4-difluoro-phenyl)-5-methylpyridine) is prepared along with model compounds. These complexes are investigated by absorption and emission spectroscopy and their photophysical and electrochemical properties are measured and compared with their corresponding non fluorinated complexes. Density functional theory (DFT) and time-dependent DFT computations corroborate the nature of the excited state as being a hybrid between the metal-to-ligand charge transfer ((1,3) MLCT) for the trans-Pt(PBu3 )2 (C≡CAr)2 unit, [Pt] and the metal-to-ligand/ligand-to-ligand' charge transfer ((1,3) ML'CT/LL'CT) for [Ir] with L = dFMeppy. Overall, the fluorination of the phenylpyridine group expectedly does not change the nature of the excited state but desirably induces a small blue shift of the absorption and emission bands along a slight decrease in emission quantum yields and lifetimes. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

IR780 based nanomaterials for cancer imaging and photothermal, photodynamic and combinatorial therapies.

PubMed

Alves, Cátia G; Lima-Sousa, Rita; de Melo-Diogo, Duarte; Louro, Ricardo O; Correia, Ilídio J

2018-05-05

IR780, a molecule with a strong optical absorption and emission in the near infrared (NIR) region, is receiving an increasing attention from researchers working in the area of cancer treatment and imaging. Upon irradiation with NIR light, IR780 can produce reactive oxygen species as well as increase the body temperature, thus being a promising agent for application in cancer photodynamic and photothermal therapy. However, IR780's poor water solubility, fast clearance, acute toxicity and low tumor uptake may limit its use. To overcome such issues, several types of nanomaterials have been used to encapsulate and deliver IR780 to tumor cells. This mini-review is focused on the application of IR780 based nanostructures for cancer imaging, and photothermal, photodynamic and combinatorial therapies. Copyright © 2018 Elsevier B.V. All rights reserved.

Infrared spectroscopy investigation of Fe-promoted Rh catalysts supported on Titania and Ceria for CO hydrogenation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Magee, Joseph W.; Palomino, Robert M.; White, Michael G.

2016-07-04

The nature of the promotional effect of Fe addition to Rh/TiO 2 and Rh/CeO 2 catalysts for CO hydrogenation was investigated using FT-IR spectroscopy in an ultrahigh vacuum compatible transmission IR cell. CO adsorption experiments on Rh and FeRh showed vibrational signatures characteristic of linear and bridge bound CO on Rh0 as well as geminal-dicarbonyl species associated with Rh +. Compared to TiO 2, the CeO 2-supported catalysts show increased dispersion, reflected by decreased particle size, and a lower signal for linear versus geminal-dicarbonyl bonded CO. The absorption frequencies for CO on Rh/CeO 2 are also redshifted relative to Rh/TiOmore » 2, which results from a weaker Rh–CO interaction, likely due to the increased reducibility of the CeO 2 support. Upon addition of Fe, a new spectral feature is observed and attributed to CO bound to Rh in close contact with Fe, likely as a surface alloy. CO hydrogenation on (Fe)Rh catalysts on both supports was also studied. Compared to bare Rh, Fe containing catalysts promote formate and methoxy species on the surface at lower temperature (180 °C), which suggests an enhancement in methanol selectivity by Fe addition. Furthermore, at higher temperatures (220 °C), the spectral features appear similar, further confirming the role of Fe as a disrupter of large Rh o crystallites and regulator of CO dissociation and CH 4 formation.« less

Helicopter- and ship-based measurements of mesoscale ocean color and thermal features in the marginal ice zone

NASA Astrophysics Data System (ADS)

Tanis, Fred J.; Manley, Thomas O.; Mitchell, Brian G.

1990-09-01

Eddies along the Polar Front/Marginal Ice Zone (MIZ) in Fram Strait are thought to make important contributions to nutrient flux and stimulation of primary productivity. During the Coordinated Eastern Arctic Regional Experiment (CEAREX) helicopter-based measurements of upwelling radiance were made in four visible spectral bands and in the thermal IR across mesoscale features associated with the MIZ. These structures were mapped by flying a grid pattern over the ocean surface to define eddy boundaries. Subsequently, the area was also sampled vertically with CTD and spectral radiometer profilers. Data obtained from a single structure were integrated to construct a three dimensional picture of physical and optical properties. Volume modeling of temperature, salinity, and density fields obtained from CTD survey define the subsurface eddy structure and are in good agreement with infrared derived characteristics. Maximum temperature in the core was found to be four degrees higher than the surrounding water. Volume modeling further indicates that a subsurface layer of Arctic Intermediate Water is intrinsically associated with the surface expression of the eddy. The ratio of upwelling radiances, L(44l)/L(565), was found to be correlated to surface chlorophyll, particulate absorption coefficient, and in water determinations of L using the optical profiling system. The remote sensing reflectance ratio along with the IR sea surface temperature were found to be useful to detect the surface expression of the eddy and to indicate near surface biological and physical processes.

Multiphoton near-infrared femtosecond laser pulse-induced DNA damage with and without the photosensitizer proflavine.

PubMed

Shafirovich, V; Dourandin, A; Luneva, N P; Singh, C; Kirigin, F; Geacintov, N E

1999-03-01

The excitation of pBr322 supercoiled plasmid DNA with intense near-IR 810 nm fs laser pulses by a simultaneous multiphoton absorption mechanism results in single-strand breaks after treatment of the irradiated samples with Micrococcus luteus UV endonuclease. This enzyme cleaves DNA strands at sites of cyclobutane dimers that are formed by the simultaneous absorption of three (or more) 810 nm IR photons (pulse width approximately 140 fs, 76 MHz pulse repetition, average power output focused through 10x microscope objective is approximately 1.2 MW/cm2). Direct single-strand breaks (without treatment with M. luteus) were not observed under these conditions. However, in the presence of 6 microM of the intercalator proflavine (PF), both direct single- and double-strand breaks are observed under conditions where substantial fractions of undamaged supercoiled DNA molecules are still present. The fraction of direct double-strand breaks is 30 +/- 5% of all measurable strand cleavage events, is independent of dosage (up to 6.4 GJ/cm2) and is proportional to In, where I is the average power/area of the 810 nm fs laser pulses, and n = 3 +/- 1. The nicking of two DNA strands in the immediate vicinity of the excited PF molecules gives rise to this double-strand cleavage. In contrast, excitation of the same samples under low-power, single-photon absorption conditions (approximately 400-500 nm) gives rise predominantly to single-strand breaks, but some double-strand breaks are observed at the higher dosages. Thus, single-photon excitation with 400-500 nm light and multiphoton activation of PF by near-IR fs laser pulses produces different distributions of single- and double-strand breaks. These results suggest that DNA strand cleavage originates from unrelaxed, higher excited states when PF is excited by simultaneous IR multiphoton absorption processes.

Photopyroelectric Monitoring of Olive's Ripening Conditions and Olive Oil Quality Using Pulsed Wideband IR Thermal Source

NASA Astrophysics Data System (ADS)

Abu-Taha, M. I.; Sarahneh, Y.; Saleh, A. M.

The present study is based on band absorption of radiation from pulsed wideband infrared (IR) thermal source (PWBS) in conjunction with polyvinylidene fluoride film (PVDF). It is the first time to be employed to monitor the ripening state of olive fruit. Olive's characteristics vary at different stages of ripening, and hence, cultivation of olives at the right time is important in ensuring the best oil quality and maximizes the harvest yield. The photopyroelectric (PPE) signal resulting from absorption of wideband infrared (IR) radiation by fresh olive juice indicates the ripening stage of olives, i.e., allows an estimate of the suitable harvest time. The technique was found to be very useful in discriminating between olive oil samples according to geographical region, shelf life, some storage conditions, and deliberate adulteration. Our results for monitoring oil accumulation in olives during the ripening season agree well with the complicated analytical studies carried out by other researchers.

Theoretical study on the electronic structures and phosphorescent properties of four Ir(III) complexes with different substituents on the ancillary ligand

NASA Astrophysics Data System (ADS)

Han, Deming; Shang, Xiaohong; Zhang, Gang; Zhao, Lihui

2013-12-01

The geometry structures, electronic structures, absorption and phosphorescent properties of four Ir(III) complexes {[(F2-ppy)2Ir(pta-X)], where F2-ppy = (2,4-difluoro)phenylpyridine; pta = pyridine-1,2,4-triazole; X = -CF3; -H; -CH3; -N(CH3)2}, are investigated using the density functional method. The results reveal that the electron-accepting group -CF3 has no obvious effect on absorption and emission properties, while the substitutive group -N(CH3)2 with strong electron-donating ability has obvious effect on the emission properties. The mobility of hole and electron were studied computationally based on the Marcus-Hush theory. Calculations of ionisation potential and electron affinity were used to evaluate the injection abilities of holes and electrons into these complexes. We hope that this theoretical work can provide a suitable guide to the future design and synthesis of novel phosphorescent materials for use in the organic light-emitting diodes.

The Response of the Ocean Thermal Skin Layer to Variations in Incident Infrared Radiation

NASA Astrophysics Data System (ADS)

Wong, Elizabeth W.; Minnett, Peter J.

2018-04-01

Ocean warming trends are observed and coincide with the increase in concentrations of greenhouse gases in the atmosphere resulting from human activities. At the ocean surface, most of the incoming infrared (IR) radiation is absorbed within the top micrometers of the ocean's surface where the thermal skin layer (TSL) exists. Thus, the incident IR radiation does not directly heat the upper few meters of the ocean. This paper investigates the physical mechanism between the absorption of IR radiation and its effect on heat transfer at the air-sea boundary. The hypothesis is that given the heat lost through the air-sea interface is controlled by the TSL, the TSL adjusts in response to variations in incident IR radiation to maintain the surface heat loss. This modulates the flow of heat from below and hence controls upper ocean heat content. This hypothesis is tested using the increase in incoming longwave radiation from clouds and analyzing vertical temperature profiles in the TSL retrieved from sea-surface emission spectra. The additional energy from the absorption of increasing IR radiation adjusts the curvature of the TSL such that the upward conduction of heat from the bulk of the ocean into the TSL is reduced. The additional energy absorbed within the TSL supports more of the surface heat loss. Thus, more heat beneath the TSL is retained leading to the observed increase in upper ocean heat content.

Application of far-infrared spectroscopy to the structural identification of protein materials.

PubMed

Han, Yanchen; Ling, Shengjie; Qi, Zeming; Shao, Zhengzhong; Chen, Xin

2018-05-03

Although far-infrared (IR) spectroscopy has been shown to be a powerful tool to determine peptide structure and to detect structural transitions in peptides, it has been overlooked in the characterization of proteins. Herein, we used far-IR spectroscopy to monitor the structure of four abundant non-bioactive proteins, namely, soybean protein isolate (SPI), pea protein isolate (PPI) and two types of silk fibroins (SFs), domestic Bombyx mori and wild Antheraea pernyi. The two globular proteins SPI and PPI result in broad and weak far-IR bands (between 50 and 700 cm-1), in agreement with those of some other bioactive globular proteins previously studied (lysozyme, myoglobin, hemoglobin, etc.) that generally only have random amino acid sequences. Interestingly, the two SFs, which are characterized by a structure composed of highly repetitive motifs, show several sharp far-IR characteristic absorption peaks. Moreover, some of these characteristic peaks (such as the peaks at 260 and 428 cm-1 in B. mori, and the peaks at 245 and 448 cm-1 in A. pernyi) are sensitive to conformational changes; hence, they can be directly used to monitor conformational transitions in SFs. Furthermore, since SF absorption bands clearly differ from those of globular proteins and different SFs even show distinct adsorption bands, far-IR spectroscopy can be applied to distinguish and determine the specific SF component within protein blends.

Atmospheric pressure and temperature profiling using near IR differential absorption lidar

NASA Technical Reports Server (NTRS)

Korb, C. L.; Schwemmer, G. K.; Dombrowski, M.; Weng, C. Y.

1983-01-01

The present investigation is concerned with differential absorption lidar techniques for remotely measuring the atmospheric temperature and pressure profile, surface pressure, and cloud top pressure-height. The procedure used in determining the pressure is based on the conduction of high-resolution measurements of absorption in the wings of lines in the oxygen A band. Absorption with respect to these areas is highly pressure sensitive in connection with the mechanism of collisional line broadening. The method of temperature measurement utilizes a determination of the absorption at the center of a selected line in the oxygen A band which originates from a quantum state with high ground state energy.

Measured Mass-Normalized Optical Cross Sections For Aerosolized Organophosphorus Chemical Warfare Simulants

DTIC Science & Technology

2007-08-01

solely to the absorption by the calibration gas. By equating the path-integrated extinction to the total absorption, we have ε(1/m) = α(1/m), where 6 α...using a high-resolution (0.02 wave-number) Bomem MR Series FTIR spectrometer. A radiometrically stabilized IR Nernst glow-bar is used as the broadband

Non-invasive Glucose Measurements Using Wavelength Modulated Differential Photothermal Radiometry (WM-DPTR)

NASA Astrophysics Data System (ADS)

Guo, X.; Mandelis, A.; Zinman, B.

2012-11-01

Wavelength-modulated differential laser photothermal radiometry (WM-DPTR) is introduced for potential development of clinically viable non-invasive glucose biosensors. WM-DPTR features unprecedented glucose-specificity and sensitivity by combining laser excitation by two out-of-phase modulated beams at wavelengths near the peak and the baseline of a prominent and isolated mid-IR glucose absorption band. Measurements on water-glucose phantoms (0 to 300 mg/dl glucose concentration) demonstrate high sensitivity to meet wide clinical detection requirements ranging from hypoglycemia to hyperglycemia. The measurement results have been validated by simulations based on fully developed WM-DPTR theory. For sensitive and accurate glucose measurements, the key is the selection and tight control of the intensity ratio and the phase shift of the two laser beams.

Reflectance spectroscopy of fresh whole leaves for the estimation of chemical concentration

NASA Technical Reports Server (NTRS)

Curran, Paul J.; Dungan, Jennifer L.; Macler, Bruce A.; Plummer, Stephen E.; Peterson, David L.

1992-01-01

Remotely sensed plant-canopy data in the visible and near-IR ranges are used to establish relations between the canopy reflectance and the chemical content of the leaves. The mathematical relation is generated by means of stepwise regression based on the derivative reflectance at certain wavelengths. Fourier filtering and sample control are used to minimize instrument noise and spectral overlap respectively, and absorption features are noted that correspond to sugar and protein. The coefficients of determination between estimated and measured concentrations are at least 0.82 for such substances as starch and chlorophyll. It is recommended in the analysis of remotly sensed canopy data that the chemicals with strong spectral overlaps with the chemical of interest be accounted for in order to estimate foliar chemical concentrations accurately.

Near Infrared Emission of Highly Electronically Excited CO: A Sensitive Probe to Study the Interstellar Medium??

NASA Technical Reports Server (NTRS)

Gudipati, Murthy S.

2002-01-01

Among the various spectroscopic features of the second most abundant molecule in the space, CO, "the triplet - triplet transitions involving the lowest triplet state a(sup 3)II and the higher-lying a(sup 1)3 SIGMA (sup +), d(sup 3) (DELTA), e (sup 3) SIGMA (sup -) states spanning near-UV to mid-IR spectral range" have so far not been explored in astrophysical observations. The energies of these transitions are highly sensitive to the surroundings in which CO exists, i.e. gas-phase, polar or non-polar condensed phase. It is proposed here that these triplet-triplet emission/absorption bands can be used as a sensitive probe to investigate the local environments of CO, whether in the planetary atmosphere, stellar atmosphere or interstellar medium.

Bulk damage and absorption in fused silica due to high-power laser applications

NASA Astrophysics Data System (ADS)

Nürnberg, F.; Kühn, B.; Langner, A.; Altwein, M.; Schötz, G.; Takke, R.; Thomas, S.; Vydra, J.

2015-11-01

Laser fusion projects are heading for IR optics with high broadband transmission, high shock and temperature resistance, long laser durability, and best purity. For this application, fused silica is an excellent choice. The energy density threshold on IR laser optics is mainly influenced by the purity and homogeneity of the fused silica. The absorption behavior regarding the hydroxyl content was studied for various synthetic fused silica grades. The main absorption influenced by OH vibrational excitation leads to different IR attenuations for OH-rich and low-OH fused silica. Industrial laser systems aim for the maximum energy extraction possible. Heraeus Quarzglas developed an Yb-doped fused silica fiber to support this growing market. But the performance of laser welding and cutting systems is fundamentally limited by beam quality and stability of focus. Since absorption in the optical components of optical systems has a detrimental effect on the laser focus shift, the beam energy loss and the resulting heating has to be minimized both in the bulk materials and at the coated surfaces. In collaboration with a laser research institute, an optical finisher and end users, photo thermal absorption measurements on coated samples of different fused silica grades were performed to investigate the influence of basic material properties on the absorption level. High purity, synthetic fused silica is as well the material of choice for optical components designed for DUV applications (wavelength range 160 nm - 260 nm). For higher light intensities, e.g. provided by Excimer lasers, UV photons may generate defect centers that effect the optical properties during usage, resulting in an aging of the optical components (UV radiation damage). Powerful Excimer lasers require optical materials that can withstand photon energy close to the band gap and the high intensity of the short pulse length. The UV transmission loss is restricted to the DUV wavelength range below 300 nm and consists of three different absorption bands centered at 165 nm (peroxy radicals), 215 nm (E'-center), and 265 nm (non-bridging oxygen hole center (NBOH)), which change the transmission behavior of material.

Light Absorption and Excitation-Emission Fluorescence of Urban Organic Aerosol Components and Their Relationship to Chemical Structure.

PubMed

Chen, Qingcai; Ikemori, Fumikazu; Mochida, Michihiro

2016-10-18

The present study used a combination of solvent and solid-phase extractions to fractionate organic compounds with different polarities from total suspended particulates in Nagoya, Japan, and their optical characteristics were obtained on the basis of their UV-visible absorption spectra and excitation-emission matrices (EEMs). The relationship between their optical characteristics and chemical structures was investigated based on high-resolution aerosol mass spectra (HR-AMS spectra), soft ionization mass spectra and Fourier transform infrared (FT-IR) spectra. The major light-absorption organics were less polar organic fractions, which tended to have higher mass absorption efficiencies (MAEs) and lower wavelength dependent Ångström exponents (Å) than the more polar organic fractions. Correlation analyses indicate that organic compounds with O and N atoms may contribute largely to the total light absorption and fluorescence of the organic aerosol components. The extracts from the aerosol samples were further characterized by a classification of the EEM profiles using a PARAFAC model. Different fluorescence components in the aerosol organic EEMs were associated with specific AMS ions and with different functional groups from the FT-IR analysis. These results may be useful to determine and further classify the chromophores in atmospheric organic aerosols using EEM spectroscopy.

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 by OKTAL-SE. PMID:27447635

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 by OKTAL-SE.

Unraveling the 10 micron "silicate" feature of protostars: the detection of frozen interstellar ammonia

NASA Technical Reports Server (NTRS)

Lacy, J. H.; Faraji, H.; Sandford, S. A.; Allamandola, L. J.

1998-01-01

We present infrared spectra of four embedded protostars in the 750-1230 cm-1 (13.3-8.1 microns) range. For NGC 7538 IRS 9, a new band is reported at 1110 cm-1 (9.01 microns, and several others may be present near 785, 820, 900, 1030, and 1075 cm-1 (12.7, 12.2, 11.1, 9.71, and 9.30 microns). The band 1110 cm-1 is attributed to frozen NH3. Its position and width imply that the NH3 is frozen in a polar, H2O-rich interstellar ice component. The NH3/H2O ice ratio inferred for NGC 7538 IRS 9 is 0.1, making NH3 as important a component as CH3OH and CO2 in the polar ices along this line of sight. At these concentrations, hydrogen bonding between the NH3 and H2O can account for much of the enigmatic low-frequency wing on the 3240 cm-1 (3.09 microns) H2O interstellar ice band. The strength of the implied NH3 deformation fundamental at 1624 cm-1 (6.158 microns) can also account for the absorption at this position reported by ISO.

Near infrared reflectance spectra: Applications to problems in asteroid-meteorite relationships

NASA Technical Reports Server (NTRS)

Mcfadden, Lucy A.; Chamberlin, Alan B.

1992-01-01

An observing program designed to search for evidence of ordinary chondrite parent bodies near the 3:1 Kirkwood Gap was carried out in 1985 and 1986. Studies by Wisdom (1985), Wetherill (1985), and subsequent work by Milani et al. (1989) indicate that the 3:1 Kirkwood gap is the most probable source region for the majority of ordinary chondrite meteorites. The diversity of the reflectance spectra among this small data set is surprising. Early work by Gaffey and McCord (1978) showed that the inner region of the main asteroid belt is dominated by high albedo objects with mafic silicate surfaces. One would expect to see mostly spectra with 1- and 2-micron absorption bands based on this earlier work. Only 5 (of 12) spectra have these expected features. The distribution of taxonomic types presented by Gradie and Tedesco (1982) is in most cases a useful simplification of the compositional structure of the asteroid belt. The range of spectral characteristics seen with higher resolution in the near-IR has not been previously reported and is not represented in the standard asteroid taxonomy. Near-IR spectra contain valuable mineralogical information which enhances knowledge of the composition and structure of asteroids.

Ground based mid-IR heterodyne spectrometer concept for planetary atmospheres observations

NASA Astrophysics Data System (ADS)

Garamov, V.; Benderov, O.; Semenov, V.; Spiridonov, M.; Rodin, A.; Stepanov, B.

2017-09-01

We present a heterodyne spectrometer concept based on distributed feedback (DFB) quantum cascade lasers (QCL) operated in midle infrared region (MIR). The instrument is assumed to be mount on the Russian infrared observatories. The core features of the concept are compact design, utilizing a novel mid-IR fiber optical components and dynamic local oscillator frequency locking using reference molecule absorption line. The instrument characteristics are similar to modern heterodyne devices THIS (Cologne University, Germany) and MILAHI (Tohoku University, Japan) in terms of fundamental parameters, including spectral resolution, spectral coverage in a single observation. At present moment we created laboratory setup including all necessary elements of MIR heterodyne spectrometer. We have studied different components of noises of our system and found optimal value of LO power. The measured signal to noise ratio (SNR) with MCT PD was about 10 times greater than LO's shot noise (theoretical limit of heterodyne technique SNR) and limited by QCL relative intensity noise (RIN). However, applying additional filtering it is possible to reduce this value better than 5 shot noise level, which is typical to TEC cooled MCT PD. Also we demonstrate heterodyne signal measurements using laboratory black body with temperature of 400 oC.

Water ice clouds observations with PFS on Mars Express

NASA Astrophysics Data System (ADS)

Moroz, V. I.; Zasova, L. V.; Formisano, V.; Grassi, D.; Ignatiev, N. I.; Giuranna, M.; Maturilli, A.; Pfs Team

The water ice cloud observation is one of the scientific goals of PFS. Presence and properties of the ice particles are identified from absorption features, observed in both spectral ranges of PFS. Being in the near perihelion condition, the temperature of the Martian atmosphere is pretty high and ice clouds exist only in some places, for example, related to topography or at north high latitudes et etc. The ice clouds are observed often above the tops of the volcanoes. We have found the ice clouds above Olympus (orbit 37) and Ascraeus Mons (orbit 68). Effective radius of particles according to the thermal IR is preliminary estimated of 1 μ m, which leads to the visual opacity of 0.2 -0.3 above Olympus and of maximum of 0.6 above Ascraeus Mons. In the case of Ascraeus Mons the ice clouds are observed on the south slope near the top of the volcano. The maximum surface temperature, observed there, results in the upward flux of warm air, which, cooling, provides the condensation of H2O. We will present a detailed analysis of the ice clouds, observed over the planet in the IR spectral range.

The development of a μ-biomimetic uncooled IR-Sensor inspired by the infrared receptors of Melanophila acuminata.

PubMed

Siebke, Georg; Holik, Peter; Schmitz, Sam; Tätzner, Simon; Thiesler, Jan; Steltenkamp, Siegfried

2015-03-30

The beetle Melanophila acuminata uses a specialized organ to detect infrared radiation. The organ consists of about 100 individual sensilla. The main component of the sensillum is a pressure chamber. Upon absorption of radiation, the pressure increases, and the tip of a dendrite is deformed. A unique feature of the organ is a compensation mechanism that prevents large pressures. The beetle uses this organ to detect forest fires and to navigate inside burning woods. However, the sensitivity is part of a long-lasting discussion, providing thresholds between [Formula: see text] and [Formula: see text]. To end the decade-long discussion and to provide a novel type of infrared sensor, we are developing an uncooled μ-biomimetic infrared (IR) sensor inspired by Melanophila acuminata using MEMS technology. Here, we present the development of a μ-capacitor that is used to detect pressure changes and the characterization of the compensation mechanism. We describe the microtechnological fabrication process for air-filled capacitors with a ratio of diameter-to-electrode distance of 1000 and a technique to fill the sensor bubble-free with water. Finally, we estimate the sensitivity of the beetle using a theoretical model of the sensillum.

Watching AGN feedback at its birth: HST observations of nascent outflow host IC860

NASA Astrophysics Data System (ADS)

Alatalo, Katherine

2016-10-01

IC860 is a nearby IR-luminous early-type spiral with a unique set of properties: it is a shocked, poststarburst galaxy that hosts an AGN-driven neutral wind and a compact core of molecular gas. IC860 can serve as a rosetta stone for the early stages of triggering AGN feedback. We propose to use WFC3 on HST to obtain NUV, optical and near-IR imaging of IC860. We will create a spatially-resolved history of star formation quenching through SED-fitting of 7 requested broadband filters, and compare the spatially resolved star formation histories to in different positions within the underlying stellar features (such as spiral structure) that might define a narrative of how star formation is quenching in IC860. These observations will also resolve the super-star cluster sites to trace the most recent star formation. Finally, these observations will trace the mass of the outflow by building an absorption map of the dust. IC860 presents a unique opportunity to study a galaxy at an early stage of transitioning from blue spiral to red early-type galaxy, that also hosts an AGN-driven neutral wind and a compact, turbulent molecular gas core.

Diagnosis of Breast Cancer Based on FT-IR Spectroscopy

NASA Astrophysics Data System (ADS)

Venkatachalam, P.; Rao, L. Lakshmana; Kumar, N. Krishna; Jose, Anupama; Nazeer, Shaiju S.

2008-11-01

Breast cancer is one of the most important malignant forms of cancer and a great threat to life for women. In the present study, the spectral characteristics of human breast tissues in normal and cancerous state have been investigated by Fourier transform infrared (FT-IR) absorption spectroscopy in the spectral region from 4000 to 400 cm-1. Several spectral differences were detected in the frequency regions N-H stretching, C-H vibrations, amide bands and 900-1300 cm-1. The ratio of intensities of the bands of A3300/A3015 & A1650/A1550, A2924/A2853, A1080/A1236, A1204/A1650, A1055/A1467 and A1045/A1467 provide conformational changes of protein, lipids, nucleic acids, collagen, carbohydrates and glycogen respectively in the human breast tissues. There are obvious differences in the spectral features between normal and cancerous tissues because of changes in molecular compositions and structures that accompany the transformation from a normal to a cancerous state. The differences suggest that the spectral information are useful for the diagnosis of breast cancer and may serve as a basis for conformational changes in tissue components during carcinogenesis.

Unusual Coexistence of Nickel(II) and Nickel(IV) in the Quadruple Perovskite Ba 4Ni 2Ir 2O 12 Containing Ir 2NiO 12 Mixed-Metal-Cation Trimers

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ferreira, Timothy; Heald, Steve M.; Smith, Mark. D.

In this paper, the crystal chemistry and magnetic properties of two hexagonal nickel(IV)-containing perovskites, Ba 4Ni 1.94Ir 2.06O 12 and BaNiO 3, are reported. The 12R perovskite, Ba 4Ni 1.94Ir 2.06O 12, possesses an unexpected coexistence of nickel(II) and nickel(IV). This quadruple perovskite structure contains Ir 2NiO 12 mixed-metal-cation units in which direct metal–metal bonding between nickel(IV) and iridium(V) is inferred. Finally, X-ray absorption near-edge spectroscopy and X-ray photoelectron spectroscopy measurements were conducted to confirm the simultaneous presence of nickel(II) and nickel(IV).

Selective laser ablation of carious lesions using simultaneous scanned near-IR diode and CO2 lasers

NASA Astrophysics Data System (ADS)

Chan, Kenneth H.; Fried, Daniel

2017-02-01

Previous studies have established that carious lesions can be imaged with high contrast using near-IR wavelengths coincident with high water absorption, namely 1450-nm, without the interference of stains. It has been demonstrated that computer-controlled laser scanning systems utilizing IR lasers operating at high pulse repetition rates can be used for serial imaging and selective removal of caries lesions. In this study, a point-to-point scanning system was developed integrating a 1450-nm diode laser with the CO2 ablation laser. This approach is advantageous since it does not require an expensive near-IR camera. In this pilot study, we demonstrate the feasibility of a combined NIR and IR laser system for the selective removal of carious lesions.

Selective Laser Ablation of Carious Lesions using Simultaneous Scanned Near-IR Diode and CO2 Lasers.

PubMed

Chan, Kenneth H; Fried, Daniel

2017-01-28

Previous studies have established that carious lesions can be imaged with high contrast using near-IR wavelengths coincident with high water absorption, namely 1450-nm, without the interference of stains. It has been demonstrated that computer-controlled laser scanning systems utilizing IR lasers operating at high pulse repetition rates can be used for serial imaging and selective removal of caries lesions. In this study, a point-to-point scanning system was developed integrating a 1450-nm diode laser with the CO 2 ablation laser. This approach is advantageous since it does not require an expensive near-IR camera. In this pilot study, we demonstrate the feasibility of a combined NIR and IR laser system for the selective removal of carious lesions.

Unusual Coexistence of Nickel(II) and Nickel(IV) in the Quadruple Perovskite Ba 4Ni 2Ir 2O 12 Containing Ir 2NiO 12 Mixed-Metal-Cation Trimers

DOE PAGES

Ferreira, Timothy; Heald, Steve M.; Smith, Mark. D.; ...

2018-03-02

In this paper, the crystal chemistry and magnetic properties of two hexagonal nickel(IV)-containing perovskites, Ba 4Ni 1.94Ir 2.06O 12 and BaNiO 3, are reported. The 12R perovskite, Ba 4Ni 1.94Ir 2.06O 12, possesses an unexpected coexistence of nickel(II) and nickel(IV). This quadruple perovskite structure contains Ir 2NiO 12 mixed-metal-cation units in which direct metal–metal bonding between nickel(IV) and iridium(V) is inferred. Finally, X-ray absorption near-edge spectroscopy and X-ray photoelectron spectroscopy measurements were conducted to confirm the simultaneous presence of nickel(II) and nickel(IV).

Structures and spectroscopic properties of nonperipherally and peripherally substituted metal-free phthalocyanines: a substitution effect study based on density functional theory calculations.

PubMed

Zhong, Aimin; Zhang, Yuexing; Bian, Yongzhong

2010-11-01

The molecular structures, molecular orbitals, atomic charges, electronic absorption spectra, and infrared (IR) and Raman spectra of a series of substituted metal-free phthalocyanine compounds with four (1, 3, 5, 7) or eight (2, 4, 6, 8) methoxyl (1, 2, 5, 6) or methylthio groups (3, 4, 7, 8) on the nonperipheral (1-4) or peripheral positions (5-8) of the phthalocyanine ring are studied by density functional theory (DFT) and time-dependent DFT (TD-DFT) calculations. The calculated structural parameters and simulated electronic absorption and IR spectra are compared with the X-ray crystallography structures and the experimentally observed electronic absorption and IR spectra of the similar molecules, and good agreement between the calculated and experimental results is found. The substitution of the methoxyl or methylthio groups at the nonperipheral positions of the phthalocyanine ring has obvious effects on the molecular structure and spectroscopic properties of the metal-free phthalocyanine. Nonperipheral substitution has a more significant influence than peripheral substitution. The substitution effect increases with an increase in the number of substituents. The methylthio group shows more significant influence than the methoxyl group, despite the stronger electron-donating property of the methoxyl group than the methylthio group. The octa-methylthio-substituted metal-free phthalocyanine compounds have nonplanar structures whose low-lying occupied molecular orbitals and electronic absorption spectra are significantly changed by the substituents. The present systematical study will be helpful for understanding the relationship between structures and properties in phthalocyanine compounds and designing phthalocyanines with typical properties. Copyright © 2010 Elsevier Inc. All rights reserved.

Adsorption and detection of Escherichia coli using an Au substrate modified with a catecholate-type artificial siderophore-Fe3+ complex.

PubMed

Inomata, Tomohiko; Tanabashi, Hirohito; Funahashi, Yasuhiro; Ozawa, Tomohiro; Masuda, Hideki

2013-12-07

A catecholate-type artificial siderophore with a terminal-NH2 group (1) and its Fe(3+) complex (2) were prepared. Siderophore 1 was characterized by (1)H NMR, FT-IR, and ESI-TOF MS spectroscopy. The corresponding Fe(3+) complex 2 was obtained by reaction of 1 with Fe(acac)3. The absorption band at 500 nm (ε = 4670 M(-1) cm(-1) at pH 7.0) of the electronic absorption spectrum of 2 is assignable as the LMCT (O(catecholate) → Fe(3+)) absorption band. This band indicates the formation of the Fe(3+) complex of 1. The biological activity of 2 with respect to Escherichia coli was clearly confirmed by observing that it permeates into the cell membrane. The self-assembled monolayer of 2 on an Au substrate, 2/Au, was prepared and its preparation was confirmed by FT-IR reflection-absorption spectroscopy (IR-RAS) and cyclic voltammetry (CV). Furthermore, a quartz crystal microbalance (QCM) chip modified with 2 effectively adsorbed E. coli. M. flavescens, an organism which is incapable of synthesizing siderophores and must therefore use exogenous hydroxamate-type siderophores for growth, did not adsorb on 2/Au. In contrast, E. coli did not adsorb on the hydroxamate-type artificial siderophore-Fe(3+) complex (3)-modified Au substrate, 3/Au. These results provide preliminary evidence that microbes recognized Fe(3+) ion-bound siderophores on the surface. The detection limit of 2/Au was ∼10(4) CFU mL(-1).

Electrochemistry of Metal Surfaces

DTIC Science & Technology

1990-06-30

i) 3-pyridine carboxylic acid ( nicotinic acid, NA) binds to Pt surfaces through both the nitrogen atom and an oxygen atom of the carboxylate group...formed from aqueous electrolytes at Pt(1l1) electrode surfaces have been compared with the IR and Raman spectra of the unadsorbed compounds in order...vibrational absorptivities between EELS spectra of adsorbed species and IR and Raman spectra of the corresponding unadsorbed compounds (146). Of

VizieR Online Data Catalog: Near-IR spectrum of 2M1207b (Patience+, 2010)

NASA Astrophysics Data System (ADS)

Patience, J.; King, R. R.; de Rosa, R. J.; Marois, C.

2010-08-01

Near-IR spectroscopy of the planetary-mass companion to 2M1207. These observations were made with the ESO VLT SINFONI spectrograph. The flux has been scaled by the J and K-band photometry in the J and HK spectral orders. In regions of high telluric absorption the data have been masked and flux set to zero. (1 data file).

Calculation of UV, IR, and NMR Spectra of Diethyl 2,2'-[(1,1'-Biphenyl)-4,4'-Diylbis(Azanediyl)]Diacetate

NASA Astrophysics Data System (ADS)

Almodarresiyeh, H. A.; Shahab, S. N.; Zelenkovsky, V. M.; Ariko, N. G.; Filippovich, L. N.; Agabekov, V. E.

2014-03-01

The new substance diethyl 2,2'-[(1,1'-biphenyl)-4,4'-diylbis(azanediyl)]diacetate (M13) was modeled using the Hartree-Fock and density functional theory methods and then synthesized. The electronic absorption spectrum of M13 in dimethylformamide solution was calculated. The UV, IR, and NMR spectra of M13 were presented.

Infrared molecular emissions from comets

NASA Technical Reports Server (NTRS)

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

1984-01-01

The possibility of detecting IR molecular line emission from cometary parent molecules is explored. Due to the non-LTE conditions in the inner coma and the large amount of near IR solar flux, IR fluorescence will be a significant source of cometary emission and, in fact, will dominate the grain radiation in a sufficiently high resolution instrument. The detection of this line emission will be difficult due to absorption in the terrestrial atmosphere, but it appears possible to measure cometary H2O emission from airplane altitudes. As IR molecular line emission represents one of the few promising methods of detecting cometary parent molecules directly, further research on this problem should be vigorously pursued. Previously announced in STAR as N83-30344

Spectral and Vertical Distribution Properties of Titan's Particulates from Thermal-IR CIRS Data: Physical Implications

NASA Technical Reports Server (NTRS)

Anderson, Carrie M.; Samuelson, Robert; Vinatier, Sandrine

2011-01-01

Analyses of far-IR spectra between 20 and 560/cm (500 and 18 micron) recorded by the Cassini Composite Infrared Spectrometer (CIRS) yield the spectral dependence and the vertical distribution of Titan's photochemical aerosol and stratospheric ice clouds. Below the stratopause (approx. 300 km) the aerosol appears to be incompletely mixed for the following reasons: 1) the altitude dependence of the aerosol mass absorption coefficient is larger at higher altitudes than at lower altitudes, 2} the aerosol scale height varies with altitude, which implies some kind of layering effect, and 3) the aerosol abundance varies with latitude. The spectral shape of the aerosol opacity appears to be independent in altitude and latitude below the stratopause, even though inhomogeneities in the abundance appear to be prevalent throughout this altitude region. This implies that aerosol chemistry is restricted to altitude regions above the stratopause, where pressures are less than approx 0.1 mbar. The aerosol exhibits an extremely broad emisSion feature with a spectral peak at 140/cm (71 micron), which is not evident in laboratory simulated Titan aerosols (tholin) that are created at pressures greater than 0.1 mbar. A strong broad emission feature centered roughly around 160 cm-1 corresponds very closely to those found in nitrile ice spectra. This feature is pervasive throughout the region from high northern to high southern latitudes. The inference of nitrile ices is consistent with the highly restricted altitude ranges over which these features are observed, and appear to be dominated by HCN and HC3N. At low and moderate latitudes these clouds are observed to be located between 60 and 100 km, whereas at high northern latitudes during northern winter these clouds are observed at altitudes between 150 and 165 km. The ubiquitous nature of these nitrile ice clouds is inconsistent with a simple meridional circulation concept, suggesting that the true dynamical situation is more complex.

On the Nature of the Hard X-Ray Sources SWIFT J1907.3-2050, IGR J12123-5802 and IGR J19552+0044

NASA Technical Reports Server (NTRS)

Bernardini, F.; deMartino, D; Mukai, K.; Falanga, M.; Andruchow, I.; Bonnet-Bidaud, J.-M.; Masetti, N.; GonzalezBuitrago, D. H.; Mouchet, M.; Tovmassian, G.

2014-01-01

The INTEGRAL and Swift hard X-ray surveys have identified a large number of new sources, among which many are proposed as Cataclysmic Variables (CVs). Here we present the first detailed study of three X-ray selected CVs, Swift J1907.3-2050, IGRJ12123-5802, and IGRJ19552+0044 based on XMM-Newton, Suzaku, Swift observations and ground based optical and archival nIR/IR data. Swift J1907.3-2050 is highly variable from hours to monthsyears at all wavelengths. No coherent X-ray pulses are detected but rather transient features. The X-ray spectrum reveals a multi-temperature optically thin plasma absorbed by complex neutral material and a soft black body component arising from a small area. These characteristics are remarkably similar to those observed in magnetic CVs. A supra-solar abundance of nitrogen could arise from nuclear processed material from the donor star. Swift J1907.3-2050 could be a peculiar magnetic CV with the second longest (20.82 h) binary period. IGRJ12123-5802 is variable in the X-rays on a timescale of approximately or greater than 7.6 h. No coherent pulsations are detected, but its spectral characteristics suggest that it could be a magnetic CV of the Intermediate Polar (IP) type. IGRJ19552+0044 shows two X-ray periods, approximately 1.38 h and approximately 1.69 h and a X-ray spectrum characterized by a multi-temperature plasma with little absorption.We derive a low accretion rate, consistent with a CV below the orbital period gap. Its peculiar nIR/IR spectrum suggests a contribution from cyclotron emission. It could either be a pre-polar or an IP with the lowest degree of asynchronism.

Infrared spectra of the 1-pyridinium (C5H5NH+) cation and pyridinyl (C5H5NH and 4-C5H6N) radicals isolated in solid para-hydrogen.

PubMed

Golec, Barbara; Das, Prasanta; Bahou, Mohammed; Lee, Yuan-Pern

2013-12-19

Protonated pyridine and its neutral counterparts (C5H6N) are important intermediates in organic and biological reactions and in the atmosphere. We have recorded the IR absorption spectra of the 1-pyridinium (C5H5NH(+)) cation, 1-pyridinyl (C5H5NH), and 4-pyridinyl (4-C5H6N) produced on electron bombardment during matrix deposition of a mixture of pyridine (C5H5N) and p-H2 at 3.2 K; all spectra were previously unreported. The IR features of C5H5NH(+) diminished in intensity after the matrix was maintained in darkness for 15 h, whereas those of C5H5NH and 4-C5H6N radicals increased. Irradiation of this matrix with light at 365 nm diminished lines of C5H5NH(+) and C5H5NH but enhanced lines of 4-C5H6N slightly, whereas irradiation at 405 nm diminished lines of 4-C5H6N significantly. Observed wavenumbers and relative intensities of these species agree satisfactorily with the anharmonic vibrational wavenumbers and IR intensities predicted with the B3LYP/6-31++G(d,p) method. Assignments of C5H5NH and 4-C5H6N radicals were further supported by the observation of similar spectra when a Cl2/C5H5N/p-H2 matrix was irradiated first at 365 nm and then with IR light to generate H atoms to induce the H + C5H5N reaction.

Qualification of security printing features

NASA Astrophysics Data System (ADS)

Simske, Steven J.; Aronoff, Jason S.; Arnabat, Jordi

2006-02-01

This paper describes the statistical and hardware processes involved in qualifying two related printing features for their deployment in product (e.g. document and package) security. The first is a multi-colored tiling feature that can also be combined with microtext to provide additional forms of security protection. The color information is authenticated automatically with a variety of handheld, desktop and production scanners. The microtext is authenticated either following magnification or manually by a field inspector. The second security feature can also be tile-based. It involves the use of two inks that provide the same visual color, but differ in their transparency to infrared (IR) wavelengths. One of the inks is effectively transparent to IR wavelengths, allowing emitted IR light to pass through. The other ink is effectively opaque to IR wavelengths. These inks allow the printing of a seemingly uniform, or spot, color over a (truly) uniform IR emitting ink layer. The combination converts a uniform covert ink and a spot color to a variable data region capable of encoding identification sequences with high density. Also, it allows the extension of variable data printing for security to ostensibly static printed regions, affording greater security protection while meeting branding and marketing specifications.

Utilizing Near-IR Tunable Laser Absorption Spectroscopy to Study Detonation and Combustion Systems

DTIC Science & Technology

2014-03-27

debris, such as soot . Velocity curves for the other equivalence ratios studied in this experiment are shown in Appendix A. Some of these curves show a...James R. Gord. “Measurements of OH mole fraction and temperature up to 20 kHz by using a diode-laser based UV absorption sensor ”. Applied Optics, 44...Davidson, and R.K. Hanson. “CO concentration and temperature sensor for combustion gases using quantum-cascade laser absorption near 4.7µm”. Applied

Evaluation of a 12-Hour Sustained-Release Acetaminophen (Paracetamol) Formulation: A Randomized, 3-Way Crossover Pharmacokinetic and Safety Study in Healthy Volunteers.

PubMed

Yue, Yong; Collaku, Agron; Liu, Dongzhou J

2018-01-01

Acetaminophen (paracetamol) is a first-line treatment for mild and moderate pain. A twice-daily sustained-release (SR) formulation may be more convenient for chronic users than standard immediate-release (IR) acetaminophen. This randomized, 3-way crossover study evaluated pharmacokinetics and safety of single-dose 1500- and 2000-mg SR acetaminophen formulations and 2 doses of IR acetaminophen 1000 mg given 6 hours apart in healthy adults (n = 14). Primary outcome was time that plasma acetaminophen concentration was ≥4 μg/mL (T C≥4μg/mL ). Key secondary outcomes were area under the plasma concentration-time curve (AUC) from time 0 to time t, when plasma acetaminophen was detectable (AUC 0-t ), AUC from 0 to infinity (AUC 0-inf ), and maximum plasma acetaminophen concentration (C max ). T C≥4μg/mL from 2000-mg SR acetaminophen was similar to that from 2 doses of IR acetaminophen, whereas T C≥4μg/mL for 1500-mg SR acetaminophen was significantly shorter than that for IR acetaminophen (P = .004). The extent of acetaminophen absorption from 2000-mg SR and 2 doses of the IR formulation was similar and within bioequivalence limits with regard to AUC 0-12 , AUC 0-t , and AUC 0-inf . The extent of acetaminophen absorption from 1500-mg SR was significantly lower than that from IR acetaminophen. The 2000-mg SR represents a potential candidate formulation for 12-hour dosing with acetaminophen. © 2017, The American College of Clinical Pharmacology.

Molecular recognition using receptor-free nanomechanical infrared spectroscopy based on a quantum cascade laser

PubMed Central

Kim, Seonghwan; Lee, Dongkyu; Liu, Xunchen; Van Neste, Charles; Jeon, Sangmin; Thundat, Thomas

2013-01-01

Speciation of complex mixtures of trace explosives presents a formidable challenge for sensors that rely on chemoselective interfaces due to the unspecific nature of weak intermolecular interactions. Nanomechanical infrared (IR) spectroscopy provides higher selectivity in molecular detection without using chemoselective interfaces by measuring the photothermal effect of adsorbed molecules on a thermally sensitive microcantilever. In addition, unlike conventional IR spectroscopy, the detection sensitivity is drastically enhanced by increasing the IR laser power, since the photothermal signal comes from the absorption of IR photons and nonradiative decay processes. By using a broadly tunable quantum cascade laser for the resonant excitation of molecules, we increased the detection sensitivity by one order of magnitude compared to the use of a conventional IR monochromator. Here, we demonstrate the successful speciation and quantification of picogram levels of ternary mixtures of similar explosives (trinitrotoluene (TNT), cyclotrimethylene trinitramine (RDX), and pentaerythritol tetranitrate (PETN)) using nanomechanical IR spectroscopy. PMID:23346368

Simultaneous multi-beam planar array IR (pair) spectroscopy

DOEpatents

Elmore, Douglas L.; Rabolt, John F.; Tsao, Mei-Wei

2005-09-13

An apparatus and method capable of providing spatially multiplexed IR spectral information simultaneously in real-time for multiple samples or multiple spatial areas of one sample using IR absorption phenomena requires no moving parts or Fourier Transform during operation, and self-compensates for background spectra and degradation of component performance over time. IR spectral information and chemical analysis of the samples is determined by using one or more IR sources, sampling accessories for positioning the samples, optically dispersive elements, a focal plane array (FPA) arranged to detect the dispersed light beams, and a processor and display to control the FPA, and display an IR spectrograph. Fiber-optic coupling can be used to allow remote sensing. Portability, reliability, and ruggedness is enhanced due to the no-moving part construction. Applications include determining time-resolved orientation and characteristics of materials, including polymer monolayers. Orthogonal polarizers may be used to determine certain material characteristics.

Dusty Winds in Active Galactic Nuclei: Reconciling Observations with Models

NASA Astrophysics Data System (ADS)

Hönig, Sebastian F.; Kishimoto, Makoto

2017-04-01

This Letter presents a revised radiative transfer model for the infrared (IR) emission of active galactic nuclei (AGNs). While current models assume that the IR is emitted from a dusty torus in the equatorial plane of the AGNs, spatially resolved observations indicate that the majority of the IR emission from ≲100 pc in many AGNs originates from the polar region, contradicting classical torus models. The new model CAT3D-WIND builds upon the suggestion that the dusty gas around the AGNs consists of an inflowing disk and an outflowing wind. Here, it is demonstrated that (1) such disk+wind models cover overall a similar parameter range of observed spectral features in the IR as classical clumpy torus models, e.g., the silicate feature strengths and mid-IR spectral slopes, (2) they reproduce the 3-5 μm bump observed in many type 1 AGNs unlike torus models, and (3) they are able to explain polar emission features seen in IR interferometry, even for type 1 AGNs at relatively low inclination, as demonstrated for NGC3783. These characteristics make it possible to reconcile radiative transfer models with observations and provide further evidence of a two-component parsec-scale dusty medium around AGNs: the disk gives rise to the 3-5 μm near-IR component, while the wind produces the mid-IR emission. The model SEDs will be made available for download.

Optical losses in p-type layers of GaN ridge waveguides in the IR region

NASA Astrophysics Data System (ADS)

Westreich, Ohad; Katz, Moti; Atar, Gil; Paltiel, Yossi; Sicron, Noam

2017-07-01

Optical losses in c-plane (0001) GaN ridge waveguides, containing Mg-doped layers, were measured at 1064 nm, using the Fabry-Perot method. The losses increase linearly with the modal content of the p-layer, indicating that the absorption in these waveguides is dominated by p-layer absorption. The p-layer absorption is strongly anisotropic with E⊥c losses 4 times higher than E∥c. The absorption is temperature independent between 10 °C and 60 °C, supporting the possibility that it is related to Mg-bound holes.

Status of the Suomi-NPP VIIRS Moisture Products

NASA Astrophysics Data System (ADS)

Borbas, E. E.; Li, Z.; Menzel, W. P.; Rada, M.

2017-12-01

The goal of the Soumi NPP VIIRS Moisture Project is to provide total column water vapor (TPW) properties from merged VIIRS infrared measurements and CrIS plus ATMS water vapor soundings to continue the depiction of global moisture at high spatial resolution started with MODIS. While MODIS has two water vapor channels within the 6.5 μm H2O absorption band and four channels within the 15 μm CO2 absorption band, VIIRS has no channels in either IR absorption band. The VIIRS/CrIS+ATMS TPW algorithm being developed at CIMSS is similar to the MOD07 synthetic regression algorithm. It uses the three VIIRS longwave IR window bands in a regression relation and adds the NUCAPS (CrIS+ATMS) water vapor product to compensate for the absence of VIIRS water vapor channels. This poster presents the methodology and evaluation of the S-NPP TPW Level 2 and 3 products with TPW data from ground-based and satellite-based measurements.

IR multiphoton absorption of SF6 in flow with Ar at moderate energy fluences

NASA Astrophysics Data System (ADS)

Makarov, G. N.; Ronander, E.; van Heerden, S. P.; Gouws, M.; van der Merwe, K.

1997-10-01

IR multiple photon absorption (MPA) of SF6 in flow with Ar (SF6: Ar=1:100) in conditions of a large vibrational/rotational temperature difference (TV𪒮 K, TR䏐 K) was studied at moderate energy fluences from ۂ.1 to 𪐬 mJ/cm2, which are of interest for isotope selective two-step dissociation of molecules. A 50 cm Laval-type slit nozzle for the flow cooling, and a TEA CO2-laser for excitation of molecules were used in the experiments. The laser energy fluence dependences of the SF6 MPA were studied for several CO2-laser lines which are in a good resonance with the linear absorption spectrum of the Ƚ vibration of SF6 at low temperature. The effect of the laser pulse duration (intensity) on MPA of flow cooled SF6 with Ar was also studied. The results are compared with those obtained in earlier studies.