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Sample records for infrared reflection-absorption spectroscopy

  1. Titanium-silicon oxide film structures for polarization-modulated infrared reflection absorption spectroscopy

    PubMed Central

    Dunlop, Iain E.; Zorn, Stefan; Richter, Gunther; Srot, Vesna; Kelsch, Marion; van Aken, Peter A.; Skoda, Maximilian; Gerlach, Alexander; Spatz, Joachim P.; Schreiber, Frank

    2010-01-01

    We present a titanium-silicon oxide film structure that permits polarization modulated infrared reflection absorption spectroscopy on silicon oxide surfaces. The structure consists of a ~6 nm sputtered silicon oxide film on a ~200 nm sputtered titanium film. Characterization using conventional and scanning transmission electron microscopy, electron energy loss spectroscopy, X-ray photoelectron spectroscopy and X-ray reflectometry is presented. We demonstrate the use of this structure to investigate a selectively protein-resistant self-assembled monolayer (SAM) consisting of silane-anchored, biotin-terminated poly(ethylene glycol) (PEG). PEG-associated IR bands were observed. Measurements of protein-characteristic band intensities showed that this SAM adsorbed streptavidin whereas it repelled bovine serum albumin, as had been expected from its structure. PMID:20418963

  2. Angle-tunable enhanced infrared reflection absorption spectroscopy via grating-coupled surface plasmon resonance.

    PubMed

    Petefish, Joseph W; Hillier, Andrew C

    2014-03-04

    Surface enhanced infrared absorption (SEIRA) spectroscopy is an attractive method for increasing the prominence of vibrational modes in infrared spectroscopy. To date, the majority of reports associated with SEIRA utilize localized surface plasmon resonance from metal nanoparticles to enhance electromagnetic fields in the region of analytes. Limited work has been performed using propagating surface plasmons as a method for SEIRA excitation. In this report, we demonstrate angle-tunable enhancement of vibrational stretching modes associated with a thin poly(methyl methacrylate) (PMMA) film that is coupled to a silver-coated diffraction grating. Gratings are fabricated using laser interference lithography to achieve precise surface periodicities, which can be used to generate surface plasmons that overlap with specific vibrational modes in the polymer film. Infrared reflection absorption spectra are presented for both bare silver and PMMA-coated silver gratings at a range of angles and polarization states. In addition, spectra were obtained with the grating direction oriented perpendicular and parallel to the infrared source in order to isolate plasmon enhancement effects. Optical simulations using the rigorous coupled-wave analysis method were used to identify the origin of the plasmon-induced enhancement. Angle-dependent absorption measurements achieved signal enhancements of more than 10-times the signal in the absence of the plasmon.

  3. Reflection-absorption infrared spectroscopy of thin films using an external cavity quantum cascade laser

    NASA Astrophysics Data System (ADS)

    Phillips, Mark C.; Craig, Ian M.; Blake, Thomas A.

    2013-01-01

    We present experimental demonstrations using a broadly tunable external cavity quantum cascade laser (ECQCL) to perform Reflection-Absorption InfraRed Spectroscopy (RAIRS) of thin layers and residues on surfaces. The ECQCL compliance voltage was used to measure fluctuations in the ECQCL output power and improve the performance of the RAIRS measurements. Absorption spectra from self-assembled monolayers of a fluorinated alkane thiol and a thiol carboxylic acid were measured and compared with FTIR measurements. RAIRS spectra of the explosive compounds PETN, RDX, and tetryl deposited on gold substrates were also measured. Rapid measurement times and low noise were demonstrated, with <1E-3 absorbance noise for a 10 second measurement time.

  4. Infrared Reflection-Absorption Spectroscopy: Principles and Applications to Lipid-Protein Interaction in Langmuir Films

    PubMed Central

    Mendelsohn, Richard; Mao, Guangru; Flach, Carol R.

    2010-01-01

    Infrared reflection-absorption spectroscopy (IRRAS) of lipid/protein monolayer films in situ at the air/water interface provides unique molecular structure and orientation information from the film constituents. The technique is thus well suited for studies of lipid/protein interaction in a physiologically relevant environment. Initially, the nature of the IRRAS experiment is described and the molecular structure information that may be obtained is recapitulated. Subsequently, several types of applications, including the determination of lipid chain conformation and tilt as well as elucidation of protein secondary structure are reviewed. The current article attempts to provide the reader with an understanding of the current capabilities of IRRAS instrumentation and the type of results that have been achieved to date from IRRAS studies of lipids, proteins and lipid/protein films of progressively increasing complexity. Finally, possible extensions of the technology are briefly considered. PMID:20004639

  5. Reflection-Absorption Infrared Spectroscopy of Thin Films Using an External Cavity Quantum Cascade Laser

    SciTech Connect

    Phillips, Mark C.; Craig, Ian M.; Blake, Thomas A.

    2013-02-04

    We present experimental demonstrations using a broadly tunable external cavity quantum cascade laser (ECQCL) to perform Reflection-Absorption InfraRed Spectroscopy (RAIRS) of thin layers and residues on surfaces. The ECQCL compliance voltage was used to measure fluctuations in the ECQCL output power and improve the performance of the RAIRS measurements. Absorption spectra from self-assembled monolayers of a fluorinated alkane thiol and a thiol carboxylic acid were measured and compared with FTIR measurements. RAIRS spectra of the explosive compounds PETN, RDX, and tetryl deposited on gold substrates were also measured. Rapid measurement times and low noise were demonstrated, with < 1E-3 absorbance noise for a 10 second measurement time.

  6. Quantum state-resolved gas/surface reaction dynamics probed by reflection absorption infrared spectroscopy.

    PubMed

    Chen, Li; Ueta, Hirokazu; Bisson, Régis; Beck, Rainer D

    2013-05-01

    We report the design and characterization of a new molecular-beam/surface-science apparatus for quantum state-resolved studies of gas/surface reaction dynamics combining optical state-specific reactant preparation in a molecular beam by rapid adiabatic passage with detection of surface-bound reaction products by reflection absorption infrared spectroscopy (RAIRS). RAIRS is a non-invasive infrared spectroscopic detection technique that enables online monitoring of the buildup of reaction products on the target surface during reactant deposition by a molecular beam. The product uptake rate obtained by calibrated RAIRS detection yields the coverage dependent state-resolved reaction probability S(θ). Furthermore, the infrared absorption spectra of the adsorbed products obtained by the RAIRS technique provide structural information, which help to identify nascent reaction products, investigate reaction pathways, and determine branching ratios for different pathways of a chemisorption reaction. Measurements of the dissociative chemisorption of methane on Pt(111) with this new apparatus are presented to illustrate the utility of RAIRS detection for highly detailed studies of chemical reactions at the gas/surface interface.

  7. Quantum state-resolved gas/surface reaction dynamics probed by reflection absorption infrared spectroscopy

    SciTech Connect

    Chen Li; Ueta, Hirokazu; Beck, Rainer D.; Bisson, Regis

    2013-05-15

    We report the design and characterization of a new molecular-beam/surface-science apparatus for quantum state-resolved studies of gas/surface reaction dynamics combining optical state-specific reactant preparation in a molecular beam by rapid adiabatic passage with detection of surface-bound reaction products by reflection absorption infrared spectroscopy (RAIRS). RAIRS is a non-invasive infrared spectroscopic detection technique that enables online monitoring of the buildup of reaction products on the target surface during reactant deposition by a molecular beam. The product uptake rate obtained by calibrated RAIRS detection yields the coverage dependent state-resolved reaction probability S({theta}). Furthermore, the infrared absorption spectra of the adsorbed products obtained by the RAIRS technique provide structural information, which help to identify nascent reaction products, investigate reaction pathways, and determine branching ratios for different pathways of a chemisorption reaction. Measurements of the dissociative chemisorption of methane on Pt(111) with this new apparatus are presented to illustrate the utility of RAIRS detection for highly detailed studies of chemical reactions at the gas/surface interface.

  8. Phase transitions of amorphous solid acetone in confined geometry investigated by reflection absorption infrared spectroscopy.

    PubMed

    Shin, Sunghwan; Kang, Hani; Kim, Jun Soo; Kang, Heon

    2014-11-26

    We investigated the phase transformations of amorphous solid acetone under confined geometry by preparing acetone films trapped in amorphous solid water (ASW) or CCl4. Reflection absorption infrared spectroscopy (RAIRS) and temperature-programmed desorption (TPD) were used to monitor the phase changes of the acetone sample with increasing temperature. An acetone film trapped in ASW shows an abrupt change in the RAIRS features of the acetone vibrational bands during heating from 80 to 100 K, which indicates the transformation of amorphous solid acetone to a molecularly aligned crystalline phase. Further heating of the sample to 140 K produces an isotropic solid phase, and eventually a fluid phase near 157 K, at which the acetone sample is probably trapped in a pressurized, superheated condition inside the ASW matrix. Inside a CCl4 matrix, amorphous solid acetone crystallizes into a different, isotropic structure at ca. 90 K. We propose that the molecularly aligned crystalline phase formed in ASW is created by heterogeneous nucleation at the acetone-water interface, with resultant crystal growth, whereas the isotropic crystalline phase in CCl4 is formed by homogeneous crystal growth starting from the bulk region of the acetone sample.

  9. Photoelastic modulation-reflection absorption infrared spectroscopy of CO on Pd(111)

    NASA Astrophysics Data System (ADS)

    Stacchiola, D.; Thompson, A. W.; Kaltchev, M.; Tysoe, W. T.

    2002-11-01

    The photoelastic modulation-reflection absorption infrared spectrum (PEM-RAIRS) of CO on single crystal Pd(111) is measured for CO pressures up to ~150 Torr. The ac component of the signal, corresponding to the infrared signal of the surface, is measured using a synchronous demodulator circuit rather than using a lock-in amplifier as used in previous experiments to measure the infrared spectra of model catalysts surfaces. This allows the spectra to be collected at almost the same speed as RAIRS spectra performed in ultrahigh vacuum. A simplified synchronous demodulator circuit is described consisting of two sample-and-hold circuits operating at 100 kHz. Spectra are obtained that are in excellent agreement with previous results showing that a combination of hcp and fcc threefold sites are occupied by CO at 300 K. Atop sites become occupied as the CO pressure increases. Heating the Pd(111) sample to ~500 K removes all adsorbed CO.

  10. Multipitched Diffraction Gratings for Surface Plasmon Resonance-Enhanced Infrared Reflection Absorption Spectroscopy.

    PubMed

    Petefish, Joseph W; Hillier, Andrew C

    2015-11-03

    We demonstrate the application of metal-coated diffraction gratings possessing multiple simultaneous pitch values for surface enhanced infrared absorption (SEIRA) spectroscopy. SEIRA increases the magnitude of vibrational signals in infrared measurements by one of several mechanisms, most frequently involving the enhanced electric field associated with surface plasmon resonance (SPR). While the majority of SEIRA applications to date have employed nanoparticle-based plasmonic systems, recent advances have shown how various metals and structures lead to similar signal enhancement. Recently, diffraction grating couplers have been demonstrated as a highly tunable platform for SEIRA. Indeed, gratings are an experimentally advantageous platform due to the inherently tunable nature of surface plasmon excitation at these surfaces since both the grating pitch and incident angle can be used to modify the spectral location of the plasmon resonance. In this work, we use laser interference lithography (LIL) to fabricate gratings possessing multiple pitch values by subjecting photoresist-coated glass slides to repetitive exposures at varying orientations. After metal coating, these gratings produced multiple, simultaneous plasmon peaks associated with the multipitched surface, as identified by infrared reflectance measurements. These plasmon peaks could then be coupled to vibrational modes in thin films to provide localized enhancement of infrared signals. We demonstrate the flexibility and tunability of this platform for signal enhancement. It is anticipated that, with further refinement, this approach might be used as a general platform for broadband enhancement of infrared spectroscopy.

  11. Structural changes in a polyelectrolyte multilayer assembly investigated by reflection absorption infrared spectroscopy and sum frequency generation spectroscopy.

    PubMed

    Kett, Peter J N; Casford, Michael T L; Yang, Amanda Y; Lane, Thomas J; Johal, Malkiat S; Davies, Paul B

    2009-02-12

    The structure of polyelectrolyte multilayer films adsorbed onto either a per-protonated or per-deuterated 11-mercaptoundecanoic acid (h-MUA/d-MUA) self assembled monolayer (SAM) on gold was investigated in air using two surface vibrational spectroscopy techniques, namely, reflection absorption infrared spectroscopy (RAIRS) and sum frequency generation (SFG) spectroscopy. Determination of film masses and dissipation values were made using a quartz crystal microbalance with dissipation monitoring (QCM-D). The films, containing alternating layers of the polyanion poly[1-[4-(3-carboxy-4-hydroxyphenylazo) benzenesulfonamido]-1,2-ethanediyl, sodium salt] (PAZO) and the polycation poly(ethylenimine) (PEI) built on the MUA SAM, were formed using the layer-by-layer electrostatic self-assembly method. The SFG spectrum of the SAM itself comprised strong methylene resonances, indicating the presence of gauche defects in the alkyl chains of the acid. The RAIRS spectrum of the SAM also contained strong methylene bands, indicating a degree of orientation of the methylene groups parallel to the surface normal. Changes in the SFG and RAIRS spectra when a PEI layer was adsorbed on the MUA monolayer showed that the expected electrostatic interaction between the polymer and the SAM, probably involving interpenetration of the PEI into the MUA monolayer, caused a straightening of the alkyl chains of the MUA and, consequently, a decrease in the number of gauche defects. When a layer of PAZO was subsequently deposited on the MUA/PEI film, further spectral changes occurred that can be explained by the formation of a complex PEI/PAZO interpenetrated layer. A per-deuterated MUA SAM was used to determine the relative contributions from the adsorbed polyelectrolytes and the MUA monolayer to the RAIRS and SFG spectra. Spectroscopic and adsorbed mass measurements combined showed that as further bilayers were constructed the interpenetration of PAZO into preadsorbed PEI layers was repeated, up to

  12. Carbon dioxide adsorption on a ZnO(101[combining macron]0) substrate studied by infrared reflection absorption spectroscopy.

    PubMed

    Buchholz, Maria; Weidler, Peter G; Bebensee, Fabian; Nefedov, Alexei; Wöll, Christof

    2014-01-28

    The adsorption of carbon dioxide on the mixed-terminated ZnO(101[combining macron]0) surface of a bulk single crystal was studied by UHV Infrared Reflection Absorption Spectroscopy (IRRAS). In contrast to metals, the classic surface selection rule for IRRAS does not apply to bulk oxide crystals, and hence vibrational bands can also be observed for s-polarized light. Although this fact substantially complicates data interpretation, a careful analysis allows for a direct determination of the adsorbate geometry. Here, we demonstrate the huge potential of IR-spectroscopy for investigations on oxide single crystal surfaces by considering all three components of the incident polarized light separately. We find that the tridentate (surface) carbonate is aligned along the [0001] direction. A comparison to data reported previously for CO2 adsorbed on the surfaces of ZnO nanoparticles provides important insight into the role of defects in the surface chemistry of powder particles.

  13. Infrared reflection absorption spectroscopy investigation of carbon nanotube growth on cobalt catalyst surfaces

    NASA Astrophysics Data System (ADS)

    Kimura, Yasuo; Numasawa, Takeru; Nihei, Mizuhisa; Niwano, Michio

    2007-02-01

    To clarify the effect the oxygen has on the carbon nanotube (CNT) growth mechanisms, the authors use infrared absorption spectroscopy for the monitoring of CNT growth on cobalt catalyst surfaces. CNT grew when methanol was used as a reaction gas, while they did not grow when methane was used. The authors observed spectral changes due to the formation of cobalt oxides and methoxides on the cobalt catalyst surfaces only during the growth of CNT. The results indicate that partial oxidation of the cobalt catalyst surface increases the adsorption probability of the reaction gas and ultimately induces growth of CNT.

  14. Polarization-modulation infrared reflection-absorption spectroscopy affording time-resolved simultaneous detection of surface and liquid phase species at catalytic solid-liquid interfaces.

    PubMed

    Meier, Daniel M; Urakawa, Atsushi; Baiker, Alfons

    2009-09-01

    Polarization-modulation infrared reflection-absorption spectroscopy (PM-IRRAS) combined with concentration modulation allows simultaneous monitoring of dynamic evolutions of surface and liquid phase species during reactions at catalytic interfaces as demonstrated for the Pt-catalysed oxidation of CO by O2 in cyclohexane.

  15. High Explosives Mixtures Detection Using Fiber Optics Coupled: Grazing Angle Probe/Fourier Transform Reflection Absorption Infrared Spectroscopy

    NASA Astrophysics Data System (ADS)

    Primera-Pedrozo, Oliva M.; Soto-Feliciano, Yadira M.; Pacheco-Londoño, Leonardo C.; Hernández-Rivera, Samuel P.

    2008-12-01

    Fourier Transform Infrared Spectroscopy operating in Reflection-Absorption mode has been demonstrated as a potential spectroscopic technique to develop new methodologies for detection of chemicals deposited on metallic surfaces. Mid-IR transmitting optical fiber bundle coupled to an external Grazing Angle Probe and an MCT detector together with a bench Michelson interferometer have been used to develop a highly sensitive and selective methodology for detecting traces of organic compounds on metal surfaces. The methodology is remote sensed, in situ and can detect surface loading concentrations of nanograms/cm2 of most target compounds. It is an environmentally friendly, solvent free technique that does not require sample preparation. In this work, the ever-important task of high explosives detection, present as traces of neat crystalline forms and in lab-made mixtures, equivalent to the important explosive formulation Pentolite, has been addressed. The sample set consisted of TNT, PETN (both pure samples) and the formulation based on them: Pentolite, present in various loading concentrations. The spectral data collected was subjected to a number of statistical pre-treatments, including first derivative and normalization transformations to make the data more suitable for the analysis. Principal Components Analysis combined with Linear Discriminant Analysis allowed the classification and discrimination of the target analytes contained in the sample set. Loading concentrations as 220 ng/cm2 were detected for each explosive in neat form and the in the simulated mixture of Pentolite.

  16. A reflection-absorption infrared spectroscopy study on the adsorption of 1-hexene on Ru(0001): coverage effect

    NASA Astrophysics Data System (ADS)

    Ilharco, L. M.; Garcia, A. R.; da Silva, J. Lopes

    1997-12-01

    Reflection-absorption infrared spectroscopy was used to study the influence of increasing exposure on the conformational equilibrium of 1-hexene chemisorbed on Ru(0001) at 92 K and at 100 K. At 92 K, it has been shown that successive increments of exposure up to 0.1 L lead to a rearrangement of the alkyl chain of the adsorbed di-σ species, from a trans conformation lying flat on the surface to a tilted geometry, with the consequent decrease in the area of influence of chemisorbed molecules. Saturation of the Ru(0001) surface with a monolayer of di-σ complex occurs between 0.1 and 0.5 L. At this exposure, evidence was obtained for the first physically adsorbed 1-hexene on top of the di-σ layer, with the C dbnd C bond parallel to the surface. A multilayer is formed upon a 4 L exposure. Adsorption at 100 K produces hexylidyne adsorbed on a threefold hollow site, whose conformation is also sensitive to increasing exposure: the predominant conformer at lower coverage involves gauche rotations (e.g. GTT). whereas for high exposures (4 L) hexylidyne is adsorbed in a more closely packed monolayer, with a larger amount of the all-trans conformer (TTT). No multilayer is formed at this temperature.

  17. Organization of T-shaped facial amphiphiles at the air/water interface studied by infrared reflection absorption spectroscopy.

    PubMed

    Schwieger, Christian; Chen, Bin; Tschierske, Carsten; Kressler, Jörg; Blume, Alfred

    2012-10-11

    We studied the behavior of monolayers at the air/water interface of T-shaped facial amphiphiles which show liquid-crystalline mesophases in the bulk. The compounds are composed of a rigid p-terphenyl core (TP) with two terminal hydrophobic ether linked alkyl chains of equal length and one facial hydrophilic tri(ethylene oxide) chain with a carboxylic acid end group. Due to their amphiphilic nature they form stable Langmuir films at the air/water interface. Depending on the alkyl chain length they show markedly different compression isotherms. We used infrared reflection absorption spectroscopy (IRRAS) to study the changes in molecular organization of the TP films upon compression. We could retrieve information on layer thickness, alkyl chain crystallization, and the orientation of the TP cores within the films. Films of TPs with long (16 carbon atoms: TP 16/3) and short (10 carbon atoms: TP 10/3) alkyl chains were compared. Compression of TP 16/3 leads to crystallization of the terminal alkyl chains, whereas the alkyl chains of TP 10/3 stay fluid over the complete compression range. TP 10/3 shows an extended plateau in the compression isotherm which is due to a layering transition. The mechanism of this layering transition is discussed. Special attention was paid to the question of whether a so-called roll-over collapse occurs during compression. From the beginning to the end of the plateau, the layer thickness is increased from 15 to 38 Å and the orientation of the TP cores changes from parallel to the water surface to isotropic. We conclude that the plateau in the compression isotherm reflects the transition of a TP monolayer to a TP multilayer. The monolayer consists of a sublayer of well-organized TP cores underneath a sublayer of fluid alkyl chains whereas the multilayer consists of a well oriented bottom layer and a disordered top layer. Our findings do not support the model of a roll-over collapse. This study demonstrates how the IRRA band intensity of OH

  18. Infrared reflection-absorption spectroscope using thin film structures

    NASA Astrophysics Data System (ADS)

    Finke, S. J.; Schrader, G. L.

    Infrared reflection-absorption spectroscopy (IRRAS) has been used extensively in the study of adsorbates and thin layers on metal surfaces, but little work has been performed on non-metals due to the low sensitivity which results when these materials are used. In this work, thin film structures consisting of a thin layer of a semiconductor (silicon) on a metal (copper) surface are used to increase the sensitivity of the technique for examining layers of poly(methylmethacrylate).

  19. Structure of collagen adsorbed on a model implant surface resolved by polarization modulation infrared reflection-absorption spectroscopy.

    PubMed

    Brand, Izabella; Habecker, Florian; Ahlers, Michael; Klüner, Thorsten

    2015-03-05

    The polarization modulation infrared reflection-absorption spectra of collagen adsorbed on a titania surface and quantum chemical calculations are used to describe components of the amide I mode to the protein structure at a sub-molecular level. In this study, imino acid rich and poor fragments, representing the entire collagen molecule, are taken into account. The amide I mode of the collagen triple helix is composed of three absorption bands which involve: (i) (∼1690cm(-1)) the CO stretching modes at unhydrated groups, (ii) (1655-1673cm(-1)) the CO stretching at carbonyl groups at imino acids and glycine forming intramolecular hydrogen bonds with H atoms at both NH2 and, unusual for proteins, CH2 groups at glycine at a neighbouring chain and (iii) (∼1640cm(-1)) the CO stretching at carbonyl groups forming hydrogen bonds between two, often charged, amino acids as well as hydrogen bonds to water along the entire helix. The IR spectrum of films prepared from diluted solutions (c<50μgml(-1)) corresponds to solution spectra indicating that native collagen molecules interact with water adsorbed on the titania surface. In films prepared from solutions (c⩾50μgml(-1)) collagen multilayers are formed. The amide I mode is blue-shifted by 18cm(-1), indicating that intramolecular hydrogen bonds at imino acid rich fragments are weakened. Simultaneous red-shift of the amide A mode implies that the strength of hydrogen bonds at the imino acid poor fragments increases. Theoretically predicted distortion of the collagen structure upon adsorption on the titania surface is experimentally confirmed.

  20. Structure of collagen adsorbed on a model implant surface resolved by polarization modulation infrared reflection-absorption spectroscopy

    NASA Astrophysics Data System (ADS)

    Brand, Izabella; Habecker, Florian; Ahlers, Michael; Klüner, Thorsten

    2015-03-01

    The polarization modulation infrared reflection-absorption spectra of collagen adsorbed on a titania surface and quantum chemical calculations are used to describe components of the amide I mode to the protein structure at a sub-molecular level. In this study, imino acid rich and poor fragments, representing the entire collagen molecule, are taken into account. The amide I mode of the collagen triple helix is composed of three absorption bands which involve: (i) (∼1690 cm-1) the Cdbnd O stretching modes at unhydrated groups, (ii) (1655-1673 cm-1) the Cdbnd O stretching at carbonyl groups at imino acids and glycine forming intramolecular hydrogen bonds with H atoms at both NH2 and, unusual for proteins, CH2 groups at glycine at a neighbouring chain and (iii) (∼1640 cm-1) the Cdbnd O stretching at carbonyl groups forming hydrogen bonds between two, often charged, amino acids as well as hydrogen bonds to water along the entire helix. The IR spectrum of films prepared from diluted solutions (c < 50 μg ml-1) corresponds to solution spectra indicating that native collagen molecules interact with water adsorbed on the titania surface. In films prepared from solutions (c ⩾ 50 μg ml-1) collagen multilayers are formed. The amide I mode is blue-shifted by 18 cm-1, indicating that intramolecular hydrogen bonds at imino acid rich fragments are weakened. Simultaneous red-shift of the amide A mode implies that the strength of hydrogen bonds at the imino acid poor fragments increases. Theoretically predicted distortion of the collagen structure upon adsorption on the titania surface is experimentally confirmed.

  1. Broadband Mid-Infrared Stand-Off Reflection-Absorption Spectroscopy Using a Pulsed External Cavity Quantum Cascade Laser.

    PubMed

    Liu, Xunchen; Chae, Inseok; Miriyala, Naresh; Lee, Dongkyu; Thundat, Thomas; Kim, Seonghwan

    2017-07-01

    Broadband mid-infrared molecular spectroscopy is essential for detection and identification of many chemicals and materials. In this report, we present stand-off mid-infrared spectra of 1,3,5-trinitro-1,3,5-triazine or cyclotrimethylene trinitramine (RDX) residues on a stainless-steel surface measured by a broadband external cavity quantum cascade laser (QCL) system. The pulsed QCL is continuously scanned over 800 cm(-1) in the molecular fingerprint region and the amplitude of the reflection signal is measured by either a boxcar-averager-based scheme or a lock-in-amplifier-based scheme with 1 MHz and 100 kHz quartz crystal oscillators. The main background noise is due to the laser source instability and is around 0.1% of normalized intensity. The direct absorption spectra have linewidth resolution around 0.1 cm(-1) and peak height sensitivity around 10(-2) due to baseline interference fringes. Stand-off detection of 5-50 µg/cm(2) of RDX trace adsorbed on a stainless steel surface at the distance of 5 m is presented.

  2. Evaluation of infrared-reflection absorption spectroscopy measurement and locally weighted partial least-squares for rapid analysis of residual drug substances in cleaning processes.

    PubMed

    Nakagawa, Hiroshi; Tajima, Takahiro; Kano, Manabu; Kim, Sanghong; Hasebe, Shinji; Suzuki, Tatsuya; Nakagami, Hiroaki

    2012-04-17

    The usefulness of infrared-reflection absorption spectroscopy (IR-RAS) for the rapid measurement of residual drug substances without sampling was evaluated. In order to realize the highly accurate rapid measurement, locally weighted partial least-squares (LW-PLS) with a new weighting technique was developed. LW-PLS is an adaptive method that builds a calibration model on demand by using a database whenever prediction is required. By adding more weight to samples closer to a query, LW-PLS can achieve higher prediction accuracy than PLS. In this study, a new weighting technique is proposed to further improve the prediction accuracy of LW-PLS. The root-mean-square error of prediction (RMSEP) of the IR-RAS spectra analyzed by LW-PLS with the new weighting technique was compared with that analyzed by PLS and locally weighted regression (LWR). The RMSEP of LW-PLS with the proposed weighting technique was about 36% and 14% smaller than that of PLS and LWR, respectively, when ibuprofen was a residual drug substance. Similarly, LW-PLS with the weighting technique was about 39% and 24% better than PLS and LWR in RMSEP, respectively, when magnesium stearate was a residual excipient. The combination of IR-RAS and LW-PLS with the proposed weighting technique is a very useful rapid measurement technique of the residual drug substances.

  3. An experimental set-up to apply polarization modulation to infrared reflection absorption spectroscopy for improved in situ studies of atmospheric corrosion processes.

    PubMed

    Wiesinger, R; Schade, U; Kleber, Ch; Schreiner, M

    2014-06-01

    A new set-up for improved monitoring of atmospheric corrosion processes in situ and in real-time is presented. To characterize chemical structures of thin films on metal surfaces surface sensitive analytical techniques are required. One possible technique is Infrared Reflection Absorption Spectroscopy (IRRAS) which has become an established method to investigate surface corrosion films of thicknesses less than 200 nm. However, there are limitations related to the sensitivity of these measurements, in case of investigating ultrathin films or absorption bands of interest, surface species are superimposed by atmospheric background absorption, which changes during in situ measurements in ambient atmospheres. These difficulties of in situ surface reflection measurements can be eliminated by availing the polarization selectivity of adsorbed surface species. At grazing angles of incidence the absorption of p-polarized infrared radiation by thin surface films on metals is enhanced, while the absorption of s-polarized light by this film is nearly zero. This different behavior of the polarization properties leads to strong selection rules at the surface and can therefore be used to identify molecules adsorbed on metal surfaces. Polarization Modulation (PM) of the infrared (IR) light takes advantage of this disparity of polarization on sample surfaces and in combination with IRRAS yielding a very sensitive and surface-selective method for obtaining IR spectra of ultra-thin films on metal surfaces. An already existing in situ IRRAS/Quartz Crystal Microbalance weathering cell was combined with PM and evaluated according to its applicability to study in situ atmospheric corrosion processes. First real-time measurements on silver samples exposed to different atmospheres were performed showing the advantage of PM-IRRAS compared to conventional IRRAS for such investigations.

  4. An experimental set-up to apply polarization modulation to infrared reflection absorption spectroscopy for improved in situ studies of atmospheric corrosion processes

    SciTech Connect

    Wiesinger, R.; Schade, U.; Kleber, Ch.; Schreiner, M.

    2014-06-15

    A new set-up for improved monitoring of atmospheric corrosion processes in situ and in real-time is presented. To characterize chemical structures of thin films on metal surfaces surface sensitive analytical techniques are required. One possible technique is Infrared Reflection Absorption Spectroscopy (IRRAS) which has become an established method to investigate surface corrosion films of thicknesses less than 200 nm. However, there are limitations related to the sensitivity of these measurements, in case of investigating ultrathin films or absorption bands of interest, surface species are superimposed by atmospheric background absorption, which changes during in situ measurements in ambient atmospheres. These difficulties of in situ surface reflection measurements can be eliminated by availing the polarization selectivity of adsorbed surface species. At grazing angles of incidence the absorption of p-polarized infrared radiation by thin surface films on metals is enhanced, while the absorption of s-polarized light by this film is nearly zero. This different behavior of the polarization properties leads to strong selection rules at the surface and can therefore be used to identify molecules adsorbed on metal surfaces. Polarization Modulation (PM) of the infrared (IR) light takes advantage of this disparity of polarization on sample surfaces and in combination with IRRAS yielding a very sensitive and surface-selective method for obtaining IR spectra of ultra-thin films on metal surfaces. An already existing in situ IRRAS/Quartz Crystal Microbalance weathering cell was combined with PM and evaluated according to its applicability to study in situ atmospheric corrosion processes. First real-time measurements on silver samples exposed to different atmospheres were performed showing the advantage of PM-IRRAS compared to conventional IRRAS for such investigations.

  5. An experimental set-up to apply polarization modulation to infrared reflection absorption spectroscopy for improved in situ studies of atmospheric corrosion processes

    NASA Astrophysics Data System (ADS)

    Wiesinger, R.; Schade, U.; Kleber, Ch.; Schreiner, M.

    2014-06-01

    A new set-up for improved monitoring of atmospheric corrosion processes in situ and in real-time is presented. To characterize chemical structures of thin films on metal surfaces surface sensitive analytical techniques are required. One possible technique is Infrared Reflection Absorption Spectroscopy (IRRAS) which has become an established method to investigate surface corrosion films of thicknesses less than 200 nm. However, there are limitations related to the sensitivity of these measurements, in case of investigating ultrathin films or absorption bands of interest, surface species are superimposed by atmospheric background absorption, which changes during in situ measurements in ambient atmospheres. These difficulties of in situ surface reflection measurements can be eliminated by availing the polarization selectivity of adsorbed surface species. At grazing angles of incidence the absorption of p-polarized infrared radiation by thin surface films on metals is enhanced, while the absorption of s-polarized light by this film is nearly zero. This different behavior of the polarization properties leads to strong selection rules at the surface and can therefore be used to identify molecules adsorbed on metal surfaces. Polarization Modulation (PM) of the infrared (IR) light takes advantage of this disparity of polarization on sample surfaces and in combination with IRRAS yielding a very sensitive and surface-selective method for obtaining IR spectra of ultra-thin films on metal surfaces. An already existing in situ IRRAS/Quartz Crystal Microbalance weathering cell was combined with PM and evaluated according to its applicability to study in situ atmospheric corrosion processes. First real-time measurements on silver samples exposed to different atmospheres were performed showing the advantage of PM-IRRAS compared to conventional IRRAS for such investigations.

  6. The CO oxidation kinetics on supported Pd model catalysts: A molecular beam/in situ time-resolved infrared reflection absorption spectroscopy study

    NASA Astrophysics Data System (ADS)

    Libuda, J.; Meusel, I.; Hoffmann, J.; Hartmann, J.; Piccolo, L.; Henry, C. R.; Freund, H.-J.

    2001-03-01

    Combining molecular beam techniques and time-resolved infrared reflection absorption spectroscopy (TR-IRAS) we have studied the kinetics of the CO oxidation reaction on an alumina-supported Pd model catalyst. The Pd particles are deposited by metal evaporation under ultrahigh vacuum (UHV) conditions onto a well-ordered alumina film, prepared on a NiAl(110) single crystal. Particle size, density and structure of the Pd deposits have been characterized in previous studies. In the low temperature region, transient and steady-state experiments have been performed over a wide range of CO and oxygen fluxes by crossing two effusive molecular beams on the sample surface. We determine the steady-state CO2 production rate as a function of the CO fraction in the impinging gas flux. Simultaneously, the occupation of CO adsorption sites under steady-state conditions is monitored by in situ IR spectroscopy. The origin of different types of CO2 transients is discussed. In particular we focus on the transient CO2 production after switching off the CO beam. For the model catalyst investigated, detailed reaction rate measurements in combination with time-resolved IRAS show that the origin of the particular transient behavior of the supported model system is not due to the presence of specific adsorption sites on small particles, as has been proposed previously. Instead, we show that the transient behavior can be semiquantitatively simulated on the basis of a simple kinetic model considering a homogeneous surface, and accounting for the inhibition of the dissociative adsorption of O2 at high CO coverage. Moreover, it is discussed how the inherent heterogeneity of the supported particle system can additionally enhance the observed effect.

  7. Elucidating the effects of cholesterol on the molecular packing of double-chained cationic lipid langmuir monolayers by infrared reflection-absorption spectroscopy.

    PubMed

    Kuo, An-Tsung; Chang, Chien-Hsiang

    2015-01-01

    Cholesterol has been suggested to play a role in stable vesicle formation by adjusting the molecular packing of the vesicular bilayer. To explore the mechanisms involved in adjusting the bilayer structure by cholesterol, the molecular packing behavior in a mimic outer layer of cationic dialkyldimethylammonium bromide (DXDAB)/cholesterol vesicular bilayer was investigated by the Langmuir monolayer approach with infrared reflection-absorption spectroscopy (IRRAS). The results indicated that the addition of cholesterol in the DXDAB Langmuir monolayers not only restrained the desorption of the DXDAB with short hydrocarbon chains, such as ditetradecyldimethylammonium bromide or dihexadecyldimethylammonium bromide, into the aqueous phase but also induced a condensing effect on the DXDAB monolayers. At a liquid-expanded (LE) state, the ordering effect of cholesterol accompanying the condensing effect occurred in the mixed DXDAB/cholesterol monolayers due to the tendency of maximizing hydrocarbon chain contact between cholesterol and the neighboring hydrocarbon chains. However, for the mixed monolayers containing the DXDAB with long hydrocarbon chains, such as dioctadecyldimethylammonium bromide (DODAB), the disordering effect of cholesterol took place at a liquid-condensed (LC) state. This was related to the molecular structure of cholesterol and hydrocarbon chain length of DODAB. The rigid sterol ring of cholesterol hindered the portion of neighboring hydrocarbon chains from motion. However, the flexible alkyl side-chain of cholesterol along with the corresponding portion of neighboring hydrocarbon chains formed a fluidic region, counteracting the enhanced conformational order induced by the sterol ring of cholesterol. Furthermore, the long hydrocarbon chains of DODAB possessed a more pronounced motion freedom, resulting in a more disordered packing of the monolayers.

  8. Adsorption of formic acid on rutile TiO2 (110) revisited: An infrared reflection-absorption spectroscopy and density functional theory study

    NASA Astrophysics Data System (ADS)

    Mattsson, A.; Hu, Shuanglin; Hermansson, K.; Österlund, L.

    2014-01-01

    Formic acid (HCOOH) adsorption on rutile TiO2 (110) has been studied by s- and p-polarized infrared reflection-absorption spectroscopy (IRRAS) and spin-polarized density functional theory together with Hubbard U contributions (DFT+U) calculations. To compare with IRRAS spectra, the results from the DFT+U calculations were used to simulate IR spectra by employing a three-layer model, where the adsorbate layer was modelled using Lorentz oscillators with calculated dielectric constants. To account for the experimental observations, four possible formate adsorption geometries were calculated, describing both the perfect (110) surface, and surfaces with defects; either O vacancies or hydroxyls. The majority species seen in IRRAS was confirmed to be the bridging bidentate formate species with associated symmetric and asymmetric frequencies of the ν(OCO) modes measured to be at 1359 cm-1 and 1534 cm-1, respectively. The in-plane δ(C-H) wagging mode of this species couples to both the tangential and the normal component of the incident p-polarized light, which results in absorption and emission bands at 1374 cm-1 and 1388 cm-1. IRRAS spectra measured on surfaces prepared to be either reduced, stoichiometric, or to contain surplus O adatoms, were found to be very similar. By comparisons with computed spectra, it is proposed that in our experiments, formate binds as a minority species to an in-plane Ti5c atom and a hydroxyl, rather than to O vacancy sites, the latter to a large extent being healed even at our UHV conditions. Excellent agreement between calculated and experimental IRRAS spectra is obtained. The results emphasize the importance of protonation and reactive surface hydroxyls - even under UHV conditions - as reactive sites in e.g., catalytic applications.

  9. Interaction of Isophorone with Pd(111): A Combination of Infrared Reflection-Absorption Spectroscopy, Near-Edge X-ray Absorption Fine Structure, and Density Functional Theory Studies.

    PubMed

    Dostert, Karl-Heinz; O'Brien, Casey P; Riedel, Wiebke; Savara, Aditya; Liu, Wei; Oehzelt, Martin; Tkatchenko, Alexandre; Schauermann, Swetlana

    2014-12-04

    Atomistic level understanding of interaction of α,β-unsaturated carbonyls with late transition metals is a key prerequisite for rational design of new catalytic materials with the desired selectivity toward C=C or C=O bond hydrogenation. The interaction of this class of compounds with transition metals was investigated on α,β-unsaturated ketone isophorone on Pd(111) as a prototypical system. In this study, infrared reflection-absorption spectroscopy (IRAS), near-edge X-ray absorption fine structure (NEXAFS) experiments, and density functional theory calculations including van der Waals interactions (DFT+vdW) were combined to obtain detailed information on the binding of isophorone to palladium at different coverages and on the effect of preadsorbed hydrogen on the binding and adsorption geometry. According to these experimental observations and the results of theoretical calculations, isophorone adsorbs on Pd(111) in a flat-lying geometry at low coverages. With increasing coverage, both C=C and C=O bonds of isophorone tilt with respect to the surface plane. The tilting is considerably more pronounced for the C=C bond on the pristine Pd(111) surface, indicating a prominent perturbation and structural distortion of the conjugated π system upon interaction with Pd. Preadsorbed hydrogen leads to higher tilting angles of both π bonds, which points to much weaker interaction of isophorone with hydrogen-precovered Pd and suggests the conservation of the in-plane geometry of the conjugated π system. The results of the DFT+vdW calculations provide further insights into the perturbation of the molecular structure of isophorone on Pd(111).

  10. Adsorption of acrolein, propanal, and allyl alcohol on Pd(111): a combined infrared reflection-absorption spectroscopy and temperature programmed desorption study.

    PubMed

    Dostert, Karl-Heinz; O'Brien, Casey P; Mirabella, Francesca; Ivars-Barceló, Francisco; Schauermann, Swetlana

    2016-05-18

    Atomistic-level understanding of the interaction of α,β-unsaturated aldehydes and their derivatives with late transition metals is of fundamental importance for the rational design of new catalytic materials with the desired selectivity towards C[double bond, length as m-dash]C vs. C[double bond, length as m-dash]O bond partial hydrogenation. In this study, we investigate the interaction of acrolein, and its partial hydrogenation products propanal and allyl alcohol, with Pd(111) as a prototypical system. A combination of infrared reflection-absorption spectroscopy (IRAS) and temperature programmed desorption (TPD) experiments was applied under well-defined ultrahigh vacuum (UHV) conditions to obtain detailed information on the adsorption geometries of acrolein, propanal, and allyl alcohol as a function of coverage. We compare the IR spectra obtained for multilayer coverages, reflecting the molecular structure of unperturbed molecules, with the spectra acquired for sub-monolayer coverages, at which the chemical bonds of the molecules are strongly distorted. Coverage-dependent IR spectra of acrolein on Pd(111) point to the strong changes in the adsorption geometry with increasing acrolein coverage. Acrolein adsorbs with the C[double bond, length as m-dash]C and C[double bond, length as m-dash]O bonds lying parallel to the surface in the low coverage regime and changes its geometry to a more upright orientation with increasing coverage. TPD studies indicate decomposition of the species adsorbed in the sub-monolayer regime upon heating. Similar strong coverage dependence of the IR spectra were found for propanal and allyl alcohol. For all investigated molecules a detailed assignment of vibrational bands is reported.

  11. Adsorption of formic acid on rutile TiO{sub 2} (110) revisited: An infrared reflection-absorption spectroscopy and density functional theory study

    SciTech Connect

    Mattsson, A.; Österlund, L.; Hu, Shuanglin Hermansson, K.

    2014-01-21

    Formic acid (HCOOH) adsorption on rutile TiO{sub 2} (110) has been studied by s- and p-polarized infrared reflection-absorption spectroscopy (IRRAS) and spin-polarized density functional theory together with Hubbard U contributions (DFT+U) calculations. To compare with IRRAS spectra, the results from the DFT+U calculations were used to simulate IR spectra by employing a three-layer model, where the adsorbate layer was modelled using Lorentz oscillators with calculated dielectric constants. To account for the experimental observations, four possible formate adsorption geometries were calculated, describing both the perfect (110) surface, and surfaces with defects; either O vacancies or hydroxyls. The majority species seen in IRRAS was confirmed to be the bridging bidentate formate species with associated symmetric and asymmetric frequencies of the ν(OCO) modes measured to be at 1359 cm{sup −1} and 1534 cm{sup −1}, respectively. The in-plane δ(C–H) wagging mode of this species couples to both the tangential and the normal component of the incident p-polarized light, which results in absorption and emission bands at 1374 cm{sup −1} and 1388 cm{sup −1}. IRRAS spectra measured on surfaces prepared to be either reduced, stoichiometric, or to contain surplus O adatoms, were found to be very similar. By comparisons with computed spectra, it is proposed that in our experiments, formate binds as a minority species to an in-plane Ti{sub 5c} atom and a hydroxyl, rather than to O vacancy sites, the latter to a large extent being healed even at our UHV conditions. Excellent agreement between calculated and experimental IRRAS spectra is obtained. The results emphasize the importance of protonation and reactive surface hydroxyls – even under UHV conditions – as reactive sites in e.g., catalytic applications.

  12. Co-adsorption of oxygen and formic acid on rutile TiO2 (110) studied by infrared reflection-absorption spectroscopy

    NASA Astrophysics Data System (ADS)

    Mattsson, Andreas; Österlund, Lars

    2017-09-01

    Adsorption of formic acid and co-adsorption with oxygen have been investigated on the rutile TiO2(110) surface using p- and s-polarized infrared reflection-absorption spectroscopy (IRRAS) at O2 exposures between 45 L to 8100 L and at temperatures between 273 K and 343 K. On the clean surface formic acid dissociates into a formate ion (formate) and a proton. Formate binds to two five-fold coordinated Ti atoms in the troughs along the [001] direction, and the proton binds to neighboring bridging O atoms. Exposure of adsorbed formate to O2 leads to a decrease in the asymmetric νas(OCO) band at 1532 cm-1 and to the concomitant formation of a new vibration band at 1516 cm-1. From the s-and p-polarized IRRAS measurements performed at different O2 exposures, surface pre-treatments and substrate temperatures, and by comparisons with previous reports, we conclude that the new species is a bidentate surface hydrogen carbonate, which is formed by reaction between formate and oxygen adatoms on the surface. The σv reflection plane of the surface hydrogen carbonate molecule is oriented along the [001] direction, i.e. the same direction as the adsorbed formate molecule. On the clean TiO2(110) surface exposed to O2 prior to formic acid adsorption, similar results are obtained. The reaction rate to form surface hydrogen carbonate from formate is found to follow first-order kinetics, with an apparent activation energy of Er=0.25 eV.

  13. Submolecular Structure and Orientation of Oligonucleotide Duplexes Tethered to Gold Electrodes Probed by Infrared Reflection Absorption Spectroscopy: Effect of the Electrode Potentials.

    PubMed

    Kékedy-Nagy, László; Ferapontova, Elena E; Brand, Izabella

    2017-02-23

    Unique electronic and ligand recognition properties of the DNA double helix provide basis for DNA applications in biomolecular electronic and biosensor devices. However, the relation between the structure of DNA at electrified interfaces and its electronic properties is still not well understood. Here, potential-driven changes in the submolecular structure of DNA double helices composed of either adenine-thymine (dAdT)25 or cytosine-guanine (dGdC)20 base pairs tethered to the gold electrodes are for the first time analyzed by in situ polarization modulation infrared reflection absorption spectroscopy (PM IRRAS) performed under the electrochemical control. It is shown that the conformation of the DNA duplexes tethered to gold electrodes via the C6 alkanethiol linker strongly depends on the nucleic acid sequence composition. The tilt of purine and pyrimidine rings of the complementary base pairs (dAdT and dGdC) depends on the potential applied to the electrode. By contrast, neither the conformation nor orientation of the ionic in character phosphate-sugar backbone is affected by the electrode potentials. At potentials more positive than the potential of zero charge (pzc), a gradual tilting of the double helix is observed. In this tilted orientation, the planes of the complementary purine and pyrimidine rings lie ideally parallel to each other. These potentials do not affect the integral stability of the DNA double helix at the charged interface. At potentials more negative than the pzc, DNA helices adopt a vertical to the gold surface orientation. Tilt of the purine and pyrimidine rings depends on the composition of the double helix. In monolayers composed of (dAdT)25 molecules the rings of the complementary base pairs lie parallel to each other. By contrast, the tilt of purine and pyrimidine rings in (dGdC)20 helices depends on the potential applied to the electrode. Such potential-induced mobility of the complementary base pairs can destabilize the helix structure

  14. Adsorption of isophorone and trimethyl-cyclohexanone on Pd(111): A combination of infrared reflection absorption spectroscopy and density functional theory studies

    NASA Astrophysics Data System (ADS)

    Dostert, Karl-Heinz; O'Brien, Casey P.; Liu, Wei; Riedel, Wiebke; Savara, Aditya; Tkatchenko, Alexandre; Schauermann, Swetlana; Freund, Hans-Joachim

    2016-08-01

    Understanding the interaction of α,β-unsaturated carbonyl compounds with late transition metals is a key prerequisite for rational design of new catalysts with desired selectivity towards C = C or C = O bond hydrogenation. The interaction of the α,β-unsaturated ketone isophorone and the saturated ketone TMCH (3,3,5-trimethylcyclohexanone) with Pd(111) was investigated in this study as a prototypical system. Infrared reflection-absorption spectroscopy (IRAS) and density functional theory calculations including van der Waals interactions (DFT + vdWsurf) were combined to form detailed assignments of IR vibrational modes in the range from 3000 cm- 1 to 1000 cm- 1 in order to obtain information on the binding of isophorone and TMCH to Pd(111) as well as to study the effect of co-adsorbed hydrogen. IRAS measurements were performed with deuterium-labeled (d5-) isophorone, in addition to unlabeled isophorone and unlabeled TMCH. Experimentally observed IR absorption features and calculated vibrational frequencies indicate that isophorone and TMCH molecules in multilayers have a mostly unperturbed structure with random orientation. At sub-monolayer coverages, strong perturbation and preferred orientations of the adsorbates were found. At low coverage, isophorone interacts strongly with Pd(111) and adsorbs in a flat-lying geometry with the C = C and C = O bonds parallel, and a CH3 group perpendicular, to the surface. At intermediate sub-monolayer coverage, the C = C bond is strongly tilted, while the C = O bond remains flat-lying, which indicates a prominent perturbation of the conjugated π system. Pre-adsorbed hydrogen leads to significant changes in the adsorption geometry of isophorone, which suggests a weakening of its binding to Pd(111). At low coverage, the structure of the CH3 groups seems to be mostly unperturbed on the hydrogen pre-covered surface. With increasing coverage, a conservation of the in-plane geometry of the conjugated π system was observed in the

  15. Adsorption state and morphology of anthraquinone-2-carboxylic acid deposited from solution onto the atomically-smooth native oxide surface of Al(111) films studied by infrared reflection absorption spectroscopy, X-ray photoelectron spectroscopy, and atomic force microscopy.

    PubMed

    Higo, Morihide; Miake, Takeshi; Mitsushio, Masaru; Yoshidome, Toshifumi; Ozono, Yoshihisa

    2008-03-01

    The adsorption state and morphology of anthraquinone-2-carboxylic acid (AQ-2-COOH) deposited from acetone solutions (0.02 - 1.00 mg ml(-1)) onto atomically-smooth native oxide surfaces of Al(111) films were investigated by infrared reflection absorption spectroscopy, X-ray photoelectron spectroscopy, and atomic force microscopy. The atomically-smooth oxide surfaces were prepared by vacuum evaporation of Al on mica substrates at 350 degrees C, followed by oxidation in an oxygen-dc glow discharge at room temperature. It was found that AQ-2-COOH is adsorbed on the film surfaces in both the neutral and ionized state, where the amount of the neutral molecules increases with increasing concentration. This molecule is adsorbed as both a uniform nanometer-scale film, and as micrometer-sized particles with heights ranging from 10 to 200 nm above the film surface. The volumes of the particles of deposited AQ-2-COOH increased with increasing concentration. It is concluded that the particles are microcrystallites of neutral AQ-2-COOH and that the thin uniform film results from AQ-2-COOH anion formation on the film surfaces. A comparison of the results obtained by use of these surface analytical techniques clearly shows the features and advantages of these tools.

  16. Diffuse Reflectance Spectroscopy of Hidden Objects, Part I: Interpretation of the Reflection-Absorption-Scattering Fractions in Near-Infrared (NIR) Spectra of Polyethylene Films.

    PubMed

    Pomerantsev, Alexey L; Rodionova, Oxana Ye; Skvortsov, Alexej N

    2017-01-01

    Investigation of a sample covered by an interfering layer is required in many fields, e.g., for process control, biochemical analysis, and many other applications. This study is based on the analysis of spectra collected by near-infrared (NIR) diffuse reflectance spectroscopy. Each spectrum is a composition of a useful, target spectrum and a spectrum of an interfering layer. To recover the target spectrum, we suggest using a new phenomenological approach, which employs the multivariate curve resolution (MCR) method. In general terms, the problem is very complex. We start with a specific problem of analyzing a system, which consists of several layers of polyethylene (PE) film and underlayer samples with known spectral properties. To separate information originating from PE layers and the target, we modify the system versus both the number of the PE layers as well as the reflectance properties of the target sample. We consider that the interfering spectrum of the layer can be modeled using three components, which can be tentatively called transmission, absorption, and scattering contributions. The novelty of our approach is that we do not remove the reflectance and scattering effects from the spectra, but study them in detail aiming to use this information to recover the target spectrum.

  17. The structure of oleamide films at the aluminum/oil interface and aluminum/air interface studied by Sum Frequency Generation (SFG) vibrational spectroscopy and Reflection Absorption Infrared Spectroscopy (RAIRS).

    PubMed

    Casford, Michael T L; Davies, Paul B

    2009-08-01

    The structure of oleamide (cis-9-octadecenamide) films on aluminum has been investigated by sum frequency generation vibrational spectroscopy (SFG) and reflection absorption infrared spectroscopy (RAIRS). Three different film deposition strategies were investigated: (i) films formed by equilibrium adsorption from oleamide solutions in oil, (ii) Langmuir-Blodgett films cast at 1 and 25 mN m(-1), (iii) thick spin-cast films. Both L-B and spin-cast films were examined in air and under oil. The adsorbate formed in the 1 mN m(-1) film in air showed little orientational order. For this film, the spectroscopic results and the ellipsometric thickness point to a relatively conformationally disordered monolayer that is oriented principally in the plane of the interface. Direct adsorption to the metal interface from oil results in SFG spectra of oleamide that are comparable to those observed for the 1 mN m(-1) L-B film in air. In contrast, SFG and RAIRS results for the 25 mN m(-1) film in air and SFG spectra of the spin-cast film in air both show strong conformational ordering and orientational alignment normal to the interface. The 25 mN m(-1) film has an ellipsometric thickness almost twice that of the 1 mN m(-1) L-B film. Taken in combination with the spectroscopic results, this is indicative of a well packed monolayer in air in which the hydrocarbon chain is in an essentially defect-free extended conformation with the methyl terminus oriented away from the surface. A similar structure is also deduced for the surface of the spin-cast film in air. Upon immersion of the 25 mN m(-1) L-B film in oil the SFG spectra show that this film rapidly adopts a relatively disordered structure similar to that seen for the 1 mN m(-1) L-B film in air. Immersion of the spin-cast film in oil results in the gradual disordering of the amide film over a period of several days until the observed spectra become essentially identical to those observed for direct adsorption of oleamide from oil.

  18. Comparison of molecular orientation and phase transition behaviors in the two kinds of ordered ultrathin films of reversed duckweed polymer ES-3 studied by infrared grazing reflection-absorption spectroscopy

    NASA Astrophysics Data System (ADS)

    Wang, Qiang; Xu, Weiqing; Zhao, Bing

    2003-03-01

    A multilayer LB film and a casting film of reversed duckweed polymer ES-3 on Au-evaporated glass slides were investigated by Fourier Transform infrared grazing reflection-absorption spectroscopy. It is found that the two kinds of ordered ultrathin films have different orientation of alkyl chains, nearly perpendicular to the substrate surface for the LB film while rather tilted for the casting film. The studies on their thermal transition behaviors indicate that both of the films have three phase transition processes, respectively, occurring near 65, 105 and 140 °C for the former while near 80, 105 and 140 °C for the latter, but show different transition behavior in the each corresponding transition process. It is referred that at room temperature there are island-like domain structures formed in the LB film, but no ones in the casting film; however, the latter can form the domain structures between the first two transition points due to the desorption of solvents. The formation of domain structure seems to play two important roles, one of which is to make alkyl chains more perpendicular to the substrate surface, and the other to make alkyl chains more packed closely. Thermal cyclic experiments reveal that neither of the films could return to its original state after thermal cyclic treatment up to the temperature, which is above the third transition point, although its alkyl chain becomes highly ordered again.

  19. Development of ultralow energy (1–10 eV) ion scattering spectrometry coupled with reflection absorption infrared spectroscopy and temperature programmed desorption for the investigation of molecular solids

    SciTech Connect

    Bag, Soumabha; Bhuin, Radha Gobinda; Methikkalam, Rabin Rajan J.; Pradeep, T.; Kephart, Luke; Walker, Jeff; Kuchta, Kevin; Martin, Dave; Wei, Jian

    2014-01-15

    Extremely surface specific information, limited to the first atomic layer of molecular surfaces, is essential to understand the chemistry and physics in upper atmospheric and interstellar environments. Ultra low energy ion scattering in the 1–10 eV window with mass selected ions can reveal extremely surface specific information which when coupled with reflection absorption infrared (RAIR) and temperature programmed desorption (TPD) spectroscopies, diverse chemical and physical properties of molecular species at surfaces could be derived. These experiments have to be performed at cryogenic temperatures and at ultra high vacuum conditions without the possibility of collisions of neutrals and background deposition in view of the poor ion intensities and consequent need for longer exposure times. Here we combine a highly optimized low energy ion optical system designed for such studies coupled with RAIR and TPD and its initial characterization. Despite the ultralow collision energies and long ion path lengths employed, the ion intensities at 1 eV have been significant to collect a scattered ion spectrum of 1000 counts/s for mass selected CH{sub 2}{sup +}.

  20. Structural analysis of HS(CD(2))(12)(O-CH(2)-CH(2))(6)OCH(3) monolayers on gold by means of polarization modulation infrared reflection absorption spectroscopy. progress of the reaction with bromine.

    PubMed

    Brand, Izabella; Nullmeier, Martina; Klüner, Thorsten; Jogireddy, Rajamalleswaramma; Christoffers, Jens; Wittstock, Gunther

    2010-01-05

    A self-assembled monolayer (SAM) on gold was formed with specifically perdeuterated hexaethylene glycol-terminated alkanethiol HS(CD(2))(12)(O-CH(2)-CH(2))(6)OCH(3) (D-OEG). The structure of the d-alkane and the oligoethylene glycol (OEG) parts of the molecule in a SAM was studied by means of polarization modulation infrared reflection absorption spectroscopy. The D-OEG monolayers are highly ordered and exist in a crystalline phase. The d-alkane chain adopts an all-trans conformation. Both, the d-alkane chain and long axis of the OEG part make an angle of 26.0 degrees +/- 1.5 degrees with respect to the surface normal, a value characteristic for the tilt of solid n-alkane thiols in the SAMs on Au. The positions of nu(as)(COC) and CH(2) wagging and rocking modes indicate a helical arrangement of the OEG chains. The D-OEG SAMs were exposed to 25 muM Br(2) in two ways: (i) by immersion into the Br(2) solution and (ii) in the galvanic cell Au|D-OEG SAM|25 muM Br(2) + 0.1 M Na(2)SO(4)|| 50 muM KBr + 0.1 M Na(2)SO(4)|Au. In the galvanic cell, the oxidant (Br(2)) is scavenged by a heterogeneous electron transfer reaction, slowing the reaction of D-OEG with Br(2). The slow progress of the reaction with Br(2) allowed us to draw conclusions about molecular rearrangements taking place during this reaction. The reaction with Br(2) starts on boundaries and/or defects present in the SAM. First, at the defect place, the alpha-C atom of the OEG chain reacts with Br(2) and the OEG part of the molecule is removed from the monolayer. In consequence an increase in disorder in the OEG part of the SAM is observed. The same mechanism of the reaction with Br(2) is applied for the d-dodecane alkanethiol part of the molecule. This reaction is slow, thus the order and the tilt of the hydrocarbon chain changes only a little during the reaction time.

  1. UV-Vis Reflection-Absorption Spectroscopy at air-liquid interfaces.

    PubMed

    Rubia-Payá, Carlos; de Miguel, Gustavo; Martín-Romero, María T; Giner-Casares, Juan J; Camacho, Luis

    2015-11-01

    UV-Visible Reflection-Absorption Spectroscopy (UVRAS) technique is reviewed with a general perspective on fundamental and applications. UVRAS is formally identical to IR Reflection-Absorption Spectroscopy (IRRAS), and therefore, the methodology developed for this IR technique can be applied in the UV-visible region. UVRAS can be applied to air-solid, air-liquid or liquid-liquid interfaces. This review focuses on the use of UVRAS for studying Langmuir monolayers. We introduce the theoretical framework for a successful understanding of the UVRAS data, and we illustrate the usage of this data treatment to a previous study from our group comprising an amphiphilic porphyrin. For ultrathin films with a thickness of few nm, UVRAS produces positive or negative bands when p-polarized radiation is used, depending on the incidence angle and the orientation of dipole absorption. UVRAS technique provides highly valuable information on tilt of chromophores at the air-liquid interface, and moreover allows the determination of optical parameters. We propose UVRAS as a powerful technique to investigate the in situ optical properties of Langmuir monolayers. Copyright © 2015 Elsevier B.V. All rights reserved.

  2. Surface Characterization Of Cold-Rolled Steel By Grazing-Angle Reflection-Absorption FT-IR Spectroscopy

    NASA Astrophysics Data System (ADS)

    Pilon, Andre; Cole, Kenneth C.; Noel, D.

    1989-12-01

    Residues from the oil-in-water emulsions used in the cold-rolling of steel are responsible in large part for an undesirable film of contamination sometimes found on the steel surface, even after the annealing stage. This contamination can have significant effects on the adhesion and corrosion resistance of paint coatings subsequently applied to the surface. The object of the work reported here was to determine the potential of grazing-angle reflection-absorption FT-IR spectroscopy for qualitative and quantitative analysis of the residues left on the surface.

  3. In situ infrared reflection absorption spectroscopic characterization of sustained kinetic oscillations in the Pt(100)/NO+CO system

    NASA Astrophysics Data System (ADS)

    Magtoto, Noel P.; Richardson, Hugh H.

    1998-11-01

    We have excited kinetic oscillations in the Pt(100)/NO+CO system at 470 K and pressure region around 2×10 -4 Torr. These oscillations are sustained and they arise by simply adjusting the partial pressures of NO and CO while holding the surface temperature at 470 K. However, they can only be induced if the partial pressure of CO is greater than that of NO (i.e., 1.4±0.05< pCO/ pNO<1.7±0.04). Infrared reflection-absorption spectra (IRAS) collected during the oscillation showed that the periodic growth and decay of the CO band are counterphase to the reaction-rate oscillations. Infrared bands due to molecularly adsorbed NO were not found during the early stages of the temporal evolution of the system into the upper reaction-rate branch. However, during the later stages of the evolution, a single IR band due to chemisorbed NO was observed. This band eventually disappeared as the reaction rate finally reached its maximum value. With the use of the model by Fink et al., we were able to rationalize the occurrence of oscillations under the present experimental conditions. Oscillations are caused by the periodic change in the level of adsorbate coverages that controls the dissociation of NO.

  4. In situ UV-visible reflection absorption wavelength modulation spectroscopy of species irreversibly adsorbed on electrode surfaces

    SciTech Connect

    Kim, Sunghyun; Scherson, D.A. )

    1992-12-15

    A method is herein described for the in situ detection of species adsorbed on electrode surfaces which employs a vibrating grating to modulate the wavelength of the incident light. This technique denoted as reflection absorption wavelength modulation spectroscopy (RAWMS) has made it possible to obtain at a fixed electrode potential normalized, differential UV-visible spectra of a single, irreversibly adsorbed monolayer of cobalt tetrasulfonated phthalocyanine (Co[sup II]TsPc) on the basal plane of highly oriented pyrolytic graphite (HOPG(bp)) and of methylene blue (MB) on graphite. The (wavelength) integrated difference RAWMS spectra for these adsorbed species were remarkably similar to those observed for the same compounds in aqueous solutions when present in the monomeric form. Complementary wavelength modulation experiments involving a conventional transmission geometry have shown that the instrument involved in the in situ RAWMS measurements is capable of resolving absorbance changes on the order of 0.002 units. 20 refs.

  5. Infrared reflection absorption spectroscopic study on the adsorption structures of acrylonitrile on Ag(111) and Ag(110) surfaces

    NASA Astrophysics Data System (ADS)

    Osaka, Naoki; Akita, Masato; Hiramoto, Shuji; Itoh, Koichi

    1999-06-01

    Infrared reflection-absorption spectra in CN stretching, CH 2 out-of-plane wagging and CH 2 twisting vibration regions were measured for acrylonitrile (CH 2CHCN) exposed to Ag(111) and Ag(110) in increasing amounts at 77 K. The adsorbate on Ag(111) takes on a series of discrete adsorption states; i.e., an isolated state, associated states, and ordered and amorphous multilayer states. The adsorbate on Ag(110) at lower exposures is in a state with the CN group weakly coordinated to a silver atom (or silver atoms). The adsorbate on Ag(110) takes the associated state and the amorphous multilayer at larger exposures. On raising the temperature to 96 K, the amorphous states on both Ag(111) and Ag(110) are converted to the ordered multilayer. The desorption temperature of the ordered multilayer is below 99 K for Ag(110), while the temperature is above 107 K for Ag(111); the result indicates the effect of the surface morphology on the stability of the ordered state.

  6. An infrared reflection-absorption spectroscopic (IRRAS) study of the interaction of lipid A and lipopolysaccharide Re with endotoxin-binding proteins.

    PubMed

    Kerth, Andreas; Garidel, Patrick; Howe, Jörg; Alexander, Christian; Mach, Jean-Pierre; Waelli, Thierry; Blume, Alfred; Th Rietschel, Ernst; Brandenburg, K

    2009-11-01

    Lipopolysaccharides (LPS, endotoxins) are main constituents of the outer membranes of Gram-negative bacteria, with the 'endotoxic principle' lipid A anchoring LPS into the membrane. When LPS is removed from the bacteria by the action of the immune system or simply by cell dividing, it may interact strongly with immunocompetent cells such as mononuclear cells. This interaction may lead, depending on the LPS concentration, to beneficial (at low) or pathophysiological (at high concentrations) reactions, the latter frequently causing the septic shock syndrome. There is a variety of endogenous LPS-binding proteins. To this class belong lactoferrin (LF) and hemoglobin (Hb), which have been shown to suppress and enhance the LPS-induced cytokine secretion in mononuclear cells, respectively. To elucidate the interaction mechanisms of endotoxins with these proteins, we have investigated in an infrared reflection-absorption spectroscopy (IRRAS) study the interaction of LPS or lipid A monolayers at the air/water interface with LF and Hb proteins, injected into the aqueous subphase. The data are clearly indicative of completely different interaction mechanisms of the endotoxins with the proteins, with the LF acting only at the LPS backbone, whereas Hb incorporates into the lipid monolayer. These data allow an understanding of the different reactivities in the biomedicinal systems.

  7. Interface specific reflection-absorption infrared spectroscopy of layered solid-state materials

    NASA Astrophysics Data System (ADS)

    Strunk, Michael R.

    Numerous advancing technologies require a thorough knowledge and precise control over factors that effect bonding between the layers of dissimilar materials. Corrosion barriers, lubricated surfaces, sensors, and integrated circuits represent an important group of layered systems, composed of dielectric materials deposited adjacent to metal surfaces. The "interfacial" region between metal and dielectric represent a very small fraction of the total thickness of a complete layered system. In order to observe and characterize the interface bonding in its native environment, it is necessary to choose a technique that recovers information specifically related to the bonding and non-bonding interactions between the metal and dielectric. It is then necessary to develop a means to selectively filter out and remove the spectral components peripheral to the interface with minimal corruption of the signal originating from the interfacial region. Methods are described to systematically collect and parse RAIRS data from layered metal dielectric systems in a manner that facilitates separation of spectral contributions from bulk and interface regions. An SP/FTIR spectrometer is introduced which can be used in multiple configurations to enhance the interface specificity of RAIRS. Energy coupled into the metal/dielectric interface as a surface plasmon polariton (SPP) is used as a secondary source of modulation for double modulation FTIR. In addition, the resonance coupling can provide specific information about the interface, which is complimentary to the FTIR spectrum. This complimentary information is used to extract interface specific spectral information from data sets using multivariate analysis. Two full spectrum multivariate methods, Classical Least Squared (CLS) and Partial Least Squared (PLS) are used to model RAIR spectral information from polyimide thin films on noble metals. Methods are presented that enable classification of the layered systems based on interfacial spectral information, and extraction of information relating to the composition of the bulk phase. A method of experimental design is introduced which minimizes the problem of correlations brought on by a two dimensional (2-D) surface (or interface). Recovery of pure and interaction (interface) spectral components from an imide thiol adhesion promoter layer is demonstrated using the above methods.

  8. Infrared reflection absorption spectroscopic study on the adsorption structures of ethylene on Ag(110) and atomic oxygen pre-covered Ag(110) surfaces

    NASA Astrophysics Data System (ADS)

    Akita, Masato; Osaka, Naoki; Hiramoto, Shuji; Itoh, Koichi

    1999-06-01

    Infrared reflection absorption spectra in the CH 2 out-of-plane wagging (ω(CH 2)) vibration region were measured for ethylene (C 2H 4) adsorbed on Ag(110) as well as on the oxygen-induced p( n×1) reconstructed surfaces of Ag(110) ( n=2, 3, 4 and 6) at 80 K. C 2H 4 on Ag(110) gives a main peak at 955 cm -1, while on p(2×1)O-Ag(110) it exhibits a broad features of at least four components (997, 984, 970 and 954 cm -1) at saturation coverage. C 2H 4 on p( n×1)O-Ag(110) ( n=6, 4, 3) gives rise to a 972-976 cm -1 band at low exposures, shifting to 966-970 cm -1 at saturation coverage. The spectral changes are interpreted by assuming a pair of adsorption sites on both sides of the added Ag-O rows of the reconstructed surfaces.

  9. Adsorption kinetics and intermolecular interactions of CO adsorbed on Cu(100) by transient laser reflection-absorption spectroscopy

    SciTech Connect

    Borguet, E.; Dai, H.L.

    1993-12-31

    IR and visible transient laser spectroscopic techniques have been developed to probe adsorption/desorption kinetics and intermolecular interactions of the CO/Cu(100) system. Vibrational spectroscopy, in general, can provide information about the nature of species adsorbed on surfaces e.g. chemical identity, site, orientation and concentration. In the presence of a few percent of CO adsorbed at step/defect sites, the spectra of the CO adsorbed on the terrace sites are greatly perturbed through dynamic-dipole coupling. This perturbation depends strongly on the intermolecular distance and the short-range order of the adsorbates. An analysis of this dynamic-dipole coupling reveals that the local arrangement of adsorbates is dominant by repulsive nearest-neighbor interactions. Successful modeling of the observed lineshapes allows the populations at each site to be determined at all coverages. The authors have also observed non-resonant adsorbate induced changes in both the IR and visible reflectance for a number of different adsorbates. This provides a simple and sensitive optical means of studying adsorption and desorption kinetics.

  10. Elucidation of intermediates and mechanisms in heterogeneous catalysis using infrared spectroscopy.

    PubMed

    Savara, Aditya; Weitz, Eric

    2014-01-01

    Infrared spectroscopy has a long history as a tool for the identification of chemical compounds. More recently, various implementations of infrared spectroscopy have been successfully applied to studies of heterogeneous catalytic reactions with the objective of identifying intermediates and determining catalytic reaction mechanisms. We discuss selective applications of these techniques with a focus on several heterogeneous catalytic reactions, including hydrogenation, deNOx, water-gas shift, and reverse-water-gas shift. The utility of using isotopic substitutions and other techniques in tandem with infrared spectroscopy is discussed. We comment on the modes of implementation and the advantages and disadvantages of the various infrared techniques. We also note future trends and the role of computational calculations in such studies. The infrared techniques considered are transmission Fourier transform infrared spectroscopy, infrared reflection-absorption spectroscopy, polarization-modulation infrared reflection-absorption spectroscopy, sum-frequency generation, diffuse reflectance infrared Fourier transform spectroscopy, attenuated total reflectance, infrared emission spectroscopy, photoacoustic infrared spectroscopy, and surface-enhanced infrared absorption spectroscopy.

  11. Infra-red reflection absorption spectroscopic study on adsorption structures of acrolein on polycrystalline gold and Au(111) surfaces under ultra-high vacuum conditions

    NASA Astrophysics Data System (ADS)

    Akita, M.; Osaka, N.; Itoh, K.

    1998-05-01

    Infra-red reflection absorption (IRA) spectra were measured at 80 K under ultra-high vacuum conditions for acrolein adsorbed on two kinds of gold films; Au(111) and polycrystalline gold surfaces. Upon increasing the amount of exposure from 0.02 to 200 L (1 L=1×10 -6 Torr·s), the adsorbate at Au(111) gave rise to a series of sharp IRA bands due to a CH 2 out-of-plane wagging vibration [ ω(CH 2)] successively, indicating discrete adsorption states, i.e. 964 (type 1)→978(type 1')→991(type 2)→1003 cm -1(type 3). All these states have the molecular plane parallel to the surface; type 1 is in an isolated state, and type 2 is in an associated state with a two-dimensional arrangement, whereas type 3 forms an ordered multilayered structure. Type 1' was tentatively assigned either to a trapped state at step sites or to an associated state forming small oligomers at the surface. Only type 3 gives rise to IRA bands due to ν(CO), which appears at 1677 cm -1 as a singlet at relatively small exposure levels and splits into doublets, giving the 1686 and 1672 cm -1 components at 2.0 L. The doublets were explained as being due to a crystal field splitting, which conforms to the fact that the adsorbate forms an ordered three-dimensional arrangement. The IRA spectrum of type 3 is readily converted to that of a more stable polycrystalline state upon increasing the temperature from 80 to 100 K. Thus, type 3 is a thermodynamically metastable state. Acrolein adsorbed on a polycrystalline gold film assumes an amorphous state in the exposure level of 0.06-4.8 L, giving broad IRA bands due to ν(CO) and ω(CH 2) in the 1686-1699 and 974-991 cm -1 regions, respectively. The IRA spectra of acrolein adsorbed on Ag(111) were also measured, which indicated that the adsorbates exist in a less ordered state than those on Au(111), although a multilayered structure gives IRA features that are almost identical with those of type 3.

  12. Infrared reflection absorption spectroscopic studies on the adsorption structures of dimethyl sulfide and methyl ethyl sulfide on Ag(1 1 0) and Cu(1 1 0)

    NASA Astrophysics Data System (ADS)

    Kasahara, T.; Shinohara, H.; Oshima, Y.; Kadokura, K.; Uriu, Y.; Ohe, C.; Itoh, K.

    2004-06-01

    Infrared reflection absorption (IRA) spectra were measured for dimethyl sulfide (CH 3SCH 3, DMS) and methyl ethyl sulfide (CH 3SCH 2CH 3, MES) with increasing exposure to metal substrates, Ag(1 1 0) and Cu(1 1 0), at 80 K. The spectral simulations performed by using the DFT calculation at the B3LYP/6-311++G** level indicated that (i) DMS adsorbs on the substrates with the CSC plane appreciably tilted from the surface normal, the tilt angle being about 80° for the adsorbate on Ag(1 1 0) and about 60° for the adsorbate on Cu(1 1 0), (ii) MES on Ag(1 1 0) at a submonolayer coverage state takes on the trans form with the molecular plane tilted from the surface normal by about 60°, and (iii) MES on Cu(1 1 0) takes the gauche form with the CSC plane almost perpendicular to the surface. The tilting of DMS is contrasted to dimethyl ether (DME) adsorbs on Ag(1 1 0) and Cu(1 1 0), where the molecular plane is perpendicular to the substrate surfaces [J. Phys. Chem. B 106 (2002) 3469]. The adsorption structures of DMS and DME are mainly determined by the coordination of the sulfur and oxygen atoms, the sulfur atom tending to coordinate to the Ag and Cu atoms through one of the 3p lone pairs (atop coordination) and the oxygen atom to the metal atoms through both of the 2p lone pairs (bridging coordination). It has been known that methyl ethyl ether (MEE) on Ag(1 1 0) takes on the trans form with the molecular plane tilted by about 45° and MEE on Cu(1 1 0) the gauche form with the COC plane almost perpendicular to the surface [J. Phys. Chem. B 107 (2003) 5008]. These results suggest that an attractive van der Waals interaction between the ethyl group of the adsorbates and the substrate surfaces play an important role in addition to the coordination of the sulfur and oxygen atoms in determining the rotational isomerism and orientation of MES and MEE on Ag(1 1 0) and Cu(1 1 0).

  13. Infrared reflection absorption spectroscopic study of the adsorption structures of dimethyl ether and methyl ethyl ether on Cu(1 1 1) and Ag(1 1 1)

    NASA Astrophysics Data System (ADS)

    Kasahara, Takahiro; Itoh, Koichi

    2007-02-01

    Infrared reflection absorption (IRA) spectra measured for dimethyl ether (DME) adsorbed at 80 K on Cu(1 1 1) and Ag(1 1 1) give IR bands belonging only to the A 1 and B 2 species, indicating that the adsorbate takes on an orientation in which the C2 axis bisecting the COC bond angle tilts away from the surface normal within the plane perpendicular to the substrates. The DFT method was applied to simulate the IRA spectra, indicating that the tilt angles of DME on Cu(1 1 1) and Ag(1 1 1) are about 50° and 55°, respectively, at submonolayer coverages. The results are in contrast to the case of DME on Cu(1 1 0) and Ag(1 1 0), where the C2 axis is perpendicular to the substrates [T. Kiyohara et al., J. Phys. Chem. A 106 (2002) 3469]. Methyl ethyl ether (MEE) adsorbed at 80 K on Cu(1 1 1) gives IRA bands mainly ascribable to the gauche ( G) form, whereas the IRA spectra measured for MEE on Ag(1 1 1) are characterized by the trans ( T) form. The rotational isomers are identical with those on Cu(1 1 0) and Ag(1 1 0); i.e., MEE on Cu(1 1 0) takes the G form and the adsorbate on Ag(1 1 0) the T form [T. Kiyohara et al., J. Phys. Chem. B 107 (2003) 5008]. The simulation of the IRA spectra indicated that (i) the G form adsorbate on Cu(1 1 1) takes an orientation, in which the axis bisecting the COC bond angle tilts away from the surface normal by ca. 30° within the plane perpendicular to the surface to make the CH 3-CH 2 bond almost parallel to the surface, and (ii) the T form adsorbate on Ag(1 1 1) takes an orientation, in which the bisecting axis tilts away by ca. 60° from the surface normal within the perpendicular plane. Comparison of these adsorption structures of MEE on the (1 1 1) substrates with those of MEE on Cu(1 1 0) and Ag(1 1 0) indicates that the structures are mainly determined by a coordination interaction of the oxygen atom to the surface metals and an attractive van der Waals interaction between the ethyl group of MEE and the substrate surfaces. The

  14. An Introductory Infrared Spectroscopy Experiment.

    ERIC Educational Resources Information Center

    Hess, Kenneth R.; Smith, Wendy D.; Thomsen, Marcus W.; Yoder, Claude H.

    1995-01-01

    Describes a project designed to introduce infrared spectroscopy as a structure-determination technique. Students are introduced to infrared spectroscopy fundamentals then try to determine the identity of an unknown liquid from its infrared spectrum and molecular weight. The project demonstrates that only rarely can the identity of even simple…

  15. An Introductory Infrared Spectroscopy Experiment.

    ERIC Educational Resources Information Center

    Hess, Kenneth R.; Smith, Wendy D.; Thomsen, Marcus W.; Yoder, Claude H.

    1995-01-01

    Describes a project designed to introduce infrared spectroscopy as a structure-determination technique. Students are introduced to infrared spectroscopy fundamentals then try to determine the identity of an unknown liquid from its infrared spectrum and molecular weight. The project demonstrates that only rarely can the identity of even simple…

  16. Infrared spectroscopy of Mars

    NASA Astrophysics Data System (ADS)

    Kirkland, Laurel Ellyn

    1999-11-01

    When measured with sufficient spectral range, resolution, and signal-to-noise ratio, nearly every mineral has a unique infrared spectral signature. However, determining which minerals are present on Mars using infrared spectroscopy has proven to be very difficult. The goal of this work is to examine complicating factors inherent to spacecraft-based infrared spectral measurements of Mars, and to determine methods to extract mineralogical information from spectra that cover the wavelength range 0.77 to 50 μm. On Earth, infrared spectra of an unknown mineral or gas can be measured under controlled conditions. However, a spacecraft spectrometer measures Mars through both atmospheric gases and aerosols, and at varying viewing geometries. Spectra of the surface of Mars have very subtle variations, so examining them requires well- calibrated spectra of excellent quality, and extended spectral range. These combined effects greatly complicate interpretations. The work presented here details a straightforward method to remove effects of varying viewing geometry on near- infrared spectra of Mars, using 1989 Phobos 2 ISM spectra. Next, it details the recovery and calibration of the 1969 Mariner Mars IRS data set, and presents IRS spectral evidence for goethite on Mars. Finally, a method is developed to utilize night spectra to examine the aerosol mineralogy, followed by a discussion of the importance of accounting for the aerosol re-emission when utilizing day measurements to examine surface mineralogy. This work utilizes spectra from all five infrared spectrometers flown to Mars. It addresses a range of issues, but the unifying theme is how to extract mineralogic information from the spectra. The results show that the most important spectral criteria for determining mineralogy from spacecraft infrared spectra are an extended spectral range, high spectral resolution, and high signal-to-noise ratio. Here, an extended spectral range is defined as coverage of at least two of the

  17. Infrared diode laser spectroscopy

    NASA Astrophysics Data System (ADS)

    Civiš, S.; Cihelka, J.; Matulková, I.

    2010-12-01

    Three types of lasers (double-heterostructure 66 K InAsSb/InAsSbP laser diode, room temperature, multi quantum wells with distributed feedback (MQW with DFB) (GaInAsSb/AlGaAsSb based) diode laser and vertical cavity surface emitting lasers (VCSELs) (GaSb based) have been characterized using Fourier transform emission spectroscopy and compared. The photoacoustic technique was employed to determine the detection limit of formaldehyde (less than 1 ppmV) for the strongest absorption line of the v3 + v5 band in the emission region of the GaInAsSb/AlGaAsSb diode laser. The detection limit (less than 10 ppbV) of formaldehyde was achieved in the 2820 cm-1 spectral range in case of InAsSb/InAsSbP laser (fundamental bands of v1, v5). Laser sensitive detection (laser absorption together with high resolution Fourier transform infrared technique including direct laser linewidth measurement, infrared photoacoustic detection of neutral molecules (methane, form-aldehyde) is discussed. Additionally, very sensitive laser absorption techniques of such velocity modulation are discussed for case of laser application in laboratory research of molecular ions. Such sensitive techniques (originally developed for lasers) contributed very much in identifying laboratory microwave spectra of a series of anions (C6H-, C4H-, C2H-, CN-) and their discovery in the interstellar space (C6H-, C4H-).

  18. Infrared heterodyne spectroscopy in astronomy

    NASA Technical Reports Server (NTRS)

    Betz, A.

    1980-01-01

    A heterodyne spectrometer was constructed and applied to problems in infrared astronomical spectroscopy. The instrument offers distinct observational advantages for the detection and analysis of individual spectral lines at Doppler-limited resolution. Observations of carbon dioxide in planetary atmospheres and ammonia in circumstellar environments demonstrate the substantial role that infrared heterodyne techniques will play in the astronomical spectroscopy of the future.

  19. Infrared spectroscopy with visible light

    NASA Astrophysics Data System (ADS)

    Kalashnikov, Dmitry A.; Paterova, Anna V.; Kulik, Sergei P.; Krivitsky, Leonid A.

    2016-02-01

    Spectral measurements in the infrared optical range provide unique fingerprints of materials, which are useful for material analysis, environmental sensing and health diagnostics. Current infrared spectroscopy techniques require the use of optical equipment suited for operation in the infrared range, components of which face challenges of inferior performance and high cost. Here, we develop a technique that allows spectral measurements in the infrared range using visible-spectral-range components. The technique is based on nonlinear interference of infrared and visible photons, produced via spontaneous parametric down conversion. The intensity interference pattern for a visible photon depends on the phase of an infrared photon travelling through a medium. This allows the absorption coefficient and refractive index of the medium in the infrared range to be determined from the measurements of visible photons. The technique can substitute and/or complement conventional infrared spectroscopy and refractometry techniques, as it uses well-developed components for the visible range.

  20. Infrared Spectroscopy of Explosives Residues: Measurement Techniques and Spectral Analysis

    SciTech Connect

    Phillips, Mark C.; Bernacki, Bruce E.

    2015-03-11

    Infrared laser spectroscopy of explosives is a promising technique for standoff and non-contact detection applications. However, the interpretation of spectra obtained in typical standoff measurement configurations presents numerous challenges. Understanding the variability in observed spectra from explosives residues and particles is crucial for design and implementation of detection algorithms with high detection confidence and low false alarm probability. We discuss a series of infrared spectroscopic techniques applied toward measuring and interpreting the reflectance spectra obtained from explosives particles and residues. These techniques utilize the high spectral radiance, broad tuning range, rapid wavelength tuning, high scan reproducibility, and low noise of an external cavity quantum cascade laser (ECQCL) system developed at Pacific Northwest National Laboratory. The ECQCL source permits measurements in configurations which would be either impractical or overly time-consuming with broadband, incoherent infrared sources, and enables a combination of rapid measurement speed and high detection sensitivity. The spectroscopic methods employed include standoff hyperspectral reflectance imaging, quantitative measurements of diffuse reflectance spectra, reflection-absorption infrared spectroscopy, microscopic imaging and spectroscopy, and nano-scale imaging and spectroscopy. Measurements of explosives particles and residues reveal important factors affecting observed reflectance spectra, including measurement geometry, substrate on which the explosives are deposited, and morphological effects such as particle shape, size, orientation, and crystal structure.

  1. Infrared spectroscopy of comets

    NASA Technical Reports Server (NTRS)

    Disanti, Michael A.; Mumma, M. J.; Hoban, S. M.; Reuter, D.; Espenak, F.; Storrs, A. D.; Lacy, J.; Parmar, R.; Joyce, R.

    1990-01-01

    An observational search for cometary parent molecules using infrared spectroscopy was conducted in the 1 to 5 micron region. The investigation involved two different observing programs, one at moderate spectral resolution and one at fairly high resolution. The lower resolution was used to study cometary spectra in the vicinity of 3.5 micron at wavelength/change in wavelength is approximately or equal to 10(exp 3). Comets P/Brorsen-Metcalf (1989o), Okazaki-Levy-Rudenko (1989r), and Austin (1990c1) were observed with the Cryogenic Spectrometer (CRSP) at Kitt Peak. The detector incorporated an InSb array with 58 spatial elements, each 2.7 min on the sky, and 62 spectral channels per spatial element. An, as yet, unidentified feature was detected at approximately 3.52 micron in Comet Austin (on 1990 May 4, 5, and 6). The feature is possibly present in P/Brorsen-Metcalf (observed on 1989 August 23 and 25), as well. Comet Okazaki-Levy-Rudenko exhibited continuum emission only in this spectral region at the time of the observations (1989 November 14 and 16). The data are presented, and the relationship between the 3.52 micron feature and cometary activity (e.g., water production rate, visibility of the 3.4 micron emission feature) are discussed. The high resolution program probed comet Austin in the 4.8 micron region. These observations were used to search for emission lines comprising the (1-0) vibration-rotation band of the ground electronic state of CO. Retrieval of the lines allows a probe of the population distribution of levels J' = 1 through 4 of the excited (v' = 1) vibrational state within the ground electronic state of CO. Knowledge of this distribution can be used to constrain the rotational temperature. Preliminary analysis suggests the P3 line was present UT May 16 at roughly the 5 sigma level. Results concerning the existence of other lines, and physical conditions inferred therefrom are discussed.

  2. Polarimetry and infrared spectroscopy in the detection of low-volatility chemical threats

    NASA Astrophysics Data System (ADS)

    Petryk, Michael W. P.; Marenco, Armando J.

    2011-05-01

    The polarization modulation infrared reflection absorption spectroscopy (PMIRRAS) spectra of the nerve agents GB (O-isopropyl methylphosphonofluoridate) and GF (cyclohexyl methylphoshonofluoridate) were recorded for the first time. A comparison of these spectra with the nerve agent VX (ethyl S-2-diisopropylaminoethyl methylphosphonothiolate) and the spectra of some trialkyl phosphates indicates that it is easy to distinguish between chemical warfare agents and simulants on militarily-relevant surfaces using PMIRRAS.

  3. Bondline Infrared Spectroscopy (BIS).

    DTIC Science & Technology

    1983-01-01

    properties can be derived based upon the infrared spectrum of the propellant . The second output from this program will be a prediction of mechanical ...of mechanical properties of the propellant based upon past aging experience. IR Data and Time"i. Infrared spectra of the propellant were taken at each...303 Propellant Data 150 Mechanical Properties and Time/Temperature 150 S IR Data iid’ nme 153 SIR Dý.ta An4d.rveelian’ical

  4. Fourier transform infrared spectroscopy as a surface science technique

    NASA Astrophysics Data System (ADS)

    Celio, Hugo; Trenary, Michael

    1998-06-01

    A central goal of modern surface science is to obtain atomic and molecular level information about the structural and chemical properties of solid surfaces. For many, if not most, problems in surface science it is necessary to work under ultra high vacuum (UHV) conditions to obtain meaningful and reproducible results. A wide array of highly specialized and hence expensive UHV surface sensitive techniques have been developed to probe the gas-solid interface. Most of these techniques rely on the finite penetration depth of charge particles to achieve surface sensitivity. In contrast, surface sensitivity can also be achieved with reflection absorption infrared spectroscopy using unmodified low-cost commercial FTIR spectrometers. In this paper we show how a variety of problems in surface chemistry can be effectively addressed with FTIR spectroscopy.

  5. Optical Properties of β-RDX Thin Films Deposited on Gold and Stainless Steel Substrates Calculated from Reflection-Absorption Infrared Spectra.

    PubMed

    Ruiz-Caballero, José L; Aparicio-Bolaño, Joaquín A; Figueroa-Navedo, Amanda M; Pacheco-Londoño, Leonardo C; Hernandez-Rivera, Samuel P

    2017-08-01

    The optical properties for crystalline films of the highly energetic material (HEM) hexahydro-1,3,5-trinitro-s-triazine, which is also known as RDX, deposited on gold (Au) and stainless steel (SS) substrates are presented. RDX has two important stable conformational polymorphs at room temperature: α-RDX and β-RDX. The optical properties obtained in the present work correspond to thin film samples of predominantly β-RDX polymorph. The infrared spectroscopic intensities measured showed significant differences in the β-RDX crystalline films deposited on the two substrates with respect to the calculated real part of refractive index. The β-RDX/Au crystalline films have a high dynamic response, which is characterized by the asymmetric stretching mode of the axial nitro groups, whereas for the β-RDX/SS crystalline films, the dynamic response was mediated by the -N-NO2 symmetric stretch mode. This result provides an idea of how the electric field vector propagates through the β-RDX crystalline films deposited on the two substrates.

  6. Infrared spectroscopy of stars

    NASA Technical Reports Server (NTRS)

    Merrill, K. M.; Ridgway, S. T.

    1979-01-01

    This paper reviews applications of IR techniques in stellar classification, studies of stellar photospheres, elemental and isotopic abundances, and the nature of remnant and ejected matter in near-circumstellar regions. Qualitative IR spectral classification of cool and hot stars is discussed, along with IR spectra of peculiar composite star systems and of obscured stars, and IR characteristics of stellar populations. The use of IR spectroscopy in theoretical modeling of stellar atmospheres is examined, IR indicators of stellar atmospheric composition are described, and contributions of IR spectroscopy to the study of stellar recycling of interstellar matter are summarized. The future of IR astronomy is also considered.

  7. Infrared Spectroscopy of Deuterated Compounds.

    ERIC Educational Resources Information Center

    MacCarthy, Patrick

    1985-01-01

    Background information, procedures used, and typical results obtained are provided for an experiment (based on the potassium bromide pressed-pellet method) involving the infrared spectroscopy of deuterated compounds. Deuteration refers to deuterium-hydrogen exchange at active hydrogen sites in the molecule. (JN)

  8. A Quantitative Infrared Spectroscopy Experiment.

    ERIC Educational Resources Information Center

    Krahling, Mark D.; Eliason, Robert

    1985-01-01

    Although infrared spectroscopy is used primarily for qualitative identifications, it is possible to use it as a quantitative tool as well. The use of a standard curve to determine percent methanol in a 2,2,2-trifluoroethanol sample is described. Background information, experimental procedures, and results obtained are provided. (JN)

  9. A Quantitative Infrared Spectroscopy Experiment.

    ERIC Educational Resources Information Center

    Krahling, Mark D.; Eliason, Robert

    1985-01-01

    Although infrared spectroscopy is used primarily for qualitative identifications, it is possible to use it as a quantitative tool as well. The use of a standard curve to determine percent methanol in a 2,2,2-trifluoroethanol sample is described. Background information, experimental procedures, and results obtained are provided. (JN)

  10. Infrared Spectroscopy of Deuterated Compounds.

    ERIC Educational Resources Information Center

    MacCarthy, Patrick

    1985-01-01

    Background information, procedures used, and typical results obtained are provided for an experiment (based on the potassium bromide pressed-pellet method) involving the infrared spectroscopy of deuterated compounds. Deuteration refers to deuterium-hydrogen exchange at active hydrogen sites in the molecule. (JN)

  11. Infrared spectroscopy of aerosols

    NASA Astrophysics Data System (ADS)

    Mentel, Th.; Sebald, H.

    2003-04-01

    In our large Aerosol Chamber at the FZ Jülich we apply HR FTIR absorption spectroscopy for the determination of trace gases. In the FTIR spectra we also observe broad absorptions of several 10 to a few 100 cm-1 widths that arise from species in the condensed aerosol phase: liquid H_2O, NO_3^-, SO_42-, HSO_4^-, or dicarboxylic acids. Moreover, the aerosol droplets caused extinctions over several 1000 cm-1 by IR scattering. This allows for in-situ observation of changes in the condensed aerosol phase e.g. on HNO_3 uptake, like the shift of the sulfate/bisulfate equilibrium or the growth by water condensation. The IR absorptions of the condensed aerosol phase provide useful extra information in process studies, if they can be quantified. Therefore the absorption cross section, respective, the absorption index which is the imaginary part of the complex refractive index is needed. We set up an aerosol flow tube in which IR spectroscopy on a 8 m light path and aerosol size distribution measurements in the range from 20 nm - 10 μm can be performed simultaneously. We measured sulfate aerosols at several relative humidities (dry, metastable, deliquescent). We will demonstrate an iterative procedure based on Mie calculations and Kramers Kronig transformation to retrieve the absorption index from the observed IR spectra and the corresponding size distribution (for dry ammonium sulfate). We will compare resulting absorption indices for aqueous sodium bisulfate aerosols at several relative humidties with thermodynamic model calculations for the Na^+/H^+/HSO_4^-/SO_42-/H_2O system.

  12. Infrared spectroscopy of NGC 1068

    NASA Astrophysics Data System (ADS)

    Depoy, D. L.

    Spectroscopy of the nucleus of the nearby Seyfert 2 galaxy NGC 1068 has been obtained using the IRTF and the facility Cooled-Grating Array Spectrometer (CGAS). The wavelengths observed covered the expected wavelengths of the Bry (n = 7 4), Br (n = 5 4), and the Pf (n = 7 5) hydrogen recombination lines between 2.2 m and 4.6 m. The CGAS has a 32-element InSb array multiplexed by a Reticon and was used at a resolution of 250 km s-1, allowing accurate determination of the line profiles and surrounding continua simultaneously. For example, the S/N at each spectral position in the Br line spectrum was 100. The data show that the infrared lines are not more broadened than the optical hydrogen recombination lines, suggesting that the presence of an obscured Seyfert 1-like active nucleus is unlikely unless the visual extinction through any obscuring material present is larger than 100 mag.

  13. Infrared spectroscopy in biomedical diagnostics

    NASA Astrophysics Data System (ADS)

    Afanasyeva, Natalia I.; Kolyakov, Sergei F.; Letokhov, Vladilen S.; Artioushenko, Vjacheslav G.; Golovkina, Viktoriya N.

    1998-01-01

    Fiberoptic evanescent wave Fourier transform infrared (FEW- FTIR) spectroscopy using fiberoptic sensors operated in the attenuated total reflection (ATR) regime in the middle infrared (IR) region of the spectrum (850 - 1850 cm-1) has recently found application in the diagnostics of tissues. The method is suitable for noninvasive and rapid (seconds) direct measurements of the spectra of normal and pathological tissues in vitro, ex vivo and in vivo. The aim of our studies is the express testing of various tumor tissues at the early stages of their development. The method is expected to be further developed for endoscopic and biopsy applications. We measured in vivo the skin normal and malignant tissues on surface (directly on patients) in various cases of basaloma, melanoma and nevus. The experiments were performed in the operating room for measurements of skin in the depth (under/in the layers of epidermis), human breast, stomach, lung, kidney tissues. The breast and skin tissues at different stages of tumor or cancer were distinguished very clearly in spectra of amide, side cyclic and noncyclic hydrogen bonded fragments of amino acid residuals, phosphate groups and sugars. Computer monitoring is being developed for diagnostics.

  14. Study of SF6 adsorption on graphite using infrared spectroscopy

    NASA Astrophysics Data System (ADS)

    Thomas, Petros; Xia, Yu; Boyd, David A.; Hopkins, Todd A.; Hess, George B.

    2009-09-01

    We report an experimental study of adsorbed monolayers of SF6 on graphite using infrared reflection absorption spectroscopy supplemented by ellipsometry. The asymmetric S-F stretch mode ν3 near 948 cm-1 in the gas is strongly blueshifted in the film by dynamic dipole coupling. This blueshift is very sensitive to the intermolecular spacing in the SF6 layer. We convert the measured frequency ν3 to a lattice spacing a, using a self-consistent field calculation, calibrated by the frequency in the commensurate phase. The resolution in lattice spacing is 0.002 Å, although there is a larger systematic uncertainty associated with nondynamic-dipole contributions to the frequency shift. We map the commensurate-incommensurate transition, a transition between two incommensurate phases, and the melting transition. These results are compared to previous x-ray data. We provide a new determination of the layer critical point (156 K), the layer condensation line down to 110 K, and the spreading pressure at saturation in this temperature range.

  15. Infrared spectroscopy and photodesorption of condensed phase ammonia

    NASA Astrophysics Data System (ADS)

    Szulczewski, G. J.; White, J. M.

    1998-05-01

    We have characterized the adsorption and thermal desorption of thick films of NH 3 and ND 3 condensed on Ag(111) with Fourier transform reflection absorption infrared spectroscopy and temperature programmed desorption. Over the coverage range of 1-50 monolayers, the asymmetric stretch (2513 cm -1 for ND 3 and 3380 cm -1 for NH 3) and symmetric deformation (832 cm -1 for ND 3 and 1078 cm -1 for NH 3) modes of ammonia are the most intense features in the vibrational spectra. Temperature programmed desorption yields an activation energy for thermal desorption of NH 3 and ND 3 multilayers of 23.8 kJ mol -1 and 24.7 kJ mol -1, respectively. At a coverage of 50 ML we used 193 nm light to stimulate molecular desorption from the multilayers and measured time-of-flight spectra. All time-of-flight spectra were bimodal; the average translational energies of the two components were 3150±100 K and 550±50 K. The fast channel is ascribed to ammonia molecules ejected from the vacuum-film interface while the slower channel is ascribed to ammonia molecules desorbing from deeper layers of the film. At 50 ML the angular distribution of photodesorbed ammonia peaks between 20° and 40° off the surface normal.

  16. Fourier Transform Infrared Spectroscopy Part III. Applications.

    ERIC Educational Resources Information Center

    Perkins, W. D.

    1987-01-01

    Discusses the use of the FT-IR spectrometer in analyses that were previously avoided. Examines some of the applications of this spectroscopy with aqueous solutions, circular internal reflection, samples with low transmission, diffuse reflectance, infrared emission, and the infrared microscope. (TW)

  17. Fourier Transform Infrared Spectroscopy Part III. Applications.

    ERIC Educational Resources Information Center

    Perkins, W. D.

    1987-01-01

    Discusses the use of the FT-IR spectrometer in analyses that were previously avoided. Examines some of the applications of this spectroscopy with aqueous solutions, circular internal reflection, samples with low transmission, diffuse reflectance, infrared emission, and the infrared microscope. (TW)

  18. [Investigation of near infrared spectroscopy of rosewood].

    PubMed

    Yang, Zhong; Jiang, Ze-Hui; Lü, Bin

    2012-09-01

    Rosewood is a kind of precious wood which include many wood species. It's difficult to most people to identify rosewood species. Near infrared spectroscopy (NIR) of eight rosewood species was investigated in the present paper. The results showed that (1) there was significant correlation between near infrared spectroscopy and color parameters expressed by L*, a* and b* values of rosewood, the correlation coefficients between NIR predicted and laboratory measured L* , a* and b* values were 0.988, 0.991 and 0.993, respectively; (2) The eight rosewood samples can be distinctly divided into eight categories by principal component analysis (PCA), the differences in the NIR among the eight rosewood species were more distinctly revealed by the three-dimensional PCA score plot than that of the two-dimensional. The results illustrated that it was feasible to identify rosewood species by near infrared spectroscopy coupled with chemometrics, and also provided a new method to rapidly identify or classify rosewood.

  19. Infrared Spectroscopy of New Molecules and Clusters

    NASA Astrophysics Data System (ADS)

    Zhou, Mingfei

    2017-06-01

    Gas phase infrared photodissociation spectroscopy and matrix isolation infrared absorption spectroscopy have proven to be effective spectroscopic methods to investigate novel molecular and cluster species. Vibrational spectroscopy combined with state-of-the-art quantum chemical calculations provides detailed information on geometric and electronic structures as well as chemical bonding of the observed species. In this presentation, I will highlight our recent studies on the formation and infrared spectroscopic characterization of a number of neutral and charged metal-containing compounds including high oxidation state transition metal and lanthanide oxide species and metal carbonyl clusters featuring unprecedented metal-metal multiple bonds. These findings help to expand chemical understanding of the behavior of elements and their compounds.

  20. [Infrared spectroscopy based on quantum cascade lasers].

    PubMed

    Wen, Zhong-Quan; Chen, Gang; Peng, Chen; Yuan, Wei-Qing

    2013-04-01

    Quantum cascade lasers (QCLs) are promising infrared coherent sources. Thanks to the quantum theory and band-gap engineering, QCL can access the wavelength in the range from 3 to 100 microm. Since the fingerprint spectrum of most gases are located in the mid-infrared range, mid-infrared quantum cascade laser based gas sensing technique has become the research focus world wide because of its high power, narrow linewidth and fast scanning. Recent progress in the QCL technology leads to a great improvement in laser output power and efficiency, which stimulates a fast development in the infrared laser spectroscopy. The present paper gives a broad review on the QCL based spectroscopy techniques according to their working principles. A discussion on their applications in gas sensing and explosive detecting is also given at the end of the paper.

  1. Nanoscale Infrared Spectroscopy of Biopolymeric Materials

    Treesearch

    Curtis Marcott; Michael Lo; Kevin Kjoller; Craig Prater; Roshan Shetty; Joseph Jakes; Isao Noda

    2012-01-01

    Atomic Force Microscopy (AFM) and infrared (IR) spectroscopy have been combined in a single instrument capable of producing 100 nm spatial resolution IR spectra and images. This new capability enables the spectroscopic characterization of biomaterial domains at levels not previously possible. A tunable IR laser source generating pulses on the order of 10 ns was used...

  2. Infrared spectroscopy of ionic clusters

    SciTech Connect

    Price, J.M. . Dept. of Chemistry Lawrence Berkeley Lab., CA )

    1990-11-01

    This thesis describes new experiments wherein the infrared vibrational predissociation spectra of a number of mass-selected ionic cluster systems have been obtained and analyzed in the 2600 to 4000 cm{sup {minus}1} region. The species studied include: the hydrated hydronium ions, H{sub 3}O{sup +} (H{sub 2}O){sub 3 {minus}10}, ammoniated ammonium ions, NH{sub 4}{sup +}(NH{sub 3}){sub 1 {minus}10} and cluster ions involving both water and ammonia around an ammonium ion core, (mixed clusters) NH{sub 4}{sup +}(NH{sub 3}){sub n}(H{sub 2}O){sub m} (n+m=4). In each case, the spectra reveal well resolved structures that can be assigned to transitions arising from the vibrational motions of both the ion core of the clusters and the surrounding neutral solvent molecules. 154 refs., 19 figs., 8 tabs.

  3. Flap monitoring using infrared spectroscopy

    NASA Astrophysics Data System (ADS)

    Keller, Alex; Wright, Leigh P.; Elmandjra, Mohamed; Mao, Jian-min

    2006-02-01

    We report results of clinical trials on flap monitoring in 65 plastic surgeries. Hemoglobin oxygen saturation of flap tissue (StO II) was monitored non-invasively by using ODISsey TM tissue oximeter, an infrared spectroscopic device. StO II measurements were conducted both intra-operatively and post-operatively. From the intra-operative measurements, we observed that StO II values dropped when the main blood vessels supplying the flap were clamped in surgery, and that StO II jumped after anastomosis to a value close to its pre-operative value. From post-operative monitoring measurements for the 65 flap cases, each lasted two days or so, we found that the StO II values approach to a level close to the baseline if the surgery was successful, and that the StO II value dropped to a value below 30% if there is a perfusion compromise, such as vascular thrombosis.

  4. Infrared spectroscopy of radiation-chemical transformation of n-hexane on a beryllium surface

    NASA Astrophysics Data System (ADS)

    Gadzhieva, N. N.

    2017-07-01

    The radiation-chemical decomposition of n-hexane in a Be- n-hexane system under the effect of γ-irradiation at room temperature is studied by infrared reflection-absorption spectroscopy. In the absorbed dose range 5 kGy ≤ Vγ ≤ 50 kGy, intermediate surface products of radiation-heterogeneous decomposition of n-hexane (beryllium alkyls, π-olefin complexes, and beryllium hydrides) are detected. It is shown that complete radiolysis occurs at Vγ = 30 kGy; below this dose, decomposition of n-hexane occurs only partially, while higher doses lead to steady-state saturation. The radiation-chemical yield of the final decomposition product—molecular hydrogen—is determined to be G ads(H2) = 24.8 molecules/100 eV. A possible mechanism of this process is discussed.

  5. Infrared microcalorimetric spectroscopy using uncooled thermal detectors

    SciTech Connect

    Datskos, P.G. |; Rajic, S.; Datskou, I.; Egert, C.M.

    1997-10-01

    The authors have investigated a novel infrared microcalorimetric spectroscopy technique that can be used to detect the presence of trace amounts of target molecules. The chemical detection is accomplished by obtaining the infrared photothermal spectra of molecules absorbed on the surface of an uncooled thermal detector. Traditional gravimetric based chemical detectors (surface acoustic waves, quartz crystal microbalances) require highly selective coatings to achieve chemical specificity. In contrast, infrared microcalorimetric based detection requires only moderately specific coatings since the specificity is a consequence of the photothermal spectrum. They have obtained infrared photothermal spectra for trace concentrations of chemical analytes including diisopropyl methylphosphonate (DIMP), 2-mercaptoethanol and trinitrotoluene (TNT) over the wavelength region2.5 to 14.5 {micro}m. They found that in the wavelength region 2.5 to 14.5 {micro}m DIMP exhibits two strong photothermal peaks. The photothermal spectra of 2-mercaptoethanol and TNT exhibit a number of peaks in the wavelength region 2.5 to 14.5 {micro}m and the photothermal peaks for 2-mercaptoethanol are in excellent agreement with infrared absorption peaks present in its IR spectrum. The photothermal response of chemical detectors based on microcalorimetric spectroscopy has been found to vary reproducibly and sensitively as a consequence of adsorption of small number of molecules on a detector surface followed by photon irradiation and can be used for improved chemical characterization.

  6. Infrared Spectroscopy of Blood for Disease Identification

    NASA Astrophysics Data System (ADS)

    Pichardo, J. L.; Huerta-Franco, R.; Álvarez, R. R.; Bernal, J.; Gutiérrez-Juárez, G.; Palomares-Anda, P.

    2003-09-01

    Total reflectance attenuated infrared Fourier transform spectroscopy was used to analyze blood samples. Plasma and red blood cells were separated by centrifugation. The spectra were recorded from 200 to 4000 cm-1 under the same conditions for all samples. Samples of healthy donors were compared with those patients with different diseases (polycythemia and high blood pressure). Patients were under medical control at the time of the study. However, the preliminary results reveal that blood samples from healthy subjects had different infrared spectra compared to the non healthy patients.

  7. [Infrared spectroscopy application in soil organic matter].

    PubMed

    Wu, J; Xi, S; Jiang, Y

    1998-02-01

    As an important method to study the constitution and properties of macromolecular organic compounds, the infrared spectroscopy has been more and more widely taken in the researches of soil organic matters (SOM). Especially,the application of FTIR and the combined uses of FTIR with chromatogram etc. have made the researches of SOM get a great progress in many aspects. In this paper, the infrared spectroscopy applications were reviewed in SOM. It includes the following contents: the methods to study SOM by IR, studies on the constitution of soil humic substances (SHS), extraction of SOM and classification of SHS, decomposition, transformation and humification of organic matters, the differences of SOM in different situations, the interactions of SHS with metais, clay minerals and other organics in soil.

  8. Nonlinear photothermal mid-infrared spectroscopy

    NASA Astrophysics Data System (ADS)

    Totachawattana, Atcha; Erramilli, Shyamsunder; Sander, Michelle Y.

    2016-10-01

    Mid-infrared photothermal spectroscopy is a pump-probe technique for label-free and non-destructive sample characterization by targeting intrinsic vibrational modes. In this method, the mid-infrared pump beam excites a temperature-induced change in the refractive index of the sample. This laser-induced change in the refractive index is measured by a near-infrared probe laser using lock-in detection. At increased pump powers, emerging nonlinear phenomena not previously demonstrated in other mid-infrared techniques are observed. Nonlinear study of a 6 μm-thick 4-Octyl-4'-Cyanobiphenyl (8CB) liquid crystal sample is conducted by targeting the C=C stretching band at 1606 cm-1. At high pump powers, nonlinear signal enhancement and multiple pitchfork bifurcations of the spectral features are observed. An explanation of the nonlinear peak splitting is provided by the formation of bubbles in the sample at high pump powers. The discontinuous refractive index across the bubble interface results in a decrease in the forward scatter of the probe beam. This effect can be recorded as a bifurcation of the absorption peak in the photothermal spectrum. These nonlinear effects are not present in direct measurements of the mid-infrared beam. Evolution of the nonlinear photothermal spectrum of 8CB liquid crystal with increasing pump power shows enhancement of the absorption peak at 1606 cm-1. Multiple pitchfork bifurcations and spectral narrowing of the photothermal spectrum are demonstrated. This novel nonlinear regime presents potential for improved spectral resolution as well as a new regime for sample characterization in mid-infrared photothermal spectroscopy.

  9. Mid infrared emission spectroscopy of carbon plasma.

    PubMed

    Nemes, Laszlo; Brown, Ei Ei; S-C Yang, Clayton; Hommerich, Uwe

    2017-01-05

    Mid infrared time-resolved emission spectra were recorded from laser-induced carbon plasma. These spectra constitute the first study of carbon materials LIB spectroscopy in the mid infrared range. The carbon plasma was induced using a Q-switched Nd: YAG laser. The laser beam was focused to high purity graphite pellets mounted on a translation stage. Mid infrared emission from the plasma in an atmospheric pressure background gas was detected by a cooled HgCdTe detector in the range 4.4-11.6μm, using long-pass filters. LIB spectra were taken in argon, helium and also in air. Despite a gate delay of 10μs was used there were strong backgrounds in the spectra. Superimposed on this background broad and noisy emission bands were observed, the form and position of which depended somewhat on the ambient gas. The spectra were digitally smoothed and background corrected. In argon, for instance, strong bands were observed around 4.8, 6.0 and 7.5μm. Using atomic spectral data by NIST it could be concluded that carbon, argon, helium and nitrogen lines from neutral and ionized atoms are very weak in this spectral region. The width of the infrared bands supports molecular origin. The infrared emission bands were thus compared to vibrational features of carbon molecules (excluding C2) of various sizes on the basis of previous carbon cluster infrared absorption and emission spectroscopic analyses in the literature and quantum chemical calculations. Some general considerations are given about the present results.

  10. Mid infrared emission spectroscopy of carbon plasma

    NASA Astrophysics Data System (ADS)

    Nemes, Laszlo; Brown, Ei Ei; Yang, Clayton S.-C.; Hommerich, Uwe

    2017-01-01

    Mid infrared time-resolved emission spectra were recorded from laser-induced carbon plasma. These spectra constitute the first study of carbon materials LIB spectroscopy in the mid infrared range. The carbon plasma was induced using a Q-switched Nd: YAG laser. The laser beam was focused to high purity graphite pellets mounted on a translation stage. Mid infrared emission from the plasma in an atmospheric pressure background gas was detected by a cooled HgCdTe detector in the range 4.4-11.6 μm, using long-pass filters. LIB spectra were taken in argon, helium and also in air. Despite a gate delay of 10 μs was used there were strong backgrounds in the spectra. Superimposed on this background broad and noisy emission bands were observed, the form and position of which depended somewhat on the ambient gas. The spectra were digitally smoothed and background corrected. In argon, for instance, strong bands were observed around 4.8, 6.0 and 7.5 μm. Using atomic spectral data by NIST it could be concluded that carbon, argon, helium and nitrogen lines from neutral and ionized atoms are very weak in this spectral region. The width of the infrared bands supports molecular origin. The infrared emission bands were thus compared to vibrational features of carbon molecules (excluding C2) of various sizes on the basis of previous carbon cluster infrared absorption and emission spectroscopic analyses in the literature and quantum chemical calculations. Some general considerations are given about the present results.

  11. Drill hole logging with infrared spectroscopy

    USGS Publications Warehouse

    Calvin, W.M.; Solum, J.G.

    2005-01-01

    Infrared spectroscopy has been used to identify rocks and minerals for over 40 years. The technique is sensitive to primary silicates as well as alteration products. Minerals can be uniquely identified based on multiple absorption features at wavelengths from the visible to the thermal infrared. We are currently establishing methods and protocols in order to use the technique for rapid assessment of downhole lithology on samples obtained during drilling operations. Initial work performed includes spectral analysis of chip cuttings and core sections from drill sites around Desert Peak, NV. In this paper, we report on a survey of 10,000 feet of drill cuttings, at 100 foot intervals, from the San Andreas Fault Observatory at Depth (SAFOD). Data from Blue Mountain geothermal wells will also be acquired. We will describe the utility of the technique for rapid assessment of lithologic and mineralogic discrimination.

  12. Infrared Spectroscopy of Anhydrous Interplanetary Dust Particles

    NASA Technical Reports Server (NTRS)

    Keller, L. P.; Flynn, G. J.

    2003-01-01

    Infrared (IR) spectroscopy is the primary means of mineralogical analysis of materials outside our solar system. The identity and properties of circumstellar grains are inferred from spectral comparisons between astronomical observations and laboratory data from natural and synthetic materials. These comparisons have been facilitated by the Infrared Space Observatory (ISO), which obtained IR spectra from numerous astrophysical objects over a wide spectral range (out to 50/cm) where crystalline silicates and other phases have distinct features. The anhydrous interplanetary dust particles (IDPs) are particularly important comparison materials because some IDPs contain carbonaceous material with non-solar D/H and N-15/N-14 ratios and amorphous and crystalline silicates with non-solar 0- isotopic ratios, demonstrating that these IDPs contain preserved interstellar material. Here, we report on micro- Fourier transform (FT) IR spectrometry of IDPs, focusing on the inorganic components of primitive IDPs (FTIR spectra from the organic/carbonacecous materials in IDPs are described elsewhere).

  13. Fourier transform infrared spectroscopy for Mars science

    NASA Astrophysics Data System (ADS)

    Anderson, Mark S.; Andringa, Jason M.; Carlson, Robert W.; Conrad, Pamela; Hartford, Wayne; Shafer, Michael; Soto, Alejandro; Tsapin, Alexandre I.; Dybwad, Jens Peter; Wadsworth, Winthrop; Hand, Kevin

    2005-03-01

    Presented here is a Fourier transform infrared spectrometer (FTIR) for field studies that serves as a prototype for future Mars science applications. Infrared spectroscopy provides chemical information that is relevant to a number of Mars science questions. This includes mineralogical analysis, nitrogen compound recognition, truth testing of remote sensing measurements, and the ability to detect organic compounds. The challenges and scientific opportunities are given for the in situ FTIR analysis of Mars soil and rock samples. Various FTIR sampling techniques are assessed and compared to other analytical instrumentation. The prototype instrument presented is capable of providing field analysis in a Mars analog Antarctic environment. FTIR analysis of endolithic microbial communities in Antarctic rocks and a Mars meteor are given as analytical examples.

  14. Infrared Spectroscopy of Anhydrous Interplanetary Dust Particles

    NASA Technical Reports Server (NTRS)

    Keller, L. P.; Flynn, G. J.

    2003-01-01

    Infrared (IR) spectroscopy is the primary means of mineralogical analysis of materials outside our solar system. The identity and properties of circumstellar grains are inferred from spectral comparisons between astronomical observations and laboratory data from natural and synthetic materials. These comparisons have been facilitated by the Infrared Space Observatory (ISO), which obtained IR spectra from numerous astrophysical objects over a wide spectral range (out to 50/cm) where crystalline silicates and other phases have distinct features. The anhydrous interplanetary dust particles (IDPs) are particularly important comparison materials because some IDPs contain carbonaceous material with non-solar D/H and N-15/N-14 ratios and amorphous and crystalline silicates with non-solar 0- isotopic ratios, demonstrating that these IDPs contain preserved interstellar material. Here, we report on micro- Fourier transform (FT) IR spectrometry of IDPs, focusing on the inorganic components of primitive IDPs (FTIR spectra from the organic/carbonacecous materials in IDPs are described elsewhere).

  15. Infrared spectroscopy of wafer-scale graphene.

    PubMed

    Yan, Hugen; Xia, Fengnian; Zhu, Wenjuan; Freitag, Marcus; Dimitrakopoulos, Christos; Bol, Ageeth A; Tulevski, George; Avouris, Phaedon

    2011-12-27

    We report spectroscopy results from the mid- to far-infrared on wafer-scale graphene, grown either epitaxially on silicon carbide or by chemical vapor deposition. The free carrier absorption (Drude peak) is simultaneously obtained with the universal optical conductivity (due to interband transitions) and the wavelength at which Pauli blocking occurs due to band filling. From these, the graphene layer number, doping level, sheet resistivity, carrier mobility, and scattering rate can be inferred. The mid-IR absorption of epitaxial two-layer graphene shows a less pronounced peak at 0.37 ± 0.02 eV compared to that in exfoliated bilayer graphene. In heavily chemically doped single-layer graphene, a record high transmission reduction due to free carriers approaching 40% at 250 μm (40 cm(-1)) is measured in this atomically thin material, supporting the great potential of graphene in far-infrared and terahertz optoelectronics.

  16. Detection of Endolithes Using Infrared Spectroscopy

    NASA Astrophysics Data System (ADS)

    Dumas, S.; Dutil, Y.; Joncas, G.

    2009-12-01

    On Earth, the Dry Valleys of Antarctica provide the closest martian-like environment for the study of extremophiles. Colonies of bacterias are protected from the freezing temperatures, the drought and UV light. They represent almost half of the biomass of those regions. Due to their resilience, endolithes are one possible model of martian biota. We propose to use infrared spectroscopy to remotely detect those colonies even if there is no obvious sign of their presence. This remote sensing approach reduces the risk of contamination or damage to the samples.

  17. Infrared spectroscopy study of irradiated PVDF

    SciTech Connect

    Chappa, Veronica; Grosso, Mariela del; Garcia Bermudez, Gerardo; Behar, Moni

    2007-10-26

    The effects induced by 1 MeV/amu ion irradiations were compared to those induced by 4-12 MeV/amu irradiations. Structural analysis with infrared spectroscopy (FTIR) was carried out on PVDF irradiated using C and He beams with different fluences. From these spectra it was observed, as a function of fluence, an overall destruction of the polymer, amorphization of the crystalline regions and the creation of in-chain unsaturations. The track dimensions were determined using a previously developed Monte Carlo simulation code and these results were compared to a semiempirical model.

  18. Infrared spectroscopy of mass-selected carbocations

    SciTech Connect

    Duncan, Michael A.

    2015-01-22

    Small carbocations are of longstanding interest in astrophysics, but there are few measurements of their infrared spectroscopy in the gas phase at low temperature. There are fewer-still measurements of spectra across the full range of IR frequencies useful to obtain an IR signature of these ions to detect them in space. We have developed a pulsed-discharge supersonic nozzle ion source producing high densities of small carbocations at low temperatures (50–70K). We employ mass-selected photodissociation spectroscopy and the method of rare gas “tagging”, together with new broadly tunable infrared OPO lasers, to obtain IR spectra for a variety of small carbocations including C{sub 2}H{sub 3}{sup +}, C{sub 3}H{sub 3}{sup +}, C{sub 3}H{sub 5}{sup +}, protonated benzene and protonated naphthalene. Spectra in the frequency range of 600–4500 cm{sup −1} provide new IR data for these ions and evidence for the presence of co-existing isomeric structures (e.g., C{sub 3}H{sub 3}{sup +} is present as both cyclopropenyl and propargyl). Protonated naphthalene has sharp bands at 6.2, 7.7 and 8.6 microns matching prominent features in the UIR spectra.

  19. Infrared Spectroscopy as a Chemical Fingerprinting Tool

    NASA Technical Reports Server (NTRS)

    Huff, Timothy L.

    2003-01-01

    Infrared (IR) spectroscopy is a powerful analytical tool in the chemical fingerprinting of materials. Any sample material that will interact with infrared light produces a spectrum and, although normally associated with organic materials, inorganic compounds may also be infrared active. The technique is rapid, reproducible and usually non-invasive to the sample. That it is non-invasive allows for additional characterization of the original material using other analytical techniques including thermal analysis and RAMAN spectroscopic techniques. With the appropriate accessories, the technique can be used to examine samples in liquid, solid or gas phase. Both aqueous and non-aqueous free-flowing solutions can be analyzed, as can viscous liquids such as heavy oils and greases. Solid samples of varying sizes and shapes may also be examined and with the addition of microscopic IR (microspectroscopy) capabilities, minute materials such as single fibers and threads may be analyzed. With the addition of appropriate software, microspectroscopy can be used for automated discrete point or compositional surface area mapping, with the latter providing a means to record changes in the chemical composition of a material surface over a defined area. Due to the ability to characterize gaseous samples, IR spectroscopy can also be coupled with thermal processes such as thermogravimetric (TG) analyses to provide both thermal and chemical data in a single run. In this configuration, solids (or liquids) heated in a TG analyzer undergo decomposition, with the evolving gases directed into the IR spectrometer. Thus, information is provided on the thermal properties of a material and the order in which its chemical constituents are broken down during incremental heating. Specific examples of these varied applications will be cited, with data interpretation and method limitations further discussed.

  20. Visualizing Infrared (IR) Spectroscopy with Computer Animation

    NASA Technical Reports Server (NTRS)

    Abrams, Charles B.; Fine, Leonard W.

    1996-01-01

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

  1. 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.

  2. Buccal microbiology analyzed by infrared spectroscopy

    NASA Astrophysics Data System (ADS)

    de Abreu, Geraldo Magno Alves; da Silva, Gislene Rodrigues; Khouri, Sônia; Favero, Priscila Pereira; Raniero, Leandro; Martin, Airton Abrahão

    2012-01-01

    Rapid microbiological identification and characterization are very important in dentistry and medicine. In addition to dental diseases, pathogens are directly linked to cases of endocarditis, premature delivery, low birth weight, and loss of organ transplants. Fourier Transform Infrared Spectroscopy (FTIR) was used to analyze oral pathogens Aggregatibacter actinomycetemcomitans ATCC 29523, Aggregatibacter actinomycetemcomitans-JP2, and Aggregatibacter actinomycetemcomitans which was clinically isolated from the human blood-CI. Significant spectra differences were found among each organism allowing the identification and characterization of each bacterial species. Vibrational modes in the regions of 3500-2800 cm-1, the 1484-1420 cm-1, and 1000-750 cm-1 were used in this differentiation. The identification and classification of each strain were performed by cluster analysis achieving 100% separation of strains. This study demonstrated that FTIR can be used to decrease the identification time, compared to the traditional methods, of fastidious buccal microorganisms associated with the etiology of the manifestation of periodontitis.

  3. Infrared spectroscopy of different phosphates structures.

    PubMed

    Jastrzębski, W; Sitarz, M; Rokita, M; Bułat, K

    2011-08-15

    Infrared (IR) spectroscopic studies of mineral and synthetic phosphates have been presented. The interpretation of the spectra has been preceded by the isolated [PO(4)](3-) tetrahedron spectra analyse. The K(3)PO(4) saturated aqueous solution was measured in the special cell for liquids. The obtained IR results have been compared with the theoretical number of IR-active modes. The number and positions of the bands due to P-O vibrations have been established. The phase composition of the phosphates has been determined using XRD and IR spectroscopy methods. The influence of non-tetrahedral cations on the shape of the spectra and the positions of bands has been analysed and the crystalline field splitting effect has been discussed.

  4. Surface Inspection using fourier transform infrared spectroscopy

    SciTech Connect

    Powell, G.L.; Smyrl, N.R.; Williams, D.M.; Meyers, H.M. III; Barber, T.E.; Marrero-Rivera, M.

    1994-08-08

    The use of reflectance Fourier transform infrared (FTIR) spectroscopy as a tool for surface inspection is described. Laboratory instruments and portable instruments can support remote sensing probes that can map chemical contaminants on surfaces. Detection limits under the best of conditions are in the subnanometer range (i.e., near absolute cleanliness), excellent performance is obtained in the submicrometer range, and useful performance may exist for films tens of microns thick. Identifying and quantifying contamination such as mineral oils and greases, vegetable oils, and silicone oils on aluminum foil, galvanized sheet steel, smooth aluminum tubing, and gritblasted 7075 aluminum alloy and D6AC steel are described. The ability to map in time and space the distribution of oil stains on metals is demonstrated. Techniques for quantitatively applying oils to metals, subsequently verifying the application, and nonlinear relationships between reflectance and the quantity of oil are discussed.

  5. Infrared Spectroscopy as a Chemical Fingerprinting Tool

    NASA Technical Reports Server (NTRS)

    Huff, Tim; Munafo, Paul M. (Technical Monitor)

    2002-01-01

    Infrared (IR) spectroscopy is a powerful analytical tool in the chemical fingerprinting of materials. The technique is rapid, reproducible and usually non-invasive. With the appropriate accessories, the technique can be used to examine samples in either a solid, liquid or gas phase. Solid samples of varying sizes and shapes may be used, and with the addition of microscopic IR (microspectroscopy) capabilities, minute materials such as single fibers and threads may be examined. With the addition of appropriate software, microspectroscopy can be used for automated discrete point or compositional surface area mapping, with the latter providing a means to record changes in the chemical composition of a material surface over a defined area. Both aqueous and non-aqueous free-flowing solutions can be analyzed using appropriate IR techniques, as can viscous liquids such as heavy oils and greases. Due to the ability to characterize gaseous samples, IR spectroscopy can also be coupled with thermal processes such as thermogravimetric (TG) analyses to provide both thermal and chemical data in a single run. In this configuration, solids (or liquids) heated in a TG analyzer undergo decomposition, with the evolving gases directed into the IR spectrometer. Thus, information is provided on the thermal properties of a material and the order in which its chemical constituents are broken down during incremental heating. Specific examples of these varied applications will be cited, with data interpretation and method limitations further discussed.

  6. Optical & Infrared Spectroscopy of Transiting Exoplanets

    NASA Astrophysics Data System (ADS)

    Griffith, C. A.; Tinetti, G.

    2010-10-01

    Two types of spectra can be measured from transiting extrasolar planets. The primary eclipse provides a transmission spectra of the exoplanet's limb as the planet passes in front of the star. These data probe the gas and particle composition of the atmosphere, as well as the atmospheric scale height. The secondary eclipse measures the emission of mainly the planet's dayside atmosphere from the planet plus star's emission minus the emission of star alone, when it eclipses the planet. These data probe the temperature and composition structure of the exoplanet. Only in the past 3 years, have infrared transmission and emission spectroscopy revealed the presence of the primary carbon and oxygen species (CH4, CO2, CO, and H2O). Efforts to constrain the abundances of these molecules are hindered by degenerate effects of the temperature and composition in the emission spectra. Transmission spectra, while less sensitive to the atmospheric temperatures, are difficult to interpret because the composition derived depends delicately on the assumed radius at a specified pressure level. This talk will discuss the correlations in the degenerate solutions that result from the radiative transfer analyses of both emission and transmission spectroscopy. The physical implications of these correlations are assessed in order to determine the temperature and composition structure of extrasolar planets, and their significance with respect to the exoplanet's chemistry and dynamics.

  7. Nonlinear infrared spectroscopy free from spectral selection

    PubMed Central

    Paterova, Anna; Lung, Shaun; Kalashnikov, Dmitry A.; Krivitsky, Leonid A.

    2017-01-01

    Infrared (IR) spectroscopy is an indispensable tool for many practical applications including material analysis and sensing. Existing IR spectroscopy techniques face challenges related to the inferior performance and the high cost of IR-grade components. Here, we develop a new method, which allows studying properties of materials in the IR range using only visible light optics and detectors. It is based on the nonlinear interference of entangled photons, generated via Spontaneous Parametric Down Conversion (SPDC). In our interferometer, the phase of the signal photon in the visible range depends on the phase of an entangled IR photon. When the IR photon is traveling through the media, its properties can be found from observations of the visible photon. We directly acquire the SPDC signal with a visible range CCD camera and use a numerical algorithm to infer the absorption coefficient and the refraction index of the sample in the IR range. Our method does not require the use of a spectrometer and a slit, thus it allows achieving higher signal-to-noise ratio than the earlier developed method. PMID:28218302

  8. Infrared spectroscopy of Jupiter and Saturn

    NASA Technical Reports Server (NTRS)

    Knacke, Roger

    1988-01-01

    High resolution infrared spectoscopy provides unique insights into the chemistry and dynamics of the atmospheres of Jupiter and Saturn. The 5 micrometer spectral region, which is transparent to deep levels, is particularly useful for the identification of molecules that are present at very low (parts per billion) concentrations. These are tracers of convective and strongly non-equilibrium processes in the atmosphere. High resolution ground-based spectroscopy complements Voyager and Galileo measurements. Spectroscopy is sensitive to lower mixing levels for selected molecules, while the on-board mass spectrometers probe molecules that are spectroscopically inaccessible. Analysis and modeling of the 4.7 micrometer carbon monoxide in Jupiter was completed. CO is present at a mole fraction of 1.6 plus or minus 0.3 x 10 to the 9th power and concentrated in the troposphere. At this abundance, it must be convected upward from much deeper levels in Jupiter where the temperature is near 1100 K. Thus CO is a tracer of the deep atmosphere which is otherwise unobservable. The oxygen abundance in Jupiter (as measured by the CO abundance) is near solar. Chemical or physical process must deplete the major oxygen carrier, water. Germane, GeH4, was discovered on Saturn at amole fraction of 4 plus or minus 2 x 10 to the 10th power.

  9. Infrared spectroscopy of Jupiter and Saturn

    NASA Astrophysics Data System (ADS)

    Knacke, Roger

    1988-08-01

    High resolution infrared spectoscopy provides unique insights into the chemistry and dynamics of the atmospheres of Jupiter and Saturn. The 5 micrometer spectral region, which is transparent to deep levels, is particularly useful for the identification of molecules that are present at very low (parts per billion) concentrations. These are tracers of convective and strongly non-equilibrium processes in the atmosphere. High resolution ground-based spectroscopy complements Voyager and Galileo measurements. Spectroscopy is sensitive to lower mixing levels for selected molecules, while the on-board mass spectrometers probe molecules that are spectroscopically inaccessible. Analysis and modeling of the 4.7 micrometer carbon monoxide in Jupiter was completed. CO is present at a mole fraction of 1.6 plus or minus 0.3 x 10 to the 9th power and concentrated in the troposphere. At this abundance, it must be convected upward from much deeper levels in Jupiter where the temperature is near 1100 K. Thus CO is a tracer of the deep atmosphere which is otherwise unobservable. The oxygen abundance in Jupiter (as measured by the CO abundance) is near solar. Chemical or physical process must deplete the major oxygen carrier, water. Germane, GeH4, was discovered on Saturn at amole fraction of 4 plus or minus 2 x 10 to the 10th power.

  10. Nonlinear infrared spectroscopy free from spectral selection

    NASA Astrophysics Data System (ADS)

    Paterova, Anna; Lung, Shaun; Kalashnikov, Dmitry A.; Krivitsky, Leonid A.

    2017-02-01

    Infrared (IR) spectroscopy is an indispensable tool for many practical applications including material analysis and sensing. Existing IR spectroscopy techniques face challenges related to the inferior performance and the high cost of IR-grade components. Here, we develop a new method, which allows studying properties of materials in the IR range using only visible light optics and detectors. It is based on the nonlinear interference of entangled photons, generated via Spontaneous Parametric Down Conversion (SPDC). In our interferometer, the phase of the signal photon in the visible range depends on the phase of an entangled IR photon. When the IR photon is traveling through the media, its properties can be found from observations of the visible photon. We directly acquire the SPDC signal with a visible range CCD camera and use a numerical algorithm to infer the absorption coefficient and the refraction index of the sample in the IR range. Our method does not require the use of a spectrometer and a slit, thus it allows achieving higher signal-to-noise ratio than the earlier developed method.

  11. Rotationally resolved infrared spectroscopy of adamantane

    NASA Astrophysics Data System (ADS)

    Pirali, O.; Boudon, V.; Oomens, J.; Vervloet, M.

    2012-01-01

    We present the first rotationally resolved spectra of adamantane (C10H16) applying gas-phase Fourier transform infrared (IR) absorption spectroscopy. High-resolution IR spectra are recorded in the 33-4500 cm-1range using as source of IR radiation both synchrotron radiation (at the AILES beamline of the SOLEIL synchrotron) as well as a classical globar. Adamantane is a spherical top molecule with tetrahedral symmetry (Td point group) and has no permanent dipole moment in its vibronic ground state. Of the 72 fundamental vibrational modes in adamantane, only 11 are IR active. Here we present rotationally resolved spectra for seven of them: ν30, ν28, ν27, ν26, ν25, ν24, and ν23. The typical rotational structure of spherical tops is observed and analyzed using the STDS software developed in the Dijon group, which provides the first accurate energy levels and rotational constants for seven fundamental modes. Rotational levels with quantum numbers as high as J = 107 have been identified and included in the fit leading to a typical standard deviation of about 10-3 cm-1.

  12. Bioprocess monitoring using near-infrared spectroscopy.

    PubMed

    Suehara, Ken-ichiro; Yano, Takuo

    2004-01-01

    Near-infrared spectroscopy (NIR) is a nondestructive analytical technique that has been used for simultaneous prediction of the concentrations of several substrates, products and constructs in mixtures sampled from fermentation processes. In this chapter, we discuss applications of NIR for the monitoring of bioprocesses involving rice vinegar, compost, glycolipid, L-glutamic acid, lactic acid fermentation, mushroom cultivation, and Koji production. This includes detailed discussion of applications of NIR to process management of rice vinegar fermentation and compost fermentation. In the present study, absorbance at wavelengths between 400 and 2500 nm was measured at 2 nm intervals. To obtain calibration equations, multiple linear regression (MLR) was performed on NIR spectral data and conventional analysis values of a calibration sample set. To validate these calibration equations, they were used to calculate concentrations of a prediction sample set, which were then compared with concentrations measured by conventional methods. There was excellent agreement between the results of the conventional method and those of the NIR method, when both were used to analyze culture broth of rice vinegar fermentation and solid-state fermented compost. These results indicate that NIR is a useful method for monitoring and control of bioprocesses.

  13. Infrared spectroscopy of anionic hydrated fluorobenzenes

    NASA Astrophysics Data System (ADS)

    Schneider, Holger; Vogelhuber, Kristen M.; Weber, J. Mathias

    2007-09-01

    We investigate the structural motifs of anionic hydrated fluorobenzenes by infrared photodissociation spectroscopy and density functional theory. Our calculations show that all fluorobenzene anions under investigation are strongly distorted from the neutral planar molecular geometries. In the anions, different F atoms are no longer equivalent, providing structurally different binding sites for water molecules and giving rise to a multitude of low-lying isomers. The absorption bands for hexa- and pentafluorobenzene show that only one isomer for the respective monohydrate complexes is populated in our experiment. For C6F6-•H2O, we can assign these bands to an isomer where water forms a weak double ionic hydrogen bond with two F atoms in the ion, in accord with the results of Bowen et al. [J. Chem. Phys. 127, 014312 (2007), following paper.] The spectroscopic motif of the binary complexes changes slightly with decreasing fluorination of the aromatic anion. For dihydrated hexafluorobenzene anions, several isomers are populated in our experiments, some of which may be due to hydrogen bonding between water molecules.

  14. Infrared Spectroscopy of SN 1987A

    NASA Astrophysics Data System (ADS)

    Polomski, Elisha; Gehrz, Robert; Sugerman, Ben; Wooden, Diane; Woodward, Charles

    2005-06-01

    We propose to conduct deep spectroscopic observations of SN 1987A with the IRS instrument on the Spitzer Space Telescope. Supernova 1987A in the Large Magellanic Cloud was the brightest and nearest supernova in almost 400 years and has been intensely scrutinized with both ground and space-based observatories (for a review see Arnett et al. 1989; Sugerman et al. 2005). Since its outburst the remnant has faded significantly and no infrared spectroscopy (with the exception of our Spitzer GTO observations), and only limited IR photometry has been possible since day 2000 (Bouchet et al. 2004; Wooden et al. 1993; Dwek et al. 1992). We will focus our study on determining the dust mass and mineralogy as well as the physical state and composition of the circumstellar material and the ejecta. These observations will provide insight into the abundances of heavy elements in Type II SN ejecta and the relative importance of SN for the production of dust. The spectral evolution of the SN 1987A was studied until 1990, when it became too faint for all IR instrumentation. Our observations will be an important contribution to nearly 20 years of temporal monitoring of this object.

  15. Fourier Transform Infrared Spectroscopy and Photoacoustic Spectroscopy for Saliva Analysis.

    PubMed

    Mikkonen, Jopi J W; Raittila, Jussi; Rieppo, Lassi; Lappalainen, Reijo; Kullaa, Arja M; Myllymaa, Sami

    2016-09-01

    Saliva provides a valuable tool for assessing oral and systemic diseases, but concentrations of salivary components are very small, calling the need for precise analysis methods. In this work, Fourier transform infrared (FT-IR) spectroscopy using transmission and photoacoustic (PA) modes were compared for quantitative analysis of saliva. The performance of these techniques was compared with a calibration series. The linearity of spectrum output was verified by using albumin-thiocyanate (SCN(-)) solution at different SCN(-) concentrations. Saliva samples used as a comparison were obtained from healthy subjects. Saliva droplets of 15 µL were applied on the silicon sample substrate, 6 drops for each specimen, and dried at 37 ℃ overnight. The measurements were carried out using an FT-IR spectrometer in conjunction with an accessory unit for PA measurements. The findings with both transmission and PA modes mirror each other. The major bands presented were 1500-1750 cm(-1) for proteins and 1050-1200 cm(-1) for carbohydrates. In addition, the distinct spectral band at 2050 cm(-1) derives from SCN(-) anions, which is converted by salivary peroxidases to hypothiocyanate (OSCN(-)). The correlation between the spectroscopic data with SCN(-) concentration (r > 0.990 for transmission and r = 0.967 for PA mode) was found to be significant (P < 0.01), thus promising to be utilized in future applications. © The Author(s) 2016.

  16. PAH Infrared Spectroscopy in the JWST Era

    NASA Astrophysics Data System (ADS)

    Ricca, Alesandra

    The extraordinary infrared instruments on the James Webb Space Telescope (JWST) will transform the field of cosmic spectroscopy. We propose to supply the astronomical community with theoretical and experimental spectra of a wide range of Polycyclic Aromatic Hydrocarbons (PAHs) and PAH clusters and to use our IR absorption spectra to calculate emission spectra that will be crucial in interpreting the new observational data. The Infrared Space Observatory and Spitzer Space Telescopes have shown that the midIR emission spectrum of the interstellar medium is dominated by strong bands at 3.3, 6.2, 7.7, 8.6, 11.3 and 12.7 microns superimposed upon broad underlying plateaus generally attributed to PAHs, PAH clusters and very small grains. Despite the limited spectral and spatial resolution of these data, detailed analysis has revealed that each band is, in fact, a blend of multiple emission features. Subtle variations in the band blending can be detected even for spectra measured at different positions within a single astronomical source. These variations can be seen to arise from multiple PAH and PAH-related carriers that are each responding differently to the local physical conditions. The James Webb Space Telescope has near-IR and mid-IR instruments, NIRSpec and MIRI, with an extremely high spectral resolution, spatial resolution, and sensitivity that will revolutionize infrared astronomy. These instruments will provide spatial maps on a subarcsecond scale with an unprecedented level of spectral detail, allowing detailed study of the interrelationship of the individual components within each emission band. This will provide a critical insight into the molecular characteristics of the emitting species and their (photo)chemical evolution in space. Exploitation of these astronomical spectra requires fundamental data on potential emitting species that fully account for all astrophysically relevant materials. Over the last two decades, spectra of neutral and charged PAHs

  17. Raman and infrared spectroscopy of selected vanadates.

    PubMed

    Frost, Ray L; Erickson, Kristy L; Weier, Matt L; Carmody, Onuma

    2005-03-01

    Raman and infrared spectroscopy has been used to study the structure of selected vanadates including pascoite, huemulite, barnesite, hewettite, metahewettite, hummerite. Pascoite, rauvite and huemulite are examples of simple salts involving the decavanadates anion (V10O28)6-. Decavanadate consists of four distinct VO6 units which are reflected in Raman bands at the higher wavenumbers. The Raman spectra of these minerals are characterised by two intense bands at 991 and 965 cm(-1). Four pascoite Raman bands are observed at 991, 965, 958 and 905 cm(-1) and originate from four distinct VO6 sites. The other minerals namely barnesite, hewettite, metahewettite and hummerite have similar layered structures to the decavanadates but are based upon (V5O14)3- units. Barnesite is characterised by a single Raman band at 1010 cm(-1), whilst hummerite has Raman bands at 999 and 962 cm(-1). The absence of four distinct bands indicates the overlap of the vibrational modes from two of the VO6 sites. Metarossite is characterised by a strong band at 953 cm(-1). These bands are assigned to nu1 symmetric stretching modes of (V6O16)2- units and terminal VO3 units. In the infrared spectra of these minerals, bands are observed in the 837-860 cm(-1) and in the 803-833 cm(-1) region. In some of the Raman spectra bands are observed for pascoite, hummerite and metahewettite in similar positions. These bands are assigned to nu3 antisymmetric stretching of (V10O28)6- units or (V5O14)3- units. Because of the complexity of the spectra in the low wavenumber region assignment of bands is difficult. Bands are observed in the 404-458 cm(-1) region and are assigned to the nu2 bending modes of (V10O28)6- units or (V5O14)3- units. Raman bands are observed in the 530-620 cm(-1) region and are assigned to the nu4 bending modes of (V10O28)6- units or (V5O14)3- units. The Raman spectra of the vanadates in the low wavenumber region are complex with multiple overlapping bands which are probably due to VO

  18. Raman and infrared spectroscopy of selected vanadates

    NASA Astrophysics Data System (ADS)

    Frost, Ray L.; Erickson, Kristy L.; Weier, Matt L.; Carmody, Onuma

    2005-03-01

    Raman and infrared spectroscopy has been used to study the structure of selected vanadates including pascoite, huemulite, barnesite, hewettite, metahewettite, hummerite. Pascoite, rauvite and huemulite are examples of simple salts involving the decavanadates anion (V 10O 28) 6-. Decavanadate consists of four distinct VO 6 units which are reflected in Raman bands at the higher wavenumbers. The Raman spectra of these minerals are characterised by two intense bands at 991 and 965 cm -1. Four pascoite Raman bands are observed at 991, 965, 958 and 905 cm -1 and originate from four distinct VO 6 sites. The other minerals namely barnesite, hewettite, metahewettite and hummerite have similar layered structures to the decavanadates but are based upon (V 5O 14) 3- units. Barnesite is characterised by a single Raman band at 1010 cm -1, whilst hummerite has Raman bands at 999 and 962 cm -1. The absence of four distinct bands indicates the overlap of the vibrational modes from two of the VO 6 sites. Metarossite is characterised by a strong band at 953 cm -1. These bands are assigned to ν1 symmetric stretching modes of (V 6O 16) 2- units and terminal VO 3 units. In the infrared spectra of these minerals, bands are observed in the 837-860 cm -1 and in the 803-833 cm -1 region. In some of the Raman spectra bands are observed for pascoite, hummerite and metahewettite in similar positions. These bands are assigned to ν 3 antisymmetric stretching of (V 10O 28) 6- units or (V 5O 14) 3- units. Because of the complexity of the spectra in the low wavenumber region assignment of bands is difficult. Bands are observed in the 404-458 cm -1 region and are assigned to the ν2 bending modes of (V 10O 28) 6- units or (V 5O 14) 3- units. Raman bands are observed in the 530-620 cm -1 region and are assigned to the ν4 bending modes of (V 10O 28) 6- units or (V 5O 14) 3- units. The Raman spectra of the vanadates in the low wavenumber region are complex with multiple overlapping bands which are

  19. [Dithiobis-succinimidyl propionate on gold island films: surface-enhanced infrared absorption spectroscopy study].

    PubMed

    Guo, Hao; Ding, Li; Zhang, Tian-Jie; Mao, Yan-Li

    2013-05-01

    Dithiobis-succinimidyl propionate (DTSP), an important homobifunctional crosslinker, has been widely used for the covalent immobilization of proteins onto solid supports by amine coupling. In the present study, adsorption of DTSP on vacuum-deposited gold island films was analyzed by means of surface-enhanced infrared absorption spectroscopy (SEIRAS). For the sake of a reliable assignment of the vibrational spectra, IR intensity of the adsorption model of TSP on one gold surface was calculated using density functional theory (DFT) at the Beck' s three-parameter Lee-Yang-Parr (B3LYP) level with the LANL2DZ basis set. SEIRAS and multiple-angle-of-incidence polarization infrared reflection-absorption spectroscopy indicated that TSP is arranged orderly in a tilted fashion with a dihedral angle of 65 degrees between the plane of succinimidyl ring and the gold surface. The binding kinetics revealed that that the time constant of self-assembly of the TSP layer is 220 sec. Furthermore, the coupling process of amino-nitrilotriacetic acid (ANTA) with surface-bound TSP monolayer was monitored in situ by SEIRAS. Three negative bands observed at 1 807, 1 776, and 1 728 cm(-1) respectively provided direct evidence for the reaction of the succinimidyl ester. The appearance of one intense band at 1 566 cm(-1) gave a clear support for the presence of the cross-link between ANTA and TSP. We hope that the results in current investigation will contribute to the better understanding of properties of DTSP and related reactions at the molecular level.

  20. Ultrafast two dimensional infrared chemical exchange spectroscopy

    NASA Astrophysics Data System (ADS)

    Fayer, Michael

    2011-03-01

    The method of ultrafast two dimensional infrared (2D IR) vibrational echo spectroscopy is described. Three ultrashort IR pulses tuned to the frequencies of the vibrational transitions of interest are directed into the sample. The interaction of these pulses with the molecular vibrational oscillators produces a polarization that gives rise to a fourth pulse, the vibrational echo. The vibrational echo pulse is combined with another pulse, the local oscillator, for heterodyne detection of the signal. For fixed time between the second and third pulses, the waiting time, the first pulse is scanned. Two Fourier transforms of the data yield a 2D IR spectrum. The waiting time is increased, and another spectrum is obtained. The change in the 2D IR spectra with increased waiting time provides information on the time evolution of the structure of the molecular system under observation. In a 2D IR chemical exchange experiment, two species A and B, are undergoing chemical exchange. A's are turning into B's, and B's are turning into A's, but the overall concentrations of the species are not changing. The kinetics of the chemical exchange on the ground electronic state under thermal equilibrium conditions can be obtained 2D IR spectroscopy. A vibration that has a different frequency for the two species is monitored. At very short time, there will be two peaks on the diagonal of the 2D IR spectrum, one for A and one for B. As the waiting time is increased, chemical exchange causes off-diagonal peaks to grow in. The time dependence of the growth of these off-diagonal peaks gives the chemical exchange rate. The method is applied to organic solute-solvent complex formation, orientational isomerization about a carbon-carbon single bond, migration of a hydrogen bond from one position on a molecule to another, protein structural substate interconversion, and water hydrogen bond switching between ions and water molecules. This work was supported by the Air Force Office of Scientific

  1. Infrared spectroscopy of Jupiter and Saturn

    NASA Technical Reports Server (NTRS)

    Knacke, Roger F.

    1993-01-01

    Infrared spectroscopy provides unique insights into the chemistry and dynamics of the atmospheres of Jupiter, Saturn, and Titan. In 1991 we obtained data at J, H, K, and M and made repeated observations of Titan's albedo as the satellite orbited Saturn. The J albedo is 12% +/- 3% greater than the albedo measured in 1979; the H and K albedos are the same. There was no evidence for variations at any wavelength over the eastern half of Titan's orbit. We also obtained low resolution (R=50) spectra of Titan between 3.1 and 5.1 microns. The spectra contain evidence for CO and CH3D absorptions. Spectra of Callisto and Ganymede in the 4.5 micron spectral region are featureless and give albedos of 0.08 and 0.04 respectively. If Titan's atmosphere is transparent near 5 microns, its surface albedo there is similar to Callisto's. In 1992 and 1993 we obtained further spectroscopic data of Titan with the UKIRT CGS4 spectrometer. We discovered two unexpected and unexplained spectral features in the 3-4 micron spectrum of Titan. An apparent emission feature near the 3 micron (nu sub 3) band of methane indicated temperatures higher than known to be present in Titan's upper stratosphere and may be caused by unexpected non-LTE emission. An absorption feature near 3.47 microns may be caused by absorption in solid grains or aerosols in Titan's clouds. The feature is similar but not identical to organics in the interstellar matter and in comets.

  2. Fourier Transform Infrared Spectroscopy of Radicals

    NASA Astrophysics Data System (ADS)

    Rohrs, Henry William

    Radicals occur in many areas of chemistry as they are intermediates in reactions. They arise in combustion processes and several atmospheric phenomena and they have been located in interstellar space. In order to elucidate these areas of chemistry it is important to understand radicals. This is no easy task as these species are short -lived. This work focuses on determining the structure and bonding of these species using experimental measurements. Since it is specifically aimed at gas phase radicals, spectroscopy is the tool of choice for probing the radicals. This work developed a general technique for taking the rotation-vibration spectra of jet-cooled radicals. The work was based in the infrared since the desired structural information can be obtained in this region of the spectrum. The jet-cooling simplifies the enormous task of spectral assignment. A BOMEM FTIR was optically coupled to a supersonic expansion of radicals streaming from a homemade silicon carbide pyrolysis nozzle. This nozzle was heated to wall temperatures of 1500 K. A suitable organic precursor was entrained in an inert carrier gas, usually helium. Conditions were adjusted such that this precursor was nearly completely decomposed to produce high number densities of the radical of choice. The gas flows were adjusted such that the time for recombination and other radical destroying reactions were minimized. The first radical species observed was nitric oxide, NO, made from the pyrolysis of alkyl nitrites. Spectra with rotational temperatures from 20 K to 80 K were observed. This proved the viability of the method. It also demonstrated that fluid dynamics modeling and a separate photoionization mass spectrometry experiment would be invaluable aids in maximizing radical concentrations since the best chance of recording the spectra is when the most radicals are present.

  3. Broadband infrared vibrational nano-spectroscopy using thermal blackbody radiation

    DOE PAGES

    O’Callahan, Brian T.; Lewis, William E.; Möbius, Silke; ...

    2015-12-03

    Infrared vibrational nano-spectroscopy based on scattering scanning near-field optical microscopy (s-SNOM) provides intrinsic chemical specificity with nanometer spatial resolution. Here we use incoherent infrared radiation from a 1400 K thermal blackbody emitter for broadband infrared (IR) nano-spectroscopy.With optimized interferometric heterodyne signal amplification we achieve few-monolayer sensitivity in phonon polariton spectroscopy and attomolar molecular vibrational spectroscopy. Near-field localization and nanoscale spatial resolution is demonstrated in imaging flakes of hexagonal boron nitride (hBN) and determination of its phonon polariton dispersion relation. The signal-to-noise ratio calculations and analysis for different samples and illumination sources provide a reference for irradiance requirements and the attainablemore » near-field signal levels in s-SNOM in general. As a result, the use of a thermal emitter as an IR source thus opens s-SNOM for routine chemical FTIR nano-spectroscopy.« less

  4. Broadband infrared vibrational nano-spectroscopy using thermal blackbody radiation

    SciTech Connect

    O’Callahan, Brian T.; Lewis, William E.; Möbius, Silke; Stanley, Jared C.; Muller, Eric A.; Raschke, Markus B.

    2015-12-03

    Infrared vibrational nano-spectroscopy based on scattering scanning near-field optical microscopy (s-SNOM) provides intrinsic chemical specificity with nanometer spatial resolution. Here we use incoherent infrared radiation from a 1400 K thermal blackbody emitter for broadband infrared (IR) nano-spectroscopy.With optimized interferometric heterodyne signal amplification we achieve few-monolayer sensitivity in phonon polariton spectroscopy and attomolar molecular vibrational spectroscopy. Near-field localization and nanoscale spatial resolution is demonstrated in imaging flakes of hexagonal boron nitride (hBN) and determination of its phonon polariton dispersion relation. The signal-to-noise ratio calculations and analysis for different samples and illumination sources provide a reference for irradiance requirements and the attainable near-field signal levels in s-SNOM in general. As a result, the use of a thermal emitter as an IR source thus opens s-SNOM for routine chemical FTIR nano-spectroscopy.

  5. Fourier transform infrared spectroscopy and near infrared spectroscopy for the quantification of defects in roasted coffees.

    PubMed

    Craig, Ana Paula; Franca, Adriana S; Oliveira, Leandro S; Irudayaraj, Joseph; Ileleji, Klein

    2015-03-01

    The coffee strip-picking harvesting method, preferred in Brazil, results in high percentages of immature and overripe beans, as the fruits in a single tree branch do not reach ripeness at the same time. This practice, together with inappropriate processing and storage conditions, contribute to the production of high amounts of defective coffee beans in Brazil, which upon roasting will impart negative sensory aspects to the beverage. Therefore, the development of analytical methodologies that will enable the discrimination and quantification of defective and non-defective coffees after roasting is rather desirable. Given that infrared spectroscopy has been successfully applied to coffee analysis, the objective of this work was to evaluate and to compare the performances of Fourier transform infrared (FTIR) and near infrared (NIR) spectroscopies for the quantification of defective beans in roasted coffees. Defective and non-defective Arabica coffee beans were manually selected, roasted, ground and sieved. Mixtures of defective and non-defective roasted and ground coffees were produced and analyzed, with % defects ranging from 0% to 30%. FTIR and NIR spectra were recorded, respectively, within a range of 3100-800 cm(-1) and 1200-2400 nm and submitted to mathematical processing. Quantitative models were developed by partial least squares regression (PLSR). Excellent predictive results were obtained indicating that defective coffees could be satisfactorily quantified. The correlation coefficients and the root mean squared errors of validation for the FTIR and NIR models developed to quantify the amount of defective roasted coffees mixed with non-defective ones were, respectively, as high as 0.891 and as low as 0.032, and as high as 0.953 and as low as 0.026. A comparison between the two techniques indicated that NIR provided more robust models.

  6. Ultrafast infrared near-field molecular nano-spectroscopy

    NASA Astrophysics Data System (ADS)

    Xu, Xiaoji; Craig, Ian M.; Rang, Matthias; Raschke, Markus B.

    2013-03-01

    We demonstrate molecular radiative infrared vibrational free-induction decay on the nano-scale and its control via near-field coupling between the transient molecular polarization and optical antenna properties of the metallic scanning near-field probe tip. This allows for pushing the sensitivity of infrared vibrational spectroscopy into the single molecule regime.

  7. New advances in the use of infrared absorption spectroscopy for the characterization of heterogeneous catalytic reactions.

    PubMed

    Zaera, Francisco

    2014-11-21

    Infrared absorption spectroscopy has proven to be one of the most powerful spectroscopic techniques available for the characterization of catalytic systems. Although the history of IR absorption spectroscopy in catalysis is long, the technique continues to provide key fundamental information about a variety of catalysts and catalytic reactions, and to also offer novel options for the acquisition of new information on both reaction mechanisms and the nature of the solids used as catalysts. In this review, an overview is provided of the main contributions that have been derived from IR absorption spectroscopy studies of catalytic systems, and a discussion is included on new trends and new potential directions of research involving IR in catalysis. We start by briefly describing the power of Fourier-transform IR (FTIR) instruments and the main experimental IR setups available, namely, transmission (TIR), diffuse reflectance (DRIFTS), attenuated total reflection (ATR-IR), and reflection-absorption (RAIRS), for advancing research in catalysis. We then discuss the different environments under which IR characterization of catalysts is carried out, including in situ and operando studies of typical catalytic processes in gas-phase, research with model catalysts in ultrahigh vacuum (UHV) and so-called high-pressure cell instruments, and work involving liquid/solid interfaces. A presentation of the type of information extracted from IR data follows in terms of the identification of adsorbed intermediates, the characterization of the surfaces of the catalysts themselves, the quantitation of IR intensities to extract surface coverages, and the use of probe molecules to identify and titrate specific catalytic sites. Finally, the different options for carrying out kinetic studies with temporal resolution such as rapid-scan FTIR, step-scan FTIR, and the use of tunable lasers or synchrotron sources, and to obtain spatially resolved spectra, by sample rastering or by 2D imaging, are

  8. Far-infrared spectroscopy of galaxies

    NASA Technical Reports Server (NTRS)

    Stacey, G. J.

    1989-01-01

    Far infrared (FIR) spectral line emission from galaxies is discussed with respect to past, present and near future observations. A review of the importance of the FIR lines as probes of the interstellar medium is presented. The various fine structure emission lines detected from the archetypal starburst galaxy M82, and the (C II) line radiation which is now observed toward a large variety of external galaxies are discussed. The improvements allowed by the advent of the Stratospheric Observatory For Infrared Astronomy (SOFIA), the Infrared Space Observatory (ISO) and the Space Infrared Telescope Facility (SIRTF) are underlined.

  9. IR Cards: Inquiry-Based Introduction to Infrared Spectroscopy

    ERIC Educational Resources Information Center

    Bennett, Jacqueline; Forster, Tabetha

    2010-01-01

    As infrared spectroscopy (IR) is frequently used in undergraduate organic chemistry courses, an inductive introduction to IR spectroscopy that uses index cards printed with spectra, structures, and chemical names is described. Groups of students are given an alphabetized deck of these "IR cards" to sort into functional groups. The students then…

  10. IR Cards: Inquiry-Based Introduction to Infrared Spectroscopy

    ERIC Educational Resources Information Center

    Bennett, Jacqueline; Forster, Tabetha

    2010-01-01

    As infrared spectroscopy (IR) is frequently used in undergraduate organic chemistry courses, an inductive introduction to IR spectroscopy that uses index cards printed with spectra, structures, and chemical names is described. Groups of students are given an alphabetized deck of these "IR cards" to sort into functional groups. The students then…

  11. Near infrared spectroscopy of stearic acid adsorbed on montmorillonite.

    PubMed

    Lu, Longfei; Cai, Jingong; Frost, Ray L

    2010-03-01

    The adsorption of stearic acid on both sodium montmorillonites and calcium montmorillonites has been studied by near infrared spectroscopy complimented with infrared spectroscopy. Upon adsorption of stearic acid on Ca-Mt additional near infrared bands are observed at 8236 cm(-1) and is assigned to an interaction of stearic acid with the water of hydration. Upon adsorption of the stearic acid on Na-Mt, the NIR bands are now observed at 5671, 5778, 5848 and 5912 cm(-1) and are assigned to the overtone and combination bands of the CH fundamentals. Additional bands at 4177, 4250, 4324, 4337, 4689 and 4809 cm(-1) are attributed to CH combination bands resulting from the adsorption of the stearic acid. Stearic acid is used as a model molecule for adsorption studies. The application of near infrared spectroscopy to the study of this adsorption proved most useful.

  12. Infrared Scattering Scanning Near-Field Optical Microscopy Using An External Cavity Quantum Cascade Laser For Nanoscale Chemical Imaging And Spectroscopy of Explosive Residues

    SciTech Connect

    Craig, Ian M.; Phillips, Mark C.; Taubman, Matthew S.; Josberger, Erik E.; Raschke, Markus Bernd

    2013-02-04

    Infrared scattering scanning near-field optical microscopy (s-SNOM) is an apertureless superfocusing technique that uses the antenna properties of a conducting atomic force microscope (AFM) tip to achieve infrared spatial resolution below the diffraction limit. The instrument can be used either in imaging mode, where a fixed wavelength light source is tuned to a molecular resonance and the AFM raster scans an image, or in spectroscopy mode where the AFM is held stationary over a feature of interest and the light frequency is varied to obtain a spectrum. In either case, a strong, stable, coherent infrared source is required. Here we demonstrate the integration of a broadly tunable external cavity quantum cascade laser (ECQCL) into an s-SNOM and use it to obtain infrared spectra of microcrystals of chemicals adsorbed onto gold substrates. Residues of the explosive compound tetryl was deposited onto gold substrates. s-SNOM experiments were performed in the 1260-1400 cm-1 tuning range of the ECQCL, corresponding to the NO2 symmetric stretch vibrational fingerprint region. Vibrational infrared spectra were collected on individual chemical domains with a collection area of *500nm2 and compared to ensemble averaged far-field reflection-absorption infrared spectroscopy (RAIRS) results.

  13. Excited triplet state spectroscopy in the infrared

    NASA Astrophysics Data System (ADS)

    Baiardo, Joseph; Mukherjee, Ranajit; Vala, Martin

    1982-03-01

    A new method for the investigation of the infrared spectra of metastable excitedelectronic states is presented. With a Fourier Transform infrared spectrometer as the probe and a CW Xe lamp source as the pump, the infrared spectrum of the lowest triplet state of triphenylene isolated in a N 2 matrix at 15K has been examined. CH out-of-plane wagging modes are prominent and shifted from their ground state frequencies. It is expected that when fully developed this method will provide important information on excited state force constants and potential energy surfaces.

  14. Infrared and Near-Infrared Spectroscopy of Acetylacetone and Hexafluoroacetylacetone.

    PubMed

    Howard, Daryl L; Kjaergaard, Henrik G; Huang, Jing; Meuwly, Markus

    2015-07-23

    The infrared and near-infrared spectra of acetylacetone, acetylacetone-d8, and hexafluoroacetylacetone are characterized from experiment and computations at different levels. In the fundamental region, the intramolecular hydrogen bonded OH-stretching transition is clearly observed as a very broad band with substantial structure and located at significantly lower frequency compared to common OH-stretching frequencies. There is no clear evidence for OH-stretching overtone transitions in the near-infrared region, which is dominated by the CH-stretching overtones of the methine and methyl CH bonds. From molecular dynamics (MD) simulations, with a potential energy surface previously validated for tunneling splittings, the infrared spectra are determined and used in assigning the experimentally measured ones. It is found that the simulated spectrum in the region associated with the proton transfer mode is exquisitely sensitive to the height of the barrier for proton transfer. Comparison of the experimental and the MD simulated spectra establishes that the barrier height is around 2.5 kcal/mol, which favorably compares with 3.2 kcal/mol obtained from high-level electronic structure calculations.

  15. AKARI NEAR-INFRARED SPECTROSCOPY OF LUMINOUS INFRARED GALAXIES

    SciTech Connect

    Lee, Jong Chul; Lee, Myung Gyoon; Hwang, Ho Seong

    2012-09-01

    We present the AKARI near-infrared (NIR; 2.5-5 {mu}m) spectroscopic study of 36 (ultra)luminous infrared galaxies ((U)LIRGs) at z = 0.01-0.4. We measure the NIR spectral features including the strengths of 3.3 {mu}m polycyclic aromatic hydrocarbon emission and hydrogen recombination lines (Br{alpha} and Br{beta}), optical depths at 3.1 and 3.4 {mu}m, and NIR continuum slope. These spectral features are used to identify optically elusive, buried active galactic nuclei (AGNs). We find that half of the (U)LIRGs optically classified as non-Seyferts show AGN signatures in their NIR spectra. Using a combined sample of (U)LIRGs with NIR spectra in the literature, we measure the contribution of buried AGNs to the infrared luminosity from the spectral energy distribution fitting to the IRAS photometry. The contribution of these buried AGNs to the infrared luminosity is 5%-10%, smaller than the typical AGN contribution of (U)LIRGs including Seyfert galaxies (10%-40%). We show that NIR continuum slopes correlate well with WISE [3.4]-[4.6] colors, which would be useful for identifying a large number of buried AGNs using the WISE data.

  16. Infrared Spectroscopy and Optical Constants of Porous Amorphous Solid Water

    SciTech Connect

    Cholette, Francois; Zubkov, Tykhon; Smith, R. Scott; Dohnalek, Zdenek; Kay, Bruce D.; Ayotte, Patrick

    2009-04-02

    Reflection-absorption infrared spectra (RAIRS) of amorphous solid water (ASW) films grown at 20K on a Pt(111) substrate at various incidence angle (θBeam = 0-85o) using a molecular beam are reported. They display complex features arising from the interplay between refraction, absorption within the sample, and interference effects between the multiple reflections at the film-substrate and film-vacuum interfaces. Using a simple classical optics model based on Fresnel equations, we obtain optical constants [i.e., n(ω) and k(ω)] for porous ASW in the 1000-4000cm-1 (10-2.5 μm) range. The behaviour of the optical properties of ASW in the intramolecular OH stretching region with increasing θBeam is shown to be strongly correlated with its decreasing density and increasing surface area. A direct comparison between the RAIRS and calculated vibrational spectra shows a large difference (~200cm-1) in the position of the coupled H-bonded intramolecular OH stretching vibrations spectral feature. Moreover, this band shifts in opposite directions with increasing θBeam in RAIRS and vibrational spectra demonstrating RAIRS spectra cannot be interpreted straightforwardly as vibrational spectra due to severe optical distortions from refraction and interference effects.

  17. Identification of uroliths by infrared spectroscopy.

    PubMed

    Manning, R A; Blaney, B J

    1986-12-01

    Wet chemical tests have deficiencies when applied to mixtures containing silica, which are common in the uroliths of some domestic animals. Consequently, the applicability of an infrared spectroscopic method was tested on 104 uroliths obtained from cattle, sheep, goats, horses, pigs, dogs, a chicken and a rabbit during diagnostic investigations. The following components were satisfactorily identified: silica, calcium oxalate, calcium carbonate, calcium phosphate, magnesium ammonium phosphate, magnesium phosphate and urates. The infrared characteristics of these compounds and their mixtures are described.

  18. Infrared spectroscopy of competitive interactions between liquid crystals, metal salts, and dimethyl methylphosphonate at surfaces.

    PubMed

    Cadwell, Katie D; Alf, Mahriah E; Abbott, Nicholas L

    2006-12-28

    We report the use of Fourier transform polarization modulation infrared reflection-absorption spectroscopy (PM-IRRAS) to characterize the influence of dimethyl methylphosphonate (DMMP) on the molecular interactions occurring within thin films of nitrile-containing liquid crystals supported on surfaces presenting metal perchlorate salts. Infrared spectra obtained using thin films of 4'-octyl-4-biphenylcarbonitrile (8CB) supported on copper(II) perchlorate salts reveal the nitrile groups of 8CB to be coordinated to the copper(II) on these surfaces, and subsequent exposure of the system to DMMP to result in the elimination of these coordinated nitrile groups. Concurrently, evidence of coordination of the phosphoryl group of DMMP with copper(II) is provided by measurement of a shift of the phosphoryl stretch from 1246 to 1198 cm(-1). In contrast, surfaces presenting nickel(II) perchlorate salts only weakly coordinate with DMMP [the phosphoryl peak shifts from 1246 to 1213 cm(-1) in the presence of nickel(II)], and exposure of 8CB to DMMP results in only partial loss of coordination of the nitrile groups of 8CB with nickel(II). These PM-IRRAS measurements and others reported in this article provide insights into the molecular origins of macroscopic ordering transitions that are observed when micrometer-thick films of nitrile-containing liquid crystals supported on copper(II) or nickel(II) perchlorate are exposed to DMMP: Upon exposure to DMMP, nematic phases of 4'-pentyl-4-biphenylcarbonitrile (5CB) supported on copper(II) perchlorate salts undergo ordering transitions, whereas 5CB supported on nickel(II) perchlorate salts do not. Our IR results support the hypothesis that these ordering transitions reflect the relative strengths of coordination interactions occurring between the 5CB, DMMP, and the metal salts at these interfaces.

  19. Fourier transform infrared spectroscopy for molecular analysis of microbial cells.

    PubMed

    Ojeda, Jesús J; Dittrich, Maria

    2012-01-01

    A rapid and inexpensive method to characterise chemical cell properties and identify the functional groups present in the cell wall is Fourier transform infrared spectroscopy (FTIR). Infrared spectroscopy is a well-established technique to identify functional groups in organic molecules based on their vibration modes at different infrared wave numbers. The presence or absence of functional groups, their protonation states, or any changes due to new interactions can be monitored by analysing the position and intensity of the different infrared absorption bands. Additionally, infrared spectroscopy is non-destructive and can be used to monitor the chemistry of living cells. Despite the complexity of the spectra, the elucidation of functional groups on Gram-negative and Gram-positive bacteria has been already well documented in the literature. Recent advances in detector sensitivity have allowed the use of micro-FTIR spectroscopy as an important analytical tool to analyse biofilm samples without the need of previous treatment. Using FTIR spectroscopy, the infrared bands corresponding to proteins, lipids, polysaccharides, polyphosphate groups, and other carbohydrate functional groups on the bacterial cells can now be identified and compared along different conditions. Despite some differences in FTIR spectra among bacterial strains, experimental conditions, or changes in microbiological parameters, the IR absorption bands between approximately 4,000 and 400 cm(-1) are mainly due to fundamental vibrational modes and can often be assigned to the same particular functional groups. In this chapter, an overview covering the different sample preparation protocols for infrared analysis of bacterial cells is given, alongside the basic principles of the technique, the procedures for calculating vibrational frequencies based on simple harmonic motion, and the advantages and disadvantages of FTIR spectroscopy for the analysis of microorganisms.

  20. Optical and Infrared Spectroscopy of CM Draconis

    NASA Astrophysics Data System (ADS)

    Viti, S.; Jones, H. R. A.; Allard, F.; Schweitzer, A.; Hauschildt, P.

    The authors compare observations of the binary system CM Draconis with synthetic spectra. Spectroscopic observations from 0.40 to 2.41 μm, combined with photometry and the accurately known surface gravity enable to estimate the temperature and metallicity using detailed spectra synthesis. They find discrepancies between the analysis of the infrared and optical spectrum while the optical spectral energy distribution (SED) yields a metal-rich solution with Teff = 3000K, the infrared SED yields around 3200K and -0.8 ≤ [M/H] ≤ -0.6 compatible with the high space motion of the system. The low-metallicity characteristics of the infrared SED could be real and is partly supported by the detailed analysis of the atomic lines in the optical region. Although, the known incompleteness of the TiO and H2O line lists in the models may cause substantial systematic errors.

  1. Cancer diagnosis by infrared spectroscopy: methodological aspects

    NASA Astrophysics Data System (ADS)

    Jackson, Michael; Kim, Keith; Tetteh, John; Mansfield, James R.; Dolenko, Brion; Somorjai, Raymond L.; Orr, F. W.; Watson, Peter H.; Mantsch, Henry H.

    1998-04-01

    IR spectroscopy is proving to be a powerful tool for the study and diagnosis of cancer. The application of IR spectroscopy to the analysis of cultured tumor cells and grading of breast cancer sections is outlined. Potential sources of error in spectral interpretation due to variations in sample histology and artifacts associated with sample storage and preparation are discussed. The application of statistical techniques to assess differences between spectra and to non-subjectively classify spectra is demonstrated.

  2. Optimization of diffuse reflectance infrared spectroscopy accessories

    SciTech Connect

    Hirschfeld, T.

    1986-11-01

    The value of diffuse reflectance as an infrared or near-infrared spectroscopic sampling procedure has been limited by the low efficiency of accessories designed for it. In terms of signal-to-noise ratio, these average 2-6% for integrating spheres and 10-12% for various ellipsoidal mirror arrangements. Much better performances, up to 37% efficiency, can be obtained by optimizing a concentric confocal ellipsoidal mirror arrangement by using a very large central opening in the amular collector mirror, and adapting the throughput of the detector to the geometry of the collected beam.

  3. Improved source of infrared radiation for spectroscopy

    NASA Technical Reports Server (NTRS)

    Burkhard, D. G.; Rao, K. N.

    1971-01-01

    Radiation from a crimped V-groove in the electrically heated metallic element of a high-resolution infrared spectrometer is more intense than that from plane areas adjacent to the element. Radiation from the vee and the flat was compared by alternately focusing on the entrance slit of a spectrograph.

  4. Infrared absorption spectroscopy and chemical kinetics of free radicals

    SciTech Connect

    Curl, R.F.; Glass, G.P.

    1993-12-01

    This research is directed at the detection, monitoring, and study of chemical kinetic behavior by infrared absorption spectroscopy of small free radical species thought to be important intermediates in combustion. During the last year, infrared kinetic spectroscopy using excimer laser flash photolysis and color-center laser probing has been employed to study the high resolution spectrum of HCCN, the rate constant of the reaction between ethynyl (C{sub 2}H) radical and H{sub 2} in the temperature region between 295 and 875 K, and the recombination rate of propargyl (CH{sub 2}CCH) at room temperature.

  5. Infrared heterodyne spectroscopy of atmospheric ozone

    NASA Technical Reports Server (NTRS)

    Frerking, M. A.; Muehlner, D. J.

    1977-01-01

    The absorption spectrum of atmospheric ozone is measured within a 1/cm region at 1100/cm, using an IR heterodyne detector (spectrometer with CO2 local oscillator) developed for astronomical work. Absorption spectra obtained by passing radiation from the tunable diode laser through an absorption cell, heterodyne spectra of atmospheric ozone, and a predicted atmospheric spectrum are compared. Water vapor absorbing in the region of interest (1100/cm) is also considered. Preliminary results encourage the use of diode laser local oscillators in tunable heterodyne detector systems for spectroscopy of atmospheric ozone and remote high-resolution spectroscopy of atmospheric constituents and pollutants.

  6. Mid-infrared spectroscopy for protein analysis: potential and challenges.

    PubMed

    López-Lorente, Ángela I; Mizaikoff, Boris

    2016-04-01

    Mid-infrared (MIR) spectroscopy investigates the interaction of MIR photons with both organic and inorganic molecules via the excitation of vibrational and rotational modes, providing inherent molecular selectivity. In general, infrared (IR) spectroscopy is particularly sensitive to protein structure and structural changes via vibrational resonances originating from the polypeptide backbone or side chains; hence information on the secondary structure of proteins can be obtained in a label-free fashion. In this review, the challenges for IR spectroscopy for protein analysis are discussed as are the potential and limitations of different IR spectroscopic techniques enabling protein analysis. In particular, the amide I spectral range has been widely used to study protein secondary structure, conformational changes, protein aggregation, protein adsorption, and the formation of amyloid fibrils. In addition to representative examples of the potential of IR spectroscopy in various fields related to protein analysis, the potential of protein analysis taking advantage of miniaturized MIR systems, including waveguide-enhanced MIR sensors, is detailed.

  7. Advances in Mid-Infrared Spectroscopy for Chemical Analysis

    NASA Astrophysics Data System (ADS)

    Haas, Julian; Mizaikoff, Boris

    2016-06-01

    Infrared spectroscopy in the 3-20 μm spectral window has evolved from a routine laboratory technique into a state-of-the-art spectroscopy and sensing tool by benefitting from recent progress in increasingly sophisticated spectra acquisition techniques and advanced materials for generating, guiding, and detecting mid-infrared (MIR) radiation. Today, MIR spectroscopy provides molecular information with trace to ultratrace sensitivity, fast data acquisition rates, and high spectral resolution catering to demanding applications in bioanalytics, for example, and to improved routine analysis. In addition to advances in miniaturized device technology without sacrificing analytical performance, selected innovative applications for MIR spectroscopy ranging from process analysis to biotechnology and medical diagnostics are highlighted in this review.

  8. Infrared microcalorimetric spectroscopy using quantum cascade lasers.

    PubMed

    Morales-Rodríguez, M E; Senesac, L R; Rajic, S; Lavrik, N V; Smith, D B; Datskos, P G

    2013-02-15

    We have investigated an IR microcalorimetric spectroscopy technique that can be used to detect the presence of trace amounts of target molecules. The chemical detection is accomplished by obtaining the IR photothermal spectra of molecules adsorbed on the surface of uncooled thermal micromechanical detectors. Although we use a chemical layer to absorb target molecules, IR microcalorimetric spectroscopy requires no chemical specific coatings. The chemical specificity of the presented method is a consequence of the wavelength-specific absorption of IR photons from tunable quantum cascade lasers due to vibrational spectral bands of the analyte. We have obtained IR photothermal spectra for trace concentrations of 1,3,5-Trinitroperhydro-1,3,5-triazine and a monolayer of 2-Sulfanylethan-1-ol (2-mercaptoethanol) over the wavelength region from 6 to 10 μm. We found that both chemicals exhibit a number of photothermal absorption features that are in good agreement with their respective IR spectra.

  9. Near-infrared spectroscopy of dark asteroids.

    PubMed

    Barucci, M A; Lazzarin, M; Owen, T; Barbieri, C; Fulchignoni, M

    1994-08-01

    Near-infrared (J, H and K bands) spectra of nine dark asteroids (chosen among a sample of supposed primitive objects between C and D classes) have been obtained at the Mauna Kea Observatory (Hawaii) with the 2.2-m telescope using KSPEC as spectrograph. The aim of this work was to search for evidence of the presence of organic materials in these objects as found in other planetary bodies as 5145 Pholus, and in some cometary nuclei. A careful analysis of the data has revealed flat or slightly redder spectra than the solar one for all observed asteroids. No evidence of distinct absorption features was found.

  10. Infrared spectroscopy assisted by entangled photons

    NASA Astrophysics Data System (ADS)

    Paterova, Anna V.; Lung, Shaun; Kalashnikov, Dmitry A.; Kulik, Sergei P.; Krivitsky, Leonid A.

    2016-11-01

    We describe a proof-of-concept of a method for measurement of both real (refraction) and imaginary (absorption) part of the refractive index in the infrared (IR) range by measuring an interference pattern in the visible range without the need for any spectral and spatial selection. The concept is based on nonlinear interference of entangled photons, generated via Spontaneous Parametric Down Conversion (SPDC). In our interferometer, the phase of the signal photon in the visible range depends on the phase of an entangled IR photon. When the IR photon is traveling through the media of interest, its properties can be found from the observations of the visible photon.

  11. Galileo infrared imaging spectroscopy measurements at venus

    USGS Publications Warehouse

    Carlson, R.W.; Baines, K.H.; Encrenaz, Th.; Taylor, F.W.; Drossart, P.; Kamp, L.W.; Pollack, James B.; Lellouch, E.; Collard, A.D.; Calcutt, S.B.; Grinspoon, D.; Weissman, P.R.; Smythe, W.D.; Ocampo, A.C.; Danielson, G.E.; Fanale, F.P.; Johnson, T.V.; Kieffer, H.H.; Matson, D.L.; McCord, T.B.; Soderblom, L.A.

    1991-01-01

    During the 1990 Galileo Venus flyby, the Near Infrared Mapping Spectrometer investigated the night-side atmosphere of Venus in the spectral range 0.7 to 5.2 micrometers. Multispectral images at high spatial resolution indicate substantial cloud opacity variations in the lower cloud levels, centered at 50 kilometers altitude. Zonal and meridional winds were derived for this level and are consistent with motion of the upper branch of a Hadley cell. Northern and southern hemisphere clouds appear to be markedly different. Spectral profiles were used to derive lower atmosphere abundances of water vapor and other species.

  12. WW domain folding complexity revealed by infrared spectroscopy.

    PubMed

    Davis, Caitlin M; Dyer, R Brian

    2014-09-02

    Although the intrinsic tryptophan fluorescence of proteins offers a convenient probe of protein folding, interpretation of the fluorescence spectrum is often difficult because it is sensitive to both global and local changes. Infrared (IR) spectroscopy offers a complementary measure of structural changes involved in protein folding, because it probes changes in the secondary structure of the protein backbone. Here we demonstrate the advantages of using multiple probes, infrared and fluorescence spectroscopy, to study the folding of the FBP28 WW domain. Laser-induced temperature jumps coupled with fluorescence or infrared spectroscopy have been used to probe changes in the peptide backbone on the submillisecond time scale. The relaxation dynamics of the β-sheets and β-turn were measured independently by probing the corresponding IR bands assigned in the amide I region. Using these wavelength-dependent measurements, we observe three kinetics phases, with the fastest process corresponding to the relaxation kinetics of the turns. In contrast, fluorescence measurements of the wild-type WW domain and tryptophan mutants exhibit single-exponential kinetics with a lifetime that corresponds to the slowest phase observed by infrared spectroscopy. Mutant sequences provide evidence of an intermediate dry molten globule state. The slowest step in the folding of this WW domain is the tight packing of the side chains in the transition from the dry molten globule intermediate to the native structure. This study demonstrates that using multiple complementary probes enhances the interpretation of protein folding dynamics.

  13. Social Perception in Infancy: A Near Infrared Spectroscopy Study

    ERIC Educational Resources Information Center

    Lloyd-Fox, Sarah; Blasi, Anna; Volein, Agnes; Everdell, Nick; Elwell, Claire E.; Johnson, Mark H.

    2009-01-01

    The capacity to engage and communicate in a social world is one of the defining characteristics of the human species. While the network of regions that compose the social brain have been the subject of extensive research in adults, there are limited techniques available for monitoring young infants. This study used near infrared spectroscopy to…

  14. WW Domain Folding Complexity Revealed by Infrared Spectroscopy

    PubMed Central

    2015-01-01

    Although the intrinsic tryptophan fluorescence of proteins offers a convenient probe of protein folding, interpretation of the fluorescence spectrum is often difficult because it is sensitive to both global and local changes. Infrared (IR) spectroscopy offers a complementary measure of structural changes involved in protein folding, because it probes changes in the secondary structure of the protein backbone. Here we demonstrate the advantages of using multiple probes, infrared and fluorescence spectroscopy, to study the folding of the FBP28 WW domain. Laser-induced temperature jumps coupled with fluorescence or infrared spectroscopy have been used to probe changes in the peptide backbone on the submillisecond time scale. The relaxation dynamics of the β-sheets and β-turn were measured independently by probing the corresponding IR bands assigned in the amide I region. Using these wavelength-dependent measurements, we observe three kinetics phases, with the fastest process corresponding to the relaxation kinetics of the turns. In contrast, fluorescence measurements of the wild-type WW domain and tryptophan mutants exhibit single-exponential kinetics with a lifetime that corresponds to the slowest phase observed by infrared spectroscopy. Mutant sequences provide evidence of an intermediate dry molten globule state. The slowest step in the folding of this WW domain is the tight packing of the side chains in the transition from the dry molten globule intermediate to the native structure. This study demonstrates that using multiple complementary probes enhances the interpretation of protein folding dynamics. PMID:25121968

  15. Detecting Counterfeit Antimalarial Tablets by Near-Infrared Spectroscopy

    USDA-ARS?s Scientific Manuscript database

    Counterfeit antimalarial drugs are found in many developing countries, but it is challenging to differentiate between genuine and fakes due to their increasing sophistication. Near-infrared spectroscopy (NIRS) is a powerful tool in pharmaceutical forensics, and we tested this technique for discrim...

  16. Predicting cotton stelometer fiber strength by fourier transform infrared spectroscopy

    USDA-ARS?s Scientific Manuscript database

    The strength of cotton fibers is one of several important end-use characteristics. In routine programs, it has been mostly assessed by automation-oriented high volume instrument (HVI) system. An alternative method for cotton strength is near infrared (NIR) spectroscopy. Although previous NIR models ...

  17. Measurement of lipid supplements in poultry feed by infrared spectroscopy

    USDA-ARS?s Scientific Manuscript database

    Rapid measurement of a fatty acid supplement in poultry feed formulations was performed using near infrared (NIR) spectroscopy with chemometric analysis. A standard feed formulation was amended with up to 10 wt% fatty acid supplement containing docosahexaenoic acid (DHA) and scanned from 10,000 cm-1...

  18. Social Perception in Infancy: A Near Infrared Spectroscopy Study

    ERIC Educational Resources Information Center

    Lloyd-Fox, Sarah; Blasi, Anna; Volein, Agnes; Everdell, Nick; Elwell, Claire E.; Johnson, Mark H.

    2009-01-01

    The capacity to engage and communicate in a social world is one of the defining characteristics of the human species. While the network of regions that compose the social brain have been the subject of extensive research in adults, there are limited techniques available for monitoring young infants. This study used near infrared spectroscopy to…

  19. Exploration of the giant planets by infrared spectroscopy

    NASA Technical Reports Server (NTRS)

    Hanel, R. A.

    1976-01-01

    The infrared spectrometer and radiometer for the Mariner-Jupiter-Saturn mission is described. Results of Nimbus and Mariner 9 IR spectroscopy of earth and Mars are used as examples to demonstrate the power and diversity of the technique. Determinations of planetary surface compositions, surface temperatures, vertical temperature profiles, surface pressures, and atmospheric constituents are summarized. Applications to Jupiter and Saturn are briefly mentioned.

  20. Enhanced Vibrational Spectroscopies as Tools for Small Molecule Biosensing

    PubMed Central

    Boujday, Souhir; Lamy de la Chapelle, Marc; Srajer, Johannes; Knoll, Wolfgang

    2015-01-01

    In this short summary we summarize some of the latest developments in vibrational spectroscopic tools applied for the sensing of (small) molecules and biomolecules in a label-free mode of operation. We first introduce various concepts for the enhancement of InfraRed spectroscopic techniques, including the principles of Attenuated Total Reflection InfraRed (ATR-IR), (phase-modulated) InfraRed Reflection Absorption Spectroscopy (IRRAS/PM-IRRAS), and Surface Enhanced Infrared Reflection Absorption Spectroscopy (SEIRAS). Particular attention is put on the use of novel nanostructured substrates that allow for the excitation of propagating and localized surface plasmon modes aimed at operating additional enhancement mechanisms. This is then be complemented by the description of the latest development in Surface- and Tip-Enhanced Raman Spectroscopies, again with an emphasis on the detection of small molecules or bioanalytes. PMID:26343666

  1. Enhanced Vibrational Spectroscopies as Tools for Small Molecule Biosensing.

    PubMed

    Boujday, Souhir; de la Chapelle, Marc Lamy; Srajer, Johannes; Knoll, Wolfgang

    2015-08-28

    In this short summary we summarize some of the latest developments in vibrational spectroscopic tools applied for the sensing of (small) molecules and biomolecules in a label-free mode of operation. We first introduce various concepts for the enhancement of InfraRed spectroscopic techniques, including the principles of Attenuated Total Reflection InfraRed (ATR-IR), (phase-modulated) InfraRed Reflection Absorption Spectroscopy (IRRAS/PM-IRRAS), and Surface Enhanced Infrared Reflection Absorption Spectroscopy (SEIRAS). Particular attention is put on the use of novel nanostructured substrates that allow for the excitation of propagating and localized surface plasmon modes aimed at operating additional enhancement mechanisms. This is then be complemented by the description of the latest development in Surface- and Tip-Enhanced Raman Spectroscopies, again with an emphasis on the detection of small molecules or bioanalytes.

  2. High resolution spectroscopy in the microwave and far infrared

    NASA Technical Reports Server (NTRS)

    Pickett, Herbert M.

    1990-01-01

    High resolution rotational spectroscopy has long been central to remote sensing techniques in atmospheric sciences and astronomy. As such, laboratory measurements must supply the required data to make direct interpretation of data for instruments which sense atmospheres using rotational spectra. Spectral measurements in the microwave and far infrared regions are also very powerful tools when combined with infrared measurements for characterizing the rotational structure of vibrational spectra. In the past decade new techniques were developed which have pushed high resolution spectroscopy into the wavelength region between 25 micrometers and 2 mm. Techniques to be described include: (1) harmonic generation of microwave sources, (2) infrared laser difference frequency generation, (3) laser sideband generation, and (4) ultrahigh resolution interferometers.

  3. On-line infrared spectroscopy for bioprocess monitoring.

    PubMed

    Landgrebe, Daniel; Haake, Claas; Höpfner, Tim; Beutel, Sascha; Hitzmann, Bernd; Scheper, Thomas; Rhiel, Martin; Reardon, Kenneth F

    2010-09-01

    One of the major aims of bioprocess engineering is the real-time monitoring of important process variables. This is the basis of precise process control and is essential for high productivity as well as the exact documentation of the overall production process. Infrared spectroscopy is a powerful analytical technique to analyze a wide variety of organic compounds. Thus, infrared sensors are ideal instruments for bioprocess monitoring. The sensors are non-invasive, have no time delay due to sensor response times, and have no influence on the bioprocess itself. No sampling is necessary, and several components can be analyzed simultaneously. In general, the direct monitoring of substrates, products, metabolites, as well as the biomass itself is possible. In this review article, insights are provided into the different applications of infrared spectroscopy for bioprocess monitoring and the complex data interpretation. Different analytical techniques are presented as well as example applications in different areas.

  4. Infrared Spectroscopy of Extra-solar Planets

    NASA Astrophysics Data System (ADS)

    Wiedemann, G.

    Giant extra-solar planets with short orbital periods may be detected directly via the infrared line spectra emitted by their heated atmospheres. Ground-based measurements of the planetary lines at ~10-4 of the stellar flux are possible if one exploits the large-amplitude Doppler modulation caused by the orbital velocity, whereby the period and phase are known for stars with established reflex motions. A measured radial velocity amplitude of the planet yields directly the star/planet mass ratio and the inclination angle of the orbital plane. A search for methane in the IR 3.3 μm spectrum of τ Boo has been carried out at the NASA IRTF. The Southern Saturn-type planet of HD 75289 has been observed over a six week period by the VLT (2.3 μm CO) and future CO and CH4 observations are scheduled.

  5. Airborne infrared spectroscopy of 1994 western wildfires

    NASA Astrophysics Data System (ADS)

    Worden, Helen; Beer, Reinhard; Rinsland, Curtis P.

    1997-01-01

    In the summer of 1994 the 0.07 cm-1 resolution infrared Airborne Emission Spectrometer (AES) acquired spectral data over two wildfires, one in central Oregon on August 3 and the other near San Luis Obispo, California, on August 15. The spectrometer was on board a NASA DC-8 research aircraft, flying at an altitude of 12 km. The spectra from both fires clearly show features due to water vapor, carbon dioxide, carbon monoxide, ammonia, methanol, formic acid, and ethylene at significantly higher abundance and temperature than observed in downlooking spectra of normal atmospheric and ground conditions. Column densities are derived for several species, and molar ratios are compared with previous biomass fire measurements. We believe that this is the first time such data have been acquired by airborne spectral remote sensing.

  6. Airborne Infrared Spectroscopy of 1994 Western Wildfires

    NASA Technical Reports Server (NTRS)

    Worden, Helen; Beer, Reinhard; Rinsland, Curtis P.

    1997-01-01

    In the summer of 1994 the 0.07/ cm resolution infrared Airborne Emission Spectrometer (AES) acquired spectral data over two wildfires, one in central Oregon on August 3 and the other near San Luis Obispo, California, on August 15. The spectrometer was on board a NASA DC-8 research aircraft, flying at an altitude of 12 km. The spectra from both fires clearly show features due to water vapor, carbon dioxide, carbon monoxide, ammonia, methanol, formic acid, and ethylene at significantly higher abundance and temperature than observed in downlooking spectra of normal atmospheric and ground conditions. Column densities are derived for several species, and molar ratios are compared with previous biomass fire measurements. We believe that this is the first time such data have been acquired by airborne spectral remote sensing.

  7. Infrared spectroscopy of exoplanets: observational constraints

    PubMed Central

    Encrenaz, Thérèse

    2014-01-01

    The exploration of transiting extrasolar planets is an exploding research area in astronomy. With more than 400 transiting exoplanets identified so far, these discoveries have made possible the development of a new research field, the spectroscopic characterization of exoplanets' atmospheres, using both primary and secondary transits. However, these observations have been so far limited to a small number of targets. In this paper, we first review the advantages and limitations of both primary and secondary transit methods. Then, we analyse what kind of infrared spectra can be expected for different types of planets and discuss how to optimize the spectral range and the resolving power of the observations. Finally, we propose a list of favourable targets for present and future ground-based observations. PMID:24664918

  8. Infrared spectroscopy of exoplanets: observational constraints.

    PubMed

    Encrenaz, Thérèse

    2014-04-28

    The exploration of transiting extrasolar planets is an exploding research area in astronomy. With more than 400 transiting exoplanets identified so far, these discoveries have made possible the development of a new research field, the spectroscopic characterization of exoplanets' atmospheres, using both primary and secondary transits. However, these observations have been so far limited to a small number of targets. In this paper, we first review the advantages and limitations of both primary and secondary transit methods. Then, we analyse what kind of infrared spectra can be expected for different types of planets and discuss how to optimize the spectral range and the resolving power of the observations. Finally, we propose a list of favourable targets for present and future ground-based observations.

  9. Infrared spectroscopy of simulated Martian surface materials

    NASA Technical Reports Server (NTRS)

    Toon, O. B.; Sagan, C.

    1978-01-01

    Mineralogy inferred from the Viking X-ray fluorescence spectrometry (XRFS) is compared with mineralogy indicated by spectral data. The comparison is done by taking laboratory spectra of Viking analog minerals. Both XRFS and infrared data are consistent with clays as the dominant SiO2 containing minerals on Mars. The X-ray fluorescence data might also be consistent with the dominance of certain mafic SiO2 igneous minerals, but the spectral data are probably inconsistent with such materials. Sulfates, inferred by XRFS, are consistent with the spectral data. Inferences following Mariner 9 that high-SiO2 minerals were important on Mars may have been biased by the presence of sulfates. Calcium carbonate, in the quantities indirectly suggested by XRFS are inconsistent with the spectral data, but smaller quantities of CaCO3 are consistent, as are large quantities of other carbonates.

  10. Computing protein infrared spectroscopy with quantum chemistry.

    PubMed

    Besley, Nicholas A

    2007-12-15

    Quantum chemistry is a field of science that has undergone unprecedented advances in the last 50 years. From the pioneering work of Boys in the 1950s, quantum chemistry has evolved from being regarded as a specialized and esoteric discipline to a widely used tool that underpins much of the current research in chemistry today. This achievement was recognized with the award of the 1998 Nobel Prize in Chemistry to John Pople and Walter Kohn. As the new millennium unfolds, quantum chemistry stands at the forefront of an exciting new era. Quantitative calculations on systems of the magnitude of proteins are becoming a realistic possibility, an achievement that would have been unimaginable to the early pioneers of quantum chemistry. In this article we will describe ongoing work towards this goal, focusing on the calculation of protein infrared amide bands directly with quantum chemical methods.

  11. Stratospheric sounding by infrared heterodyne spectroscopy

    NASA Technical Reports Server (NTRS)

    Abbas, M. M.; Kunde, V. G.; Mumma, M. J.; Kostiuk, T.; Buhl, D.; Frerking, M. A.

    1978-01-01

    Intensity profiles of infrared spectral lines of stratospheric constituents can be fully resolved with a heterodyne spectrometer of sufficiently high resolution. The constituents' vertical distributions can then be evaluated accurately by analytic inversion of the measured line profiles. Estimates of the detection sensitivity of a heterodyne receiver are given in terms of minimum detectable volume mixing ratios of stratospheric constituents, indicating a large number of minor constituents which can be studied. Stratospheric spectral line shapes, and the resolution required to measure them are discussed in light of calculated synthetic line profiles for some stratospheric molecules in a model atmosphere. The inversion technique for evaluation of gas concentration profiles is briefly described and applications to synthetic lines of O3, CO2, CH4 and N2O are given.

  12. Mass loss from red giants - Infrared spectroscopy

    NASA Technical Reports Server (NTRS)

    Wannier, P. G.

    1985-01-01

    A discussion is presented of IR spectroscopy, particularly high-resolution spectroscopy in the approximately 1-20 micron band, as it impacts the study of circumstellar envelopes. The molecular bands within this region contain an enormous amount of information, especially when observed with sufficient resolution to obtain kinematic information. In a single spectrum, it is possible to resolve lines from up to 50 different rotational/vibrational levels of a given molecule and to detect several different isotopic variants. When high resolution techniques are combined with mapping techniques and/or time sequence observations of variable stars, the resulting information can paint a very detailed picture of the mass-loss phenomenon. To date, near-IR observations have been made of 20 molecular species. CO is the most widely observed molecule and useful information has been gleaned from the observed rotational excitation, kinematics, time variability and spatial structure of its lines. Examples of different observing techniques are discussed in the following sections.

  13. Bird sexing by Fourier transform infrared spectroscopy

    NASA Astrophysics Data System (ADS)

    Steiner, Gerald; Bartels, Thomas; Krautwald-Junghanns, Maria-Elisabeth; Koch, Edmund

    2010-02-01

    Birds are traditionally classified as male or female based on their anatomy and plumage color as judged by the human eye. Knowledge of a bird's gender is important for the veterinary practitioner, the owner and the breeder. The accurate gender determination is essential for proper pairing of birds, and knowing the gender of a bird will allow the veterinarian to rule in or out gender-specific diseases. Several biochemical methods of gender determination have been developed for avian species where otherwise the gender of the birds cannot be determined by their physical appearances or characteristics. In this contribution, we demonstrate that FT-IR spectroscopy is a suitable tool for a quick and objective determination of the bird's gender. The method is based on differences in chromosome size. Male birds have two Z chromosomes and female birds have a W-chromosome and a Z-chromosome. Each Z-chromosome has approx. 75.000.000 bps whereas the W-chromosome has approx. 260.00 bps. This difference can be detected by FT-IR spectroscopy. Spectra were recorded from germ cells obtained from the feather pulp of chicks as well as from the germinal disk of fertilized but non-bred eggs. Significant changes between cells of male and female birds occur in the region of phosphate vibrations around 1080 and 1120 cm-1.

  14. Infrared microcalorimetric spectroscopy using uncooled thermal detectors

    NASA Astrophysics Data System (ADS)

    Datskos, Panos G.; Rajic, Slobodan; Datskou, Irene; Egert, Charles M.

    1997-10-01

    We have investigated a novel IR microcalorimetric spectroscopy technique that can be used to detect the presence of trace amounts of target molecules. The chemical detection is accomplished by obtaining the IR photothermal spectra of molecules absorbed on the surface of an uncooled thermal detector. Traditional gravimetric based chemical detectors require highly selective coatings to achieve chemical specificity. In contrast, IR microcalorimetric based detection requires only moderately specific coatings since the specificity is a consequence of the photothermal spectrum. We have obtained IR photothermal spectra for trace concentrations of chemical analytes including diisopropyl methylphosphonate (DIMP), 2-mercaptoethanol and trinitrotoluene (TNT) over the wavelength region 2.5 to 14.5 micrometers . We found that in the wavelength region 2.5 to 14.5 micrometers DIMP exhibits two strong photothermal peaks. The photothermal spectra of 2-mercaptoethanol and TNT exhibit a number of peaks in the wavelength region 2.5 to 14.5 micrometers and the photothermal peaks for 2-mercaptoethanol are in excellent agreement with IR absorption peaks present in its IR spectrum. The photothermal response of chemical detectors based on microcalorimetric spectroscopy has been found to vary reproducibly and sensitively as a consequence of adsorption of small number of molecules on a detector surface followed by photon irradiation and can be used for improved chemical characterization.

  15. Time-resolved surface infrared spectroscopy during atomic layer deposition of TiO{sub 2} using tetrakis(dimethylamido)titanium and water

    SciTech Connect

    Sperling, Brent A. Hoang, John; Kimes, William A.; Maslar, James E.; Steffens, Kristen L.; Nguyen, Nhan V.

    2014-05-15

    Atomic layer deposition of titanium dioxide using tetrakis(dimethylamido)titanium (TDMAT) and water vapor is studied by reflection-absorption infrared spectroscopy (RAIRS) with a time resolution of 120 ms. At 190 °C and 240 °C, a decrease in the absorption from adsorbed TDMAT is observed without any evidence of an adsorbed product. Ex situ measurements indicate that this behavior is not associated with an increase in the impurity concentration or a dramatic change in the growth rate. A desorbing decomposition product is consistent with these observations. RAIRS also indicates that dehydroxylation of the growth surface occurs only among one type of surface hydroxyl groups. Molecular water is observed to remain on the surface and participates in reactions even at a relatively high temperature (110 °C) and with long purge times (30 s)

  16. Infrared Spectroscopy of Black Hole Candidates

    NASA Technical Reports Server (NTRS)

    Colgan, Sean W.; Cotera, A. S.; Maloney, P. R.; Hollenbach, D. J.; DeVincenzi, Donald L. (Technical Monitor)

    2000-01-01

    ISO LWS and SWS observations of the approx. solar mass black hole candidates 1E1740.7-2942 and GRS1758-258 are presented. For 1E1740.7-2942, it has been suggested that the luminosity is provided in whole or part by Bondi-Hoyle accretion from a surrounding black hole (Bally & Leventhal 1991, Nat, 353,234). Maloney et al. (1997, ApJ482, L41) have predicted that detectable far-infrared line emission from [0I] (63 microns), [CII] (158 microns), [SiII] (35 microns) and other lines will arise from black holes which are embedded in molecular clouds. No strong line emission associated with either 1E1740.7-2942 or GRS1758-258 was detected, implying either that 1) these sources are not embedded in dense molecular clouds, or 2) that their average X-ray luminosity over the past 100 years is significantly lower than its current value. The measured upper limits to the line fluxes are compared with the models of Maloney et al.to constrain the properties of the ISM in the vicinity of these X-ray sources.

  17. Infrared Spectroscopy of Black Hole Candidates

    NASA Technical Reports Server (NTRS)

    Colgan, Sean W.; Cotera, A. S.; Maloney, P. R.; Hollenbach, D. J.; DeVincenzi, Donald L. (Technical Monitor)

    2000-01-01

    ISO LWS and SWS observations of the approx. solar mass black hole candidates 1E1740.7-2942 and GRS1758-258 are presented. For 1E1740.7-2942, it has been suggested that the luminosity is provided in whole or part by Bondi-Hoyle accretion from a surrounding black hole (Bally & Leventhal 1991, Nat, 353,234). Maloney et al. (1997, ApJ482, L41) have predicted that detectable far-infrared line emission from [0I] (63 microns), [CII] (158 microns), [SiII] (35 microns) and other lines will arise from black holes which are embedded in molecular clouds. No strong line emission associated with either 1E1740.7-2942 or GRS1758-258 was detected, implying either that 1) these sources are not embedded in dense molecular clouds, or 2) that their average X-ray luminosity over the past 100 years is significantly lower than its current value. The measured upper limits to the line fluxes are compared with the models of Maloney et al.to constrain the properties of the ISM in the vicinity of these X-ray sources.

  18. [Identification of pearl powder using microscopic infrared reflectance spectroscopy].

    PubMed

    Zhang, Xuan; Hu, Chao; Yan, Yan; Yang, Hai-Feng; Li, Jun-Fang; Bai, Hua; Xi, Guang-Cheng; Liao, Jie

    2014-09-01

    Pearl is a precious ornament and traditional Chinese medicine, which application history in China is more than 2000 years. It is well known that the chemical ingredients of shell and pearl are very similar, which all of them including calcium carbonate and various amino acids. Generally, shell powders also can be used as medicine; however, its medicinal value is much lower than that of pearl powders. Due to the feature similarity between pearl powders and shell powders, the distinguishment of them by detecting chemical composition and morphology is very difficult. It should be noted that shell powders have been often posing as pearl powders in markets, which seriously infringes the interests of consumers. Identification of pearl powder was investigated by microscopic infrared reflectance spectroscopy, and pearl powder as well as shell powder was calcined at different temperatures for different time before infrared reflectance spectroscopy analysis. The experimental results indicated that when calcined at 400 °C for 30 minutes under atmospheric pressure, aragonite in pearl powder partly transformed into calcite, while aragonite in shell powder completely transformed into calcite. At the same time, the difference in phase transition between the pearl powders 'and shell powders can be easily detected by using the microscopic infrared reflectance spectroscopy. Therefore, based on the difference in their phase transition process, infrared reflectance spectroscopy can be used to identify phase transformation differences between pearl powder and shell powder. It's more meaningfully that the proposed infrared reflectance spec- troscopy method was also investigated for the applicability to other common counterfeits, such as oyster shell powders and abalone shell powders, and the results show that the method can be a simple, efficiently and accurately method for identification of pearl powder.

  19. Infrared Transit Spectroscopy of HD 209458b

    NASA Astrophysics Data System (ADS)

    Harrington, J.; Deming, D.; Goukenleuque, C.; Matthews, K.; Richardson, L. J.; Steyert, D.; Wiedemann, G.; Zeehandelaar, D.

    We measure spectra during transits of planet HD 209458b in front of its star to determine its composition and temperature. Transits should modulate the stellar spectrum because tangent rays of different wavelengths become extinct at different levels in the extrasolar planet atmosphere, changing the occulting area. S/N calculations show that ground-based spectroscopy can measure or place useful limits on the atmospheric abundances of water, methane, and carbon monoxide. Carbon forms predominantly methane below 1400 K and carbon monoxide if hotter. Since the equilibrium temperature is about 1400 K, detecting methane and/or carbon monoxide would constrain atmospheric temperatures. We have observed on 12 transit and 4 non-transit nights from Palomar, Keck, VLT, and IRTF. The expected modulation of the stellar spectrum is model-dependent. Since the effect is subtle compared to the noise in the data, we correlate model vs. observed spectra and average the correlations to test whether the data support a given model. We are developing a tangent-geometry radiative-transfer model to predict the spectrum of a given planetary model, and we are measuring water, methane, and carbon monoxide in the laboratory at 1300 K, with pressure-broadening by molecular hydrogen, to make our model spectra realistic at these elevated temperatures. We solicit participation by those who wish to test their planetary models.

  20. Near Infrared Laser Spectroscopy of Scandium Monobromide

    NASA Astrophysics Data System (ADS)

    Xia, Ye; Cheung, A. S.-C.; Liao, Zhenwu; Yang, Mei; Chan, Man-Chor

    2012-06-01

    High resolution laser spectrum of scandium monobromide (ScBr) between 787 and 845 nm has been investigated using the technique of laser vaporization/reaction with free jet expansion and laser induced fluorescence spectroscopy. ScBr was produced by reacting laser vaporized Sc atoms with ethyl bromide (C2H5Br). Spectra of six vibrational bands of both Sc79Br and Sc81Br isotopomers of the C1 Σ+ - X1 Σ+ transition and seven vibrational bands of the e3 Δ - a3 Δ transition were obtained and analyzed. Least-squares fit of the measured line positions for the singlet transitions yielded accurate molecular constants for the v = 0 - 3 levels of the C1 Σ+ state and the v = 0 - 2 levels of the X1 Σ+ state. Similar least-squares fit for the triplet transitions yielded molecular constants for the v = 0 - 2 levels of both e3 Δ and a3 Δ states. The equilibrium bond length, r_0, of the a3 Δ state has been determined to be 2.4789 Å. Financial support from the Research Grants Council of the Hong Kong Special Administrative Region, China (Project No. HKU 701008P) is gratefully acknowledged

  1. Emerging techniques for soil analysis via mid-infrared spectroscopy

    NASA Astrophysics Data System (ADS)

    Linker, R.; Shaviv, A.

    2009-04-01

    Transmittance and diffuse reflectance (DRIFT) spectroscopy in the mid-IR range are well-established methods for soil analysis. Over the last five years, additional mid-IR techniques have been investigated, and in particular: 1. Attenuated total reflectance (ATR) Attenuated total reflectance is commonly used for analysis of liquids and powders for which simple transmittance measurements are not possible. The method relies on a crystal with a high refractive index, which is in contact with the sample and serves as a waveguide for the IR radiation. The radiation beam is directed in such a way that it hits the crystal/sample interface several times, each time penetrating a few microns into the sample. Since the penetration depth is limited to a few microns, very good contact between the sample and the crystal must be ensured, which can be achieved by working with samples close to water saturation. However, the strong absorbance of water in the mid-infrared range as well as the absorbance of some soil constituents (e.g., calcium carbonate) interfere with some of the absorbance bands of interest. This has led to the development of several post-processing methods for analysis of the spectra. The FTIR-ATR technique has been successfully applied to soil classification as well as to determination of nitrate concentration [1, 6-8, 10]. Furthermore, Shaviv et al. [12] demonstrated the possibility of using fiber optics as an ATR devise for direct determination of nitrate concentration in soil extracts. Recently, Du et al. [5] showed that it is possible to differentiate between 14N and 15N in such spectra, which opens very promising opportunities for developing FTIR-ATR based methods for investigating nitrogen transformation in soils by tracing changes in N-isotopic species. 2. Photo-acoustic spectroscopy Photoacoustic spectroscopy (PAS) is based on absorption-induced heating of the sample, which produces pressure fluctuations in a surrounding gas. These fluctuations are

  2. NEWS: the near-infrared Echelle for wideband spectroscopy

    NASA Astrophysics Data System (ADS)

    Veyette, Mark J.; Muirhead, Philip S.; Hall, Zachary J.; Taylor, Brian; Ye, Jimmy

    2016-08-01

    We present an updated optical and mechanical design of NEWS: the Near-infrared Echelle for Wide-band Spectroscopy (formerly called HiJaK: the High-resolution J, H and K spectrometer), a compact, high-resolution, near-infrared spectrometer for 5-meter class telescopes. NEWS provides a spectral resolution of 60,000 and covers the full 0.8-2.5 μm range in 5 modes. We adopt a compact, lightweight, monolithic design and have developed NEWS to be mounted to the instrument cube at the Cassegrain focus of the new 4.3-meter Discovery Channel Telescope.

  3. AO imaging and infrared spectroscopy of exoplanet host stars

    NASA Astrophysics Data System (ADS)

    Skillen, I.; Pollacco, D.

    2013-05-01

    The telescopes of the ORM, La Palma have gained a worldwide reputation in the discovery and characterisation of exoplanets, which demonstrates the powerful synergy that exists between small, mid-size and large facilities such as SuperWASP, the WHT and GTC, in this rapidly evolving field. We outline a WHT programme of near-infrared adaptive optics imaging with NAOMI/INGRID, and near-infrared spectroscopy with LIRIS, of exoplanet host stars to search for associated stellar and brown dwarf companions.

  4. Synchrotron-based far-infrared spectroscopy of nickel tungstate

    NASA Astrophysics Data System (ADS)

    Kalinko, A.; Kuzmin, A.; Roy, P.; Evarestov, R. A.

    2016-07-01

    Monoclinic antiferromagnetic NiWO4 was studied by far-infrared (30-600 cm-1) absorption spectroscopy in the temperature range of 5-300 K using the synchrotron radiation from SOLEIL source. Two isomorphous CoWO4 and ZnWO4 tungstates were investigated for comparison. The phonon contributions in the far-infrared range of tungstates were interpreted using the first-principles spin-polarized linear combination of atomic orbital calculations. No contributions from magnetic excitations were found in NiWO4 and CoWO4 below their Neel temperatures down to 5 K.

  5. Breast phantom for mammary tissue characterization by near infrared spectroscopy

    NASA Astrophysics Data System (ADS)

    Miranda, D. A.; Cristiano, K. L.; Gutiérrez, J. C.

    2013-11-01

    Breast cancer is a disease associated to a high morbidity and mortality in the entire world. In the study of early detection of breast cancer the development of phantom is so important. In this research we fabricate a breast phantom using a ballistic gel with special modifications to simulate a normal and abnormal human breast. Optical properties of woman breast in the near infrared region were modelled with the phantom we developed. The developed phantom was evaluated with near infrared spectroscopy in order to study its relation with breast tissue. A good optical behaviour was achieved with the model fabricated.

  6. Titan's Propane from Cassini Infrared Spectroscopy

    NASA Astrophysics Data System (ADS)

    Nixon, C. A.; Jennings, D. E.; Flaud, J.-M.; Bezard, B.; Teanby, N. A.; Irwin, P. G. J.; Ansty, T. M.; Coustenis, A.; Flasar, F. M.

    2009-04-01

    Propane gas (C3H8) was first detected in the atmosphere of Titan by the Voyager 1 IRIS spectrometer, during the 1980 encounter (Maguire et al., 1981), and remains the heaviest saturated hydrocarbon (alkane) found there to date. Although the identification was based on the detection of several bands (including 748, 922, 1054, 1158 cm-1), only the ν26 band at 748 cm-1 has been subsequently modeled to retrieve the abundance, due to the unique availability of its line parameters in the GEISA database (Husson et al. 1992). Subsequent measurements from the ground (Roe et al., 2003) and Earth-orbit (ISO - Coustenis et al. 2003) have also focused on this one band, deriving an abundance of ~0.5 ppm, although it remains compromised by coincidence with the R-branch of the much stronger acetylene (C2H2) gas. The Composite Infrared Spectrometer (CIRS) instrument carried on-board the Cassini spacecraft in Saturn orbit has now been observing Titan during more than 50 flybys over 5 years, and offers a fresh perspective on the prevalence of propane. With much improved spectral and spatial resolution and sensitivity over IRIS, CIRS is also able to perform repeated limb sounding (viewing through the atmosphere above the surface) to increase signal-to-noise still further. Modeling and removal of the emissions of other gases now shows clearly for the first time a multitude of propane bands: including the four seen by IRIS and at least four others (869, 1338, 1376, 1472 cm-1). In addition, a new line atlas for three bands of propane at shorter wavelengths (1300-1500 cm-1) has now been compiled, based on the work of Flaud et al. (2001). With this, we now have the potential to model these weaker bands, and to check the measurements made by CIRS using the 748 cm-1 band alone. Preliminary analysis has shown that the retrievals are very sensitive to the spectral baseline (haze model) assumed, and that existing lab tholin spectral properties (Khare et al. 1984) do not well match the opacity

  7. [Study on the wood grading by near infrared spectroscopy].

    PubMed

    Wang, Xiao-Xu; Huang, An-Min; Yang, Zhong; Yang, Yao

    2011-04-01

    The present paper discussed wood grading according to modulus of rupture (MOR) by near infrared (NIR) spectroscopy. The calibration model was built between MOR of wood and NIR data in the range of 1 000-1 400 nm with partial least square regression (PLS). The correlation coefficient (r) was 0.89 and the standard error of calibration (SEC) was 6.30 MPa. The MOR of 35 unknown samples was predicted using the model. Wood samples were graded according to their predicted values and true values. The rate of right prediction for A, B and C was 75.0%, 91.3% and 80.0% respectively, and the whole rate of right prediction was 88.6%. The result has proved that near infrared spectroscopy is a fast method for the determination of wood grade in the small clear samples.

  8. Imperial College near infrared spectroscopy neuroimaging analysis framework.

    PubMed

    Orihuela-Espina, Felipe; Leff, Daniel R; James, David R C; Darzi, Ara W; Yang, Guang-Zhong

    2018-01-01

    This paper describes the Imperial College near infrared spectroscopy neuroimaging analysis (ICNNA) software tool for functional near infrared spectroscopy neuroimaging data. ICNNA is a MATLAB-based object-oriented framework encompassing an application programming interface and a graphical user interface. ICNNA incorporates reconstruction based on the modified Beer-Lambert law and basic processing and data validation capabilities. Emphasis is placed on the full experiment rather than individual neuroimages as the central element of analysis. The software offers three types of analyses including classical statistical methods based on comparison of changes in relative concentrations of hemoglobin between the task and baseline periods, graph theory-based metrics of connectivity and, distinctively, an analysis approach based on manifold embedding. This paper presents the different capabilities of ICNNA in its current version.

  9. Noninvasive detection of gas exchange rate by near infrared spectroscopy

    NASA Astrophysics Data System (ADS)

    Xu, Guodong; Mao, Zongzhen; Wang, Bangde

    2008-12-01

    In order to study the relationship among the oxygen concentration in skeletal muscle tissues and the heart rate (HR), oxygen uptake (VO2), respiratory exchange ratio (RER) during incremental running exercises on a treadmill, a near-infrared spectroscopy muscle oxygen monitor system is employed to measure the relative change in muscle oxygenation, with the heart rate, oxygen uptake, production of carbon dioxide (VCO2) and respiratory exchange ratio are recorded synchronously. The results indicate parameters mentioned above present regular changes during the incremental exercise. High correlations are discovered between relative change of oxy-hemoglobin concentration and heart rate, oxygen uptake, respiratory exchange ratio at the significance level (P=0.01). This research might introduce a new measurement technology and/or a novel biological monitoring parameter to the evaluation of physical function status, control the training intensity, estimation of the effectiveness of exercise. Keywords: near-infrared spectroscopy; muscle oxygen concentration; heart rate; oxygen uptake; respiratory exchange ratio.

  10. Infrared Spectroscopy Study of the SP-250 Epoxy Resin System.

    DTIC Science & Technology

    1984-07-01

    It necessary and identify by block nambo,) Epoxy resins Dicyandiamide 4 Curing agents Infrared spectroscopy Monuron 20. ABSTRACT (Crntimse on revse...investigation, the mixtures containing Monuron were cured at 130 0 C and those con- sisting of dicyandiamide and having "no Monuron" were hardened at 2000...uncured specimens were meas- ured from 4000 cm- 1 to 400 cm- I . DISCUSSION AND RESULTS The accelerated cure of dicyandiamide (Dicy)-containing epoxy resins

  11. [Near infrared spectroscopy study on water content in turbine oil].

    PubMed

    Chen, Bin; Liu, Ge; Zhang, Xian-Ming

    2013-11-01

    Near infrared (NIR) spectroscopy combined with successive projections algorithm (SPA) was investigated for determination of water content in turbine oil. Through the 57 samples of different water content in turbine oil scanned applying near infrared (NIR) spectroscopy, with the water content in the turbine oil of 0-0.156%, different pretreatment methods such as the original spectra, first derivative spectra and differential polynomial least squares fitting algorithm Savitzky-Golay (SG), and successive projections algorithm (SPA) were applied for the extraction of effective wavelengths, the correlation coefficient (R) and root mean square error (RMSE) were used as the model evaluation indices, accordingly water content in turbine oil was investigated. The results indicated that the original spectra with different water content in turbine oil were pretreated by the performance of first derivative + SG pretreatments, then the selected effective wavelengths were used as the inputs of least square support vector machine (LS-SVM). A total of 16 variables selected by SPA were employed to construct the model of SPA and least square support vector machine (SPA-LS-SVM). There is 9 as The correlation coefficient was 0.975 9 and the root of mean square error of validation set was 2.655 8 x 10(-3) using the model, and it is feasible to determine the water content in oil using near infrared spectroscopy and SPA-LS-SVM, and an excellent prediction precision was obtained. This study supplied a new and alternative approach to the further application of near infrared spectroscopy in on-line monitoring of contamination such as water content in oil.

  12. Spectroscopy of Metamaterials from Infrared to Optical Frequencies

    DTIC Science & Technology

    2006-03-01

    negative permeability,” Phys. Rev. Lett. 94, 37402 (2005). 14. F . Wooten , Optical Properties of Solids (Academic, 1972). 15. For example, see M. Born...for materials with differ- ent symmetry properties of the constitutive relations. The terms and are called the magneto- optical permittivi- ties...Spectroscopy of metamaterials from infrared to optical frequencies Willie J. Padilla Materials Science and Technology Division, Center for Integrated

  13. Gold nanoparticle mediated graphene plasmon for broadband enhanced infrared spectroscopy

    NASA Astrophysics Data System (ADS)

    Peng, Lilan; Zhang, Lei; Yuan, Jian; Chen, Chen; Bao, Qiaoliang; Qiu, Cheng-Wei; Peng, Zeping; Zhang, Kai

    2017-06-01

    Graphene plasmonics, with dynamic tunable resonance wavelength, has been successfully used in broadband plasmon-enhanced infrared spectroscopy. However, the requirement for external voltage loading makes the practical application sophisticated. In this work, the hybrid structure of graphene nanodot array (GNA) and gold nanoparticles (AuNPs) has been proposed as a passive platform for broadband infrared absorption enhancement. Numerical simulations show that the plasmon resonance peak of GNA becomes stiffer and broader when introducing AuNPs, and this is also proved by experimental results that the vibrational modes of polyethylene oxide molecule in a broad spectral range can be simultaneously enhanced. The metal-graphene hybrid plasmonic system has been proved to be a promising candidate for infrared sensing, which is significant for safety and healthy applications.

  14. [Infrared spectroscopy and XRD studies of coral fossils].

    PubMed

    Chen, Quan-li; Zhou, Guan-min; Yin, Zuo-wei

    2012-08-01

    Coral fossil is an old remain of multicellular animal on the earth, and formed by various geological processes. The structural characteristics and compositions of the coral fossils with different color and radial texture on the surface were studied by infrared absorption spectroscopy and X-ray powder diffraction analyses. The results show that the studied coral fossils mainly are composed of SiO2, and the radial microstructure characterized by the calcareous coral cross-section is preserved. It is formed by metasomatism by SiO2. The infrared absorption spectra of the coral fossil with different color and texture are essentially the same, showing typical infrared absorption spectra of the quartz jade. XRD analysis shows that the main components of the coral fossils with different color and texture are consistent and mainly composed of SiO2 with a trace amount of other minerals and without CaCO3.

  15. Enhancing the Responsivity of Uncooled Infrared Detectors Using Plasmonics for High-Performance Infrared Spectroscopy

    PubMed Central

    Ahmed, Amr Shebl; Kim, Hye Jin; Kim, Jinsik; Hwang, Kyo Seon; Kim, Seonghwan

    2017-01-01

    A lead zirconate titanate (PZT;Pb(Zr0.52Ti0.48)O3) layer embedded infrared (IR) detector decorated with wavelength-selective plasmonic crystals has been investigated for high-performance non-dispersive infrared (NDIR) spectroscopy. A plasmonic IR detector with an enhanced IR absorption band has been designed based on numerical simulations, fabricated by conventional microfabrication techniques, and characterized with a broadly tunable quantum cascade laser. The enhanced responsivity of the plasmonic IR detector at specific wavelength band has improved the performance of NDIR spectroscopy and pushed the limit of detection (LOD) by an order of magnitude. In this paper, a 13-fold enhancement in the LOD of a methane gas sensing using NDIR spectroscopy is demonstrated with the plasmonic IR detector. PMID:28425964

  16. Enhancing the Responsivity of Uncooled Infrared Detectors Using Plasmonics for High-Performance Infrared Spectroscopy.

    PubMed

    Ahmed, Amr Shebl; Kim, Hye Jin; Kim, Jinsik; Hwang, Kyo Seon; Kim, Seonghwan

    2017-04-20

    A lead zirconate titanate (PZT;Pb(Zr0.52Ti0.48)O₃) layer embedded infrared (IR) detector decorated with wavelength-selective plasmonic crystals has been investigated for high-performance non-dispersive infrared (NDIR) spectroscopy. A plasmonic IR detector with an enhanced IR absorption band has been designed based on numerical simulations, fabricated by conventional microfabrication techniques, and characterized with a broadly tunable quantum cascade laser. The enhanced responsivity of the plasmonic IR detector at specific wavelength band has improved the performance of NDIR spectroscopy and pushed the limit of detection (LOD) by an order of magnitude. In this paper, a 13-fold enhancement in the LOD of a methane gas sensing using NDIR spectroscopy is demonstrated with the plasmonic IR detector.

  17. Transient infrared spectroscopy of charge transport in emerging photovoltaic materials

    NASA Astrophysics Data System (ADS)

    Jeong, Kwang Seob

    Colloidal quantum dot (CQD) photovoltaic and organic photovoltaic (OPV) materials are promising alternative light absorbers for solar cells. Both CQD photovoltaics and OPVs can be fabricated on flexible substrates using low-cost solution cast fabrication methods at room temperature. Although intense research has been done for the last two decades in both materials, photophysical events underlying the device performance remain unclear. Here, the origin of the charge transport state in PbS CQD solids was explored and identified. The charge transport state was investigated using various optical and electrical methods: ultrafast transient infrared spectroscopy (UFIR), microsecond transient infrared spectroscopy (TRIR), steady state absorption spectroscopy, steady state photoluminescence emission spectroscopy, temperature dependent TRIR, temperature dependent transient photoconductivity and temperature dependent transient short-circuit current measurements. Furthermore, it was found that the mobility-lifetime product, which is dependent on the surface passivation strategy, significantly influences the device performance in CQD solar cells. Additionally, it was examined how the dielectric permittivity influences the photophysics in organic photovoltaic materials in conjunction with device performance. The experiments revealed that the increase of dielectric permittivity leads to enhancement of the mobility-lifetime product. For efficient conversion of excitons into charge carriers, it was suggested that high surface area between electron donor and acceptor materials is necessary. The findings provide better understanding of the fundamental properties of CQD and OPV materials and suggest pathways to improve the efficiency of solar cell based on these materials.

  18. [Near-infrared Raman spectroscopy for diagnosis of gastric cancer].

    PubMed

    Jin, Shaoqin; Mao, Hua

    2014-03-01

    To establish a method for early diagnosis of gastric cancer using near-infrared Raman spectroscopy. A rapid near-infrared Raman system was used to examine the tissue specimens of pathologically confirmed gastric cancer (33 cases), gastric precancerous lesions (27 cases), and normal gastric mucosa (45 cases). All the specimens were obtained from 105 patients undergoing gastrectomy or endoscopic biopsy of suspected gastric lesions. High-quality Raman spectra ranging from 700 to 1800 cm(-1) were acquired from the gastric tissues within 5 s. The distribution pattern of Raman spectra in gastric cancer differed significantly from those of gastric precancerous lesions and normal gastric mucosa, particularly in the spectral ranges of 853 cm(-1), 936 cm(-1), 1003 cm(-1), 1032 cm(-1), 1174 cm(-1), 1208 cm(-1), 1323 cm(-1), 1335 cm(-1), 1450 cm(-1), and 1655 cm(-1), which contained signals related to proteins, nucleic acids and lipids. The diagnostic decision algorithm based on the Raman peak intensity ratios of I1003/ I1337, I1003/I1445, I1003/I1655, and I1156/I1655 yielded remarkable differences in gastric cancer from gastric precancerous lesions and normal gastric mucosa, and the ratios were significantly higher in normal gastric tissues (P<0.05). The discrimination based on near-infrared Raman spectroscopy using PCA-LDA algorithms associated with leave- one-out and cross-validation method showed diagnostic sensitivities of 81.5%, 85.3%, and 100%, and specificities of 86.4%, 100%, and 97.4% for normal gastric mucosa, precancerous lesions and gastric cancer, respectively. near-infrared Raman spectroscopy in conjunction with intensity ratio algorithms shows the potential for noninvasive diagnosis and detection of gastric malignancy at the molecular level.

  19. PREFACE: 3rd International Workshop on Infrared Plasma Spectroscopy

    NASA Astrophysics Data System (ADS)

    Davies, P. B.; Röpcke, Jürgen; Hempel, Frank

    2009-07-01

    This volume containsd a selection of papers from the third Infrared Plasma Spectroscopy (IPS) Workshop held in Greifswald, Germany in July 2008. Although not all the contributions have been written up in time for the deadline for this volume, nevertheless the 12 contributions presented here give a fair representation of the conference topics. The conference comprised four different types of contribution. Firstly, four invited lectures focussed on the prime areas of interest. Secondly, eight shorter contributed talks, grouped as closely as possible with the appropriate invited lecture. These contributed talks covered topics in both pure and applied infrared plasma spectroscopy. A feature of the two previous IPS conferences has been a contribution from commercial organisations namely those involved in manufacturing devices, detectors and spectrometers. This group of participants formed the third part of the conference programme and gave five oral presentations covering topics like QCL and detector/detection developments and novel spectrometer designs. The fourth contributing group comprised 27 poster presentations. It should be mentioned that some of the latter were poster versions of contributed talks. The conference was remarkable for the wide spread of topics covered in a relatively small meeting, consisting of 44 participants. The participants were made up of 34 scientists from within Europe and 4 from the rest of the world. It is interesting to reflect on changes that have occurred since the previous meeting just a year earlier. Two clear developments which have occurred are the emergence of Quantum Cascade Lasers (QCL) and their use in Cavity Ring Down (CRD) spectroscopy. A major shift from cw lead salt diode lasers to cw and pulsed QCL in both pure and applied projects now seems to be well under way. The topics covered in the earlier conferences focussed more on applying infrared spectroscopy to plasma monitoring and control. When choosing the topics to cover

  20. An infrared spectroscopy method to detect ammonia in gastric juice.

    PubMed

    Giovannozzi, Andrea M; Pennecchi, Francesca; Muller, Paul; Balma Tivola, Paolo; Roncari, Silvia; Rossi, Andrea M

    2015-11-01

    Ammonia in gastric juice is considered a potential biomarker for Helicobacter pylori infection and as a factor contributing to gastric mucosal injury. High ammonia concentrations are also found in patients with chronic renal failure, peptic ulcer disease, and chronic gastritis. Rapid and specific methods for ammonia detection are urgently required by the medical community. Here we present a method to detect ammonia directly in gastric juice based on Fourier transform infrared spectroscopy. The ammonia dissolved in biological liquid samples as ammonium ion was released in air as a gas by the shifting of the pH equilibrium of the ammonium/ammonia reaction and was detected in line by a Fourier transform infrared spectroscopy system equipped with a gas cell for the quantification. The method developed provided high sensitivity and selectivity in ammonia detection both in pure standard solutions and in a simulated gastric juice matrix over the range of diagnostic concentrations tested. Preliminary analyses were also performed on real gastric juice samples from patients with gastric mucosal injury and with symptoms of H. pylori infection, and the results were in agreement with the clinicopathology information. The whole analysis, performed in less than 10 min, can be directly applied on the sample without extraction procedures and it ensures high specificity of detection because of the ammonia fingerprint absorption bands in the infrared spectrum. This method could be easily used with endoscopy instrumentation to provide information in real time and would enable the endoscopist to improve and integrate gastroscopic examinations.

  1. Composition of Polar Stratospheric Clouds from Infrared Spectroscopy

    NASA Technical Reports Server (NTRS)

    Tolbert, M. A.; Anthony, S. E.; Disselkamp, R.; Toon, O. B.; Condon, Estelle P. (Technical Monitor)

    1995-01-01

    Heterogeneous reactions on polar stratospheric clouds (PSCs) have recently been implicated in Arctic and Antarctic ozone destruction. Although the chemistry is well documented, the composition of the clouds remains uncertain. The most common PSCs (type I) are thought to be composed of HNO3/H2O mixtures. Although the exact process is not clear, type I PSCs are believed to nucleate on preexisting stratospheric sulfate aerosols (SSAs) composed of sulfuric acid and water. We are using infrared spectroscopy to study the composition and formation mechanism of type I PSCs. In the laboratory, we have used FTIR spectroscopy to probe the composition and phase of H2SO4/HNO3/H2O aerosols under winter polar stratospheric conditions. We have also used recently measured infrared optical constants for HNO3/H2O mixtures to analyze solar infrared extinction measurements of type I PSCs obtained in September 1987 over Antarctica. The results of these studies will be discussed in the context of current theories for polar stratospheric clouds formation.

  2. Infrared polarization spectroscopy of CO 2 at atmospheric pressure

    NASA Astrophysics Data System (ADS)

    Alwahabi, Z. T.; Li, Z. S.; Zetterberg, J.; Aldén, M.

    2004-04-01

    Polarisation spectroscopy (PS) was used to probe CO 2 gas concentration in a CO 2/N 2 binary mixture at atmospheric pressure and ambient temperature. The CO 2 molecules were probed by a direct laser excitation to an overtone and combination vibrational state. The tuneable narrow linewidth infrared laser radiation at 2 μm was obtained by Raman shifting of the output from a single-longitudinal-mode pulsed alexandrite laser-system to the second Stokes component in a H 2 gas cell. Infrared polarisation spectroscopy (IRPS) and time-resolved infrared laser-induced fluorescence (IRLIF) spectra were collected. A linear dependence of the IRPS signal on the CO 2 mole fraction has been found. This indicates that the IRPS signal is only weakly affected by the molecular collisions and that the inter- and intra- molecular energy transfer processes do not strongly influence the molecular alignment at the time scale of the measurements. Thus IRPS holds great potential for quantitative instantaneous gas concentration diagnostics in general. This is especially important for molecules which do not posses an accessible optical transition such as CO, CO 2 and N 2O. In addition, an accurate experimental method to measure the extinction ratio of the IR polarisers employed in this study has been developed and applied. With its obvious merits as simplicity, easy alignment and high accuracy, the method can be generalized to all spectral regions, different polarisers and high extinction ratios.

  3. Composition of Polar Stratospheric Clouds from Infrared Spectroscopy

    NASA Technical Reports Server (NTRS)

    Tolbert, M. A.; Anthony, S. E.; Disselkamp, R.; Toon, O. B.; Condon, Estelle P. (Technical Monitor)

    1995-01-01

    Heterogeneous reactions on polar stratospheric clouds (PSCs) have recently been implicated in Arctic and Antarctic ozone destruction. Although the chemistry is well documented, the composition of the clouds remains uncertain. The most common PSCs (type I) are thought to be composed of HNO3/H2O mixtures. Although the exact process is not clear, type I PSCs are believed to nucleate on preexisting stratospheric sulfate aerosols (SSAs) composed of sulfuric acid and water. We are using infrared spectroscopy to study the composition and formation mechanism of type I PSCs. In the laboratory, we have used FTIR spectroscopy to probe the composition and phase of H2SO4/HNO3/H2O aerosols under winter polar stratospheric conditions. We have also used recently measured infrared optical constants for HNO3/H2O mixtures to analyze solar infrared extinction measurements of type I PSCs obtained in September 1987 over Antarctica. The results of these studies will be discussed in the context of current theories for polar stratospheric clouds formation.

  4. Plant species discrimination using emissive thermal infrared imaging spectroscopy

    NASA Astrophysics Data System (ADS)

    Rock, Gilles; Gerhards, Max; Schlerf, Martin; Hecker, Christoph; Udelhoven, Thomas

    2016-12-01

    Discrimination of plant species in the optical reflective domain is somewhat limited by the similarity of their reflectance spectra. Spectral characteristics in the visible to shortwave infrared (VSWIR) consist of combination bands and overtones of primary absorption bands, situated in the Thermal Infrared (TIR) region and therefore resulting in broad spectral features. TIR spectroscopy is assumed to have a large potential for providing complementary information to VSWIR spectroscopy. So far, in the TIR, plants were often considered featureless. Recently and following advances in sensor technology, plant species were discriminated based on specific emissivity signatures by Ullah et al. (2012) using directional-hemispherical reflectance (DHR) measurements in the laboratory. Here we examine if an accurate discrimination of plant species is equally possible using emissive thermal infrared imaging spectroscopy, an explicit spatial technique that is faster and more flexible than non-imaging measurements. Hyperspectral thermal infrared images were acquired in the 7.8⿿11.56 μm range at 40 nm spectral resolution (@10 μm) using a TIR imaging spectrometer (Telops HyperCam-LW) on seven plants each, of eight different species. The images were radiometrically calibrated and subjected to temperature and emissivity separation using a spectral smoothness approach. First, retrieved emissivity spectra were compared to laboratory reference spectra and then subjected to species discrimination using a random forest classifier. Second, classification results obtained with emissivity spectra were compared to those obtained with VSWIR reflectance spectra that had been acquired from the same leaf samples. In general, the mean emissivity spectra measured by the TIR imaging spectrometer showed very good agreement with the reference spectra (average Nash-Sutcliffe-Efficiency Index = 0.64). In species discrimination, the resulting accuracies for emissivity spectra are highly dependent on

  5. Mid-Infrared Frequency-Agile Dual-Comb Spectroscopy

    NASA Astrophysics Data System (ADS)

    Luo, Pei-Ling; Yan, Ming; Iwakuni, Kana; Millot, Guy; Hänsch, Theodor W.; Picqué, Nathalie

    2016-06-01

    We demonstrate a new approach to mid-infrared dual-comb spectroscopy. It opens up new opportunities for accurate real-time spectroscopic diagnostics and it significantly simplifies the technique of dual-comb spectroscopy. Two mid-infrared frequency combs of slightly different repetition frequencies and moderate, but rapidly tunable, spectral span are generated in the 2800-3200 cm-1 region. The generators rely on electro-optic modulators, nonlinear fibers for spectral broadening and difference frequency generation and do not involve mode-locked lasers. Flat-top frequency combs span up to 10 cm-1 with a comb line spacing of 100 MHz (3×10-3 cm-1). The performance of the spectrometer without any phase-lock electronics or correction scheme is illustrated with spectra showing resolved comb lines and Doppler-limited spectra of methane. High precision on the spectroscopic parameter (line positions and intensities) determination is demonstrated for spectra measured on a millisecond time scale and it is validated with comparison with literature data. G. Millot, S. Pitois, M. Yan, T. Hovannysyan, A. Bendahmane, T.W. Hänsch, N. Picqué, Frequency-agile dual-comb spectroscopy, Nature Photonics 10, 27-30 (2016).

  6. Photoacoustic-based detector for infrared laser spectroscopy

    SciTech Connect

    Scholz, L.; Palzer, S.

    2016-07-25

    In this contribution, we present an alternative detector technology for use in direct absorption spectroscopy setups. Instead of a semiconductor based detector, we use the photoacoustic effect to gauge the light intensity. To this end, the target gas species is hermetically sealed under excess pressure inside a miniature cell along with a MEMS microphone. Optical access to the cell is provided by a quartz window. The approach is particularly suitable for tunable diode laser spectroscopy in the mid-infrared range, where numerous molecules exhibit large absorption cross sections. Moreover, a frequency standard is integrated into the method since the number density and pressure inside the cell are constant. We demonstrate that the information extracted by our method is at least equivalent to that achieved using a semiconductor-based photon detector. As exemplary and highly relevant target gas, we have performed direct spectroscopy of methane at the R3-line of the 2v{sub 3} band at 6046.95 cm{sup −1} using both detector technologies in parallel. The results may be transferred to other infrared-active transitions without loss of generality.

  7. Fourier transform infrared spectroscopy approach for measurements of photoluminescence and electroluminescence in mid-infrared.

    PubMed

    Zhang, Y G; Gu, Y; Wang, K; Fang, X; Li, A Z; Liu, K H

    2012-05-01

    An improved Fourier transform infrared spectroscopy approach adapting to photoluminescence and electroluminescence measurements in mid-infrared has been developed, in which diode-pumped solid-state excitation lasers were adopted for photoluminescence excitation. In this approach, three different Fourier transform infrared modes of rapid scan, double modulation, and step scan were software switchable without changing the hardware or connections. The advantages and limitations of each mode were analyzed in detail. Using this approach a group of III-V and II-VI samples from near-infrared extending to mid-infrared with photoluminescence intensities in a wider range have been characterized at room temperature to demonstrate the validity and overall performances of the system. The weaker electroluminescence of quantum cascade lasers in mid-infrared band was also surveyed at different resolutions. Results show that for samples with relatively strong photoluminescence or electroluminescence out off the background, rapid scan mode is the most preferable. For weaker photoluminescence or electroluminescence overlapped with background, double modulation is the most effective mode. To get a better signal noise ratio when weaker photoluminescence or electroluminescence signal has been observed in double modulation mode, switching to step scan mode should be an advisable option despite the long data acquiring time and limited resolution.

  8. Infrared and infrared emission spectroscopy of the zinc carbonate mineral smithsonite

    NASA Astrophysics Data System (ADS)

    Frost, Ray L.; Martens, Wayde N.; Wain, Daria L.; Hales, Matt C.

    2008-10-01

    Infrared emission and infrared spectroscopy has been used to study a series of selected natural smithsonites from different origins. An intense broad infrared band at 1440 cm -1 is assigned to the ν CO 32- antisymmetric stretching vibration. An additional band is resolved at 1335 cm -1. An intense sharp Raman band at 1092 cm -1 is assigned to the CO 32- symmetric stretching vibration. Infrared emission spectra show a broad antisymmetric band at 1442 cm -1 shifting to lower wavenumbers with thermal treatment. A band observed at 870 cm -1 with a band of lesser intensity at 842 cm -1 shifts to higher wavenumbers upon thermal treatment and is observed at 865 cm -1 at 400 °C and is assigned to the CO 32-ν mode. No ν bending modes are observed in the Raman spectra for smithsonite. The band at 746 cm -1 shifts to 743 cm -1 at 400 °C and is attributed to the CO 32-ν in phase bending modes. Two infrared bands at 744 and around 729 cm -1 are assigned to the ν in phase bending mode. Multiple bands may be attributed to the structural distortion ZnO 6 octahedron. This structural distortion is brought about by the substitution of Zn by some other cation. A number of bands at 2499, 2597, 2858, 2954 and 2991 cm -1 in both the IE and infrared spectra are attributed to combination bands.

  9. Infrared Heterodyne Spectroscopy and its Unique Application to Planetary Studies

    NASA Technical Reports Server (NTRS)

    Kostiuk, Theodore

    2009-01-01

    Since the early 1970's the infrared heterodyne technique has evolved into a powerful tool for the study of molecular constituents, temperatures, and dynamics in planetary atmospheres. Its extremely high spectral resolution (Lambda/(Delta)Lambda/>10(exp 6)) and highly accurate frequency measurement (to 1 part in 10(exp 8)) enabled the detection of nonthermal/natural lasing phenomena on Mars and Venus; direct measurements of winds on Venus, Mars, and Titan; study of mid-infrared aurorae on Jupiter; direct measurement of species abundances on Mars (ozone, isotopic CO2), hydrocarbons on Jupiter, Saturn., Neptune, and Titan, and stratospheric composition in the Earth's stratosphere (O3, CIO, N2O, CO2 ....). Fully resolved emission and absorption line shapes measured by this method enabled the unambiguous retrieval of molecular abundances and local temperatures and thermal structure in regions not probed by other techniques. The mesosphere of Mars and thermosphere of Venus are uniquely probed by infrared heterodyne spectroscopy. Results of these studies tested and constrained photochemical and dynamical theoretical models describing the phenomena measured. The infrared heterodyne technique will be described. Highlights in its evolution to today's instrumentation and resultant discoveries will be presented, including work at Goddard Space Flight Center and the University of Koln. Resultant work will include studies supporting NASA and ESA space missions and collaborations between instrumental and theoretical groups.

  10. Infrared Heterodyne Spectroscopy and its Unique Application to Planetary Studies

    NASA Technical Reports Server (NTRS)

    Kostiuk, Theodore

    2009-01-01

    Since the early 1970's the infrared heterodyne technique has evolved into a powerful tool for the study of molecular constituents, temperatures, and dynamics in planetary atmospheres. Its extremely high spectral resolution (Lambda/(Delta)Lambda/>10(exp 6)) and highly accurate frequency measurement (to 1 part in 10(exp 8)) enabled the detection of nonthermal/natural lasing phenomena on Mars and Venus; direct measurements of winds on Venus, Mars, and Titan; study of mid-infrared aurorae on Jupiter; direct measurement of species abundances on Mars (ozone, isotopic CO2), hydrocarbons on Jupiter, Saturn., Neptune, and Titan, and stratospheric composition in the Earth's stratosphere (O3, CIO, N2O, CO2 ....). Fully resolved emission and absorption line shapes measured by this method enabled the unambiguous retrieval of molecular abundances and local temperatures and thermal structure in regions not probed by other techniques. The mesosphere of Mars and thermosphere of Venus are uniquely probed by infrared heterodyne spectroscopy. Results of these studies tested and constrained photochemical and dynamical theoretical models describing the phenomena measured. The infrared heterodyne technique will be described. Highlights in its evolution to today's instrumentation and resultant discoveries will be presented, including work at Goddard Space Flight Center and the University of Koln. Resultant work will include studies supporting NASA and ESA space missions and collaborations between instrumental and theoretical groups.

  11. [Application of near-infrared spectroscopy in golf turfgrass management].

    PubMed

    Li, Shu-Ying; Han, Jian-Guo

    2008-07-01

    The management of golf course is different from other turfs. Its particularity lies in its higher and more precise requirement during maintenance compare with other turfs. In case something happened to turf of golf course, more effective and higher speed detecting and resolution are required. Only the data about turf growth and environment were mastered precisely in time, the friendly environmental and scientific management goal could be completed effectively and economically. The near infrared spectroscopy is a new kind of effective, convenient and non-destructive analytical method in the turfgrass management of golf course in recent years. Many factors of turf-soil system in golf course could be determined by near infrared spectroscopy at the same time. In this paper, the existing literature that use of near infrared spectroscopy to study turfgrass and soil nutrient content, soil hygroscopic moisture, feasible fertilizer application time and rate, to fix the time and volume of irrigation, turfgrass visual quality evaluation, turfgrass disease prediction and prevention were reviewed. Most researchers considered the nutrition condition of turf impacted the visual and playing quality of golf course directly and then indirectly influenced most of assistant cultivation such as fertilization, mowing and irrigation and so on. The using of NIRS can detect the nutrient content of turfgrass effectively and estimate the nutrient is excessive or deficient quickly. And then the feasible time and rate of fertilizers can be decided. Comparing with the common judgment ways based on the season fertilization and visual estimation, the using of NIRS can reduce the application of fertilizers on the base of keeping the same turf quality simultaneously. NIRS can analysis many items of soil such as moisture, elements concentration, textures on the spot by the thousands. This method can get lots of cover-all data non-destructively. What's more, NIRS can analysis soil betimes quickly

  12. [Identification of gastrodia elata blume by Fourier transform infrared spectroscopy].

    PubMed

    Liu, Gang; Dong, Qin; Yu, Fan; Liu, Jian-hong; Sun, Shi-zhong

    2004-03-01

    In this paper, a method of rapid and undamaged identification of wild and cultivated Gastrodia elata Blume, and one of its fakes by Fourier transform infrared spectroscopy (FTIR) is reported. The results show that Gastrodia elata Blume and its fake have different characteristic infrared spectra, by which Gastrodia elata Blume can be identified from its fake. Wild winter, wild spring, and cultivated Gastrodia elata Blume can be discriminated by FTIR, according to the differences of their spectral peaks and absorbance ratios. By the differences of absorbance ratios of several peaks, different grade of Gastrodia elata Blume may be classified. FTIR has proved to be a rapid, simple and nondestructive method for the identification of Gastrodia elata Blume.

  13. Infrared Spectroscopy of Halogenated Species for Atmospheric Remote Sensing

    NASA Astrophysics Data System (ADS)

    Harrison, Jeremy J.

    2014-06-01

    Fluorine- and chlorine-containing molecules in the atmosphere are very strong greenhouse gases, meaning that even small amounts of these gases contribute significantly to the radiative forcing of climate. Chlorofluorocarbons (CFCs) and hydrochlorofluorocarbons (HCFCs) are regulated by the 1987 Montreal Protocol because they deplete the ozone layer. Hydrofluorocarbons (HFCs), which do not deplete the ozone layer and are not regulated by the Montreal Protocol, have been introduced as replacements for CFCs and HCFCs. HFCs have global-warming potentials many times greater than carbon dioxide, and are increasing in the atmosphere at a very fast rate. Various satellite instruments monitor many of these molecules by detecting infrared radiation that has passed through the Earth's atmosphere. However, the quantification of their atmospheric abundances crucially requires accurate quantitative infrared spectroscopy. This talk will focus on new and improved laboratory spectroscopic measurements for a number of important halogenated species.

  14. Infrared-emission spectroscopy of CO on Ni

    SciTech Connect

    Chiang, S.; Tobin, R.G.; Richards, P.L.

    1982-09-01

    We report the first observation of thermally emitted infrared radiation from vibrational modes of molecules adsorbed on clean, single-crystal metal surfaces. The observation of emission from CO adsorbed on Ni demonstrates the surface sensitivity of a novel apparatus for infrared vibrational spectroscopy, with a resolution of 1 to 15 cm/sup -1/ over the frequency range from 330 to 3000 cm/sup -1/. A liquid-helium-cooled grating spectrometer measures the thermal radiation from a room-temperature, single-crystal sample, which is mounted in an ultrahigh-vacuum system. Measurements of frequencies and linewidths of CO on a single-crystal Ni sample, as a function of coverage, are discussed.

  15. Nanostructured diamond layers enhance the infrared spectroscopy of biomolecules.

    PubMed

    Kozak, Halyna; Babchenko, Oleg; Artemenko, Anna; Ukraintsev, Egor; Remes, Zdenek; Rezek, Bohuslav; Kromka, Alexander

    2014-03-04

    We report on the fabrication and practical use of high-quality optical elements based on Au mirrors coated with diamond layers with flat, nanocolumnar, and nanoporous morphologies. Diamond layers (100 nm thickness) are grown at low temperatures (about 300 °C) from a methane, carbon dioxide, and hydrogen gas mixture by a pulsed microwave plasma system with linear antennas. Using grazing angle reflectance (GAR) Fourier transform infrared spectroscopy with p-polarized light, we compare the IR spectra of fetal bovine serum proteins adsorbed on diamond layers with oxidized (hydrophilic) surfaces. We show that the nanoporous diamond layers provide IR spectra with a signal gain of about 600% and a significantly improved sensitivity limit. This is attributed to its enhanced internal surface area. The improved sensitivity enabled us to distinguish weak infrared absorption peaks of <10-nm-thick protein layers and thereby to analyze the intimate diamond-molecule interface.

  16. Cloud identification in atmospheric trace molecule spectroscopy infrared occultation measurements.

    PubMed

    Kahn, Brian H; Eldering, Annmarie; Irion, Fredrick W; Mills, Franklin P; Sen, Bhaswar; Gunson, Michael R

    2002-05-20

    High-resolution infrared nongas absorption spectra derived from the Atmospheric Trace Molecule Spectroscopy (ATMOS) experiment are analyzed for evidence of the presence of cirrus clouds. Several nonspherical ice extinction models based on realistic size distributions and crystal habits along with a stratospheric sulfate aerosol model are fit to the spectra, and comparisons are made with different model combinations. Nonspherical ice models often fit observed transmission spectra better than a spherical Mie ice model, and some discrimination among nonspherical models is noted. The ATMOS lines of sight for eight occultations are superimposed on coincident geostationary satellite infrared imagery, and brightness temperatures along the lines of sight are compared with retrieved vertical temperature profiles. With these comparisons, studies of two cases of clear sky, three cases of opaque cirrus, and three cases of patchy cirrus are discussed.

  17. Measuring cloud thermodynamic phase with shortwave infrared imaging spectroscopy

    SciTech Connect

    Thompson, David R.; McCubbin, Ian; Gao, Bo Cai; Green, Robert O.; Matthews, Alyssa A.; Mei, Fan; Meyer, Kerry G.; Platnick, Steven; Schmid, Beat; Tomlinson, Jason; Wilcox, Eric

    2016-08-12

    Shortwave Infrared imaging spectroscopy enables accurate remote mapping of cloud thermodynamic phase at high spatial resolution. We describe a measurement strategy to exploit signatures of liquid and ice absorption in cloud top apparent reflectance spectra from 1.4 to 1.8 μm. This signal is generally insensitive to confounding factors such as solar angles, view angles, and surface albedo. We first evaluate the approach in simulation and then apply it to airborne data acquired in the Calwater-2/ACAPEX campaign of Winter 2015. Here NASA’s “Classic” Airborne Visible Infrared Imaging Spectrometer (AVIRIS-C) remotely observed diverse cloud formations while the U.S. Department of Energy ARM Aerial Facility G-1 aircraft measured cloud integral and microphysical properties in situ. Finally, the coincident measurements demonstrate good separation of the thermodynamic phases for relatively homogeneous clouds.

  18. Measuring cloud thermodynamic phase with shortwave infrared imaging spectroscopy

    NASA Astrophysics Data System (ADS)

    Thompson, David R.; McCubbin, Ian; Gao, Bo Cai; Green, Robert O.; Matthews, Alyssa A.; Mei, Fan; Meyer, Kerry G.; Platnick, Steven; Schmid, Beat; Tomlinson, Jason; Wilcox, Eric

    2016-08-01

    Shortwave Infrared imaging spectroscopy enables accurate remote mapping of cloud thermodynamic phase at high spatial resolution. We describe a measurement strategy to exploit signatures of liquid and ice absorption in cloud top apparent reflectance spectra from 1.4 to 1.8 μm. This signal is generally insensitive to confounding factors such as solar angles, view angles, and surface albedo. We first evaluate the approach in simulation and then apply it to airborne data acquired in the Calwater-2/ACAPEX campaign of Winter 2015. Here NASA's "Classic" Airborne Visible Infrared Imaging Spectrometer (AVIRIS-C) remotely observed diverse cloud formations while the U.S. Department of Energy ARM Aerial Facility G-1 aircraft measured cloud integral and microphysical properties in situ. The coincident measurements demonstrate good separation of the thermodynamic phases for relatively homogeneous clouds.

  19. Two-Photon-Excited Fluorescence-Encoded Infrared Spectroscopy.

    PubMed

    Mastron, Joseph N; Tokmakoff, Andrei

    2016-11-23

    We report on a method for performing ultrafast infrared (IR) vibrational spectroscopy using fluorescence detection. Vibrational dynamics on the ground electronic state driven by femtosecond mid-infrared pulses are detected by changes in fluorescence amplitude resulting from modulation of a two-photon visible transition by nuclear motion. We examine a series of coumarin dyes and study the signals as a function of solvent and excitation pulse parameters. The measured signal characterizes the relaxation of vibrational populations and coherences but yields different information than conventional IR transient absorption measurements. These differences result from the manner in which the ground-state dynamics are projected by the two-photon detection step. Extensions of this method can be adapted for a variety of increased-sensitivity IR measurements.

  20. [Progress in noninvasive biochemical examination by near infrared spectroscopy].

    PubMed

    Ding, Hai-quan; Lu, Qi-peng; Peng, Zhong-qi; Chen, Xing-dan

    2010-08-01

    In the early nineties of last century, great importance had been gradually attached to the potential of near-infrared spectroscopy (NIRS) in the human body noninvasive biochemical examination. However, the human body is extremely complex. Although research teams have made some achievements in experimental simulations and in-vitro analysis, there is still no substantive breakthrough in clinical application now. The present paper discusses the key problems which prevent NIRS from achieving human noninvasive clinical biochemical examination, such as weak signal, the interference of human tissue background and the problem of blood volume change. The thoughts of noninvasive biomedical examination using NIRS are divided into two categories in terms of analytical method, that is classical near-infrared analysis and issue background interference elimination analysis. This paper also introduces in detail the current status of the two categories in the world, and believes that the second category is more promising to be successful in clinical application under the existing conditions.

  1. Infrared Spectroscopy on Smoke Produced by Cauterization of Animal Tissue

    PubMed Central

    Gianella, Michele; Sigrist, Markus W.

    2010-01-01

    In view of in vivo surgical smoke studies a difference-frequency-generation (DFG) laser spectrometer (spectral range 2900–3144 cm−1) and a Fourier-transform infrared (FTIR) spectrometer were employed for infrared absorption spectroscopy. The chemical composition of smoke produced in vitro with an electroknife by cauterization of different animal tissues in different atmospheres was investigated. Average concentrations derived are: water vapor (0.87%), methane (20 ppm), ethane (4.8 ppm), ethene (17 ppm), carbon monoxide (190 ppm), nitric oxide (25 ppm), nitrous oxide (40 ppm), ethyne (50 ppm) and hydrogen cyanide (25 ppm). No correlation between smoke composition and the atmosphere or the kind of cauterized tissue was found. PMID:22319267

  2. Neuroimaging with functional near infrared spectroscopy: From formation to interpretation

    NASA Astrophysics Data System (ADS)

    Herrera-Vega, Javier; Treviño-Palacios, Carlos G.; Orihuela-Espina, Felipe

    2017-09-01

    Functional Near Infrared Spectroscopy (fNIRS) is gaining momentum as a functional neuroimaging modality to investigate the cerebral hemodynamics subsequent to neural metabolism. As other neuroimaging modalities, it is neuroscience's tool to understand brain systems functions at behaviour and cognitive levels. To extract useful knowledge from functional neuroimages it is critical to understand the series of transformations applied during the process of the information retrieval and how they bound the interpretation. This process starts with the irradiation of the head tissues with infrared light to obtain the raw neuroimage and proceeds with computational and statistical analysis revealing hidden associations between pixels intensities and neural activity encoded to end up with the explanation of some particular aspect regarding brain function.To comprehend the overall process involved in fNIRS there is extensive literature addressing each individual step separately. This paper overviews the complete transformation sequence through image formation, reconstruction and analysis to provide an insight of the final functional interpretation.

  3. Infrared spectroscopy and spectroscopic imaging in forensic science.

    PubMed

    Ewing, Andrew V; Kazarian, Sergei G

    2017-01-16

    Infrared spectroscopy and spectroscopic imaging, are robust, label free and inherently non-destructive methods with a high chemical specificity and sensitivity that are frequently employed in forensic science research and practices. This review aims to discuss the applications and recent developments of these methodologies in this field. Furthermore, the use of recently emerged Fourier transform infrared (FT-IR) spectroscopic imaging in transmission, external reflection and Attenuated Total Reflection (ATR) modes are summarised with relevance and potential for forensic science applications. This spectroscopic imaging approach provides the opportunity to obtain the chemical composition of fingermarks and information about possible contaminants deposited at a crime scene. Research that demonstrates the great potential of these techniques for analysis of fingerprint residues, explosive materials and counterfeit drugs will be reviewed. The implications of this research for the examination of different materials are considered, along with an outlook of possible future research avenues for the application of vibrational spectroscopic methods to the analysis of forensic samples.

  4. Visible and infrared reflectance imaging spectroscopy of paintings: pigment mapping and improved infrared reflectography

    NASA Astrophysics Data System (ADS)

    Delaney, John K.; Zeibel, Jason G.; Thoury, Mathieu; Littleton, Roy; Morales, Kathryn M.; Palmer, Michael; de la Rie, E. René

    2009-07-01

    Reflectance imaging spectroscopy, the collection of images in narrow spectral bands, has been developed for remote sensing of the Earth. In this paper we present findings on the use of imaging spectroscopy to identify and map artist pigments as well as to improve the visualization of preparatory sketches. Two novel hyperspectral cameras, one operating from the visible to near-infrared (VNIR) and the other in the shortwave infrared (SWIR), have been used to collect diffuse reflectance spectral image cubes on a variety of paintings. The resulting image cubes (VNIR 417 to 973 nm, 240 bands, and SWIR 970 to 1650 nm, 85 bands) were calibrated to reflectance and the resulting spectra compared with results from a fiber optics reflectance spectrometer (350 to 2500 nm). The results show good agreement between the spectra acquired with the hyperspectral cameras and those from the fiber reflectance spectrometer. For example, the primary blue pigments and their distribution in Picasso's Harlequin Musician (1924) are identified from the reflectance spectra and agree with results from X-ray fluorescence data and dispersed sample analysis. False color infrared reflectograms, obtained from the SWIR hyperspectral images, of extensively reworked paintings such as Picasso's The Tragedy (1903) are found to give improved visualization of changes made by the artist. These results show that including the NIR and SWIR spectral regions along with the visible provides for a more robust identification and mapping of artist pigments than using visible imaging spectroscopy alone.

  5. [Application of near infrared spectroscopy in analysis of wood properties].

    PubMed

    Yao, Sheng; Pu, Jun-wen

    2009-04-01

    There is substantial interest in the improvement of wood properties through genetic selection or a change in silviculture prescription. Tree breeding purpose requires measurement of a large number of samples. However, traditional methods of assessing wood properties are both time consuming and destructive, limiting the numbers of samples that can be processed, so new method would be needed to find. Near infrared spectroscopy (NIR) is an advanced spectroscopic tool for nondestructive evaluation of wood and it can quickly, accurately estimate the properties of increment core, solid wood or wood meal. The present paper reviews the advances in the research on the wood chemistry properties and anatomical properties using NIR.

  6. Fingerprints of polycyclic aromatic hydrocarbons (PAHs) in infrared absorption spectroscopy.

    PubMed

    Tommasini, Matteo; Lucotti, Andrea; Alfè, Michela; Ciajolo, Anna; Zerbi, Giuseppe

    2016-01-05

    We have analyzed a set of 51 PAHs whose structures have been hypothesized from mass spectrometry data collected on samples extracted from carbon particles of combustion origin. We have obtained relationships between infrared absorption signals in the fingerprint region (mid-IR) and the chemical structures of PAHs, thus proving the potential of IR spectroscopy for the characterization of the molecular structure of aromatic combustion products. The results obtained here for the spectroscopic characterization of PAHs can be also of interest in Materials Science and Astrophysics.

  7. Trace water determination in gases by infrared spectroscopy

    SciTech Connect

    Stallard, B.R.; Espinoza, L.H.; Niemczyk, T.M.

    1995-05-01

    Water determination in semiconductor process gases is desirable in order to extend the life of gas delivery systems and improve wafer yields. The authors review their work in applying Fourier transform infrared spectroscopy to this problem, where a 10 ppb detection limit has been demonstrated for water in N{sub 2}, HCl, and HBr. The potential for optical determination of other contaminants in these gases is discussed. Also, alternative optical spectroscopic approaches are briefly described. Finally, they discuss methods for dealing with interference arising from water in the instrument beam path, yet outside the sample cell.

  8. Near-infrared spectroscopy. Innovative technology summary report

    SciTech Connect

    Not Available

    1999-07-01

    A near-infrared (NIR) spectroscopy system with a remote fiber-optic probe was developed and demonstrated to measure the water content of high-level radioactive wastes from the underground storage tanks at the Hanford Site in richland Washington. The technology was developed as a cost-effective and safer alternative to the thermogravimetric analysis (TGA) technique in use as the baseline. This work was supported by the Tanks Focus Area (TFA) within the Department of Energy`s (DOE) Office of Science and Technology (OST) in cooperation with the Hanford Tank Waste Remediation System (TWRS) Program.

  9. Band Structure Asymmetry of Bilayer Graphene Revealed by Infrared Spectroscopy

    SciTech Connect

    Li, Z.Q.; Henriksen, E.A.; Jiang, Z.; Hao, Zhao; Martin, Michael C.; Kim, P.; Stormer, H.L.; Basov, Dimitri N.

    2008-12-10

    We report on infrared spectroscopy of bilayer graphene integrated in gated structures. We observe a significant asymmetry in the optical conductivity upon electrostatic doping of electrons and holes. We show that this finding arises from a marked asymmetry between the valence and conduction bands, which is mainly due to the inequivalence of the two sublattices within the graphene layer and the next-nearest-neighbor interlayer coupling. From the conductivity data, the energy difference of the two sublattices and the interlayer coupling energy are directly determined.

  10. Investigation of Membrane Peptides by Two-Dimensional Infrared Spectroscopy

    NASA Astrophysics Data System (ADS)

    Blanco, Emily Ann; Zanni, Martin T.

    2009-06-01

    Two-dimensional infrared spectroscopy (2D IR) is a useful tool for studying the structure of membrane peptides. Isotope labeling individual amino acids with 13C=18O decouples the isotope labeled amide I from the other amide I modes in the peptide. Work has been done on both the M2 ion channel and ovispirin antimicrobial peptide, studying the diagonal linewidths of the isotope labeled amide I. The diagonal linewidth of the isotope labeled amide I gives information about the local environment of that residue, which in turn gives structural information about the membrane peptide.

  11. Near infrared spectroscopy in the development of solid dosage forms.

    PubMed

    Räsänen, Eetu; Sandler, Niklas

    2007-02-01

    The use of near infrared (NIR) spectroscopy has rapidly grown partly due to demands of process analytical applications in the pharmaceutical industry. Furthermore, newest regulatory guidelines have advanced the increase of the use of NIR technologies. The non-destructive and non-invasive nature of measurements makes NIR a powerful tool in characterization of pharmaceutical solids. These benefits among others often make NIR advantageous over traditional analytical methods. However, in addition to NIR, a wide variety of other tools are naturally also available for analysis in pharmaceutical development and manufacturing, and those can often be more suitable for a given application. The versatility and rapidness of NIR will ensure its contribution to increased process understanding, better process control and improved quality of drug products. This review concentrates on the use of NIR spectroscopy from a process research perspective and highlights recent applications in the field.

  12. A spectroelectrochemical cell for ultrafast two-dimensional infrared spectroscopy.

    PubMed

    El Khoury, Youssef; Van Wilderen, Luuk J G W; Vogt, Tim; Winter, Ernst; Bredenbeck, Jens

    2015-08-01

    A spectroelectrochemical cell has been designed to combine electrochemistry and ultrafast two-dimensional infrared (2D-IR) spectroscopy, which is a powerful tool to extract structure and dynamics information on the femtosecond to picosecond time scale. Our design is based on a gold mirror with the dual role of performing electrochemistry and reflecting IR light. To provide the high optical surface quality required for laser spectroscopy, the gold surface is made by electron beam evaporation on a glass substrate. Electrochemical cycling facilitates in situ collection of ultrafast dynamics of redox-active molecules by means of 2D-IR. The IR beams are operated in reflection mode so that they travel twice through the sample, i.e., the signal size is doubled. This methodology is optimal for small sample volumes and successfully tested with the ferricyanide/ferrocyanide redox system of which the corresponding electrochemically induced 2D-IR difference spectrum is reported.

  13. Background-Limited Infrared-Submillimeter Spectroscopy (BLISS)

    NASA Technical Reports Server (NTRS)

    Bradford, Charles Matt

    2004-01-01

    The bulk of the cosmic far-infrared background light will soon be resolved into its individual sources with Spitzer, Astro-F, Herschel, and submm/mm ground-based cameras. The sources will be dusty galaxies at z approximately equal to 1-4. Their physical conditions and processes in these galaxies are directly probed with moderate-resolution spectroscopy from 20 micrometers to 1 mm. Currently large cold telescopes are being combined with sensitive direct detectors, offering the potential for mid-far-IR spectroscopy at the background limit (BLISS). The capability will allow routine observations of even modest high-redshift galaxies in a variety of lines. The BLISS instrument's capabilities are described in this presentation.

  14. A spectroelectrochemical cell for ultrafast two-dimensional infrared spectroscopy

    NASA Astrophysics Data System (ADS)

    El Khoury, Youssef; Van Wilderen, Luuk J. G. W.; Vogt, Tim; Winter, Ernst; Bredenbeck, Jens

    2015-08-01

    A spectroelectrochemical cell has been designed to combine electrochemistry and ultrafast two-dimensional infrared (2D-IR) spectroscopy, which is a powerful tool to extract structure and dynamics information on the femtosecond to picosecond time scale. Our design is based on a gold mirror with the dual role of performing electrochemistry and reflecting IR light. To provide the high optical surface quality required for laser spectroscopy, the gold surface is made by electron beam evaporation on a glass substrate. Electrochemical cycling facilitates in situ collection of ultrafast dynamics of redox-active molecules by means of 2D-IR. The IR beams are operated in reflection mode so that they travel twice through the sample, i.e., the signal size is doubled. This methodology is optimal for small sample volumes and successfully tested with the ferricyanide/ferrocyanide redox system of which the corresponding electrochemically induced 2D-IR difference spectrum is reported.

  15. Investigating the thermodynamics of UNCG tetraloops using infrared spectroscopy.

    PubMed

    Stancik, Aaron L; Brauns, Eric B

    2013-10-31

    Using infrared (IR) absorption spectroscopy, we have explored the folding thermodynamics of the UNCG class of RNA hairpin tetraloops (N = U, A, C, or G). Without the need to introduce non-native probes, IR spectroscopy makes it possible to distinguish specific structural elements such as base pairing versus base stacking or loop versus stem motions. Our results show that different structural components exhibit different thermodynamics. Specifically, we have found that tetraloop melting proceeds in a thermally sequential fashion, where base pairing in the stem is disrupted before (i.e., at a lower temperature) base stacking along the entire chain. In addition, for N = A, our data argue that the structure immediately surrounding adenine is particularly stable and melts at a higher temperature than either base-pairing or base-stacking interactions. Taken together, these results suggest that hairpin loop formation is not a simple two-state process, even in the equilibrium limit.

  16. A spectroelectrochemical cell for ultrafast two-dimensional infrared spectroscopy

    SciTech Connect

    El Khoury, Youssef; Van Wilderen, Luuk J. G. W.; Vogt, Tim; Winter, Ernst; Bredenbeck, Jens E-mail: bredenbeck@biophysik.uni-frankfurt.de

    2015-08-15

    A spectroelectrochemical cell has been designed to combine electrochemistry and ultrafast two-dimensional infrared (2D-IR) spectroscopy, which is a powerful tool to extract structure and dynamics information on the femtosecond to picosecond time scale. Our design is based on a gold mirror with the dual role of performing electrochemistry and reflecting IR light. To provide the high optical surface quality required for laser spectroscopy, the gold surface is made by electron beam evaporation on a glass substrate. Electrochemical cycling facilitates in situ collection of ultrafast dynamics of redox-active molecules by means of 2D-IR. The IR beams are operated in reflection mode so that they travel twice through the sample, i.e., the signal size is doubled. This methodology is optimal for small sample volumes and successfully tested with the ferricyanide/ferrocyanide redox system of which the corresponding electrochemically induced 2D-IR difference spectrum is reported.

  17. Mid-infrared absorption spectroscopy using quantum cascade lasers

    NASA Astrophysics Data System (ADS)

    Haibach, Fred; Erlich, Adam; Deutsch, Erik

    2011-06-01

    Block Engineering has developed an absorption spectroscopy system based on widely tunable Quantum Cascade Lasers (QCL). The QCL spectrometer rapidly cycles through a user-selected range in the mid-infrared spectrum, between 6 to 12 μm (1667 to 833 cm-1), to detect and identify substances on surfaces based on their absorption characteristics from a standoff distance of up to 2 feet with an eye-safe laser. It can also analyze vapors and liquids in a single device. For military applications, the QCL spectrometer has demonstrated trace explosive, chemical warfare agent (CWA), and toxic industrial chemical (TIC) detection and analysis. The QCL's higher power density enables measurements from diffuse and highly absorbing materials and substrates. Other advantages over Fourier Transform Infrared (FTIR) spectroscopy include portability, ruggedness, rapid analysis, and the ability to function from a distance through free space or a fiber optic probe. This paper will discuss the basic technology behind the system and the empirical data on various safety and security applications.

  18. Differentiation and quality estimation of Cordyceps with infrared spectroscopy

    NASA Astrophysics Data System (ADS)

    Yang, Ping; Song, Ping; Sun, Su-Qin; Zhou, Qun; Feng, Shu; Tao, Jia-Xun

    2009-11-01

    Heretofore, a scientific and systemic method for differentiation and quality estimation of a well-known Chinese traditional medicine, 'Cordyceps', has not been established in modern market. In this paper, Fourier-transform infrared spectroscopy (FTIR) and two-dimensional correlation infrared spectroscopy (2D-IR) are employed to propose a method for analysis of Cordyceps. It has presented that IR spectra of real Cordyceps of different origins and counterfeits have their own macroscopic fingerprints, with discriminated shapes, positions and intensities. Their secondary derivative spectra can amplify the differences and confirm the potentially characteristic IR absorption bands 1400-1700 cm -1 to be investigated in 2D-IR. Many characteristic fingerprints are discovered in 2D-IR spectra in the range of 1400-1700 cm -1 and hetero 2D spectra of 670-780 cm -1 × 1400-1700 cm -1. The different fingerprints display different chemical constitutes. Through the three steps, different Cordyceps and their counterfeits can be discriminated effectively and their qualities distinctly display. Successful analysis of eight Cordyceps capsule products has proved the practicability of the method, which can also be applied to the quality estimation of other Chinese traditional medicines.

  19. Near-infrared spectroscopy as a tool for driving research.

    PubMed

    Liu, Tao; Pelowski, Matthew; Pang, Changle; Zhou, Yuanji; Cai, Jianfeng

    2016-03-01

    Driving a motor vehicle requires various cognitive functions to process surrounding information, to guide appropriate actions, and especially to respond to or integrate with numerous contextual and perceptual hindrances or risks. It is, thus, imperative to examine driving performance and road safety from a perspective of cognitive neuroscience, which considers both the behaviour and the functioning of the brain. However, because of technical limitations of current brain imaging approaches, studies have primarily adopted driving games or simulators to present participants with simulated driving environments that may have less ecological validity. Near-infrared spectroscopy (NIRS) is a relatively new, non-invasive brain-imaging technique allowing measurement of brain activations in more realistic settings, even within real motor vehicles. This study reviews current NIRS driving research and explores NIRS' potential as a new tool to examine driving behaviour, along with various risk factors in natural situations, promoting our understanding about neural mechanisms of driving safety. Practitioner Summary: Driving a vehicle is dependent on a range of neurocognitive processing abilities. Near-infrared spectroscopy (NIRS) is a non-invasive brain-imaging technique allowing measurement of brain activation even in on-road studies within real motor vehicles. This study reviews current NIRS driving research and explores the potential of NIRS as a new tool to examine driving behaviour.

  20. Ante mortem identification of BSE from serum using infrared spectroscopy

    NASA Astrophysics Data System (ADS)

    Schmitt, Jürgen; Lasch, Peter; Beekes, Michael; Udelhoven, Thomas; Eiden, Michael; Fabian, Heinz; Petrich, Wolfgang H.; Naumann, Dieter

    2004-07-01

    In our former studies a diagnostic approach for the detection of transmissible spongiform encephalopaties (TSE) based on FT-IR spectroscopy in combination with artificial neural networks was described, based on a controlled animal study with terminally ill Syrian hamsters and control animals. As a consequence of the bovine spongiform encephalopathy (BSE) crisis in Europe, the development of a disgnostic ante mortem test for cattle has become a matter of great scientific importance and public interest. Since 1986 more than 180,000 clinical cases of BSE have been observed in the UK alone. Most of these cases were confirmed by post mortem examination of brain tissue. However, BSE-related risk assessment and risk-management would greatly benefit from ante mortem testing on living animals. For example, a serum-based test could allow for screening of the cattle population, thus, even a BSE eradication program would be conceivable. Here we report on a novel method for ante mortem BSE testing, which combines infrared spectroscopy of serum samples with multivariate pattern recognition analysis. A classification algorithm was trained using infrared spectra of sera from more than 800 animals from a field study (including BSE positive, healthy controls and animals suffering from viral or bacterial infections). In two validation studies sensitivities of 85% and 87% and specificities of 84% and 91% were achieved, respectively. The combination of classification algorithms increased sensitivity and specificity to 96% and 92%, respectively.

  1. INFRARED SPECTROSCOPY OF INTERMEDIATE-MASS YOUNG STELLAR OBJECTS

    SciTech Connect

    Pitann, Jan; Bouwman, Jeroen; Krause, Oliver; Henning, Thomas; Hennemann, Martin

    2011-12-10

    In this paper, we present Spitzer Infrared Spectrograph spectroscopy for 14 intermediate-mass young stellar objects (YSOs). We use Spitzer spectroscopy to investigate the physical properties of these sources and their environments. Our sample can be divided into two types of objects: young isolated, embedded objects with spectra that are dominated by ice and silicate absorption bands, and more evolved objects that are dominated by extended emission from polycyclic aromatic hydrocarbons (PAHs) and pure H{sub 2} rotational lines. We are able to constrain the illuminating FUV fields by classifying the PAH bands below 9 {mu}m. For most of the sources we are able to detect several atomic fine structure lines. In particular, the [Ne II] line appearing in two regions could originate from unresolved photodissociation regions or J-shocks. We relate the identified spectral features to observations obtained from NIR through submillimeter imaging. The spatial extent of several H{sub 2} and PAH bands is matched with morphologies identified in previous Infrared Array Camera observations. This also allows us to distinguish between the different H{sub 2} excitation mechanisms. In addition, we calculate the optical extinction from the silicate bands and use this to constrain the spectral energy distribution fit, allowing us to estimate the masses of these YSOs.

  2. Identifications of household's spores using mid infrared spectroscopy.

    PubMed

    Dixit, Vivechana; Cho, Byoung Kwan; Obendorf, Kay; Tewari, Jagdish

    2014-04-05

    Exposure to household fungi is very common both inside and outside the house and can cause health issues. The application of fourier transforms mid infrared spectroscopy (FTIR) as a screening technique for the detection and identification of household fungi was investigated. Early detection and identification of these household pathogens is very important and critical for their control. The current available methods for identification of fungi are time consuming, expensive and not very specific. Mid IR spectroscopy is a reliable and sensitive technique for the detection of spores. FTIR Spectra of four household fungi such as Aspergillus Ochraceus, Aspergillus Niger, Candida Glabrata and Penicillium Roguefortii were recorded in the mid infrared range from 600 to 4000cm(-1) using attenuated total reflectance (ATR) sampling accessory. Chemometrics analysis using principal component analysis (PCA), canonical variate analysis (CVA) and linear discriminant analysis (LDA) were performed to discriminate the fungi samples. Correspondence analysis (CA) was performed in order to visualize the relationship between different spores. An optimum classification of 100% was achieved for four different fungi. Results demonstrated that discriminant analysis of the FTIR spectra of fungi could be used for rapid detection of household fungi. Copyright © 2013 Elsevier B.V. All rights reserved.

  3. Fringes in FTIR spectroscopy revisited: understanding and modelling fringes in infrared spectroscopy of thin films.

    PubMed

    Konevskikh, Tatiana; Ponossov, Arkadi; Blümel, Reinhold; Lukacs, Rozalia; Kohler, Achim

    2015-06-21

    The appearance of fringes in the infrared spectroscopy of thin films seriously hinders the interpretation of chemical bands because fringes change the relative peak heights of chemical spectral bands. Thus, for the correct interpretation of chemical absorption bands, physical properties need to be separated from chemical characteristics. In the paper at hand we revisit the theory of the scattering of infrared radiation at thin absorbing films. Although, in general, scattering and absorption are connected by a complex refractive index, we show that for the scattering of infrared radiation at thin biological films, fringes and chemical absorbance can in good approximation be treated as additive. We further introduce a model-based pre-processing technique for separating fringes from chemical absorbance by extended multiplicative signal correction (EMSC). The technique is validated by simulated and experimental FTIR spectra. It is further shown that EMSC, as opposed to other suggested filtering methods for the removal of fringes, does not remove information related to chemical absorption.

  4. Photoacoustic infrared spectroscopy of Syncrude post-extraction oil sand

    NASA Astrophysics Data System (ADS)

    Michaelian, Kirk H.; Hall, Robert H.; Kenny, Kimberly I.

    2006-06-01

    Rapid- and step-scan photoacoustic (PA) infrared spectra of three fractions of a Syncrude post-extraction oil sand were analyzed in detail in this work. The rapid-scan spectra showed that the samples were comprised primarily of kaolinite, quartz, silica, siderite, and residual hydrocarbons, and that the proportions of these constituents were different for each fraction. Depth profiling of the three post-extraction oil sands was accomplished using both rapid- and step-scan PA infrared spectroscopy. The results confirmed that kaolinite is more abundant in the near-surface region, whereas quartz and hydrocarbons are concentrated at greater depths. The modulation frequency dependence of the PA intensities for all three fractions was consistent with a model in which the samples are thermally thick; in other words, the thermal diffusion length (roughly equal to the sampling depth) was less than the particle sizes of all three samples. The results of this study are consistent with published reports on the PA infrared spectra of fine tailings generated during bitumen extraction and the spectroscopic and thermophysical characterization of clay soils and an appropriate model clay.

  5. Photoacoustic infrared spectroscopy of Syncrude post-extraction oil sand.

    PubMed

    Michaelian, Kirk H; Hall, Robert H; Kenny, Kimberly I

    2006-06-01

    Rapid- and step-scan photoacoustic (PA) infrared spectra of three fractions of a Syncrude post-extraction oil sand were analyzed in detail in this work. The rapid-scan spectra showed that the samples were comprised primarily of kaolinite, quartz, silica, siderite, and residual hydrocarbons, and that the proportions of these constituents were different for each fraction. Depth profiling of the three post-extraction oil sands was accomplished using both rapid- and step-scan PA infrared spectroscopy. The results confirmed that kaolinite is more abundant in the near-surface region, whereas quartz and hydrocarbons are concentrated at greater depths. The modulation frequency dependence of the PA intensities for all three fractions was consistent with a model in which the samples are thermally thick; in other words, the thermal diffusion length (roughly equal to the sampling depth) was less than the particle sizes of all three samples. The results of this study are consistent with published reports on the PA infrared spectra of fine tailings generated during bitumen extraction and the spectroscopic and thermophysical characterization of clay soils and an appropriate model clay.

  6. Infrared spectroscopy as a screening technique for colitis

    NASA Astrophysics Data System (ADS)

    Titus, Jitto; Ghimire, Hemendra; Viennois, Emilie; Merlin, Didier; Perera, A. G. Unil

    2017-05-01

    There remains a great need for diagnosis of inflammatory bowel disease (IBD), for which the current technique, colonoscopy, is not cost-effective and presents a non-negligible risk for complications. Attenuated Total Reflectance Fourier Transform Infrared (ATR-FTIR) spectroscopy is a new screening technique to evaluate colitis. Comparing infrared spectra of sera to study the differences between them can prove challenging due to the complexity of its biological constituents giving rise to a plethora of vibrational modes. Overcoming these inherent infrared spectral analysis difficulties involving highly overlapping absorbance peaks and the analysis of the data by curve fitting to improve the resolution is discussed. The proposed technique uses colitic and normal wild type mice dried serum to obtain ATR/FTIR spectra to effectively differentiate colitic mice from normal mice. Using this method, Amide I group frequency (specifically, alpha helix to beta sheet ratio of the protein secondary structure) was identified as disease associated spectral signature in addition to the previously reported glucose and mannose signatures in sera of chronic and acute mice models of colitis. Hence, this technique will be able to identify changes in the sera due to various diseases.

  7. Investigating lignin key features in maize lignocelluloses using infrared spectroscopy.

    PubMed

    Chazal, Richard; Robert, Paul; Durand, Sylvie; Devaux, Marie-Françoise; Saulnier, Luc; Lapierre, Catherine; Guillon, Fabienne

    2014-01-01

    Lignins and their cross-linking to hemicelluloses detrimentally affect the cellulose-to-ethanol conversion of grass lignocelluloses. Screening appropriate grass cell walls and their compositional changes during the various steps of the process calls for a high-throughput analytical technique. Such a performance can be fulfilled by Fourier transform mid-infrared (FT-MIR) spectroscopy. In the present paper, a set of maize cell walls from mature stems were selected, including brown midrib samples. Lignin fractions were isolated by mild acidolysis to obtain a set of purified maize lignin standards. The lignin content and the percentage of lignin-derived p-hydroxyphenyl (H), guaiacyl (G), and syringyl (S) thioacidolysis monomers were determined. In addition, the composition of cell wall polysaccharides, as well as the amount of ester-linked p-coumaric (CA) and ferulic (FA) acids, was measured by wet chemistry. Partial least square (PLS) analyses were applied to infrared and chemical data of cell walls. The resulting models showed a good predictive ability with regard to the lignin content, to the frequency of S (or G) thioacidolysis monomers, and to the level of ester-linked CA of maize cell walls. The loading plots and regression coefficients revealed relevant infrared absorption bands.

  8. [Study on the soil mid-infrared photoacoustic spectroscopy].

    PubMed

    Du, Chang-wen; Zhou, Jian-min; Wang, Huo-yan; Zhang, Jia-bao; Zhu, An-ning

    2008-06-01

    Infrared photoacoustic spectroscopy (PAS) is a new style to obtain data based on photoacoustic theory. Photoacoustic thoeory is based on the absorption of electromagnetic radiation by analyte molecules, and the absorbed energy is measured by detecting pressure fluctuations in the form of sound waves or shock pulses. In contrast to conventional absorption spectroscopy, PAS allows the determination of absorption coefficients over several orders of magnitude, even in very black and strongly scattering soil samples. Red soil, fulvic soil and paddy soil were collected from Fengqiu National Ecological Experimental Station, Yingtan Red Soil Experimental Station, and Changshu Ecological Experimental Station, respectively. These soil samples were used as experimental materials to characterize the Fourier transform mid-infrared photoacoustic spectra (FTIR-PAS). Compared with infrared transmittance spectra and reflectance spectra, the testing of FTIR-PAS spectra was very fast and convenient without any pr-treatment, and there were more abundant absorptions as well as appropriate absorption values in the spectra; The main soil components (kaolin, bentonite, sand and CaCO3) also showed several strong absorptions with specific characteristics in the spectra; Further more, the interference of water with the PAS spectra was significantly smaller than that with reflectance spectra. Therefore, the soil properties could be better characterized by FTIR-PAS. The principal components analysis based on the FTIR-PAS spectra indicated that there were two main principal components (PCA1, PCA2) which contained 98.17% variance of the spectra, and the two-dimensionol distribution was made by plotting these two principal components to classify the soil type, and the results indicated that this distribution could be applied to distinguish soil type, which provided new technique for soil identification as well as further quantitative analysis in soil science.

  9. Metallicity determination of M dwarfs. High-resolution infrared spectroscopy

    NASA Astrophysics Data System (ADS)

    Lindgren, Sara; Heiter, Ulrike; Seifahrt, Andreas

    2016-02-01

    Context. Several new techniques to determine the metallicity of M dwarfs with better precision have been developed over the last decades. However, most of these studies were based on empirical methods. In order to enable detailed abundance analysis, standard methods established for warmer solar-like stars, i.e. model-dependent methods using fitting of synthetic spectra, still need to be used. Aims: In this work we continue the reliability confirmation and development of metallicity determinations of M dwarfs using high-resolution infrared spectra. The reliability was confirmed through analysis of M dwarfs in four binary systems with FGK dwarf companions and by comparison with previous optical studies of the FGK dwarfs. Methods: The metallicity determination was based on spectra taken in the J band (1.1-1.4 μm) with the CRIRES spectrograph. In this part of the infrared, the density of stellar molecular lines is limited, reducing the amount of blends with atomic lines enabling an accurate continuum placement. Lines of several atomic species were used to determine the stellar metallicity. Results: All binaries show excellent agreement between the derived metallicity of the M dwarf and its binary companion. Our results are also in good agreement with values found in the literature. Furthermore, we propose an alternative way to determine the effective temperature of M dwarfs of spectral types later than M2 through synthetic spectral fitting of the FeH lines in our observed spectra. Conclusions: We have confirmed that a reliable metallicity determination of M dwarfs can be achieved using high-resolution infrared spectroscopy. We also note that metallicites obtained with photometric metallicity calibrations available for M dwarfs only partly agree with the results we obtain from high-resolution spectroscopy. Based on data obtained at ESO-VLT, Paranal Observatory, Chile, Program ID 082.D-0838(A) and 084.D-1042(A).

  10. Infrared molecular binding spectroscopy realized in sorbent coated microfabricated devices

    NASA Astrophysics Data System (ADS)

    McGill, R. Andrew; Stievater, Todd H.; Pruessner, Marcel W.; Holmstrom, Scott A.; Nierenberg, Kerry; McGill, Rachel; Nguyen, Viet; Park, Doewon; Kendziora, Christopher; Furstenberg, Robert

    2014-05-01

    Sorbent materials are utilized in a range of analytical applications including coatings for preconcentrator devices, chromatography stationary phases, and as thin film transducer coatings used to concentrate analyte molecules of interest for detection. In this work we emphasize the use of sorbent materials to target absorption of analyte vapors and examine their molecular interaction with the sorbent by optically probing it with infrared (IR) light. The complex spectral changes which may occur during molecular binding of specific vapors to target sites in a sorbent can significantly aid in analyte detection. In this work a custom hydrogen-bond (HB) acidic polymer, HCSFA2, was used as the sorbent. HCSFA2 exhibits a high affinity for hazardous vapors with hydrogen-bond (HB) basic properties such as the G-nerve agents. Using bench top ATR-FTIR spectroscopy the HFIP hydroxyl stretching frequency has been observed in the mid wave infrared (MWIR) to shift by up to 700 wavenumbers when exposed to a strong HB base. The amount of shift is related to the HB basicity of the vapor. In addition, the large analyte polymer-gas partition coefficients sufficiently concentrate the analyte in the sorbent coating to allow spectral features of the analyte to be observed in the MWIR and long wave infrared (LWIR) while it is sorbed to HCSFA2. These spectral changes, induced by analyte-sorbent molecular binding, provide a rich signal feature space to consider selective detection of a wide range of chemical species as single components or complex mixtures. In addition, we demonstrate an HCSFA2 coated microbridge structure and micromechanical photothermal spectroscopy to monitor spectral changes when a vapor sorbs to HCSFA2. Example ATR-FTIR and microbridge spectra with exposures to dimethylmethylphosphonate (DMMP - G nerve agent simulant) and other vapors are compared. In a generic form we illustrate the concept of this work in Figure 1. The results of this work provide the potential to

  11. Characterizing Aeroallergens by Infrared Spectroscopy of Fungal Spores and Pollen

    PubMed Central

    Zimmermann, Boris; Tkalčec, Zdenko; Mešić, Armin; Kohler, Achim

    2015-01-01

    Background Fungal spores and plant pollen cause respiratory diseases in susceptible individuals, such as asthma, allergic rhinitis and hypersensitivity pneumonitis. Aeroallergen monitoring networks are an important part of treatment strategies, but unfortunately traditional analysis is time consuming and expensive. We have explored the use of infrared spectroscopy of pollen and spores for an inexpensive and rapid characterization of aeroallergens. Methodology The study is based on measurement of spore and pollen samples by single reflectance attenuated total reflectance Fourier transform infrared spectroscopy (SR-ATR FTIR). The experimental set includes 71 spore (Basidiomycota) and 121 pollen (Pinales, Fagales and Poales) samples. Along with fresh basidiospores, the study has been conducted on the archived samples collected within the last 50 years. Results The spectroscopic-based methodology enables clear spectral differentiation between pollen and spores, as well as the separation of confamiliar and congeneric species. In addition, the analysis of the scattering signals inherent in the infrared spectra indicates that the FTIR methodology offers indirect estimation of morphology of pollen and spores. The analysis of fresh and archived spores shows that chemical composition of spores is well preserved even after decades of storage, including the characteristic taxonomy-related signals. Therefore, biochemical analysis of fungal spores by FTIR could provide economical, reliable and timely methodologies for improving fungal taxonomy, as well as for fungal identification and monitoring. This proof of principle study shows the potential for using FTIR as a rapid tool in aeroallergen studies. In addition, the presented method is ready to be immediately implemented in biological and ecological studies for direct measurement of pollen and spores from flowers and sporocarps. PMID:25867755

  12. Characterizing aeroallergens by infrared spectroscopy of fungal spores and pollen.

    PubMed

    Zimmermann, Boris; Tkalčec, Zdenko; Mešić, Armin; Kohler, Achim

    2015-01-01

    Fungal spores and plant pollen cause respiratory diseases in susceptible individuals, such as asthma, allergic rhinitis and hypersensitivity pneumonitis. Aeroallergen monitoring networks are an important part of treatment strategies, but unfortunately traditional analysis is time consuming and expensive. We have explored the use of infrared spectroscopy of pollen and spores for an inexpensive and rapid characterization of aeroallergens. The study is based on measurement of spore and pollen samples by single reflectance attenuated total reflectance Fourier transform infrared spectroscopy (SR-ATR FTIR). The experimental set includes 71 spore (Basidiomycota) and 121 pollen (Pinales, Fagales and Poales) samples. Along with fresh basidiospores, the study has been conducted on the archived samples collected within the last 50 years. The spectroscopic-based methodology enables clear spectral differentiation between pollen and spores, as well as the separation of confamiliar and congeneric species. In addition, the analysis of the scattering signals inherent in the infrared spectra indicates that the FTIR methodology offers indirect estimation of morphology of pollen and spores. The analysis of fresh and archived spores shows that chemical composition of spores is well preserved even after decades of storage, including the characteristic taxonomy-related signals. Therefore, biochemical analysis of fungal spores by FTIR could provide economical, reliable and timely methodologies for improving fungal taxonomy, as well as for fungal identification and monitoring. This proof of principle study shows the potential for using FTIR as a rapid tool in aeroallergen studies. In addition, the presented method is ready to be immediately implemented in biological and ecological studies for direct measurement of pollen and spores from flowers and sporocarps.

  13. Application of supercontinuum radiation for mid-infrared spectroscopy

    NASA Astrophysics Data System (ADS)

    Kilgus, Jakob; Müller, Petra; Moselund, Peter M.; Brandstetter, Markus

    2016-04-01

    The emergence of new laser-based mid-infrared (MIR) sources, such as quantum cascade lasers (QCL), led to substantial developments in the field of MIR spectroscopy in the last decade. Recently, also MIR supercontinuum (SC) sources became available. They combine broadband spectral emission known from thermal sources emission with coherent properties known from laser sources like QCLs. Nevertheless, while the latter already find practical application in the field of optical sensing, SC sources have yet to prove their applicability. In this contribution we present the development, characterization and application of a measurement concept consisting of a fiber-coupled broadband MIR SC source (1.75 μm-4.2 μm, 75 mW optical power) and a fully-integrated MOEMS-based Fabry-Pérot microspectrometer (FPMS) for MIR spectroscopy. The main hindrance for the use of SC sources in spectroscopy so far, are the significant pulse-to-pulse fluctuations arising from the non-linear nature of the SC generation process. We show to what extent spectral averaging makes sense and evaluate the noise performance. By combining a SC source and a FPMS it was possible to significantly reduce noise in spectral, time and polarization domain, resulting in a set-up suitable for MIR spectroscopy. The performance of the set-up was characterized both in transmission and reflection geometry. Low-noise absorption spectra of oils, polymers and aqueous solutions of acetic acid were acquired . Furthermore, time-resolved measurements of the curing process of ethyl-2-cyanoacrylate and results of the chemical mapping of a painted metal surface are reported. The obtained results prove the concept of SC-FPMS promising for MIR spectroscopy, characterized by its simplicity and versatility.

  14. [Rapid determination of beet sugar content using near infrared spectroscopy].

    PubMed

    Yang, Yong; Ren, Jian; Zheng, Xi-Qun; Zhao, Li-Ying; Li, Mao-Mao

    2014-10-01

    In order to classify and set different prices on basis of difference of beet sugar content in the acquisition process and promote the development of beet sugar industry healthily, a fast, nondestructive, accurate method to detect sugar content of beet was determined by applying near infrared spectroscopy technology. Eight hundred twenty samples from 28 representative varieties of beet were collected as calibration set and 70 samples were chosen as prediction set. Then near infrared spectra of calibration set samples were collected by scanning, effective information was extracted from NIR spectroscopy, and the original spectroscopy data was optimized by data preprocessing methods appropriately. Then partial least square(PLS)regression was used to establish beet sugar quantitative prediction mathematical model. The performances of the models were evaluated by the root mean square of cross-validation (RMSECV), the coefficient of determination (R2) of the calibration model and the standard error of prediction (SEP), and the predicted results of these models were compared. Results show that the established mathematical model by using first derivative (FD) and standard normal variate transformation (SNV) coupled with partial least squares has good predictive ability. The R2 of calibration models of sugar content of beet is 0.908 3, and the RMSECV is 0.376 7. Using this model to forecast the prediction set including 70 samples, the correlation coefficient is 0.921 4 between predicted values and measured values, and the standard error of prediction (SEP) is 0.439, without significant difference (p > 0.05) between predicted values and measured values. These results demonstrated that NIRS can take advantage of simple, rapid, nondestructive and environmental detection method and could be applied to predict beet sugar content. This model owned high accuracy and can meet the precision need of determination of beet sugar content. This detection method could be used to classify

  15. Far-infrared spectroscopy of impurities in semiconductors

    NASA Astrophysics Data System (ADS)

    Stradling, R. A.

    1991-06-01

    Far-infrared spectroscopy of the electronic transitions between bound states of impurities provides a very high resolution technique for studying chemical shifts and thereby identifying residual contaminants. The use of photoconductivity generated within the sample itself, usually by the photothermal mechanism ("photothermal ionisation spectroscopy"), enables very high sensitivity to be achieved even with very thin films or ultrahigh-purity material. The current knowledge about the identity of the residual shallow donors in GaAs, InP, InAs and InSb obtained with this technique is reviewed. With high-purity materials the magneto-optical spectrum of the shallow donors can be particularly rich and more than fifty lines can be observed with both GaAs and InP. Hydrostatic pressure provides a valuable additional experimental parameter in studies of impurities. Not only does the pressure-induced increase in mass improve the resolution of the "fine structure" due to different chemical species but additional states can be introduced into the forbidden energy gap. Results with both InSb and GaAs have shown that generally donors in direct-gap III-V materials may be expected to have three types of state: the familiar gamma-associated donors, localised states with A 1 symmetry which are normally resonant within the conduction band and metastable DX states. Negatively charged shallow donor states (D - states) and "molecular" combinations where the electrons are shared between two or more donor sites have been studied by infrared spectroscopy of III-V materials. These states are important precursors of the metal-insulator transition. Recently there have been a number of studies of impurities within quantum wells and heterostructures. The dependence of impurity energy on distance from the well edge has been established and it has been shown that high concentrations of D - states can be formed by remote deping of the structures.

  16. Application of Near Infrared (NIR) Spectroscopy to Peanut Grading and Quality Analysis: Overview

    USDA-ARS?s Scientific Manuscript database

    Techniques using near infrared (NIR) spectroscopy for quality measurements are becoming more popular in food processing and quality inspection of agricultural commodities. NIR spectroscopy has several advantages over conventional physical and chemical analytical methods of food quality analysis. It ...

  17. Fourier Transform Infrared Spectroscopy: Part II. Advantages of FT-IR.

    ERIC Educational Resources Information Center

    Perkins, W. D.

    1987-01-01

    This is Part II in a series on Fourier transform infrared spectroscopy (FT-IR). Described are various advantages of FT-IR spectroscopy including energy advantages, wavenumber accuracy, constant resolution, polarization effects, and stepping at grating changes. (RH)

  18. Fourier Transform Infrared Spectroscopy: Part II. Advantages of FT-IR.

    ERIC Educational Resources Information Center

    Perkins, W. D.

    1987-01-01

    This is Part II in a series on Fourier transform infrared spectroscopy (FT-IR). Described are various advantages of FT-IR spectroscopy including energy advantages, wavenumber accuracy, constant resolution, polarization effects, and stepping at grating changes. (RH)

  19. 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.

  20. Potential of Raman and Infrared Spectroscopy for Plant Analysis

    NASA Astrophysics Data System (ADS)

    Schulz, H.

    2008-11-01

    Various mid-infrared (MIR) and Raman spectroscopic methods applied to the analysis of valuable plant substances or quality parameters in selected horticultural and agricultural crops are presented. Generally, both spectroscopy techniques allow to identify simultaneously characteristic key bands of individual plant components (e.g. carotenoids, alkaloids, polyacetylenes, fatty acids, amino acids, terpenoids). In contrast to MIR methods Raman spectroscopy mostly does not need any sample pre-treatment; even fresh plant material can be analysed without difficulty because water shows only weak Raman scattering properties. In some cases a significant sensivity enhancement of Raman signals can be achieved if the exciting laser wavelength is adjusted to the absorption range of particular plant chromophores such as carotenoids (Resonance Raman effect). Applying FT-IR or FT Raman micro-spectroscopy the distribution of certain plant constituents in the cell wall can be identified without the need for any physical separation. Furthermore it is also possible to analyse secondary metabolites occurring in the cell vacuoles if significant key bands do not coincide with the spectral background of the plant matrix.

  1. Assessment of hyaline cartilage matrix composition using near infrared spectroscopy.

    PubMed

    Palukuru, Uday P; McGoverin, Cushla M; Pleshko, Nancy

    2014-09-01

    Changes in the composition of the extracellular matrix (ECM) are characteristic of injury or disease in cartilage tissue. Various imaging modalities and biochemical techniques have been used to assess the changes in cartilage tissue but lack adequate sensitivity, or in the case of biochemical techniques, result in destruction of the sample. Fourier transform near infrared (FT-NIR) spectroscopy has shown promise for the study of cartilage composition. In the current study NIR spectroscopy was used to identify the contributions of individual components of cartilage in the NIR spectra by assessment of the major cartilage components, collagen and chondroitin sulfate, in pure component mixtures. The NIR spectra were obtained using homogenous pellets made by dilution with potassium bromide. A partial least squares (PLS) model was calculated to predict composition in bovine cartilage samples. Characteristic absorbance peaks between 4000 and 5000 cm(-1) could be attributed to components of cartilage, i.e. collagen and chondroitin sulfate. Prediction of the amount of collagen and chondroitin sulfate in tissues was possible within 8% (w/dw) of values obtained by gold standard biochemical assessment. These results support the use of NIR spectroscopy for in vitro and in vivo applications to assess matrix composition of cartilage tissues, especially when tissue destruction should be avoided. Copyright © 2014. Published by Elsevier B.V.

  2. Label free detection of phospholipids by infrared absorption spectroscopy

    NASA Astrophysics Data System (ADS)

    Ahmed, Tahsin; Foster, Erick; Vigil, Genevieve; Khan, Aamir A.; Bohn, Paul; Howard, Scott S.

    2014-08-01

    We present our study on compact, label-free dissolved lipid sensing by combining capillary electrophoresis separation in a PDMS microfluidic chip online with mid-infrared (MIR) absorption spectroscopy for biomarker detection. On-chip capillary electrophoresis is used to separate the biomarkers without introducing any extrinsic contrast agent, which reduces both cost and complexity. The label free biomarker detection could be done by interrogating separated biomarkers in the channel by MIR absorption spectroscopy. Phospholipids biomarkers of degenerative neurological, kidney, and bone diseases are detectable using this label free technique. These phospholipids exhibit strong absorption resonances in the MIR and are present in biofluids including urine, blood plasma, and cerebrospinal fluid. MIR spectroscopy of a 12-carbon chain phosphatidic acid (PA) (1,2-dilauroyl-snglycero- 3-phosphate (sodium salt)) dissolved in N-methylformamide, exhibits a strong amide peak near wavenumber 1660 cm-1 (wavelength 6 μm), arising from the phosphate headgroup vibrations within a low-loss window of the solvent. PA has a similar structure to many important phospholipids molecules like phosphatidylcholine (PC), phosphatidylinositol (PI), phosphatidylethanolamine (PE), phosphatidylglycerol (PG), and phosphatidylserine (PS), making it an ideal molecule for initial proof-of-concept studies. This newly proposed detection technique can lead us to minimal sample preparation and is capable of identifying several biomarkers from the same sample simultaneously.

  3. Infrared spectroscopy of nonclassical ions and their complexes

    SciTech Connect

    Boo, Doo Wan

    1995-01-01

    This thesis describes an infrared spectroscopic study on the structures and dynamics of the nonclassical ions and their complexes, using ion trap vibrational predissociation spectroscopy. Chapter One provides an introduction to the experimental apparatus used in this work. Chapter Two describes the previous theoretical and experimental works on the carbonium ion CH5+ and infrared spectroscopic and theoretical works on CH5+. CH5+ was predicted to scramble constantly without possessing a stable structure. In Chapter Three, the infrared spectroscopy for the molecular hydrogen solvated carbonium ions CH5+(H2)n (n=1-6) in the frequency region of 2700-4200 cm-1 are presented and compared with the results of ab initio molecular dynamics simulation on CH5+(H2)n (n=0-3). The results suggested that the scrambling of CH5+ slowed down considerably by the stabilization effects of the solvent H2 molecules, and it was completely frozen out when the first three H2 molecules were bound to the core CH5+. Chapter Four presents the complete infrared spectra for the solvated carbonium ions, CH5+(A)x(B)y (A,B=H2, Ar, N2, CH4;x,y=0-5) in the frequency region of 2500-3200 cm-1. As the binding affinities of the solvent molecules and the number of the solvent molecules in the clusters increased, the scrambling of CH5+ slowed down substantially. The structures of the solvated carbonium ions and the evidence for rapid proton transfer in CH5+(CH4) were also presented. Chapter Five presents the vib-rotational spectrum for the H-H stretching mode of the silanium ion SiH5+. The results suggested that Si

  4. Cerebral near-infrared spectroscopy during cardiopulmonary bypass predicts superior vena cava oxygen saturation.

    PubMed

    Ginther, Richard; Sebastian, Vinod A; Huang, Rong; Leonard, Steven R; Gorney, Ronald; Guleserian, Kristine J; Forbess, Joseph M

    2011-08-01

    Cerebral and flank near-infrared spectroscopy are used to monitor tissue oxygenation during cardiopulmonary bypass in pediatric patients. We sought to validate these noninvasive measurements as predictors of oxygen saturation in the superior and inferior venae cavae during cardiopulmonary bypass. Eight patients underwent elective repair of congenital heart defects with bicaval cannulation. Ultrasonic flow probes and oximetric catheters were placed in the superior and inferior venae cavae limbs of the perfusion circuit. Cerebral and flank near-infrared spectroscopy and 12 additional variables were recorded each minute on cardiopulmonary bypass. Relationships between these variables and superior and inferior venae cavae oxygen saturation were analyzed by linear mixed modeling. The regression of superior vena cava oxygen saturation by current cerebral near-infrared spectroscopy and 1-minute lag cerebral near-infrared spectroscopy, which are equivalent to the regression of the superior vena cava saturation by the current cerebral near-infrared spectroscopy and the 1-minute change in cerebral near-infrared spectroscopy, were used to assess cerebral near-infrared spectroscopy as a trend monitor. The mean number of observation time points per patient was 86 (median 72, range 34-194) for 690 total observations. The root mean square percentage error was 6.39% for the prediction model of superior vena cava saturation by single-factor cerebral near-infrared spectroscopy. The root mean square percentage error was 10.8% for the prediction model of inferior vena cava saturation by single-factor flank near-infrared spectroscopy. Cerebral near-infrared spectroscopy accurately predicts superior vena cava oxygen saturation and changes in superior vena cava oxygen saturation on cardiopulmonary bypass. The relationship between flank near-infrared spectroscopy and inferior vena cava saturation is not as strong. Copyright © 2011. Published by Mosby, Inc.

  5. Infrared, Fourier transform far infrared spectroscopy, and viscosimetry research of aqueous-glycol fluids with thickener reology properties

    NASA Astrophysics Data System (ADS)

    Melnikov, Vyacheslav; Komarova, Tatyana; Vatagin, Vladimir; Bronnikova, Alla; Usol'tseva, Nadezhda

    1997-03-01

    At the first time Fourier transform far infrared spectroscopy in sequences with infrared spectroscopy and viscosimetry was applied to research of new water soluble oil composition possessing higher antiwear resistance, and antirust properties than produced by industry ones. A new structure for these compounds like micelleformation or hexagonal mesogenes without optical anisotropy at 55 - 65 degrees Celsius and defined composition have been found. Obtained data are discussed on base of modern advantages in the field of intermolecular interaction.

  6. Infrared spectroscopy of V2+(H2O) complexes

    NASA Astrophysics Data System (ADS)

    Bandyopadhyay, B.; Duncan, M. A.

    2012-03-01

    Doubly charged vanadium-water complexes are produced by laser vaporization in a pulsed supersonic expansion. Size-selected ions are studied with infrared photodissociation spectroscopy in the O-H stretch region using argon complex predissociation. Density functional theory calculations provide structures and vibrational spectra of these ions. The O-H stretches of V2+(H2O) appear at lower frequencies than those of the free water molecule or V+(H2O). The symmetric stretch is more intense than the asymmetric stretch in both V+(H2O) and V2+(H2O) complexes. Spectra of V2+(H2O)Arn (n = 2-7) show that the coordination of the V2+ is filled with six ligands, i.e. one water and five argon atoms.

  7. Near-infrared Spectroscopy in the Brewing Industry.

    PubMed

    Sileoni, Valeria; Marconi, Ombretta; Perretti, Giuseppe

    2015-01-01

    This article offers an exhaustive description of the use of Near-Infrared (NIR) Spectroscopy in the brewing industry. This technique is widely used for quality control testing of raw materials, intermediates, and finished products, as well as process monitoring during malting and brewing. In particular, most of the reviewed works focus on the assessment of barley properties, aimed at quickly selecting the best barley varieties in order to produce a high-quality malt leading to high-quality beer. Various works concerning the use of NIR in the evaluation of raw materials, such as barley, malt, hop, and yeast, are also summarized here. The implementation of NIR sensors for the control of malting and brewing processes is also highlighted, as well as the use of NIR for quality assessment of the final product.

  8. Detecting counterfeit antimalarial tablets by near-infrared spectroscopy.

    PubMed

    Dowell, Floyd E; Maghirang, Elizabeth B; Fernandez, Facundo M; Newton, Paul N; Green, Michael D

    2008-11-04

    Counterfeit antimalarial drugs are found in many developing countries, but it is challenging to differentiate between genuine and fakes due to their increasing sophistication. Near-infrared spectroscopy (NIRS) is a powerful tool in pharmaceutical forensics, and we tested this technique for discriminating between counterfeit and genuine artesunate antimalarial tablets. Using NIRS, we found that artesunate tablets could be identified as genuine or counterfeit with high accuracy. Multivariate classification models indicated that this discriminatory ability was based, at least partly, on the presence or absence of spectral signatures related to artesunate. This technique can be field-portable and requires little training after calibrations are developed, thus showing great promise for rapid and accurate fake detection.

  9. Functional Near Infrared Spectroscopy: Watching the Brain in Flight

    NASA Technical Reports Server (NTRS)

    Harrivel, Angela; Hearn, Tristan A.

    2012-01-01

    Functional Near Infrared Spectroscopy (fNIRS) is an emerging neurological sensing technique applicable to optimizing human performance in transportation operations, such as commercial aviation. Cognitive state can be determined via pattern classification of functional activations measured with fNIRS. Operational application calls for further development of algorithms and filters for dynamic artifact removal. The concept of using the frequency domain phase shift signal to tune a Kalman filter is introduced to improve the quality of fNIRS signals in real-time. Hemoglobin concentration and phase shift traces were simulated for four different types of motion artifact to demonstrate the filter. Unwanted signal was reduced by at least 43%, and the contrast of the filtered oxygenated hemoglobin signal was increased by more than 100% overall. This filtering method is a good candidate for qualifying fNIRS signals in real time without auxiliary sensors.

  10. Functional Near Infrared Spectroscopy: Watching the Brain in Flight

    NASA Technical Reports Server (NTRS)

    Harrivel, Angela; Hearn, Tristan

    2012-01-01

    Functional Near Infrared Spectroscopy (fNIRS) is an emerging neurological sensing technique applicable to optimizing human performance in transportation operations, such as commercial aviation. Cognitive state can be determined via pattern classification of functional activations measured with fNIRS. Operational application calls for further development of algorithms and filters for dynamic artifact removal. The concept of using the frequency domain phase shift signal to tune a Kalman filter is introduced to improve the quality of fNIRS signals in realtime. Hemoglobin concentration and phase shift traces were simulated for four different types of motion artifact to demonstrate the filter. Unwanted signal was reduced by at least 43%, and the contrast of the filtered oxygenated hemoglobin signal was increased by more than 100% overall. This filtering method is a good candidate for qualifying fNIRS signals in real time without auxiliary sensors

  11. [Near infrared spectroscopy of wood sections and rapid density prediction].

    PubMed

    Jiang, Ze-hui; Huang, An-min; Wang, Bin

    2006-06-01

    In the present report, the use of calibrated near infrared (NIR) spectroscopy for rapid prediction of solid wood density is described. NIR spectra were obtained from the three sections (cross, radial and tangential section) of each Chinese fir sample. The authors found that the spectra of the three sections are different and the correlation coefficients between the laboratory-determined density and the NIR-fitted data are different, too. The prediction results showed that the model based on NIR spectra taken from the cross section is the best, and the correlation coefficients are 0.94 (cross), 0.85 (radial) and 0.81 (tangential), respectively. Using the cross model to predict the density of unknown wood samples, we can see: r2 is 0.977 and the standard deviation (STDEV) is only 0.006.

  12. Development of Noninvasive Blood Glucose Sensor Using the Infrared Spectroscopy

    NASA Astrophysics Data System (ADS)

    Fujita, Keiichi; Tamura, Kazuto; Kaneko, Wataru; Ishizawa, Hiroaki; Toba, Eiji

    Recently, diabetics have been steadily increasing, because change of diet, lack of exercise, increase an alcoholic intake, and increase a stress. It is a very serious problem for us. About 23.6 millions of people in Japan approach the danger of diabetes. Therefore, it is necessary to get insulin injection. And they have to measure blood glucose again and again a day. So, they are burden too heavy. This paper describes a new noninvasive measurement of blood glucose based on optical sensing. This uses Fourier transform infrared spectroscopy of attenuated total reflection. Non-invasive measurement was carried out by using 3 methods. And standard error of prediction is about ±20mg/dl by 3 method. This paper also describes practical application of this method.

  13. Discrimination and content analysis of fritillaria using near infrared spectroscopy.

    PubMed

    Meng, Yu; Wang, Shisheng; Cai, Rui; Jiang, Bohai; Zhao, Weijie

    2015-01-01

    Fritillaria is a traditional Chinese herbal medicine which can be used to moisten the lungs. The objective of this study is to develop simple, accurate, and solvent-free methods to discriminate and quantify Fritillaria herbs from seven different origins. Near infrared spectroscopy (NIRS) methods are established for the rapid discrimination of seven different Fritillaria samples and quantitative analysis of their total alkaloids. The scaling to first range method and the partial least square (PLS) method are used for the establishment of qualitative and quantitative analysis models. As a result of evaluation for the qualitative NIR model, the selectivity values between groups are always above 2, and the mistaken judgment rate of fifteen samples in prediction sets was zero. This means that the NIR model can be used to distinguish different species of Fritillaria herbs. The established quantitative NIR model can accurately predict the content of total alkaloids from Fritillaria samples.

  14. Aquaphotomics: Near Infrared Spectroscopy and Water States in Biological Systems.

    PubMed

    Tsenkova, Roumiana; Kovacs, Zoltan; Kubota, Yosuke

    2015-01-01

    Aquaphotomics is a new discipline that provides a framework for understanding changes in water molecular system presented as a water spectral pattern, to mirror the rest of the solution and to give a holistic description related to system functionality. One of its main purposes is to identify water bands as main coordinates of future absorbance patterns to be used as a system biomarker. This chapter presents the Aquaphotomics methodology and illustrates a way to identify specific water bands using temperature change and addition of solutions of different ionic strength as perturbations. Rapid and precise measurement of low concentration solutes has been given as a strong evidence of the vast information that "the water spectral pattern as molecular mirror" approach provides. Few applications using near infrared spectroscopy and multivariate analysis as main tools of Aquaphotomics have been presented.

  15. Demonstration of a Fast, Precise Propane Measurement Using Infrared Spectroscopy

    NASA Astrophysics Data System (ADS)

    Zahniser, M. S.; Roscioli, J. R.; Nelson, D. D.; Herndon, S. C.

    2016-12-01

    Propane is one of the primary components of emissions from natural gas extraction and processing activities. In addition to being an air pollutant, its ratio to other hydrocarbons such as methane and ethane can serve as a "fingerprint" of a particular facility or process, aiding in identifying emission sources. Quantifying propane has typically required laboratory analysis of flask samples, resulting in low temporal resolution and making plume-based measurements infeasible. Here we demonstrate fast (1-second), high precision (<300 ppt) measurements of propane using high resolution mid-infrared spectroscopy at 2967 wavenumbers. In addition, we explore the impact of nearby water and ethane absorption lines on the accuracy and precision of the propane measurement. Finally, we discuss development of a dual-laser instrument capable of simultaneous measurements of methane, ethane, and propane (the C1-C3 compounds), all within a small spatial package that can be easily deployed aboard a mobile platform.

  16. Identification of Amanita mushrooms by fourier transform infrared spectroscopy

    NASA Astrophysics Data System (ADS)

    Zhao, Dezhang; Liu, Gang; Song, Dingshan; Liu, Jian-hong; Zhou, Yilan; Ou, Jiaming; Sun, Shizhong

    2006-09-01

    Amanita is one of cosmopolitan genera of basidiomycetes. This genus contains some of the most poisonous toadstools, as well as several species of the most favorite edible mushrooms. In this paper, Fourier transform infrared spectroscopy was used for obtaining vibrational spectra of the fruiting bodies of wild growing Amanita mushrooms. The results show that the mushrooms exhibit characteristic spectra, whose strong absorption bands appear at about 1655, 1076, and 1040 cm -1. The vibrational spectra indicate that the main compositions of the Amanita mushrooms are proteins and polysaccharides. The observed spectral differences might be used to discriminate different species of Amanita. It is showed that FTIR spectroscopic method is a valuable tool for rapid and nondestructive identification of Amanita mushrooms.

  17. Mid-Infrared Spectroscopy of Persistent Leonid Trains

    NASA Technical Reports Server (NTRS)

    Russell, Ray W.; Rossano, George S.; Chatelain, Mark A.; Lynch, David K.; Tessensohn, Ted K.; Abendroth, Eric; Kim, Daryl; Jenniskens, Peter; DeVincenzi, Donald L. (Technical Monitor)

    2000-01-01

    The first infrared spectroscopy in the 3-13 micron region has been obtained of several persistent Leonid meteor trains with two different instrument types, one at a desert ground-based site and the other on-board a high-flying aircraft. The spectra exhibit common structures assigned to enhanced emissions of warm CH4, CO2, CO and H2O which may originate from heated trace air compounds or materials created in the wake of the meteor. This is the first time that any of these molecules has been observed in the spectra of persistent trains. Hence, the mid-IR observations offer a new perspective on the physical processes that occur in the path of the meteor at some time after the meteor itself has passed by. Continuum emission is observed also, but its origin has not yet been established. No 10 micron dust emission feature has been observed.

  18. Chemical analysis of surgical smoke by infrared laser spectroscopy

    NASA Astrophysics Data System (ADS)

    Gianella, Michele; Sigrist, Markus W.

    2012-11-01

    The chemical composition of surgical smoke, a gaseous by-product of some surgical devices—lasers, drills, vessel sealing devices—is of great interest due to the many toxic components that have been found to date. For the first time, surgical smoke samples collected during routine keyhole surgery were analyzed with infrared laser spectroscopy. Traces (ppm range) of methane, ethane, ethylene, carbon monoxide and sevoflurane were detected in the samples which consisted mostly of carbon dioxide and water vapor. Except for the anaesthetic sevoflurane, none of the compounds were present at dangerous concentrations. Negative effects on the health of operation room personnel can be excluded for many toxic compounds found in earlier studies, since their concentrations are below recommended exposure limits.

  19. A rheumatoid arthritis study by Fourier transform infrared spectroscopy

    NASA Astrophysics Data System (ADS)

    Carvalho, Carolina S.; Silva, Ana Carla A.; Santos, Tatiano J. P. S.; Martin, Airton A.; dos Santos Fernandes, Ana Célia; Andrade, Luís E.; Raniero, Leandro

    2012-01-01

    Rheumatoid arthritis is a systemic inflammatory disease of unknown causes and a new methods to identify it in early stages are needed. The main purpose of this work is the biochemical differentiation of sera between normal and RA patients, through the establishment of a statistical method that can be appropriately used for serological analysis. The human sera from 39 healthy donors and 39 rheumatics donors were collected and analyzed by Fourier Transform Infrared Spectroscopy. The results show significant spectral variations with p<0.05 in regions corresponding to protein, lipids and immunoglobulins. The technique of latex particles, coated with human IgG and monoclonal anti-CRP by indirect agglutination known as FR and CRP, was performed to confirm possible false-negative results within the groups, facilitating the statistical interpretation and validation of the technique.

  20. Analysis of silage composition by near-infrared reflectance spectroscopy

    NASA Astrophysics Data System (ADS)

    Reeves, James B., III; Blosser, Timothy H.; Colenbrander, V. F.

    1991-02-01

    Two studies were performed to investigate the feasibility of using near infrared reflectance spectroscopy (NIRS) with undried silages. In the first study silages were analyzed for major components (e. g. dry matter crude protein and other forms of nitrogen fiber and in vitro digestible dry matter) and short chain fatty acids (SCFA). NIRS was found to operate satisfactorily except for some forms of nitrogen and SCFA. In study two various methods of grinding spectral regions and sample presentation were examined. Undried Wiley ground samples in a rectangular cell gave the best overall results for non-dry ice undried grinds with wavelengths between 1100 and 2498 nm. Silages scanned after drying however produced the best results. Intact samples did not perform as well as ground samples and wavelengths below 1100 nm were of little use. 2 .

  1. Recent advances in fetal near-infrared spectroscopy

    NASA Astrophysics Data System (ADS)

    D'Antona, Donato; Aldrich, Clive J.; O'Brien, Patrick; Lawrence, Sally; Delpy, David T.; Wyatt, John S.

    1997-01-01

    Fetal brain injury resulting from hypoxia and ischemia during labor remains an important cause of death and long- term disability. However, little is known about fetal brain oxygenation and hemodynamics. There are currently no satisfactory clinical techniques for fetal monitoring and there remains a need for a new method to assess brain oxygenation. Fetal near infrared spectroscopy (NIRS) is a new technique that allows noninvasive observation of changes in the cerebral concentrations of oxyhemoglobin and deoxyhemoglobin to be made during labor. A specially designed optical probe is inserted through the dilated cervix and placed against the fetal head. It is then possible to compare changes in NIRS data with other observations of fetal conditions, such as fetal heart rate and acid-base status.

  2. Review of functional near-infrared spectroscopy in neurorehabilitation

    PubMed Central

    Mihara, Masahito; Miyai, Ichiro

    2016-01-01

    Abstract. We provide a brief overview of the research and clinical applications of near-infrared spectroscopy (NIRS) in the neurorehabilitation field. NIRS has several potential advantages and shortcomings as a neuroimaging tool and is suitable for research application in the rehabilitation field. As one of the main applications of NIRS, we discuss its application as a monitoring tool, including investigating the neural mechanism of functional recovery after brain damage and investigating the neural mechanisms for controlling bipedal locomotion and postural balance in humans. In addition to being a monitoring tool, advances in signal processing techniques allow us to use NIRS as a therapeutic tool in this field. With a brief summary of recent studies investigating the clinical application of NIRS using motor imagery task, we discuss the possible clinical usage of NIRS in brain–computer interface and neurofeedback. PMID:27429995

  3. Gas emission analysis based on Fourier transformed infrared spectroscopy

    NASA Astrophysics Data System (ADS)

    Shu, Xiaowen; Zhang, Xiaofu; Lian, Xu; Jin, Hui

    2014-12-01

    Solar occultation flux (SOF), a new optical technology to detect the gas based on the traditional Fourier transformed infrared spectroscopy (FTIR) developed quickly recently. In this paper, the system and the data analysis is investigated. First a multilayer transmission model of solar radiation is simulated. Then the retrieval process is illustrated. In the proceeding of the data analysis, the Levenberg-Marquardt non-linear square fitting is used to obtain the gas column concentration and the related emission ratio. After the theory certification, the built up system is conducted in a fertilizer plant in Hefei city .The results show SOF is available in the practice and the retrieved gas column concentration can give important information about the pollution emission and dispersion

  4. Cardiac tissue characterization using near-infrared spectroscopy

    NASA Astrophysics Data System (ADS)

    Singh Moon, Rajinder; Hendon, Christine P.

    2014-03-01

    Cardiac tissue from swine and canine hearts were assessed using diffuse reflectance near-infrared spectroscopy (NIRS) ex vivo. Slope measured between 800-880 nm reflectance was found to reveal differences between epicardial fat and normal myocardium tissue. This parameter was observed to increase monotonically from measurements obtained from the onset of radiofrequency ablation (RFA). A sheathe-style fiber optic catheter was then developed to allow real-time sampling of the zone of resistive heating during RFA treatment. A model was developed and used to extract changes in tissue absorption and reduced scattering based on the steady-state diffusion approximation. It was found that key changes in tissue optical properties occur during application of RF energy and can be monitored using NIRS. These results encourage the development of NIRS integrated catheters for real-time guidance of the cardiac ablation treatment.

  5. Infrared Spectroscopy of Disilicon-Carbide Si_2C

    NASA Astrophysics Data System (ADS)

    Witsch, Daniel; Lutter, Volker; Fuchs, Guido W.; Gauss, Jürgen; Giesen, Thomas

    2017-06-01

    Small silicon and carbon containing molecules are thought to be important building blocks of interstellar grains. Some of them have been detected in circumstellar environments of late-type stars by means of rotational spectroscopy e.g., SiC, SiC_2, Si_2C, c-SiC_3, SiC_4, while centro-symmetric species, e.g., C_3, C_4, C_5, Si_2C_2, Si_2C_3, can only be detected by vibrational transitions, mainly in the infrared. In view of a new generation of high resolution infrared telescope instruments, e.g., EXES (Echelon-Cross-Echelle Spectrograph) onboard SOFIA (Observatory for Infrared Astronomy) and TEXES (Texas Echelon Cross Echelle Spectrograph) at the Gemini-North observatory, accurate laboratory data of small silicon-carbides in the infrared region are of high demand. In this talk we present first laboratory data of the Si_2C asymmetric stretching mode at 1200 cm^{-1}. A pulsed Nd:YAG-laser is used to vaporize a solid target of silicon exposed to a dilute sample of methane in helium buffer gas. Si_2C is formed in an adiabatic expansion of a supersonic jet and radiation of a quantum cascade laser is used to record rotationally resolved spectra. To date, 160 ro-vibrational lines and have been assigned to the asymmetric stretching vibration of Si_2C, and derived molecular parameters are in excellent agreement with ab initio calculations. In our global fit analysis recently published microwave laboratory data (McCarthy et al. 2015) and astronomical data (Cernicharo et al. 2015) were taken into account. Our new results allow for the identification of Si_2C by means of high resolution infrared astronomy towards the warm background of carbon-rich stars. McCarthy M.C., Baraban J.H., Changala P.B., Stanton J.F., Martin-Drumel M.A, Thorwirth S., et al., J. Chem. Phys. Lett. 6, 2107-2111 (2015). Cernicharo J., McCarthy M.C., Gottlieb C.A., Agundez M., Velilla Prieto L., Baraban J.H., et al. Astrophys. J. Lett. 806,L3 (2015).

  6. Infrared spectroscopy and microscopy in cancer research and diagnosis

    PubMed Central

    Bellisola, Giuseppe; Sorio, Claudio

    2012-01-01

    Since the middle of 20th century infrared (IR) spectroscopy coupled to microscopy (IR microspectroscopy) has been recognized as a non destructive, label free, highly sensitive and specific analytical method with many potential useful applications in different fields of biomedical research and in particular cancer research and diagnosis. Although many technological improvements have been made to facilitate biomedical applications of this powerful analytical technique, it has not yet properly come into the scientific background of many potential end users. Therefore, to achieve those fundamental objectives an interdisciplinary approach is needed with basic scientists, spectroscopists, biologists and clinicians who must effectively communicate and understand each other's requirements and challenges. In this review we aim at illustrating some principles of Fourier transform (FT) Infrared (IR) vibrational spectroscopy and microscopy (microFT-IR) as a useful method to interrogate molecules in specimen by mid-IR radiation. Penetrating into basics of molecular vibrations might help us to understand whether, when and how complementary information obtained by microFT-IR could become useful in our research and/or diagnostic activities. MicroFT-IR techniques allowing to acquire information about the molecular composition and structure of a sample within a micrometric scale in a matter of seconds will be illustrated as well as some limitations will be discussed. How biochemical, structural, and dynamical information about the systems can be obtained by bench top microFT-IR instrumentation will be also presented together with some methods to treat and interpret IR spectral data and applicative examples. The mid-IR absorbance spectrum is one of the most information-rich and concise way to represent the whole “… omics” of a cell and, as such, fits all the characteristics for the development of a clinically useful biomarker. PMID:22206042

  7. Trace water vapor determination in corrosive gases by infrared spectroscopy

    SciTech Connect

    Stallard, B.R.; Rowe, R.K.; Garcia, M.J.; Haaland, D.M.; Espinoza, L.H.; Niemczyk, T.M.

    1993-12-01

    To extend the life of gas delivery systems and improve wafer yields, there is a need for an in-line monitor of H{sub 2}O contamination. Goal of this project is to develop such an instrument, based on infrared spectroscopy, that has a detection limit of 30 ppB or better and costs $50K or less. This year`s work considered the application of Fourier transform infrared (FTIR) spectroscopy to H{sub 2}O detection in N{sub 2} and HCl. Using a modified commercial FTIR spectrometer and a long-path gas cell, a detection limit of about 10 ppB was demonstrated for H{sub 2}O in N{sub 2} and HCl. This includes about a factor of three improvement achieved by applying quantitative multivariate calibration methods to the problem. Absolute calibration of the instrument was established from absorptivities of prominent H{sub 2}O bands between 3600 and 3910 cm{sup {minus}1}. Methods are described to minimize background moisture in the beam path. Spectral region, detector type, resolution, cell type, and path length were optimized. Resolving the narrow H{sub 2}O bands (FWHM {approx} 0.20 cm{sup {minus}1}) is not necessary to achieve optimal sensitivity. In fact, optimal sensitivity is achieved at 2 to 4 cm{sup {minus}1} resolution, allowing the use of an inexpensive interferometer. A much smaller, second generation instrument is described that will have a conservatively estimated detection limit of 1 ppB. Since the present laboratory instrument can be duplicated in its essential parts for about $90K, it is realistic to project a cost of $50K for the new instrument. An accessory for existing FTIR spectrometers was designed that may be marketed for as little as $10K.

  8. Europa Composition Using Visible to Short Wavelength Infrared Spectroscopy

    NASA Astrophysics Data System (ADS)

    Blaney, Diana L.; Dalton, J. B.; Green, R. O.; Hibbits, K.; McCord, T.; Murchie, S.; Piccioni, G.; Tosi, F.

    2010-10-01

    One of the major goals of the Jupiter Europa Orbiter (JEO) is to understand the chemistry of Europa's inorganic and organic materials. Europa's surface material composition is controlled by the original materials forming Europa and by their differentiation and chemical alterations. Material is probably still being transported to the surface by active processes in the interior. At the surface, the material is exposed to the effects of vacuum and temperature, irradiated by solar UV, and bombarded by material entrained in Jupiter's magnetic field. The materials on the surface and their distributions are evidence of the processes operating, both endogenic and exogenic. These processes include effects of a subsurface liquid ocean and its chemistry; the mechanisms of material emplacement from below; and photolysis and radiolysis. Visible to Short Wavelength Infrared (VSWIR) spectroscopy is a well-understood technique for mapping key inorganic, organic, and volatile compositions on remote surfaces such as Europa. Key spectral absorption features have been detected in both the icy and the non-icy Europa materials and many important constituents of the surface have been identified or proposed (e.g. hydrated salts, sulfuric acid hydrate, organics, CO2, H2O2, SO2). The determination of planetary surface composition from remote infrared spectroscopy depends upon adequate signal-to-noise, spectral resolution, and spatial scale to distinguish the diagnostic spectral features of the compounds of interest. For icy satellites, laboratory reference spectra obtained at the temperatures of the target bodies are also required. We have compared diagnostic spectral features in cryogenic laboratory spectra of hydrated salts relevant to Europa in order to optimize detection of these materials under realistic mission conditions. Effects of spectral resolution, signal to noise ratio, and areal mixtures are explored to determine the impacts on detection. This work was carried out at the Jet

  9. Kinetics and Near-Infrared Spectroscopy of Organic Peroxy Radicals

    NASA Astrophysics Data System (ADS)

    Smarte, M. D.; Okumura, M.

    2016-12-01

    Organic peroxy radicals are important intermediates in atmospheric chemistry with fates that control the rate of radical propagation in an oxidation mechanism. Laboratory methods for detecting peroxy radicals are essential to measuring precise rate constants that constrain these fates. In this work, we discuss the use of near-infrared cavity ringdown spectroscopy to detect organic peroxy radicals for the purpose of laboratory kinetics measurements. We focus on chlorine-substituted peroxy radicals generated in the oxidation of alkenes by chlorine, a minor tropospheric oxidant found in marine and coastal regions. Previous kinetics experiments on peroxy radicals have largely used UV absorption spectroscopy via the dissociative B-X transition. However, the spectra produced are featureless and exhibit substantial overlap; determining the concentration profile of an individual peroxy radical can be an arduous task. In our work, we probe the forbidden peroxy radical A-X transition in the near-infrared. While this approach requires overcoming small cross sections ( 10-21 cm2), the A state is bound and leads to structured absorption spectra that may be useful in constraining the kinetics of mixtures of organic peroxy radicals formed in the oxidation of complex hydrocarbons. Only a few kinetics studies utilizing the A-X transition exist in the literature and they are focused on small, unsubstituted species. This presentation explores the ability of the A-X transition to unravel the kinetics of more complex peroxy radicals in laboratory experiments using several example systems: (1) Determining rate constants for the self and cross reactions of β-chloroethylperoxy and HO2. (2) Detecting the second generation of peroxy radicals formed from alkoxy radical decomposition in the chlorine-initiated oxidation of 2-butene. (3) Observing different rates of reactivity with NO across the pool of peroxy radical isomers formed in the chlorine-initiated oxidation of isoprene.

  10. Fourier transform infrared spectroscopy and Raman spectroscopy as tools for identification of steryl ferulates.

    PubMed

    Mandak, Eszter; Zhu, Dan; Godany, Tamas A; Nyström, Laura

    2013-03-13

    Steryl ferulates are a mixture of minor bioactive compounds, possessing well-established health benefits. However, individual steryl ferulate species show structural differences, which seem to substantially influence their health-promoting potential. In this study, we tested Fourier transform infrared (FTIR) spectroscopy and Raman spectroscopy, as potential tools in the identification of steryl ferulates. On the basis of our spectral data obtained from various individual steryl ferulates and steryl ferulate mixtures extracted from rice (γ-oryzanol), corn bran, and wheat bran, we provide comprehensive peak assignment tables for both FTIR and Raman. With the help of FTIR spectroscopy, structural differences between individual steryl ferulates were possible to identify, such as the presence of the cyclopropane ring and additional differences in the side chain of the sterane skeleton. Data obtained with Raman spectroscopy provided us with a control for FTIR peak assignment and also with some additional information on the samples. However, detecting structural differences between steryl ferulates was not possible with this method. We consider that FTIR spectroscopy alone or combined with Raman provides detailed data on the structures of steryl ferulates. Moreover, thorough peak assignment tables presented in this study could prove to be helpful tools when identifying steryl ferulates, especially as a group, in future studies.

  11. Infrared Spectroscopy of Hydrogen in Fullerite and MOF-5 Hosts

    NASA Astrophysics Data System (ADS)

    Fitzgerald, Stephen; Churchill, Hugh; Korngut, Phil; Simmons, Christie; Strangas, Yorgos

    2006-03-01

    We present a novel use of diffuse reflectance infrared spectroscopy to study the quantum dynamics of hydrogen molecules trapped within a host material. This technique is particularly useful for the study of hydrogen storage materials since it provides detailed information about the intermolecular potential at the binding site. Because H2 has no intrinsic infrared activity any observed features arise solely through interaction with the host material and as such are very sensitive to the symmetry of the binding site. The drawback is that the induced spectra are quite weak. However, a technique based on diffuse reflectance has been shown to produce a sufficiently large signal [1]. We have now constructed a cryogenic system that allows spectra to be obtained in this manner at pressures as high as 100 atm. and at temperatures as low as 10 K. Data will be presented for H2 in both C60 and MOF-5 showing a series of absorption features arising from the quantized vibrational, rotational, and translational motion of the trapped H2. At the lowest temperature these peaks become quite sharp, FWHM less than 1 cm-1, with a detailed fine structure arising from the H2 host interactions. 1. S. A. FitzGerald et al., Phys. Rev. B 65, 140302. (2002)

  12. Cooled Multi-pass Cells for Visible and Infrared Spectroscopy

    NASA Astrophysics Data System (ADS)

    Mickelson, M. E.; Steyert, D. W.; Sirota, J. M.; Reuter, D. C.

    2001-11-01

    Modeling of Planetary Atmospheres depends in a crucial way on the availability of high quality laboratory data for the molecular constituents assumed for the atmosphere in question. This paper describes two new cooled multi-pass cells which are based on a design originally articulated by Chernin and Baraskala1 and which are specifically suited for long path length spectroscopy of gaseous samples. This type of cell was first implemented at Denison University2 for use in the visible and near infrared in conjunction with tunable dye and diode lasers. The second, at GSFC, is designed for use in the mid to far infrared for use with tunable lead-salt diode lasers. The Denison 3 meter cell is equipped with two sets of first surface Pyrex mirrors using enhanced silver and dielectric coatings. The GSFC 2 meter cell uses gold-coated aluminum mirrors. Details of the mechanical and thermal design and operating specifications such as temperature and pressure ranges will be given along with examples of typical spectra obtained for water vapor and methane. 1 S. M. Chernin and E. G. Barskaya, Appl. Opt. 30, 51 (1991). 2 M. E. Mickelson, L.E. Larson and A. Schubert, J. Geophys. Res. 96, E2 17.507 (1991). Work at Denison University was performed under NASA Planetary Atmospheres Program grant NAG5-4341. Work at Goddard Space Flight Center was supported by NASA Planetary Atmospheres Program RTOP 344-33-80.

  13. Influence of earlobe thickness on near infrared spectroscopy

    NASA Astrophysics Data System (ADS)

    Jiang, Jingying; Wang, Tianpei; Li, Si; Li, Lin; Liu, Jiajia; Xu, Kexin

    2017-03-01

    Near-infrared spectroscopy has been recognized as a potential technology for noninvasive blood glucose sensing. However, the detected spectral signal is unstable mainly because of (1) the weak light absorption of glucose itself within NIR range, (2) the influence of temperature and individual differences of biotissue. Our previous results demonstrated that the synergistic effect of both transmittance and reflectance could enhance the strength of the detection signal. In this talk, we design a set of experiments to analyze the effect of earlobe thickness on Near Infrared spectroscopic measurement by using home-made optical fiber probe within the wavelength of 1000-1600nm. Firstly, we made a MC simulation of single-layer skin model and five-layer skin model to get the diffused transmittance spectra and diffused reflectance spectra under different optaical path lengths. And then we obtain the spectra of the earlobes from different volunteers by the same way. The experimental results showed that with the increase of the thickness,the light intensity of diffused transmittance decreases, and the light intensity of diffused reflectance remaines substantially unchanged.

  14. Wavelet minimum description length detrending for near-infrared spectroscopy

    NASA Astrophysics Data System (ADS)

    Jang, Kwang Eun; Tak, Sungho; Jung, Jinwook; Jang, Jaeduck; Jeong, Yong; Ye, Jong Chul

    2009-05-01

    Near-infrared spectroscopy (NIRS) can be employed to investigate brain activities associated with regional changes of the oxy- and deoxyhemoglobin concentration by measuring the absorption of near-infrared light through the intact skull. NIRS is regarded as a promising neuroimaging modality thanks to its excellent temporal resolution and flexibility for routine monitoring. Recently, the general linear model (GLM), which is a standard method for functional MRI (fMRI) analysis, has been employed for quantitative analysis of NIRS data. However, the GLM often fails in NIRS when there exists an unknown global trend due to breathing, cardiac, vasomotion, or other experimental errors. We propose a wavelet minimum description length (Wavelet-MDL) detrending algorithm to overcome this problem. Specifically, the wavelet transform is applied to decompose NIRS measurements into global trends, hemodynamic signals, and uncorrelated noise components at distinct scales. The minimum description length (MDL) principle plays an important role in preventing over- or underfitting and facilitates optimal model order selection for the global trend estimate. Experimental results demonstrate that the new detrending algorithm outperforms the conventional approaches.

  15. Localized photothermal infrared spectroscopy using a proximal probe

    NASA Astrophysics Data System (ADS)

    Bozec, L.; Hammiche, A.; Pollock, H. M.; Conroy, M.; Chalmers, J. M.; Everall, N. J.; Turin, L.

    2001-11-01

    A near-field thermal probe, as used in scanning thermal microscopy, is used to obtain photothermal Fourier transform infrared (FT-IR) spectra of polymers, as a first step toward developing FT-IR microscopy at a spatial resolution better than the diffraction limit. The signal from the probe after amplification provides an interferogram, and the resultant spectra are consistent with those obtained by means of the established technique of attenuated total reflection FT-IR spectroscopy. We have extended this technique to the analysis of "real-world" industrial samples, both solid (a fungicide in a fine powder form) and liquid (a concentrated surfactant solution). The overall shapes of the main peaks or bands reflect the fact that the spectrum is a convolution of different contributions from both optical and thermal properties. To confirm the feasibility of subsurface detection of polymers, we demonstrate the ability of the technique to perform spectroscopic detection of a model polymeric bilayer system, polyisobutylene on top of polystyrene. A quantitative analysis of the variation of peak height with coating thickness allows values of thermal diffusion length to be derived. This investigation provides a preliminary result for the understanding of the depth sensitivity of the current setup. Relative intensity distortions are seen, and are attributed to photothermal saturation. A complementary technique has been developed that uses tunable monochromatic radiation, using an optical parametric generator as the infrared source. Spectra have successfully been obtained using the same localized photothermal detection principle.

  16. Near-infrared transmittance spectroscopy for radiochemical ageing of EPDM.

    PubMed

    Lachenal, G; Stevenson, I; Celette, N

    2001-12-01

    The feasibility of using near-infrared spectroscopy as a sensitive technique to follow the influence of gamma-irradiation upon ageing of different EPDM (ethylene propylene diene monomer) elastomers has been evaluated. Although identification is difficult, differences can be observed between the non-irradiated and irradiated materials for total integrated doses from 50 to 450 kGy using a dose rate of 1 kGy h(-1) under an oxygen flow. The decrease in intensity of bands at 7040, 4610 and 4910 cm(-1) are linked to the disappearance of additives present in the elastomer such as excess of vulcanising or antioxidant agents and occur for the lowest irradiation dose. This disappearance is confirmed by TGA (thermogravimetric analysis). The increase in band intensities assigned to the formation of hydroxyl and carbonyl groups (5100, 4860 and 4670 cm(-1)) irradiation indicates an increase in oxidation with irradiation in the presence of oxygen. No bands linked to the presence of C=C from the diene have been detected, probably owing to the low concentration in the material and the weak intensity in near-infrared region. For strong irradiation doses (450 kGy), the three formulations studied show no difference in their NIR spectra, which is confirmed by the TGA of these irradiated materials. PCA performed at 5000-4600 cm(-1) or 7090-6980 cm(-1) shows efficient discrimination.

  17. Aerosol collection and analysis using diffuse reflectance infrared spectroscopy

    NASA Astrophysics Data System (ADS)

    Samuels, Alan C.; Wong, Diane M.; Meyer, Gerald J.; Roelant, Geoffrey J.; Williams, Barry R.; Miles, Ronald W., Jr.; Manning, Christopher J.

    2004-08-01

    Infrared spectroscopy is routinely employed for the identification of organic molecules and, more recently, for the classification of biological materials. We have developed a sample collection method that facilitates infrared analysis of airborne particulates using a diffuse reflectance (DR) technique. Efforts are underway to extend the method to include simultaneous analysis of vapor phase organics by using adsorbent substrates compatible with the DR technique. This series of laboratory results provides proof-of-principle for both the sample collection and data collection processes. Signal processing of the DR spectra is shown to provide rapid qualitative identification of representative aerosol materials, including particulate matter commonly found in the environment. We compare the results for such materials as bacterial spores, pollens and molds, clays and dusts, smoke and soot. Background correction analysis is shown to be useful for differentiation and identification of these constituents. Issues relating to complex mixtures of environmental samples under highly variable conditions are considered. Instrumentation development and materials research are now underway with the aim of constructing a compact sampling system for near real-time monitoring of aerosol and organic pollutants. A miniature, tilt-compensated Fourier transform spectrometer will provide spectroscopic interrogation. A series of advanced digital signal processing methods are also under development to enhance the sensor package. The approach will be useful for industrial applications, chemical and biological agent detection, and environmental monitoring for chemical vapors, hazardous air pollutants, and allergens.

  18. Structure analysis of aromatic medicines containing nitrogen using near-infrared spectroscopy and generalized two-dimensional correlation spectroscopy

    NASA Astrophysics Data System (ADS)

    Liu, Hao; Gao, Hongbin; Qu, Lingbo; Huang, Yanping; Xiang, Bingren

    2008-12-01

    Four aromatic medicines (acetaminophen; niacinamide; p-aminophenol; nicotinic acid) containing nitrogen were investigated by FT-NIR (Fourier transform near-infrared) spectroscopy and generalized two-dimensional (2D) correlation spectroscopy. The FT-NIR spectra were measured over a temperature range of 30-130 °C. By combining near-infrared spectroscopy, generalized 2D correlation spectroscopy and references, the molecular structures (especially the hydrogen bond related with nitrogen) were analyzed and the NIR band assignments were performed. The results will be helpful to the understanding of aromatic medicines containing nitrogen and the utility of these substances.

  19. Infrared Spectroscopy of Star Formation in Galactic and Extragalactic Regions

    NASA Technical Reports Server (NTRS)

    Smith, Howard A.; Hasan, Hashima (Technical Monitor)

    2003-01-01

    In this program we proposed to perform a series of spectroscopic studies, including data analysis and modeling, of star formation regions using an ensemble of archival space-based data from the Infrared Space Observatory's Long Wavelength Spectrometer and Short Wavelength Spectrometer, and to take advantage of other spectroscopic databases including the first results from SIRTF. Our emphasis has been on star formation in external, bright IR galaxies, but other areas of research have included young, low or high mass pre-main sequence stars in star formation regions, and the galactic center. The OH lines in the far infrared were proposed as one key focus of this inquiry, because the Principal Investigator (H. Smith) had a full set of OH IR lines from IS0 observations. It was planned that during the proposed 2-1/2 year timeframe of the proposal other data (including perhaps from SIRTF) would become available, and we intended to be responsive to these and other such spectroscopic data sets. The program has the following goals: 1) Refine the data analysis of IS0 observations to obtain deeper and better SNR results on selected sources. The IS0 data itself underwent pipeline 10 reductions in early 2001, and the more 'hands-on data reduction packages' have been released. The IS0 Fabry-Perot database is particularly sensitive to noise and can have slight calibration errors, and improvements are anticipated. We plan to build on these deep analysis tools and contribute to their development. Model the atomic and molecular line shapes, in particular the OH lines, using revised montecarlo techniques developed by the Submillimeter Wave Astronomy Satellite (SWAS) team at the Center for Astrophysics. 2) 3) Use newly acquired space-based SIRTF or SOFIA spectroscopic data as they become available, and contribute to these observing programs as appropriate. 4) Attend scientific meetings and workshops. 5) E&PO activities, especially as related to infrared astrophysics and

  20. Infrared spectroscopy of ionized corannulene in the gas phase

    NASA Astrophysics Data System (ADS)

    Galué, Héctor Alvaro; Rice, Corey A.; Steill, Jeffrey D.; Oomens, Jos

    2011-02-01

    The gas-phase infrared spectra of radical cationic and protonated corannulene were recorded by infrared multiple-photon dissociation (IRMPD) spectroscopy using the IR free electron laser for infrared experiments. Electrospray ionization was used to generate protonated corannulene and an IRMPD spectrum was recorded in a Fourier-transform ion cyclotron resonance mass spectrometer monitoring H-loss as a function of IR frequency. The radical cation was produced by 193-nm UV photoionization of the vapor of corannulene in a 3D quadrupole trap and IR irradiation produces H, H2, and C2Hx losses. Summing the spectral response of the three fragmentation channels yields the IRMPD spectrum of the radical cation. The spectra were analyzed with the aid of quantum-chemical calculations carried out at various levels of theory. The good agreement of theoretical and experimental spectra for protonated corannulene indicates that protonation occurs on one of the peripheral C-atoms, forming an sp3 hybridized carbon. The spectrum of the radical cation was examined taking into account distortions of the C5v geometry induced by the Jahn-Teller effect as a consequence of the degenerate 2E1 ground electronic state. As indicated by the calculations, the five equivalent Cs minima are separated by marginal barriers, giving rise to a dynamically distorted system. Although in general the character of the various computed vibrational bands appears to be in order, only a qualitative match to the experimental spectrum is found. Along with a general redshift of the calculated frequencies, the IR intensities of modes in the 1000-1250 cm-1 region show the largest discrepancy with the harmonic predictions. In addition to CH "in-plane" bending vibrations, these modes also exhibit substantial deformation of the pentagonal inner ring, which may relate directly to the vibronic interaction in the radical cation.

  1. Infrared Predissociation Spectroscopy of H_2-TAGGED Dicarboxylic Acid Anions

    NASA Astrophysics Data System (ADS)

    Wolk, Arron B.; Kamrath, Michael Z.; Leavitt, Christopher M.; Johnson, Mark A.

    2011-06-01

    Singly charged dicarboxylic acid anions, studied in depth by Wang et al. offer insight into the role of ring strain and conformation on the formation of intramolecular hydrogen bonds. These shared proton bonds, common in proteins and polymer systems, can be crucial in secondary and tertiary structure formation. By tracking the infrared spectra of dicarboxylic acid anions as charge and aliphatic chain length are varied, the tendency of these anions to form ring-like structures with an internally shared proton can be asssesed. To adapt the time-of-flight mass spectrometry/infrared presdissociation experiment to larger systems with significant latent vibrational energy and negligible vapor pressure, an electrospray ionization (ESI)/cryogenic quadrupole trap ion source has been interfaced to the Yale time of flight mass spectrometer. Infrared predissociation spectroscopy is carried out on a series of carboxylate anions cooled to 10K and H_2-tagged in a cryogenic ion trap, underscoring the power of this technique to vibrationally quench and structurally characterize large (> 20 atoms) gaseous ions. This technique recovers sharp transitions (~6 cm^-^1 FWHM) in the linear single photon absorption regime which greatly facilitates comparison with ab initio calculations. The methodology used to condense H_2 on these ions is described, revealing the benefits of a pulsed trapping gas paired with a time delay before ion extraction. The sensitivity of the perturbed H_2 transition to charge center exposure is probed by varying the charge and aliphatic chain length of carboxylate anions. Finally, the structure of four carboxylate anions are characterized using their predissociation spectra. H. K. Woo, X. B. Wang, K. C. Lau and L. S. Wang J. Chem. Phys. A 110, 7801-7805 2006.

  2. Infrared spectroscopy analysis of mixed DPPC/fibrinogen layer behavior at the air/liquid interface under a continuous compression-expansion condition.

    PubMed

    Yin, Chia-Lin; Chang, Chien-Hsiang

    2006-07-18

    The mixed layer behavior of dipalmitoyl phosphatidylcholine (DPPC) with fibrinogen at continuously compressed-expanded air/liquid interfaces was analyzed in situ by infrared reflection-absorption spectroscopy (IRRAS). The reflectance-absorbance (RA) intensities and/or wavenumbers of nu(a)-CH2 and amide I bands for a mixed DPPC/fibrinogen layer at the interface were obtained directly by an infrared spectrometer with a monolayer/grazing angle accessory and a removable Langmuir trough. The nu(a)-CH2 RA intensity-area hysteresis curves of a DPPC monolayer indicate a significant loss of free DPPC molecules at the interface during the first compression stage, which is also supported by the corresponding nu(a)-CH2 wavenumber-area hysteresis curves. For a mixed DPPC/fibrinogen layer at the interface, the amide I RA intensity-area hysteresis curves suggest that the fibrinogen molecules were expelled from the interface upon compression, apparently because of the presence of insoluble DPPC molecules. The squeeze-out of fibrinogen evidently removed a pronounced amount of DPPC from the interface, as judged from the corresponding nu(a)-CH2 intensity and wavenumber data. Moreover, significant adsorption of fibrinogen was found during the subsequent interface expansion stage. With the in situ IRRAS analysis of the mixed layer behavior at the interface, the induced loss of DPPC by fibrinogen expulsion from the compressed interface and the dominant adsorption of fibrinogen to the expanded interface were clearly demonstrated.

  3. 7 CFR 801.7 - Reference methods and tolerances for near-infrared spectroscopy (NIRS) analyzers.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 7 Agriculture 7 2010-01-01 2010-01-01 false Reference methods and tolerances for near-infrared spectroscopy (NIRS) analyzers. 801.7 Section 801.7 Agriculture Regulations of the Department of Agriculture... methods and tolerances for near-infrared spectroscopy (NIRS) analyzers. (a) Reference methods. (1)...

  4. 7 CFR 801.7 - Reference methods and tolerances for near-infrared spectroscopy (NIRS) analyzers.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 7 Agriculture 7 2011-01-01 2011-01-01 false Reference methods and tolerances for near-infrared spectroscopy (NIRS) analyzers. 801.7 Section 801.7 Agriculture Regulations of the Department of Agriculture... methods and tolerances for near-infrared spectroscopy (NIRS) analyzers. (a) Reference methods. (1)...

  5. 7 CFR 801.7 - Reference methods and tolerances for near-infrared spectroscopy (NIRS) analyzers.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 7 Agriculture 7 2014-01-01 2014-01-01 false Reference methods and tolerances for near-infrared spectroscopy (NIRS) analyzers. 801.7 Section 801.7 Agriculture Regulations of the Department of Agriculture... methods and tolerances for near-infrared spectroscopy (NIRS) analyzers. (a) Reference methods. (1)...

  6. Near- and Mid-Infrared Reflectance Spectroscopy for the Quantitative and Qualitative Analysis of Agricultural Products

    USDA-ARS?s Scientific Manuscript database

    For several decades near-infrared diffuse reflectance spectroscopy (NIRS) has been used to determine the composition of a variety of agricultural products. More recently, diffuse reflectance Fourier transform mid-infrared spectroscopy (DRIFTS) has similarly been shown to be able to determine the co...

  7. Reliability of Near-Infrared Spectroscopy for Determining Muscle Oxygen Saturation during Exercise

    ERIC Educational Resources Information Center

    Austin, Krista G.; Daigle, Karen A.; Patterson, Patricia; Cowman, Jason; Chelland, Sara; Haymes, Emily M.

    2005-01-01

    Near-infrared spectroscopy is currently used to assess changes in the oxygen saturation of the muscle during exercise. The primary purpose of this study was to assess the reliability of near-infrared spectroscopy in determining muscle oxygen saturation (StO[subscript 2]) in the vastus lateralis during cycling and the gastrocnemius during running…

  8. Reliability of Near-Infrared Spectroscopy for Determining Muscle Oxygen Saturation during Exercise

    ERIC Educational Resources Information Center

    Austin, Krista G.; Daigle, Karen A.; Patterson, Patricia; Cowman, Jason; Chelland, Sara; Haymes, Emily M.

    2005-01-01

    Near-infrared spectroscopy is currently used to assess changes in the oxygen saturation of the muscle during exercise. The primary purpose of this study was to assess the reliability of near-infrared spectroscopy in determining muscle oxygen saturation (StO[subscript 2]) in the vastus lateralis during cycling and the gastrocnemius during running…

  9. Detecting and Segregating Black Tip-Damaged Wheat Kernels Using Visible and Near Infrared Spectroscopy

    USDA-ARS?s Scientific Manuscript database

    Detection of individual wheat kernels with black tip symptom (BTS) and black tip damage (BTD) was demonstrated using near infrared reflectance spectroscopy (NIRS) and silicon light-emitting-diode (LED) based instruments. The two instruments tested, a single kernel near-infrared spectroscopy instrume...

  10. Near-infrared spectroscopy: a methodology-focused review.

    PubMed

    Pellicer, Adelina; Bravo, María del Carmen

    2011-02-01

    Near infrared spectroscopy (NIRS) is a light-based technology used to monitor tissue oxygen status. Refinements to the method since it was first described have extended its applicability to different research and clinical settings due to its non-invasiveness, instrument portability and ease of use. Classic NIRS recordings, based in the Beer-Lambert law, can be used for the trend monitoring of changes in tissue perfusion-oxygenation parting from an arbitrary zero point. However, in order to derive intermittently quantitative values in absolute terms, certain manoeuvres must be performed. More recently, the evolution of the technique has led to the development of instruments that provide an absolute value of regional hemoglobin saturation in a continuous manner. This review will focus on the physical principles of tissue spectroscopy including a brief description of the different operating principles that are currently in use or under development. The theoretical details, experimental procedures and data analysis involved in the measurements of physiological variables using NIRS will be described. The future beyond the scope of NIRS and potential lines of research will also be discussed.

  11. Hydrogen Tunneling above Room Temperature Evidenced by Infrared Ion Spectroscopy.

    PubMed

    Schäfer, Mathias; Peckelsen, Katrin; Paul, Mathias; Martens, Jonathan; Oomens, Jos; Berden, Giel; Berkessel, Albrecht; Meijer, Anthony J H M

    2017-04-26

    While hydrogen tunneling at elevated temperatures has, for instance, often been postulated in biochemical processes, spectroscopic proof is thus far limited to cryogenic conditions, under which thermal reactivity is negligible. We report spectroscopic evidence for H-tunneling in the gas phase at temperatures around 320-350 K observed in the isomerization reaction of a hydroxycarbene into an aldehyde. The charge-tagged carbene was generated in situ in a tandem mass spectrometer by decarboxylation of oxo[4-(trimethylammonio)phenyl]acetic acid upon collision induced dissociation. All ion structures involved are characterized by infrared ion spectroscopy and quantum chemical calculations. The charge-tagged phenylhydroxycarbene undergoes a 1,2-H-shift to the corresponding aldehyde with an half-life of about 10 s, evidenced by isomer-selective two-color (IR-IR) spectroscopy. In contrast, the deuterated (OD) carbene analogue showed much reduced 1,2-D-shift reactivity with an estimated half-life of at least 200 s under the experimental conditions, and provides clear evidence for hydrogen atom tunneling in the H-isotopologue. This is the first spectroscopic confirmation of hydrogen atom tunneling governing 1,2-H-shift reactions at noncryogenic temperatures, which is of broad significance for a range of (bio)chemical processes, including enzymatic transformations and organocatalysis.

  12. Near-infrared spectroscopy for burning plasma diagnostic applications.

    PubMed

    Soukhanovskii, V A

    2008-10-01

    Ultraviolet and visible (UV-VIS, 200-750 nm) atomic spectroscopy of neutral and ionized fuel species (H, D, T, and Li) and impurities (e.g., He, Be, C, and W) is a key element of plasma control and diagnosis on International Thermonuclear Experimental Reactor and future magnetically confined burning plasma experiments (BPXs). Spectroscopic diagnostic implementation and performance issues that arise in the BPX harsh nuclear environment in the UV-VIS range, e.g., degradation of first mirror reflectivity under charge-exchange atom bombardment (erosion) and impurity deposition, permanent and dynamic loss of window, and optical fiber transmission under intense neutron and gamma-ray fluxes, are either absent or not as severe in the near-infrared (NIR, 750-2000 nm) range. An initial survey of NIR diagnostic applications has been undertaken on the National Spherical Torus Experiment. It is demonstrated that NIR spectroscopy can be used for machine protection and plasma control applications, as well as contribute to plasma performance evaluation and physics studies. Emission intensity estimates demonstrate that NIR measurements are possible in the BPX plasma operating parameter range. Complications in the NIR range due to the parasitic background emissions are expected to occur at very high plasma densities, low impurity densities, and at high plasma-facing component temperatures.

  13. Near-infrared spectroscopy for burning plasma diagnostic applicationsa)

    NASA Astrophysics Data System (ADS)

    Soukhanovskii, V. A.

    2008-10-01

    Ultraviolet and visible (UV-VIS, 200-750nm) atomic spectroscopy of neutral and ionized fuel species (H, D, T, and Li) and impurities (e.g., He, Be, C, and W) is a key element of plasma control and diagnosis on International Thermonuclear Experimental Reactor and future magnetically confined burning plasma experiments (BPXs). Spectroscopic diagnostic implementation and performance issues that arise in the BPX harsh nuclear environment in the UV-VIS range, e.g., degradation of first mirror reflectivity under charge-exchange atom bombardment (erosion) and impurity deposition, permanent and dynamic loss of window, and optical fiber transmission under intense neutron and γ-ray fluxes, are either absent or not as severe in the near-infrared (NIR, 750-2000nm) range. An initial survey of NIR diagnostic applications has been undertaken on the National Spherical Torus Experiment. It is demonstrated that NIR spectroscopy can be used for machine protection and plasma control applications, as well as contribute to plasma performance evaluation and physics studies. Emission intensity estimates demonstrate that NIR measurements are possible in the BPX plasma operating parameter range. Complications in the NIR range due to the parasitic background emissions are expected to occur at very high plasma densities, low impurity densities, and at high plasma-facing component temperatures.

  14. Indirect absorption spectroscopy using quantum cascade lasers: mid-infrared refractometry and photothermal spectroscopy.

    PubMed

    Pfeifer, Marcel; Ruf, Alexander; Fischer, Peer

    2013-11-04

    We record vibrational spectra with two indirect schemes that depend on the real part of the index of refraction: mid-infrared refractometry and photothermal spectroscopy. In the former, a quantum cascade laser (QCL) spot is imaged to determine the angles of total internal reflection, which yields the absorption line via a beam profile analysis. In the photothermal measurements, a tunable QCL excites vibrational resonances of a molecular monolayer, which heats the surrounding medium and changes its refractive index. This is observed with a probe laser in the visible. Sub-monolayer sensitivities are demonstrated.

  15. Spectral Similarity Assessment Based on a Spectrum Reflectance-Absorption Index and Simplified Curve Patterns for Hyperspectral Remote Sensing.

    PubMed

    Ma, Dan; Liu, Jun; Huang, Junyi; Li, Huali; Liu, Ping; Chen, Huijuan; Qian, Jing

    2016-01-26

    Hyperspectral images possess properties such as rich spectral information, narrow bandwidth, and large numbers of bands. Finding effective methods to retrieve land features from an image by using similarity assessment indices with specific spectral characteristics is an important research question. This paper reports a novel hyperspectral image similarity assessment index based on spectral curve patterns and a reflection-absorption index. First, some spectral reflection-absorption features are extracted to restrict the subsequent curve simplification. Then, the improved Douglas-Peucker algorithm is employed to simplify all spectral curves without setting the thresholds. Finally, the simplified curves with the feature points are matched, and the similarities among the spectral curves are calculated using the matched points. The Airborne Visible Infrared Imaging Spectrometer (AVIRIS) and Reflective Optics System Imaging Spectrometer (ROSIS) hyperspectral image datasets are then selected to test the effect of the proposed index. The practical experiments indicate that the proposed index can achieve higher precision and fewer points than the traditional spectral information divergence and spectral angle match.

  16. Spectral Similarity Assessment Based on a Spectrum Reflectance-Absorption Index and Simplified Curve Patterns for Hyperspectral Remote Sensing

    PubMed Central

    Ma, Dan; Liu, Jun; Huang, Junyi; Li, Huali; Liu, Ping; Chen, Huijuan; Qian, Jing

    2016-01-01

    Hyperspectral images possess properties such as rich spectral information, narrow bandwidth, and large numbers of bands. Finding effective methods to retrieve land features from an image by using similarity assessment indices with specific spectral characteristics is an important research question. This paper reports a novel hyperspectral image similarity assessment index based on spectral curve patterns and a reflection-absorption index. First, some spectral reflection-absorption features are extracted to restrict the subsequent curve simplification. Then, the improved Douglas-Peucker algorithm is employed to simplify all spectral curves without setting the thresholds. Finally, the simplified curves with the feature points are matched, and the similarities among the spectral curves are calculated using the matched points. The Airborne Visible Infrared Imaging Spectrometer (AVIRIS) and Reflective Optics System Imaging Spectrometer (ROSIS) hyperspectral image datasets are then selected to test the effect of the proposed index. The practical experiments indicate that the proposed index can achieve higher precision and fewer points than the traditional spectral information divergence and spectral angle match. PMID:26821030

  17. High Resolution Infrared Spectroscopy of Pyrazine and Naphthalene in a Molecular Bean

    DTIC Science & Technology

    1993-10-26

    Infrared Spectroscopy of Pyrazine and Naphthalene in a Molecular Beamby Kevin B. Hewett, Meihua Shen, Christopher L. Brummel, and Laura A. Philips...public release and sale; its distribution is unlimited. 93-26699 HIGH RESOLUTION INFRARED SPECTROSCOPY OF PYRAZINE AND NAPHTHALENE IN A MOLECULAR BEAM...Abstract The high resolution infrared spectrum of pyrazine and naphthalene were measured in a molecular beam in the vicinity of the C-H stretching

  18. High-speed high-sensitivity infrared spectroscopy using mid-infrared swept lasers (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Childs, David T. D.; Groom, Kristian M.; Hogg, Richard A.; Revin, Dmitry G.; Cockburn, John W.; Rehman, Ihtesham U.; Matcher, Stephen J.

    2016-03-01

    Infrared spectroscopy is a highly attractive read-out technology for compositional analysis of biomedical specimens because of its unique combination of high molecular sensitivity without the need for exogenous labels. Traditional techniques such as FTIR and Raman have suffered from comparatively low speed and sensitivity however recent innovations are challenging this situation. Direct mid-IR spectroscopy is being speeded up by innovations such as MEMS-based FTIR instruments with very high mirror speeds and supercontinuum sources producing very high sample irradiation levels. Here we explore another possible method - external cavity quantum cascade lasers (EC-QCL's) with high cavity tuning speeds (mid-IR swept lasers). Swept lasers have been heavily developed in the near-infrared where they are used for non-destructive low-coherence imaging (OCT). We adapt these concepts in two ways. Firstly by combining mid-IR quantum cascade gain chips with external cavity designs adapted from OCT we achieve spectral acquisition rates approaching 1 kHz and demonstrate potential to reach 100 kHz. Secondly we show that mid-IR swept lasers share a fundamental sensitivity advantage with near-IR OCT swept lasers. This makes them potentially able to achieve the same spectral SNR as an FTIR instrument in a time x N shorter (N being the number of spectral points) under otherwise matched conditions. This effect is demonstrated using measurements of a PDMS sample. The combination of potentially very high spectral acquisition rates, fundamental SNR advantage and the use of low-cost detector systems could make mid-IR swept lasers a powerful technology for high-throughput biomedical spectroscopy.

  19. Chemical Sensing Using Infrared Cavity Enhanced Spectroscopy: Short Wave Infrared Cavity Ring Down Spectroscopy (SWIR CRDS) Sensor

    SciTech Connect

    Williams, Richard M.; Harper, Warren W.; Aker, Pam M.; Thompson, Jason S.; Stewart, Timothy L.

    2003-10-01

    The principal goal of Pacific Northwest National Laboratory's (PNNL's) Remote Spectroscopy Project is to explore and develop the science and technology behind point and stand off infrared (IR) spectroscopic chemical sensors that are needed for detecting weapons proliferation activity and countering terrorism. Missions addressed include detecting chemical, biological, and nuclear weapons and their production; counter terrorism measures that involve screening luggage, personnel, and shipping containers for explosives, firearms, narcotics, chemical weapons and/or their residues; and mapping of contaminated areas. The science and technology developed in this program is dual use in that it additionally supports progress in a diverse set of agendas that include chemical weapons defense programs, air operations activities, emissions monitoring, law enforcement, and medical diagnostics. Sensors for these missions require extremely low limits of detection because many of the targeted signature species are either present in low concentrations or have extremely low vapor pressures. The sensors also need to be highly selective as the environments that they will be operated in will contain a variety of interferent species and false positive detection is not an option. PNNL has been working on developing a class of sensors that draw vapor into optical cavities and use laser-based spectroscopy to identify and quantify the vapor chemical content. The cavity enhanced spectroscopies (CES) afford extreme sensitivity, excellent selectivity, noise immunity, and rapid, real-time, in-situ chemical characterization. PNNL's CES program is currently focused on developing two types of sensors. The first one, which is based on cavity ring down spectroscopy (CRDS), uses short wave infrared (SWIR) lasers to interrogate species. The second sensor, which is based on noise immune cavity-enhanced optical heterodyne molecular spectroscopy (NICE OHMS), uses long wave infrared (LWIR) quantum cascade

  20. Helium Tagging Infrared Photodissociation Spectroscopy of Reactive Ions.

    PubMed

    Roithová, Jana; Gray, Andrew; Andris, Erik; Jašík, Juraj; Gerlich, Dieter

    2016-02-16

    The interrogation of reaction intermediates is key for understanding chemical reactions; however their direct observation and study remains a considerable challenge. Mass spectrometry is one of the most sensitive analytical techniques, and its use to study reaction mixtures is now an established practice. However, the information that can be obtained is limited to elemental analysis and possibly to fragmentation behavior, which is often challenging to analyze. In order to extend the available experimental information, different types of spectroscopy in the infrared and visible region have been combined with mass spectrometry. Spectroscopy of mass selected ions usually utilizes the powerful sensitivity of mass spectrometers, and the absorption of photons is not detected as such but rather translated to mass changes. One approach to accomplish such spectroscopy involves loosely binding a tag to an ion that will be removed by absorption of one photon. We have constructed an ion trapping instrument capable of reaching temperatures that are sufficiently low to enable tagging by helium atoms in situ, thus permitting infrared photodissociation spectroscopy (IRPD) to be carried out. While tagging by larger rare gas atoms, such as neon or argon is also possible, these may cause significant structural changes to small and reactive species, making the use of helium highly beneficial. We discuss the "innocence" of helium as a tag in ion spectroscopy using several case studies. It is shown that helium tagging is effectively innocent when used with benzene dications, not interfering with their structure or IRPD spectrum. We have also provided a case study where we can see that despite its minimal size there are systems where He has a huge effect. A strong influence of the He tagging was shown in the IRPD spectra of HCCl(2+) where large spectral shifts were observed. While the presented systems are rather small, they involve the formation of mixtures of isomers. We have therefore

  1. Determination of styrene-butadiene rubber composition by attenuated total internal reflection infrared spectroscopy

    NASA Astrophysics Data System (ADS)

    Orlov, A. S.; Kiselev, S. A.; Kiseleva, E. A.; Budeeva, A. V.; Mashukov, V. I.

    2013-03-01

    A rapid method for determining the composition of styrene-butadiene rubber using attenuated total internal reflection infrared spectroscopy was proposed. PMR and 13C NMR spectroscopy and infrared transmission spectroscopy were used as absolute techniques for determining the compositions of calibration samples. It was shown that the method was applicable to a wide range of styrene-butadiene rubbers, did not require additional sample preparation, and was easily reproducible.

  2. [Investigation of fibrous cultural materials by infrared spectroscopy].

    PubMed

    Luo, Xi-yun; Du, Yi-ping; Shen, Mei-hua; Zhang, Wen-qing; Zhou, Xin-guang; Fang, Shu-ying; Zhang, Xuan

    2015-01-01

    Cultural fibrous material includes both important categories, i. e. textile and paper, consisting of precious cultural materials in museum, such as costume, painting, and manuscript. In recent years more and more connoisseur and conservator's concerns are, through nondestructive method, the authenticity and the ageing identification of these cultural relics especially made from fragile materials. In this research, we used attenuated total reflection infrared spectroscopy to identify five traditional textile fibers, alongside cotton, linen, wool, mulberry silk and tussah silk, and another five paper fibers alongside straw, wheat straw, long qisong, Chinese alpine rush and mulberry bar, which are commonly used for making Chinese traditional xuan paper. The research result showed that the animal fiber (wool, mulberry silk and tussah silk) and plant fiber (cotton and linen) were easier to be distinguished by comparing the peaks at 3 280 cm-1 belonging to NH stretching vibration and a serious peaks related to amide I to amide III. In the spectrum of wool, the peak at 1 076 cm-1 was assigned to the S-O stretching vibration absorption of cystine in wool structure and can be used to tell wool from silk. The spectrum of mulberry silk and tussah silk seems somewhat difficult to be identified, as well as the spectrum of cotton and linen. Five rural paper fibers all have obvious characteristic peaks at 3 330, 2 900 cm-1 which are related to OH and CH stretching vibration. In the fingerprint wavenumber range of 1 600 - 800 cm, the similar peaks also appeared at 1 370, 1 320 cm-1 and 1 162, 1 050 cm-1, both group peaks respectively are related to CH and CO vibration in the structure of cellulose and hemicellulose in paper fibers. Although there is more similarity of the infrared spectroscopy of these 5 paper fibers, some tiny difference in absorbance also can be found at 3 300 cm-1 and in the fingerprint range at 1 332, 1 203, and 1 050 cm-1 which are related to C-O-C vibration

  3. [Study on the Tibetan medicine Swertia mussotii Franch and its extracts by Fourier transform infrared spectroscopy].

    PubMed

    Yang, Hong-Xia; Ma, Fang; Du, Yu-Zhi; Sun, Su-Qin; Wei, Li-Xin

    2014-11-01

    The objective of the present study is to research the herb of Swertia mussotii Franch and its different extracts by tristep infrared spectroscopy. The main constitute of Swertia mussotii Franch-gentiamarin, which is also the higher content constitute, was selected as the control components to analyze the infrared spectroscopy and second derivative infrared spectroscopy of different extracts of Swertia mussotii Franch, at the same time, the different concentration of ethanol extracts were also analyzed by two-dimensional correlation spectroscopy (2D-COS). The results indicated that the intensity of 1 611 and 1 075 cm(-1) of gentiamarin, which are its two main absorptions in the infrared spectra, has the positive correlation with the content change in different extracts. The infrared spectroscopy of extracts are similar if the polarity of extract solvents is close; with the decreases in solution polarity, the intensity of 2 853, 1 733, 1 464, 1 277 and 1 161 cm(-1) in infrared spectroscopy of different extracts is increased, the content of esters and the extraction percentage terpenoid compounds are also increased; the different concentration of ethanol extracts has obviously difference when they are analyzed by two-dimensional correlation spectroscopy (2D-COS). The positive correlation between the intensity of absorptions and the content of the gentiamarin indicates that the infrared spectroscopy can reflect the content change in constitute; the similar and the change trend of the different concentrations of ethanol extract infrared spectroscopy approve the scientificalness of decoction of traditional medicine; infrared spectroscopy that used in the research can be used as an accurate, rapid and effective method in the pharmacological activity tests of transitional herbal Swertia mussotii F. and it's different extracts, even in the research on the tibetan medicine.

  4. Optimal hemodynamic response model for functional near-infrared spectroscopy

    PubMed Central

    Kamran, Muhammad A.; Jeong, Myung Yung; Mannan, Malik M. N.

    2015-01-01

    Functional near-infrared spectroscopy (fNIRS) is an emerging non-invasive brain imaging technique and measures brain activities by means of near-infrared light of 650–950 nm wavelengths. The cortical hemodynamic response (HR) differs in attributes at different brain regions and on repetition of trials, even if the experimental paradigm is kept exactly the same. Therefore, an HR model that can estimate such variations in the response is the objective of this research. The canonical hemodynamic response function (cHRF) is modeled by two Gamma functions with six unknown parameters (four of them to model the shape and other two to scale and baseline respectively). The HRF model is supposed to be a linear combination of HRF, baseline, and physiological noises (amplitudes and frequencies of physiological noises are supposed to be unknown). An objective function is developed as a square of the residuals with constraints on 12 free parameters. The formulated problem is solved by using an iterative optimization algorithm to estimate the unknown parameters in the model. Inter-subject variations in HRF and physiological noises have been estimated for better cortical functional maps. The accuracy of the algorithm has been verified using 10 real and 15 simulated data sets. Ten healthy subjects participated in the experiment and their HRF for finger-tapping tasks have been estimated and analyzed. The statistical significance of the estimated activity strength parameters has been verified by employing statistical analysis (i.e., t-value > tcritical and p-value < 0.05). PMID:26136668

  5. Isotope effects in liquid water by infrared spectroscopy

    NASA Astrophysics Data System (ADS)

    Max, Jean-Joseph; Chapados, Camille

    2002-03-01

    The light and heavy liquid water (H2O-D2O) mixtures in the 0-1 molar fraction were studied in the mid-infrared by Fourier transform infrared attenuated total reflectance (FTIR-ATR) spectroscopy. Five principal factors were retrieved by factor analysis (FA). When D2O is mixed with H2O, the HDO formed because of the hopping nature of the proton (H or D) results in three types of molecules in equilibrium. Because of the nearest-neighbor interactions, the three molecules give rise to nine species. Some of the species evolve concomitantly with other species giving the five principal factors observed. We present the spectra of these factors with their abundances. The calculated probability of the species present at different molar fractions which when the concomitant species are combined gives the observed abundances. To appreciate clearly the difference between the principal spectra, a Gaussian simulation of the bands was made. Because of the numerous components that make up the stretch bands, they are not very sensitive to changes in composition of the solutions; nevertheless, they do indicate the presence of new entities other than the pure species. The deformation bands, more sensitive to such changes than the stretch bands, clearly indicate the presence of the three types of molecules as well as of intermediate species. These bands are sensitive to the two hydrogen bonds on the oxygen atom that a reference molecule makes with its nearest-neighbors, but not to the hydrogen bonds that the nearest-neighbors make with the next nearest neighbors.

  6. Quantification of the extracerebral contamination of near infrared spectroscopy signals

    NASA Astrophysics Data System (ADS)

    Mudra, R.; Niederer, P.; Keller, E.

    2005-04-01

    Recently, conventional near infrared spectroscopy (NIRS) for oxymetry has been extended with an indocyanine green (ICG) dye dilution method which allows the estimation of cerebral blood flow (CBF) and cerebral blood volume (CBV). The signal obtained through the skull is substantially influenced by extracerebral tissue. In order to quantify and eliminate extracerebral contamination of the optical density signal we have applied two approaches. Firstly, we used spatially resolved spectroscopy (SRS) with a two receiver arrangement, with separations between emitter and two receivers in distances of d1=4.0cm and d2=6.5cm. The magnitude of the determined extracerebral contamination was verified with NIRS measurements in patients after brain herniation. Intracerebral circulatory arrest was confirmed by transcerebral Doppler examination. Secondly, Monte Carlo simulation was used to simulate the light propagation through the head to quantify the extracerebral contamination of the optical density signal of NIRS. The anatomical structure is determined from 3D-magnetic resonance imaging (MRI) using a voxel resolution of 0.8 x 0.8 x 0 .8 mm3 for three different pairs of T1/T2 values. We segment the MRI data to obtain a material matrix describing the composition of skin, skull, cerebral spinal fluid (CSF), grey and white matter. Each voxel in this material matrix characterizes the light absorption and dispersion coefficient of the identified material. This material matrix is applied in the Monte Carlo simulation. With SRS an extracerebral contamination of 65% of the optical density signal is extracted, while the Monte Carlo simulation results show that the extracerebral contamination decreases from 70% to 30% with increasing emitter-receiver distance. Differences between the NIRS ICG dye dilution technique and conventional NIRS oxymetry concerning the extracerebral contamination are discussed.

  7. Visible/Infrared Imaging Spectroscopy and Energy-Resolving Detectors

    NASA Astrophysics Data System (ADS)

    Eisenhauer, Frank; Raab, Walfried

    2015-08-01

    Imaging spectroscopy has seen rapid progress over the past 25 years, leading to breakthroughs in many fields of astronomy that would not have been otherwise possible. This review overviews the visible/infrared imaging spectroscopy techniques as well as energy-resolving detectors. We introduce the working principle of scanning Fabry-Perot and Fourier transform spectrometers and explain the most common integral field concepts based on mirror slicers, lenslet arrays, and fibers. The main advantage of integral field spectrographs is the simultaneous measurement of spatial and spectral information. Although Fabry-Perot and Fourier transform spectrometers can provide a larger field of view, it is ultimately the higher sensitivity of integral field units that make them the technique of choice. This is arguably the case for image slicers, which make the most efficient use of the available detector pixels and have equal or higher transmission than lenslet arrays and fiber integral field units, respectively. We also address the more specific issues of large étendue operation, focal ratio degradation, anamorphic magnification, and diffraction-limited operation. This review also covers the emerging technology of energy-resolving detectors, which promise very simple and efficient instrument designs. These energy-resolving detectors are based on superconducting thin film technology and exploit either the very small superconducting energy to count the number of quasi-particles excited in the absorption of the photon or the extremely steep phase transition between the normal- and superconducting phase to measure a temperature increase. We have put special emphasis on an overview of the underlying physical phenomena as well as on the recent technological progress and astronomical path finder experiments.

  8. Nondestructive Assessment of Engineered Cartilage Composition by Near Infrared Spectroscopy.

    PubMed

    McGoverin, Cushla M; Hanifi, Arash; Palukuru, Uday P; Yousefi, Farzad; Glenn, Padraig B M; Shockley, Michael; Spencer, Richard G; Pleshko, Nancy

    2016-03-01

    Tissue engineering presents a strategy to overcome the limitations of current tissue healing methods. Scaffolds, cells, external growth factors and mechanical input are combined in an effort to obtain constructs with properties that mimic native tissues. However, engineered constructs developed using similar culture environments can have very different matrix composition and biomechanical properties. Accordingly, a nondestructive technique to assess constructs during development such that appropriate compositional endpoints can be defined is desirable. Near infrared spectroscopy (NIRS) analysis is a modality being investigated to address the challenges associated with current evaluation techniques, which includes nondestructive compositional assessment. In the present study, cartilage tissue constructs were grown using chondrocytes seeded onto polyglycolic acid (PGA) scaffolds in similar environments in three separate tissue culture experiments and monitored using NIRS. Multivariate partial least squares (PLS) analysis models of NIR spectra were calculated and used to predict tissue composition, with biochemical assay information used as the reference data. Results showed that for combined data from all tissue culture experiments, PLS models were able to assess composition with significant correlations to reference values, including engineered cartilage water (at 5200 cm(-1), R = 0.68, p = 0.03), proteoglycan (at 4310 cm(-1), R = 0.82, p = 0.007), and collagen (at 4610 cm(-1), R = 0.84, p = 0.005). In addition, degradation of PGA was monitored using specific NIRS frequencies. These results demonstrate that NIR spectroscopy combined with multivariate analysis provides a nondestructive modality to assess engineered cartilage, which could provide information to determine the optimal time for tissue harvest for clinical applications.

  9. Infrared and near infrared transient absorption spectroscopy of molecular free radicals

    SciTech Connect

    Sears, T.J.; Wu, M.; Hall, G.E.; Chang, B.C.; Hansford, G.; Bloch, J.C.; Field, R.W.

    1993-12-31

    The advantages of absorption spectroscopy at low absorbances include a linear relationship between signal size and number of absorbing molecules, line of sight measurement, and easily interpretable lineshape functions. The main disadvantage is due to the necessity of measuring a small change in light intensity, usually in the presence of a strong background, which limits the sensitivity. In this work, recent results obtained using absorption techniques with continuous wave lasers to measure vibrational and electronic spectra in the mid- and near-infrared of small free radicals are reported. The radical of interest was generated by excimer laser photolysis of a chemically stable precursor molecule and detected by measuring the transient decrease in power of a continuous wave probe laser that traversed the photolyzed volume before being imaged onto a detector.

  10. Dynamic infrared study of polyphenylene sulfide using planar array infrared spectroscopy.

    PubMed

    Pesapane, Andrea; Snively, Christopher M; Ikeda, Richard M; Chase, D Bruce; Rabolt, John F

    2008-10-01

    Planar array infrared (PA-IR) spectroscopy was used to study polyphenylene sulfide (PPS) at room temperature during the application of a sinusoidal elastic deformation. All of the intensity in the dynamic spectra was contained within the in-phase spectrum, which was expected since the measurements were carried out at room temperature, far below the glass transition temperature. The contributions of chain orientation, sample thinning, and stress-induced band shifts were separated in the dynamic spectra. It was found that the effects of chain orientation and sample thinning canceled each other out. Stress-induced band shifts far below the spectral resolution, on the order of 0.01 cm(-1), were quantified and used to calculate the stress optical coefficients and mode Gruneisen parameters for PPS.

  11. Fourier Transform Infrared Spectroscopy of CH{_3}OO Radical in Mid-Infrared Range

    NASA Astrophysics Data System (ADS)

    Hsu, Kuo-Hsiang; Lee, Yuan-Pern; Huang, Meng; Miller, Terry A.

    2013-06-01

    A mid-infrared spectrum of the CH{_3}OO radical at room temperature has been measured by Fourier-transform infrared spectroscopy. The CH{_3}OO radicals were produced by photolysis of a CH{_3}I/O{_2} mixture at 248 nm or a CH3COCH3/O2 mixture at 193 nm; the total pressure is 100 Torr and the precursor is about 1.6-2.0%. The {ν_2}, {ν_5}, {ν_6}, {ν_7}, and {ν_9} fundamental bands with origins at 2954.0, 1182.6, 1118.0, 910.8, and 3021.4 cm^{-1} have been observed, which are in good agreement with previous low-resolution work. Particular attention has been given to simulate the rotational structure of the {ν_2} band. Sequence band structure from the methyl torsion mode {ν_{12}} was included in the simulation of this band as well as some transitions from the precursor. The simulation shows generally good consistency with the experimental spectrum and allows the determination of the molecule's rotational constants. D.-R. Huang, L.-K. Chu, and Y.-P. Lee J. Chem. Phys. 127, 7 (2007)

  12. Fresh Soil Sensing using Visible and Near Infrared Spectroscopy

    NASA Astrophysics Data System (ADS)

    Maleki, M. R.

    2009-04-01

    Fast, precise and affordable soil analytical techniques are needed for the determination of soil fertility of each zone of a field in site specific land management. The objective of this poster is to demonstrate how nutrients can be estimated from fresh soil using visible (VIS) and near infrared (NIR) spectroscopy method. This could be carried out by summarizing the methodology to develop a calibration model for soil phosphorus with the VIS-NIR spectroscopy method. Obviously, it can be simply extended for other nutrients with the same methodology. A large samples set should be collected from different fields with a wide range of soil type and texture. The samples in this set should be represented a wide range of moisture content and soil nutrient which is desired to be calibrated by the spectroscopy technique. Immediately after sampling, the samples should be kept in a cold room (± 1 °C) until the time of the spectral measurement and the chemical analysis. The samples should be taken from the cold room one hour before the spectral measurement to ensure that the samples were at room temperature and no condensation occurs on the optical instruments. Each soil sample was thoroughly mixed and debris such as plant material and stones were removed. The soil sample was divided into three parts, one part for spectral measurement, another part for chemical analysis and the rest was archived. The part for chemical analysis should be examined for their soil nutrients. A small amount of soil (about 30 g) should be placed in a small plastic petridish (e.g. 7.5 mm depth and 30 mm diameter). The soil in the petridish should be first pressed and then carefully levelled in order to obtain a smooth surface for a maximum light reflectance. Soil samples should be put under the spectrophotometer. Three reflectance spectra should be measured on each soil specimen by rotating the plastic cups over 120°. Having finished measuring, the reflectance data should be put against the chemical

  13. Near-infrared spectroscopy of Type Ia supernovae

    NASA Astrophysics Data System (ADS)

    Hsiao, Eric; Phillips, Mark; Burns, Christopher R.; Contreras, Carlos; Gall, Christa; Hoeflich, Peter; Kirshner, Robert P.; Marion, Howie H.; Morrell, Nidia; Sand, David J.; Stritzinger, Maximillian; Carnegie Supernova Project

    2016-01-01

    Improving the cosmological experiments with Type Ia supernovae (SNe Ia) is now not simply a question of observing more supernovae, since any survey, no matter how large, will ultimately be limited by the systematic errors. It has been clearly demonstrated in a number of studies that SNe Ia are better distance indicators in the near-infrared compared to the optical. As exciting as these new results are, SNe Ia in the NIR are expected to be even better than these studies indicate. A key ingredient for improving SN Ia in the NIR as distance indicators is to obtain NIR spectroscopy to determine precise k-corrections, which account for the effect of cosmological expansion upon the measured magnitudes. Better knowledge of the NIR spectroscopic behaviors, akin to that in the optical, is necessary to reach the distance precision required to identify viable models for dark energy. Carnegie Supernova Project II has built a definitive data set, much improved from previous samples, both in size and quality. With this previously unavailable window, we are also beginning to gain new insight on the physics of these events.

  14. Textile integrated sensors and actuators for near-infrared spectroscopy.

    PubMed

    Zysset, Christoph; Nasseri, Nassim; Büthe, Lars; Münzenrieder, Niko; Kinkeldei, Thomas; Petti, Luisa; Kleiser, Stefan; Salvatore, Giovanni A; Wolf, Martin; Tröster, Gerhard

    2013-02-11

    Being the closest layer to our body, textiles provide an ideal platform for integrating sensors and actuators to monitor physiological signals. We used a woven textile to integrate photodiodes and light emitting diodes. LEDs and photodiodes enable near-infrared spectroscopy (NIRS) systems to monitor arterial oxygen saturation and oxygenated and deoxygenated hemoglobin in human tissue. Photodiodes and LEDs are mounted on flexible plastic strips with widths of 4 mm and 2 mm, respectively. The strips are woven during the textile fabrication process in weft direction and interconnected with copper wires with a diameter of 71 μm in warp direction. The sensor textile is applied to measure the pulse waves in the fingertip and the changes in oxygenated and deoxygenated hemoglobin during a venous occlusion at the calf. The system has a signal-to-noise ratio of more than 70 dB and a system drift of 0.37% ± 0.48%. The presented work demonstrates the feasibility of integrating photodiodes and LEDs into woven textiles, a step towards wearable health monitoring devices.

  15. Portable Infrared Laser Spectroscopy for On-site Mycotoxin Analysis.

    PubMed

    Sieger, Markus; Kos, Gregor; Sulyok, Michael; Godejohann, Matthias; Krska, Rudolf; Mizaikoff, Boris

    2017-03-09

    Mycotoxins are toxic secondary metabolites of fungi that spoil food, and severely impact human health (e.g., causing cancer). Therefore, the rapid determination of mycotoxin contamination including deoxynivalenol and aflatoxin B1 in food and feed samples is of prime interest for commodity importers and processors. While chromatography-based techniques are well established in laboratory environments, only very few (i.e., mostly immunochemical) techniques exist enabling direct on-site analysis for traders and manufacturers. In this study, we present MYCOSPEC - an innovative approach for spectroscopic mycotoxin contamination analysis at EU regulatory limits for the first time utilizing mid-infrared tunable quantum cascade laser (QCL) spectroscopy. This analysis technique facilitates on-site mycotoxin analysis by combining QCL technology with GaAs/AlGaAs thin-film waveguides. Multivariate data mining strategies (i.e., principal component analysis) enabled the classification of deoxynivalenol-contaminated maize and wheat samples, and of aflatoxin B1 affected peanuts at EU regulatory limits of 1250 μg kg(-1) and 8 μg kg(-1), respectively.

  16. Dynamic causal modelling for functional near-infrared spectroscopy

    PubMed Central

    Tak, S.; Kempny, A.M.; Friston, K.J.; Leff, A.P.; Penny, W.D.

    2015-01-01

    Functional near-infrared spectroscopy (fNIRS) is an emerging technique for measuring changes in cerebral hemoglobin concentration via optical absorption changes. Although there is great interest in using fNIRS to study brain connectivity, current methods are unable to infer the directionality of neuronal connections. In this paper, we apply Dynamic Causal Modelling (DCM) to fNIRS data. Specifically, we present a generative model of how observed fNIRS data are caused by interactions among hidden neuronal states. Inversion of this generative model, using an established Bayesian framework (variational Laplace), then enables inference about changes in directed connectivity at the neuronal level. Using experimental data acquired during motor imagery and motor execution tasks, we show that directed (i.e., effective) connectivity from the supplementary motor area to the primary motor cortex is negatively modulated by motor imagery, and this suppressive influence causes reduced activity in the primary motor cortex during motor imagery. These results are consistent with findings of previous functional magnetic resonance imaging (fMRI) studies, suggesting that the proposed method enables one to infer directed interactions in the brain mediated by neuronal dynamics from measurements of optical density changes. PMID:25724757

  17. Portable Infrared Laser Spectroscopy for On-site Mycotoxin Analysis

    PubMed Central

    Sieger, Markus; Kos, Gregor; Sulyok, Michael; Godejohann, Matthias; Krska, Rudolf; Mizaikoff, Boris

    2017-01-01

    Mycotoxins are toxic secondary metabolites of fungi that spoil food, and severely impact human health (e.g., causing cancer). Therefore, the rapid determination of mycotoxin contamination including deoxynivalenol and aflatoxin B1 in food and feed samples is of prime interest for commodity importers and processors. While chromatography-based techniques are well established in laboratory environments, only very few (i.e., mostly immunochemical) techniques exist enabling direct on-site analysis for traders and manufacturers. In this study, we present MYCOSPEC - an innovative approach for spectroscopic mycotoxin contamination analysis at EU regulatory limits for the first time utilizing mid-infrared tunable quantum cascade laser (QCL) spectroscopy. This analysis technique facilitates on-site mycotoxin analysis by combining QCL technology with GaAs/AlGaAs thin-film waveguides. Multivariate data mining strategies (i.e., principal component analysis) enabled the classification of deoxynivalenol-contaminated maize and wheat samples, and of aflatoxin B1 affected peanuts at EU regulatory limits of 1250 μg kg−1 and 8 μg kg−1, respectively. PMID:28276454

  18. Portable Infrared Laser Spectroscopy for On-site Mycotoxin Analysis

    NASA Astrophysics Data System (ADS)

    Sieger, Markus; Kos, Gregor; Sulyok, Michael; Godejohann, Matthias; Krska, Rudolf; Mizaikoff, Boris

    2017-03-01

    Mycotoxins are toxic secondary metabolites of fungi that spoil food, and severely impact human health (e.g., causing cancer). Therefore, the rapid determination of mycotoxin contamination including deoxynivalenol and aflatoxin B1 in food and feed samples is of prime interest for commodity importers and processors. While chromatography-based techniques are well established in laboratory environments, only very few (i.e., mostly immunochemical) techniques exist enabling direct on-site analysis for traders and manufacturers. In this study, we present MYCOSPEC - an innovative approach for spectroscopic mycotoxin contamination analysis at EU regulatory limits for the first time utilizing mid-infrared tunable quantum cascade laser (QCL) spectroscopy. This analysis technique facilitates on-site mycotoxin analysis by combining QCL technology with GaAs/AlGaAs thin-film waveguides. Multivariate data mining strategies (i.e., principal component analysis) enabled the classification of deoxynivalenol-contaminated maize and wheat samples, and of aflatoxin B1 affected peanuts at EU regulatory limits of 1250 μg kg‑1 and 8 μg kg‑1, respectively.

  19. Fully Automated Lipid Pool Detection Using Near Infrared Spectroscopy

    PubMed Central

    Wojakowski, Wojciech

    2016-01-01

    Background. Detecting and identifying vulnerable plaque, which is prone to rupture, is still a challenge for cardiologist. Such lipid core-containing plaque is still not identifiable by everyday angiography, thus triggering the need to develop a new tool where NIRS-IVUS can visualize plaque characterization in terms of its chemical and morphologic characteristic. The new tool can lead to the development of new methods of interpreting the newly obtained data. In this study, the algorithm to fully automated lipid pool detection on NIRS images is proposed. Method. Designed algorithm is divided into four stages: preprocessing (image enhancement), segmentation of artifacts, detection of lipid areas, and calculation of Lipid Core Burden Index. Results. A total of 31 NIRS chemograms were analyzed by two methods. The metrics, total LCBI, maximal LCBI in 4 mm blocks, and maximal LCBI in 2 mm blocks, were calculated to compare presented algorithm with commercial available system. Both intraclass correlation (ICC) and Bland-Altman plots showed good agreement and correlation between used methods. Conclusions. Proposed algorithm is fully automated lipid pool detection on near infrared spectroscopy images. It is a tool developed for offline data analysis, which could be easily augmented for newer functions and projects. PMID:27610191

  20. The application of near infrared spectroscopy in nutritional intervention studies

    PubMed Central

    Jackson, Philippa A.; Kennedy, David O.

    2013-01-01

    Functional near infrared spectroscopy (NIRS) is a non-invasive optical imaging technique used to monitor cerebral blood flow (CBF) and by proxy neuronal activation. The use of NIRS in nutritional intervention studies is a relatively novel application of this technique, with only a small, but growing, number of trials published to date. These trials—in which the effects on CBF following administration of dietary components such as caffeine, polyphenols and omega-3 polyunsaturated fatty acids are assessed—have successfully demonstrated NIRS as a sensitive measure of change in hemodynamic response during cognitive tasks in both acute and chronic treatment intervention paradigms. The existent research in this area has been limited by the constraints of the technique itself however advancements in the measurement technology, paired with studies endeavoring increased sophistication in number and locations of channels over the head should render the use of NIRS in nutritional interventions particularly valuable in advancing our understanding of the effects of nutrients and dietary components on the brain. PMID:23964231

  1. Infrared spectroscopy of trapped hydrogen in metal-organic-frameworks

    NASA Astrophysics Data System (ADS)

    Fitzgerald, Stephen; Allen, Kelty; Landerman, Patrick; Rowsell, Jesse

    2007-03-01

    We present a novel use of diffuse reflectance infrared spectroscopy to study the quantum dynamics of molecular hydrogen trapped within metal-organic-framework (MOF) hosts. This technique is particularly useful in the context of hydrogen storage since it provides detailed information about the intermolecular potential at the binding site. The spectra consist of quite sharp bands associated with the quantized vibrational and rotational motion of the trapped hydrogen. The vibrational bands are redshifted relative to the gas phase while the rotational sidebands contain an additional fine structure due to the orientational dependence of the binding potential. Results on MOF-5 reveal the presence of two primary binding sites. The first saturates at a loading concentration on the order of 4 H2 per Zn ion and has a binding energy of roughly 4 kJ/mole. The second has a somewhat lower binding energy. Both site produce an ortho to para conversion rate on the order of 30-50 % per hour.

  2. Mental fatigue detection based on the functional near infrared spectroscopy

    NASA Astrophysics Data System (ADS)

    Zhang, Zhen; Xu, Fenggang; Yang, Hanjun; Jiang, Jin; Cao, Yong; Jiao, Xuejun

    2017-02-01

    Mental fatigue can be induced by long time mental work, mental fatigue caused worse performance and accidents. As a non-invasive technique, functional near-infrared spectroscopy (fNIRS) can measure blood oxygen activity in the cerebral cortex which reflect the cognitive function of brain indirectly. Aiming at investigating whether fNIRS can measure the mental fatigue and study the spatial pattern of hemodynamic response for mental fatigue, we used three sessions of verbal 2-back working memory task for a total of 120 minutes to induce mental fatigue, 15 healthy subjects were recruited and 30 channels including prefrontal cortex (PFC) and motor cortex (MC) were measured by fNIRS. The mean oxyhemoglobin feature for 20s was extracted as well as subjective fatigue level and performance. The results showed significant increase of subjected fatigue level as well as significant decrease performance from session one to three task. With the increased level of fatigue, oxyhemoglobin in PFC increase significantly and the spatial pattern of hemodynamic response in the all 30 channels varied with task duration as well. These findings indicated the potential of fNIRS measured hemodynamic as a mental fatigue indicator.

  3. Coherent sources for mid-infrared laser spectroscopy

    NASA Astrophysics Data System (ADS)

    Honzátko, Pavel; Baravets, Yauhen; Mondal, Shyamal; Peterka, Pavel; Todorov, Filip

    2016-12-01

    Mid-infrared laser absorption spectroscopy (LAS) is useful for molecular trace gas concentration measurements in gas mixtures. While the gas chromatography-mass spectrometry is still the gold standard in gas analysis, LAS offers several advantages. It takes tens of minutes for a gas mixture to be separated in the capillary column precluding gas chromatography from real-time control of industrial processes, while LAS can measure the concentration of gas species in seconds. LAS can be used in a wide range of applications such as gas quality screening for regulation, metering and custody transfer,1 purging gas pipes to avoid explosions,1 monitoring combustion processes,2 detection and quantification of gas leaks,3 by-products monitoring to provide feedback for the real-time control of processes in petrochemical industry,4 real-time control of inductively coupled plasma etch reactors,5, 6 and medical diagnostics by means of time-resolved volatile organic compound (VOC) analysis in exhaled breath.7 Apart from the concentration, it also permits us to determine the temperature, pressure, velocity and mass flux of the gas under observation. The selectivity and sensitivity of LAS is linked to a very high spectral resolution given by the linewidth of single-frequency lasers. Measurements are performed at reduced pressure where the collisional and Doppler broadenings are balanced. The sensitivity can be increased to ppb and sometimes to ppt ranges by increasing the interaction length in multi-pass gas cells or resonators and also by adopting modulation techniques.8

  4. Characterization and Infrared Emission Spectroscopy of Ball Plasmoid Discharges

    NASA Astrophysics Data System (ADS)

    Dubowsky, Scott E.; McCall, Benjamin J.

    2015-06-01

    Plasmas at atmospheric pressure serve many purposes, from ionization sources for ambient mass spectrometry (AMS) to plasma-assisted wound healing. Of the many naturally occurring ambient plasmas, ball lightning is one of the least understood; there is currently no solid explanation in the literature for the formation and lifetime of natural ball lightning. With the first measurements of naturally occurring ball lightning being reported last year, we have worked to replicate the natural phenomenon in order to elucidate the physical and chemical processes by which the plasma is sustained at ambient conditions. We are able to generate ball-shaped plasmoids (self-sustaining plasmas) that are analogous to natural ball lightning using a high-voltage, high-current, pulsed DC system. Improvements to the discharge electronics used in our laboratory and characterization of the plasmoids that are generated from this system will be described. Infrared emission spectroscopy of these plasmoids reveals emission from water and hydroxyl radical -- fitting methods for these molecular species in the complex experimental spectra will be presented. Rotational temperatures for the stretching and bending modes of H2O along with that of OH will be presented, and the non-equilibrium nature of the plasmoid will be discussed in this context. Cen, J.; Yuan, P,; Xue, S. Phys. Rev. Lett. 2014, 112, 035001. Dubowsky, S.E.; Friday, D.M.; Peters, K.C.; Zhao, Z.; Perry, R.H.; McCall, B.J. Int. J. Mass Spectrom. 2015, 376, 39-45.

  5. Prediction of brain tissue temperature using near-infrared spectroscopy.

    PubMed

    Holper, Lisa; Mitra, Subhabrata; Bale, Gemma; Robertson, Nicola; Tachtsidis, Ilias

    2017-04-01

    Broadband near-infrared spectroscopy (NIRS) can provide an endogenous indicator of tissue temperature based on the temperature dependence of the water absorption spectrum. We describe a first evaluation of the calibration and prediction of brain tissue temperature obtained during hypothermia in newborn piglets (animal dataset) and rewarming in newborn infants (human dataset) based on measured body (rectal) temperature. The calibration using partial least squares regression proved to be a reliable method to predict brain tissue temperature with respect to core body temperature in the wavelength interval of 720 to 880 nm with a strong mean predictive power of [Formula: see text] (animal dataset) and [Formula: see text] (human dataset). In addition, we applied regression receiver operating characteristic curves for the first time to evaluate the temperature prediction, which provided an overall mean error bias between NIRS predicted brain temperature and body temperature of [Formula: see text] (animal dataset) and [Formula: see text] (human dataset). We discuss main methodological aspects, particularly the well-known aspect of over- versus underestimation between brain and body temperature, which is relevant for potential clinical applications.

  6. Prediction of chicken quality attributes by near infrared spectroscopy.

    PubMed

    Barbin, Douglas Fernandes; Kaminishikawahara, Cintia Midori; Soares, Adriana Lourenco; Mizubuti, Ivone Yurika; Grespan, Moises; Shimokomaki, Massami; Hirooka, Elisa Yoko

    2015-02-01

    In the present study, near-infrared (NIR) reflectance was tested as a potential technique to predict quality attributes of chicken breast (Pectoralis major). Spectra in the wavelengths between 400 and 2500nm were analysed using principal component analysis (PCA) and quality attributes were predicted using partial least-squares regression (PLSR). PCA performed on NIR dataset revealed the influence of muscle reflectance (L(∗)) influencing the spectra. PCA was not successful to completely discriminate between pale, soft and exudative (PSE) and pale-only muscles. High-quality PLSR were obtained for L(∗) and pH models predicted individually (R(2)CV of 0.91 and 0.81, and SECV of 1.99 and 0.07, respectively). Water-holding capacity was the most challenging attribute to determine (R(2)CV of 0.70 and SECV of 2.40%). Sample mincing and different spectra pre-treatments were not necessary to maximise the predictive performance of models. Results suggest that NIR spectroscopy can become useful tool for quality assessment of chicken meat. Copyright © 2014 Elsevier Ltd. All rights reserved.

  7. Infrared spectroscopy and structure of (NO)n clusters

    DOE PAGES

    Hoshina, Hiromichi; Slipchenko, Mikhail; Prozument, Kirill; ...

    2016-01-12

    Nitrogen oxide clusters (NO)n have been studied in He droplets via infrared depletion spectroscopy and by quantum chemical calculations. The ν1 and ν5 bands of cis-ON-NO dimer have been observed at 1868.2 and 1786.5 cm–1, respectively. Furthermore, spectral bands of the trimer and tetramer have been located in the vicinity of the corresponding dimer bands in accord with computed frequencies that place NO-stretch bands of dimer, trimer, and tetramer within a few wavenumbers of each other. In addition, a new line at 1878.1 cm–1 close to the band origin of single molecules was assigned to van der Waals bound dimersmore » of (NO)2, which are stabilized due to the rapid cooling in He droplets. Spectra of larger clusters (n > 5), have broad unresolved features in the vicinity of the dimer bands. As a result, experiments and calculations indicate that trimers consist of a dimer and a loosely bound third molecule, whereas the tetramer consists of two weakly bound dimers.« less

  8. Near-infrared spectroscopy for the evaluation of anesthetic depth.

    PubMed

    Hernandez-Meza, Gabriela; Izzetoglu, Meltem; Osbakken, Mary; Green, Michael; Izzetoglu, Kurtulus

    2015-01-01

    The standard-of-care guidelines published by the American Society of Anesthesiologists (ASA) recommend monitoring of pulse oximetry, blood pressure, heart rate, and end tidal CO2 during the use of anesthesia and sedation. This information can help to identify adverse events that may occur during procedures. However, these parameters are not specific to the effects of anesthetics or sedatives, and therefore they offer little, to no, real time information regarding the effects of those agents and do not give the clinician the lead-time necessary to prevent patient "awareness." Since no "gold-standard" method is available to continuously, reliably, and effectively monitor the effects of sedatives and anesthetics, such a method is greatly needed. Investigation of the use of functional near-infrared spectroscopy (fNIRS) as a method for anesthesia or sedation monitoring and for the assessment of the effects of various anesthetic drugs on cerebral oxygenation has started to be conducted. The objective of this paper is to provide a thorough review of the currently available published scientific studies regarding the use of fNIRS in the fields of anesthesia and sedation monitoring, comment on their findings, and discuss the future work required for the translation of this technology to the clinical setting.

  9. Water near lipid membranes as seen by infrared spectroscopy.

    PubMed

    Binder, Hans

    2007-04-01

    The ordering and H-bonding characteristics of the hydration water of the lipid 1-palmitoyl-2-oleoylphosphatidylcholine (POPC) were studied using polarized infrared spectroscopy by varying either the temperature or the relative humidity of the ambient atmosphere of multibilayer samples. The OH-stretching band of lipid-bound water was interpreted by a simplified two-state model of well-structured, low density "network" water and of less-structured dense "multimer" water. The IR-spectroscopic data reflect a rather continuous change of the water properties with increasing distance from the membrane and with changing temperature. Network and multimer water distribute across the whole polar interphase with changing composition and orientation. Upon dehydration the fraction of network water increases from about 30 to 60%, a value which is similar to that in supercooled water at -25 degrees C. The highly ordered gel phase gives rise to an increased fraction of structured network water compared with the liquid crystalline phase. The IR order parameter shows that the water dipoles rearrange from a more parallel towards a more perpendicular orientation with respect to the membrane normal with progressive hydration.

  10. Forsterite amorphisation by ion irradiation: Monitoring by infrared spectroscopy

    NASA Astrophysics Data System (ADS)

    Brucato, J. R.; Strazzulla, G.; Baratta, G.; Colangeli, L.

    2004-01-01

    We present experimental results on the crystal-amorphous transition of forsterite (Mg2SiO4) silicate under ion irradiation. The aim of this work is to study the structural evolution of one of the most abundant crystalline silicates observed in space driven by ion irradiation. To this aim, forsterite films have been synthesised in the laboratory and irradiated with low energy (30-60 keV) ion beams. Structural changes during irradiation with H+, He+, C+, and Ar++ have been observed and monitored by infrared spectroscopy. The fraction of crystalline forsterite converted into the amorphous form is a function of the energy deposited by nuclear collision by ions in the target. Laboratory results indicate that ion irradiation is a mechanism potentially active in space for the amorphisation of silicates. Physical properties obtained in this work can be used to model the evolution of silicate grains during their life cycle from evolved stars, through different interstellar environments and up to being incorporated in Solar System objects.

  11. FINESSE - the Fast INfrared Exoplanet Spectroscopy Survey Explorer

    NASA Astrophysics Data System (ADS)

    Swain, M.

    2012-04-01

    FINESSE, the Fast Infrared Exoplanet Spectroscopy Survey Explorer, is the first mission dedicated to finding out what exoplanet atmospheres are made of, what conditions or processes are responsible for the composition, and how our own solar system fits into the larger family of planets. The last 15 years have witnessed extraordinary success in finding exoplanets. FINESSE is designed to take the next step - characterizing exoplanet atmospheres. Using proven methods and an instrument optimized for stability, FINESSE would be the first mission dedicated to the spectroscopic characterization of exoplanets as a class of objects. During a two-year mission, FINESSE would survey 200 transiting exoplanets ranging from the most extreme hot-Jovians to cool Neptunes and Super-Earths. FINESSE's science instrument, a spectrograph covering 0.7-5.0 microns, provides excellent sensitivity to important molecular bands of water, methane, carbon monoxide, carbon dioxide, and other molecules. Interpretation of FINESSE measurements will reveal the composition, temperature structure, and chemistry of exoplanet atmospheres and provides a basis for comparing exoplanets in a uniform way. Engineered for exquisite 100 ppm stability, FINESSE will determine the differences between the dayside and nightside of exoplanet atmospheres by precision measurements of the system phase curve. Implemented as a rapid, low-cost, high-heritage mission, FINESSE is scientifically well matched to the rapidly expanding field of exoplanets.

  12. Prediction of brain tissue temperature using near-infrared spectroscopy

    PubMed Central

    Holper, Lisa; Mitra, Subhabrata; Bale, Gemma; Robertson, Nicola; Tachtsidis, Ilias

    2017-01-01

    Abstract. Broadband near-infrared spectroscopy (NIRS) can provide an endogenous indicator of tissue temperature based on the temperature dependence of the water absorption spectrum. We describe a first evaluation of the calibration and prediction of brain tissue temperature obtained during hypothermia in newborn piglets (animal dataset) and rewarming in newborn infants (human dataset) based on measured body (rectal) temperature. The calibration using partial least squares regression proved to be a reliable method to predict brain tissue temperature with respect to core body temperature in the wavelength interval of 720 to 880 nm with a strong mean predictive power of R2=0.713±0.157 (animal dataset) and R2=0.798±0.087 (human dataset). In addition, we applied regression receiver operating characteristic curves for the first time to evaluate the temperature prediction, which provided an overall mean error bias between NIRS predicted brain temperature and body temperature of 0.436±0.283°C (animal dataset) and 0.162±0.149°C (human dataset). We discuss main methodological aspects, particularly the well-known aspect of over- versus underestimation between brain and body temperature, which is relevant for potential clinical applications. PMID:28630878

  13. Transcranial doppler and near infrared spectroscopy in the perioperative period.

    PubMed

    Kampf, Stephanie; Schramm, Patrick; Klein, Klaus Ulrich

    2013-10-01

    Maintenance of adequate blood flow and oxygen to the brain is one of the principal endpoints of all surgery and anesthesia. During operations in general anesthesia, however, the brain is at particular risk for silent ischemia. Despite this risk, the brain still remains one of the last monitored organs in clincial anesthesiology. Transcranial Doppler (TCD) sonography and near-infrared spectroscopy (NIRS) experience a revival as these noninvasive technologies help to detect silent cerebral ischemia. TCD allows for quantification of blood flow velocities in basal intracranial arteries. TCD-derived variables such as the pulsatility index might hint toward diminished cognitive reserve or raised intracranial pressure. NIRS allows for assessment of regional cerebral oxygenation. Monitoring should be performed during high-risk surgery for silent cerebral ischemia and special circumstances during critical care medicine. Both techniques allow for the assessment of cerebrovascular autoregulation and individualized management of cerebral hemodynamics. TCD and NIRS are noninvasive monitors that anesthesiologists apply to tailor cerebral oxygen delivery, aiming to safeguard brain function in the perioperative period.

  14. Near-infrared imaging spectroscopy for counterfeit drug detection

    NASA Astrophysics Data System (ADS)

    Arnold, Thomas; De Biasio, Martin; Leitner, Raimund

    2011-06-01

    Pharmaceutical counterfeiting is a significant issue in the healthcare community as well as for the pharmaceutical industry worldwide. The use of counterfeit medicines can result in treatment failure or even death. A rapid screening technique such as near infrared (NIR) spectroscopy could aid in the search for and identification of counterfeit drugs. This work presents a comparison of two laboratory NIR imaging systems and the chemometric analysis of the acquired spectroscopic image data. The first imaging system utilizes a NIR liquid crystal tuneable filter and is designed for the investigation of stationary objects. The second imaging system utilizes a NIR imaging spectrograph and is designed for the fast analysis of moving objects on a conveyor belt. Several drugs in form of tablets and capsules were analyzed. Spectral unmixing techniques were applied to the mixed reflectance spectra to identify constituent parts of the investigated drugs. The results show that NIR spectroscopic imaging can be used for contact-less detection and identification of a variety of counterfeit drugs.

  15. [Oil spill identification by near-infrared spectroscopy].

    PubMed

    Wang, Li; Zhuo, Lin; He, Ying; Zhao, Ying; Li, Wei; Wang, Xiao-ru; Lee, Frank

    2004-12-01

    Petroleum oil spill happens occasionally at sea. It's important to differentiate the exact products in order to carry out following actions to decrease harmfulness. In the present study, a rapid oil spill identification method by near infrared spectroscopy coupled with pattern recognition techniques is proposed. 56 simulated spilled oils of gasoline, diesel fuel and lubricating oil in marine were chosen to develop the method. Organic reagent of CCl4 was used to extract the oil. Pattern recognition techniques were established by principal component analysis (PCA) coupled with Mahalanobis' distance with the multiplicative signal correction (MSC) and Norris first derivative pretreatment. The study shows that PCA technique is a useful method to extract the main characteristics, and Mahalanobis' distance is an ellipsoidal boundary that circumscribes a data cluster. And oil spill samples with concentration above 0.4 microL x mL(-1) can be successfully identified by the method. The developed technique could be further applied to the identification of spilled oil in marine.

  16. Rapid analysis of Radix puerariae by near-infrared spectroscopy.

    PubMed

    Lau, Ching-Ching; Chan, Chi-On; Chau, Foo-Tim; Mok, Daniel Kam-Wah

    2009-03-13

    A new, rapid analytical method using near-infrared spectroscopy (NIRS) was developed to differentiate two species of Radix puerariae (GG), Pueraria lobata (YG) and Pueraria thomsonii (FG), and to determine the contents of puerarin, daidzin and total isoflavonoid in the samples. Five isoflavonoids, puerarin, daidzin, daidzein, genistin and genistein were analyzed simultaneously by high-performance liquid chromatography-diode array detection (HPLC-DAD). The total isoflavonoid content was exploited as critical parameter for successful discrimination of the two species. Scattering effect and baseline shift in the NIR spectra were corrected and the spectral features were enhanced by several pre-processing methods. By using linear discriminant analysis (LDA) and soft independent modeling class analogy (SIMCA), samples were separated successfully into two different clusters corresponding to the two GG species. Furthermore, sensitivity and specificity of the classification models were determined to evaluate the performance. Finally, partial least squares (PLS) regression was used to build the correlation models. The results showed that the correlation coefficients of the prediction models are R=0.970 for the puerarin, R=0.939 for daidzin and R=0.969 for total isoflavonoid. The outcome showed that NIRS can serve as routine screening in the quality control of Chinese herbal medicine (CHM).

  17. Near-infrared spectroscopy of renal tissue in vivo

    NASA Astrophysics Data System (ADS)

    Grosenick, Dirk; Steinkellner, Oliver; Wabnitz, Heidrun; Macdonald, Rainer; Niendorf, Thoralf; Cantow, Kathleen; Flemming, Bert; Seeliger, Erdmann

    2013-03-01

    We have developed a method to quantify hemoglobin concentration and oxygen saturation within the renal cortex by near-infrared spectroscopy. A fiber optic probe was used to transmit the radiation of three semiconductor lasers at 690 nm, 800 nm and 830 nm to the tissue, and to collect diffusely remitted light at source-detector separations from 1 mm to 4 mm. To derive tissue hemoglobin concentration and oxygen saturation of hemoglobin the spatial dependence of the measured cw intensities was fitted by a Monte Carlo model. In this model the tissue was assumed to be homogeneous. The scaling factors between measured intensities and simulated photon flux were obtained by applying the same setup to a homogeneous semi-infinite phantom with known optical properties and by performing Monte Carlo simulations for this phantom. To accelerate the fit of the tissue optical properties a look-up table of the simulated reflected intensities was generated for the needed range of absorption and scattering coefficients. The intensities at the three wavelengths were fitted simultaneously using hemoglobin concentration, oxygen saturation, the reduced scattering coefficient at 800 nm and the scatter power coefficient as fit parameters. The method was employed to study the temporal changes of renal hemoglobin concentration and blood oxygenation on an anesthetized rat during a short period of renal ischemia induced by aortic occlusion and during subsequent reperfusion.

  18. Quantification of atmospheric formaldehyde by infrared absorption spectroscopy

    NASA Astrophysics Data System (ADS)

    Hoffnagle, John; Fleck, Derek; Rella, Chris; Kim-Hak, David

    2017-04-01

    Formaldehyde is a toxic, carcinogenic compound that can contaminate ambient air as a result of combustion or outgassing of commercial products such as adhesives used to fabricate plywood and to affix indoor carpeting. Like many small molecules, formaldehyde has an infrared absorption spectrum exhibiting bands of ro-vibrational transitions that are well resolved at low pressure and therefore well suited for optical analysis of formaldehyde concentration. We describe progress in applying cavity ring-down spectroscopy of the 2v5 band (the first overtone of the asymmetric C-H stretch, origin at 1770 nm) to the quantitative analysis of formaldehyde concentration in ambient air. Preliminary results suggest that a sensitivity of 1-2 ppb in a measurement interval of a few seconds, and 0.1-0.2 ppb in a few minutes, should be achievable with a compact, robust, and field-deployable instrument. Finally, we note that recent satellites monitoring snapshots of formaldehyde columns give insights into global formaldehyde production, migration and lifetime. The ability to monitor formaldehyde with a small and portable analyzer has the potential to aid in validation of these snapshots and to provide complementary data to show vertical dispersions with high spatial accuracy.

  19. Near-infrared Spectroscopy Of Outer Main Belt Asteroids

    NASA Astrophysics Data System (ADS)

    Takir, Driss; Emery, J.

    2009-09-01

    We have recently begun a spectral survey of the outer Main Belt population (3.2 AU < a < 4.6 AU), using near-infrared spectroscopy (0.8-2.5 μm). The objective of this survey is to search for signatures of H2O, organics, hydrated silicates, and/or anhydrous silicates on this group of asteroids. Studying the outer Main Belt asteroids will allow us to better understand the dynamical evolution of the Solar System and provide crucial constrains on nebular composition. Our first observing run, using the SpeX spectrograph/imager at the NASA IRTF, took place remotely form the University of Tennessee Knoxville on the nights of April 15, 16, and 17, 2009 (UT). More observing runs will be conducted this year and the beginning of next year. The initial data reduction process reveals that some of these asteroids exhibit weak and strong absorption features. We will present some of these initial spectra and results.

  20. Rapid Characterization of Tanshinone Extract Powder by Near Infrared Spectroscopy

    PubMed Central

    Luo, Gan; Xu, Bing; Shi, Xinyuan; Li, Jianyu; Dai, Shengyun; Qiao, Yanjiang

    2015-01-01

    Chemical and physical quality attributes of herbal extract powders play an important role in the research and development of Chinese medicine preparations. The active pharmaceutical ingredients have a direct impact on the herbal extract's efficacy, while the physical properties of raw material affect the pharmaceutical manufacturing process and the final products' quality. In this study, tanshinone extract powders from Salvia miltiorrhiza which are widely used for the treatment of cardiovascular diseases in the clinic are taken as the research object. Both the chemical information and physical information of tanshinone extract powders are analyzed by near infrared (NIR) spectroscopy. The partial least squares (PLS) and least square support vector machine (LS-SVM) models are investigated to build the relationship between NIR spectra and reference values. PLS models performed well for the content of crytotanshinone, tanshinone IIA, the moisture, and average median particle size, while, for specific surface area and tapped density, the LS-SVM models performed better than the PLS models. Results demonstrated NIR to be a valid and fast process analytical technology tool to simultaneously determine multiple quality attributes of herbal extract powders and indicated that there existed some nonlinear relationship between NIR spectra and physical quality attributes. PMID:25866511

  1. Functional data analysis view of functional near infrared spectroscopy data.

    PubMed

    Barati, Zeinab; Zakeri, Issa; Pourrezaei, Kambiz

    2013-11-01

    Functional near infrared spectroscopy (fNIRS) is a powerful tool for the study of oxygenation and hemodynamics of living tissues. Despite the continuous nature of the processes generating the data, analysis of fNIRS data has been limited to discrete-time methods. We propose a technique, namely functional data analysis (fDA), that converts discrete samples to continuous curves. We used fNIRS data collected on forehead during a cold pressor test (CPT) from 20 healthy subjects. Using functional principal component analysis, oxyhemoglobin (HbO2) and deoxyhemoglobin (Hb) curves were decomposed into several components based on variability across the subjects. Each component corresponded to an experimental condition and provided qualitative and quantitative information of the shape and weight of that component. Furthermore, we applied functional canonical correlation analysis to investigate the interaction between Hb and HbO2 curves. We showed that the variation of Hb and HbO2 was positively correlated during the CPT, with a "far" channel on right forehead showing a smaller and faster HbO2 variation than Hb. This research suggests the fDA platform for the analysis of fNIRS data, which solves problem of high dimensionality, enables study of response dynamics, enhances characterization of the evoked response, and may improve design of future fNIRS experiments.

  2. Near infrared spectroscopy based brain-computer interface

    NASA Astrophysics Data System (ADS)

    Ranganatha, Sitaram; Hoshi, Yoko; Guan, Cuntai

    2005-04-01

    A brain-computer interface (BCI) provides users with an alternative output channel other than the normal output path of the brain. BCI is being given much attention recently as an alternate mode of communication and control for the disabled, such as patients suffering from Amyotrophic Lateral Sclerosis (ALS) or "locked-in". BCI may also find applications in military, education and entertainment. Most of the existing BCI systems which rely on the brain's electrical activity use scalp EEG signals. The scalp EEG is an inherently noisy and non-linear signal. The signal is detrimentally affected by various artifacts such as the EOG, EMG, ECG and so forth. EEG is cumbersome to use in practice, because of the need for applying conductive gel, and the need for the subject to be immobile. There is an urgent need for a more accessible interface that uses a more direct measure of cognitive function to control an output device. The optical response of Near Infrared Spectroscopy (NIRS) denoting brain activation can be used as an alternative to electrical signals, with the intention of developing a more practical and user-friendly BCI. In this paper, a new method of brain-computer interface (BCI) based on NIRS is proposed. Preliminary results of our experiments towards developing this system are reported.

  3. Adulteration identification in raw milk using Fourier transform infrared spectroscopy.

    PubMed

    Coitinho, Tatiane Barbosa; Cassoli, Laerte Dagher; Cerqueira, Pedro Henrique Ramos; da Silva, Helen Krystine; Coitinho, Juliana Barbosa; Machado, Paulo Fernando

    2017-07-01

    Adulteration of milk is a common practice that concerns regulatory agencies, industry, and the population. Despite the growing need for checking adulteration, the current methods employed generally have low performance and are highly dependent on manual labor. This study aims to calibrate and validate a compact equipment (MilkoScan FT1) that adopts a Fourier transform infrared spectroscopy methodology to monitor adulteration in raw milk. Almost 2500 milk samples were used for reference spectrum construction and 1650 samples were used to validate the identification of the following five most commonly used adulterants (at three different concentrations each): (1) cornstarch, (2) sodium bicarbonate, (3) sodium citrate, (4) formaldehyde, and (5) saccharose, plus the additions of two levels of water or whey. To define the calibration with the best performance in milk adulteration identification, 12 calibrations involving 8, 10, 12, 14, 16, or 18 factors, with one or two outlier eliminations, were developed. The results of sensitivity and specificity analyses, as well as Kruskal-Wallis and Dunn multiple comparison tests, revealed that the calibration that best identified the adulterants was the one involving 14 factors, with a single elimination of outliers, exhibiting for all adulterants simultaneously, 84% sensitivity and 100% specificity. The calibration showed excellent sensitivity to cornstarch (>98%), sodium bicarbonate (100%), sodium citrate (99%), and formaldehyde (>84%), indicating that this calibration has good capacity for adulteration detection. Thus, this methodology is a viable option for the dairy industry to identify adulteration of raw milk.

  4. A novel storage method for near infrared spectroscopy chemometric models.

    PubMed

    Zhang, Zhi-Min; Chen, Shan; Liang, Yi-Zeng

    2010-06-04

    Chemometric Modeling Markup Language (CMML) is developed by us for containing chemometrics models within one document through converting binary data into strings by base64 encode/decode algorithms to solve the interoperability issue in sharing chemometrics models. It provides a base functionality for storage of sampling, variable selection, pretreating, outlier and modeling parameters and data. With the help of base64 algorithm, the usability of CMML is in equilibrium with size by transforming the binary data into base64 encoded string. Due to the advantages of Extensible Markup Language (XML), models stored in CMML can be easily reused in various other software and programming languages as long as the programming language has XML parsing library. One can also use the XML Path Language (XPath) query language to select desired data from the CMML file effectively. The application of this language in near infrared spectroscopy model storage is implemented as a class in C++ language and available as open source software (http://code.google.com/p/cmml), and the implementations in other languages, such as MATLAB and R are in progress.

  5. Bundled-Optode Method in Functional Near-Infrared Spectroscopy

    PubMed Central

    Nguyen, Hoang-Dung; Hong, Keum-Shik; Shin, Yong-Il

    2016-01-01

    In this paper, a theory for detection of the absolute concentrations of oxy-hemoglobin (HbO) and deoxy-hemoglobin (HbR) from hemodynamic responses using a bundled-optode configuration in functional near-infrared spectroscopy (fNIRS) is proposed. The proposed method is then applied to the identification of two fingers (i.e., little and thumb) during their flexion and extension. This experiment involves a continuous-wave-type dual-wavelength (760 and 830 nm) fNIRS and five healthy male subjects. The active brain locations of two finger movements are identified based on the analysis of the t- and p-values of the averaged HbOs, which are quite distinctive. Our experimental results, furthermore, revealed that the hemodynamic responses of two-finger movements are different: The mean, peak, and time-to-peak of little finger movements are higher than those of thumb movements. It is noteworthy that the developed method can be extended to 3-dimensional fNIRS imaging. PMID:27788178

  6. Application of functional near-infrared spectroscopy in psychiatry.

    PubMed

    Ehlis, Ann-Christine; Schneider, Sabrina; Dresler, Thomas; Fallgatter, Andreas J

    2014-01-15

    Two decades ago, the introduction of functional near-infrared spectroscopy (fNIRS) into the field of neuroscience created new opportunities for investigating neural processes within the human cerebral cortex. Since then, fNIRS has been increasingly used to conduct functional activation studies in different neuropsychiatric disorders, most prominently schizophrenic illnesses, affective disorders and developmental syndromes, such as attention-deficit/hyperactivity disorder as well as normal and pathological aging. This review article provides a comprehensive overview of state of the art fNIRS research in psychiatry covering a wide range of applications, including studies on the phenomenological characterization of psychiatric disorders, descriptions of life-time developmental aspects, treatment effects, and genetic influences on neuroimaging data. Finally, methodological shortcomings as well as current research perspectives and promising future applications of fNIRS in psychiatry are discussed. We conclude that fNIRS is a valid addition to the range of neuroscientific methods available to assess neural mechanisms underlying neuropsychiatric disorders. Future research should particularly focus on expanding the presently used activation paradigms and cortical regions of interest, while additionally fostering technical and methodological advances particularly concerning the identification and removal of extracranial influences on fNIRS data as well as systematic artifact correction. Eventually, fNIRS might be a useful tool in practical psychiatric settings involving both diagnostics and the complementary treatment of psychological disorders using, for example, neurofeedback applications.

  7. Mid-infrared dual-comb spectroscopy with an optical parametric oscillator.

    PubMed

    Zhang, Zhaowei; Gardiner, Tom; Reid, Derryck T

    2013-08-15

    We present the first implementation of mid-infrared dual-comb spectroscopy with an optical parametric oscillator. Methane absorption spectroscopy was demonstrated with a resolution of 0.2 cm(-1) (5 GHz) at an acquisition time of ~10.4 ms over a spectral coverage at 2900-3050 cm(-1). The average power from each individual mid-infrared comb line was ~1 μW, representing a power level much greater than typical difference-frequency-generation sources. Mid-infrared dual-comb spectroscopy opens up unique opportunities to perform broadband spectroscopic measurements with high resolution, high requisition rate, and high detection sensitivity.

  8. Enhanced visible and near-infrared capabilities of the JET mirror-linked divertor spectroscopy system

    SciTech Connect

    Lomanowski, B. A. Sharples, R. M.; Meigs, A. G.; Conway, N. J.; Zastrow, K.-D.; Heesterman, P.; Kinna, D. [EURATOM Collaboration: JET-EFDA Team

    2014-11-15

    The mirror-linked divertor spectroscopy diagnostic on JET has been upgraded with a new visible and near-infrared grating and filtered spectroscopy system. New capabilities include extended near-infrared coverage up to 1875 nm, capturing the hydrogen Paschen series, as well as a 2 kHz frame rate filtered imaging camera system for fast measurements of impurity (Be II) and deuterium Dα, Dβ, Dγ line emission in the outer divertor. The expanded system provides unique capabilities for studying spatially resolved divertor plasma dynamics at near-ELM resolved timescales as well as a test bed for feasibility assessment of near-infrared spectroscopy.

  9. Enhanced visible and near-infrared capabilities of the JET mirror-linked divertor spectroscopy systema)

    NASA Astrophysics Data System (ADS)

    Lomanowski, B. A.; Meigs, A. G.; Conway, N. J.; Zastrow, K.-D.; Sharples, R. M.; Heesterman, P.; Kinna, D.

    2014-11-01

    The mirror-linked divertor spectroscopy diagnostic on JET has been upgraded with a new visible and near-infrared grating and filtered spectroscopy system. New capabilities include extended near-infrared coverage up to 1875 nm, capturing the hydrogen Paschen series, as well as a 2 kHz frame rate filtered imaging camera system for fast measurements of impurity (Be II) and deuterium Dα, Dβ, Dγ line emission in the outer divertor. The expanded system provides unique capabilities for studying spatially resolved divertor plasma dynamics at near-ELM resolved timescales as well as a test bed for feasibility assessment of near-infrared spectroscopy.

  10. Near infrared spectroscopic imaging assessment of cartilage composition: Validation with mid infrared imaging spectroscopy.

    PubMed

    Palukuru, Uday P; Hanifi, Arash; McGoverin, Cushla M; Devlin, Sean; Lelkes, Peter I; Pleshko, Nancy

    2016-07-05

    Disease or injury to articular cartilage results in loss of extracellular matrix components which can lead to the development of osteoarthritis (OA). To better understand the process of disease development, there is a need for evaluation of changes in cartilage composition without the requirement of extensive sample preparation. Near infrared (NIR) spectroscopy is a chemical investigative technique based on molecular vibrations that is increasingly used as an assessment tool for studying cartilage composition. However, the assignment of specific molecular vibrations to absorbance bands in the NIR spectrum of cartilage, which arise from overtones and combinations of primary absorbances in the mid infrared (MIR) spectral region, has been challenging. In contrast, MIR spectroscopic assessment of cartilage is well-established, with many studies validating the assignment of specific bands present in MIR spectra to specific molecular vibrations. In the current study, NIR imaging spectroscopic data were obtained for compositional analysis of tissues that served as an in vitro model of OA. MIR spectroscopic data obtained from the identical tissue regions were used as the gold-standard for collagen and proteoglycan (PG) content. MIR spectroscopy in transmittance mode typically requires a much shorter pathlength through the sample (≤10 microns thick) compared to NIR spectroscopy (millimeters). Thus, this study first addressed the linearity of small absorbance bands in the MIR region with increasing tissue thickness, suitable for obtaining a signal in both the MIR and NIR regions. It was found that the linearity of specific, small MIR absorbance bands attributable to the collagen and PG components of cartilage (at 1336 and 856 cm(-1), respectively) are maintained through a thickness of 60 μm, which was also suitable for NIR data collection. MIR and NIR spectral data were then collected from 60 μm thick samples of cartilage degraded with chondroitinase ABC as a model

  11. Application of Raman Spectroscopy and Infrared Spectroscopy in the Identification of Breast Cancer.

    PubMed

    Depciuch, Joanna; Kaznowska, Ewa; Zawlik, Izabela; Wojnarowska, Renata; Cholewa, Marian; Heraud, Philip; Cebulski, Józef

    2016-02-01

    Raman spectroscopy and infrared (IR) spectroscopy are both techniques that allow for the investigation of vibrating chemical particles. These techniques provide information not only about chemical particles through the identification of functional groups and spectral analysis of so-called "fingerprints", these methods allow for the qualitative and quantitative analyses of chemical substances in the sample. Both of these spectral techniques are frequently being used in biology and medicine in diagnosing illnesses and monitoring methods of therapy. The type of breast cancer found in woman is often a malignant tumor, causing 1.38 million new cases of breast cancer and 458 000 deaths in the world in 2013. The most important risk factors for breast cancer development are: sex, age, family history, specific benign breast conditions in the breast, ionizing radiation, and lifestyle. The main purpose of breast cancer screening tests is to establish early diagnostics and to apply proper treatment. Diagnoses of breast cancer are based on: (1) physical techniques (e.g., ultrasonography, mammography, elastography, magnetic resonance, positron emission tomography [PET]); (2) histopathological techniques; (3) biological techniques; and (4) optical techniques (e.g., photo acoustic imaging, fluorescence tomography). However, none of these techniques provides unique or especially revealing answers. The aim of our study is comparative spectroscopic measurements on patients with the following: normal non-cancerous breast tissue; breast cancer tissues before chemotherapy; breast cancer tissues after chemotherapy; and normal breast tissues received around the cancerous breast region. Spectra collected from breast cancer patients shows changes in amounts of carotenoids and fats. We also observed changes in carbohydrate and protein levels (e.g., lack of amino acids, changes in the concentration of amino acids, structural changes) in comparison with normal breast tissues. This fact

  12. [Application of near infrared reflectance spectroscopy to predict meat chemical compositions: a review].

    PubMed

    Tao, Lin-Li; Yang, Xiu-Juan; Deng, Jun-Ming; Zhang, Xi

    2013-11-01

    In contrast to conventional methods for the determination of meat chemical composition, near infrared reflectance spectroscopy enables rapid, simple, secure and simultaneous assessment of numerous meat properties. The present review focuses on the use of near infrared reflectance spectroscopy to predict meat chemical compositions. The potential of near infrared reflectance spectroscopy to predict crude protein, intramuscular fat, fatty acid, moisture, ash, myoglobin and collagen of beef, pork, chicken and lamb is reviewed. This paper discusses existing questions and reasons in the current research. According to the published results, although published results vary considerably, they suggest that near-infrared reflectance spectroscopy shows a great potential to replace the expensive and time-consuming chemical analysis of meat composition. In particular, under commercial conditions where simultaneous measurements of different chemical components are required, near infrared reflectance spectroscopy is expected to be the method of choice. The majority of studies selected feature-related wavelengths using principal components regression, developed the calibration model using partial least squares and modified partial least squares, and estimated the prediction accuracy by means of cross-validation using the same sample set previously used for the calibration. Meat fatty acid composition predicted by near-infrared spectroscopy and non-destructive prediction and visualization of chemical composition in meat using near-infrared hyperspectral imaging and multivariate regression are the hot studying field now. On the other hand, near infrared reflectance spectroscopy shows great difference for predicting different attributes of meat quality which are closely related to the selection of calibration sample set, preprocessing of near-infrared spectroscopy and modeling approach. Sample preparation also has an important effect on the reliability of NIR prediction; in particular

  13. Infrared Spectroscopy of Star Formation in Galactic and Extragalactic Regions

    NASA Technical Reports Server (NTRS)

    Smith, Howard A.; Hasan, Hashima (Technical Monitor)

    2004-01-01

    Last year we submitted and had accepted a paper entitled "The Far-Infrared Emission Line and Continuum Spectrum of the Seyfert Galaxy NGC 1068," by Spinoglio, L., Malkan, M., Smith. HA, Gonzalez-Alfonso, E., and Fischer, J. This analysis was based on the SWAS Monte Carlo code modeling of the OH lines in galaxies observed by ISO. Since that meeting last spring considerable effort has been put into improving the Monte Carlo code. A group of European astronomers, including Prof. Eduardo Gonzalez-Alfonso, had been performing Monte Carlo modeling of other molecules seen in ISO galaxies. We used portions of this grant to bring Prof. Gonzalez-Alfonso to Cambridge for an intensive working visit. A second major paper on the ISO IR spectroscopy of galaxies, "The Far Infrared Spectrum of Arp 220," Gonzalez-Alfonso, E., Smith. H., Fischer, J., and Cernicharo, J., is in press. Spitzer science development was the major component of this past year;s research. This program supported the development of five Early Release Objects for Spitzer observations on which Dr. Smith was Principal Investigator or Co-Investigator, and another five proposals for GO time. The early release program is designed to rapidly present to the public and the scientific community some exciting results from Spitzer in the first months of its operation. The Spitzer instrument and science teams submitted proposals for ERO objects, and a competitive selection process narrowed these down to a small group with exciting science and realistic observational parameters. This grant supported Dr. Smith's participation in the ERO process, including developing science goals, identifying key objects for observation, and developing the detailed AOR (observing formulae) to be use by the instruments for mapping, integrating, etc.). During this year Dr. Smith worked on writing up and publishing these early results. The attached bibliography includes six of Dr. Smith's articles. During this past year Dr. Smith also led or

  14. Jupiter's atmospheric composition from the Cassini thermal infrared spectroscopy experiment

    NASA Technical Reports Server (NTRS)

    Kunde, V. G.; Flasar, F. M.; Jennings, D. E.; Bezard, B.; Strobel, D. F.; Conrath, B. J.; Nixon, C. A.; Bjoraker, G. L.; Romani, P. N.; Achterberg, R. K.; hide

    2004-01-01

    The Composite Infrared Spectrometer observed Jupiter in the thermal infrared during the swing-by of the Cassini spacecraft. Results include the detection of two new stratospheric species, the methyl radical and diacetylene, gaseous species present in the north and south auroral infrared hot spots; determination of the variations with latitude of acetylene and ethane, the latter a tracer of atmospheric motion; observations of unexpected spatial distributions of carbon dioxide and hydrogen cyanide, both considered to be products of comet Shoemaker-Levy 9 impacts; characterization of the morphology of the auroral infrared hot spot acetylene emission; and a new evaluation of the energetics of the northern auroral infrared hot spot.

  15. Jupiter's atmospheric composition from the Cassini thermal infrared spectroscopy experiment.

    PubMed

    Kunde, V G; Flasar, F M; Jennings, D E; Bézard, B; Strobel, D F; Conrath, B J; Nixon, C A; Bjoraker, G L; Romani, P N; Achterberg, R K; Simon-Miller, A A; Irwin, P; Brasunas, J C; Pearl, J C; Smith, M D; Orton, G S; Gierasch, P J; Spilker, L J; Carlson, R C; Mamoutkine, A A; Calcutt, S B; Read, P L; Taylor, F W; Fouchet, T; Parrish, P; Barucci, A; Courtin, R; Coustenis, A; Gautier, D; Lellouch, E; Marten, A; Prangé, R; Biraud, Y; Ferrari, C; Owen, T C; Abbas, M M; Samuelson, R E; Raulin, F; Ade, P; Césarsky, C J; Grossman, K U; Coradini, A

    2004-09-10

    The Composite Infrared Spectrometer observed Jupiter in the thermal infrared during the swing-by of the Cassini spacecraft. Results include the detection of two new stratospheric species, the methyl radical and diacetylene, gaseous species present in the north and south auroral infrared hot spots; determination of the variations with latitude of acetylene and ethane, the latter a tracer of atmospheric motion; observations of unexpected spatial distributions of carbon dioxide and hydrogen cyanide, both considered to be products of comet Shoemaker-Levy 9 impacts; characterization of the morphology of the auroral infrared hot spot acetylene emission; and a new evaluation of the energetics of the northern auroral infrared hot spot.

  16. Infrared Spectroscopy of Phenol-Triethylsilane Dihydrogen-Bonded Cluster

    NASA Astrophysics Data System (ADS)

    Ishikawa, Haruki; Kawasaki, Takayuki

    2013-06-01

    Dihydrogen bond is a hydrogen bond between oppositely charged two hydrogen atoms, X-H\\cdotsH-Y, where X = O, N and Y = B, metal atoms, for example. In 2005, Ishikawa and coworkers reported the observation of the dihydrogen-bond system involving Si-H group as the proton acceptor. They carried out infrared (IR) spectroscopy of phenol(PhOH)-Diethylmethylsilane(DEMS) clusters. All of the three isomers of PhOH-DEMS 1:1 clusters observed exhibit a small red-shift of ˜{ν}_{ OH} of the PhOH moiety in the cluster compared with that of bare PhOH. The largest shift is -29 cm^{-1}. The small red-shift is considered to be the result of the competition between the O-H\\cdotsH-Si dihydrogen-bond and the dispersion interaction of alkyl group of DEMS with phenyl ring. It means that the strength of the O-H\\cdotsH-Si dihydrogen-bond is comparable to the dispersion force. In the present study, we have performed fluorescence excitation (FE) and IR spectroscopies of phenol-triethylsilane(TES) to widen the knowledge of the dihydrogen bond. Similar to the case of PhOH-DEMS system, the electronic origin bands of three PhOH-TES isomers appear in the vicinity of that of PhOH monomer in the FE spectrum. In the present study, we have found an origin band of another PhOH-TES isomer showing a red-shift of -120 cm^{-1}. The shift of ˜{ν}_{ OH} of this cluster is found to be -78 cm^{-1}. This value is much larger than those of the other PhOH-TES 1:1 clusters. It is expected that the spatial overlap of between the TES and the phenyl ring in this cluster is small so that the contribution of the O-H\\cdotsH-Si dihydrogen-bond becomes larger than the other isomers. We have performed density-functional-theory (DFT) calculation of the PhOH-TES clusters using M05-2X functional. The result of the DFT calculation supported the cluster structure and the large red-shift of ˜{ν}_{ OH} of the newly found isomer of PhOH-TES. H. Ishikawa, A. Saito, M. Sugiyama, N. Mikami, J. Chem. Phys. 123, 224309 (2005).

  17. Multi-mode heterodyned 5th-order infrared spectroscopy

    NASA Astrophysics Data System (ADS)

    Leger, Joel D.; Varner, Clyde; Rubtsov, Igor V.

    2016-10-01

    Fifth-order multidimensional infrared spectroscopy with heterodyned detection was carried out in the three-beam dual-frequency configuration. Numerous 5th-order cross peaks were detected for the 4-azidobutyrate-N-hydroxysuccinimide ester compound in solution involving several vibrational modes ranging in frequency from 1045 to 2100 cm-1. Cross peaks involving overtones (2X/Z) and combination bands (XY/Z) among the tags, modes X and Y excited by the first two mid-IR laser pulses, and the reporter, modes Z excited by the third laser pulse, were acquired and the factors affecting the amplitude of 5th-order cross peaks are discussed. The 5th-order cross peaks were detected among modes that are spatially close (a few bonds apart) as well as for modes spatially separated by ca. 12 Å (eight bonds apart). In both cases, the waiting time dependences for the 3rd and 5th order cross peaks were found to be different. In particular, the waiting time at which the cross-peak maximum is reached, the decay time, and the value of a plateau at large waiting times were all differing strongly. The differences are explained by reduced sensitivity of the 5th-order signals to modes coupled weakly to the reporter mode and different relaxation dynamics involving overtone state of the tag. The ability of the 5th-order peaks to single out the modes coupled strongly to the reporter can help identifying specific energy relaxation and transport pathways, which will be useful for understanding energy transport dynamics in molecules. The absorptive 5th-order cross peaks were constructed which report on three-point correlation functions. It is shown that in addition to the triple-frequency correlation functions, a correlation of the frequencies with the mode coupling (anharmonicity) can be naturally measured by the 5th-order spectroscopy. The current limit for detecting 5th-order signals was estimated at the level of 1 × 10-3 in reduced anharmonicity, which is determined by the corresponding two

  18. Cirrus cloud mimics in the laboratory: an infrared spectroscopy study of thin films of mixed ice of water with organic acids and ammonia.

    PubMed

    Hellebust, Stig; O'Riordan, Brian; Sodeau, John

    2007-02-28

    The structures of formic and acetic acids deposited on a thin gold substrate held in vacuum at low temperatures and their related water-ice promoted chemistry have been investigated. The condensed water/guest films were taken to act as cirrus cloud "mimics." Such laboratory representations provide a necessary prelude to understanding how low temperature surfaces can affect chemical composition changes in the upper atmosphere. The systems were characterized by reflection-absorption infrared spectroscopy and temperature-programmed desorption spectrometry. The interaction behavior of the binary acid ices was compared to that observed when ternary mixtures of water, formic acid, and ammonia were deposited. Differences in the chemistry were observed depending on deposition method: layering or mixing. The more atmospherically relevant codeposition approach showed that at low temperatures, amorphous formic acid can be ionized to its monodentate form by water ice within the bulk rather than on the surface. In contrast, the introduction of ammonia leads to full bidentate ionization on the ice surface. The thermal desorption profiles of codeposited films of water, ammonia, and formic acid indicate that desorption occurs in three stages. The first is a slow release of ammonia between 120 and 160 K, then the main water desorption event occurs with a maximum rate close to 180 K, followed by a final release of ammonia and formic acid at about 230 K originating from nonhydrous ammonium formate on the surface. The behavior of acetic acid is similar to formic acid but shows lesser propensity to ionize in bulk water ice.

  19. [Study on Identification of Three Medicinal Plant Leaves from Elaeagnus Genus by Infrared Spectroscopy].

    PubMed

    Zhang, Fei; Li, Lu-yang; Ding, Qi; Hu, Ji-qing; Long, Wei-fang; Wan, Ding-rong

    2015-01-01

    To study and identify the three species of dry medicinal plant leaves trom Elaeagnus genus (E. pungens, E. lanceolata and E. henryi) by Infrared Spectroscopy(IR). Fourier transform infrared spectroscopy and second derivative infrared spectroscopy were used to study and compare the characteristics of leaves of three Elaeagnus medicinal plants. The IR spectra and second derivative infrared spectra of the three Elaeagnus plants leaves were similar on the whole, the intensity or ratio of intensity of some absorption peaks still had certain distinctions, and the differences of the second derivative infrared spectra were more obvious. There were only slight differences between large and small leaf type of samples of Elaeagnus lanceolata; the differences of the plant leaves of one species collected in different harvest periods were far smaller than those of others belonging to the same genus. IR can be relatively reliably used for identification of the three Elaeagnus leaves.

  20. [Research progress in using functional near-infrared spectroscopy for monitoring depth of anesthesia].

    PubMed

    Hong, Wen-Xue; Zhang, Zhong-Peng; Song, Jia-Lin; Li, Shao-Xiong; Luan, Jing-Min; Chen, Ning; Tan, Jian-Qiang

    2012-11-01

    Intra-operation monitoring depth of anesthesia is an important method to insure the quality and safety of clinical anesthesia. As a noninvasive brain function monitoring technology, functional near-infrared spectroscopy can provide objective and reliable brain activity monitoring and imaging in real time. The characteristic of this technique is highly suitable for interrelated research on depth of anesthesia monitoring. The present paper briefly introduced the fundamental and instruments of functional near-infrared spectroscopy, reviewed the current situation about the application of functional near-infrared spectroscopy in research on depth of anesthesia monitoring, pointed out the possible way of using functional near-infrared spectroscopy in depth of anesthesia monitoring research, and expounded the unsolved problems and future prospects.

  1. Rapid discrimination of china sponges by Tri-step infrared spectroscopy: A preliminary study

    NASA Astrophysics Data System (ADS)

    Gan, Jian-Hong; Xu, Chang-Hua; Yu, Hao-Bing; Lin, Hou-Wen; Zhou, Qun; Sun, Su-Qin

    2014-07-01

    Trip-step infrared spectroscopy, Fourier transform infrared spectroscopy combined with second derivative infrared spectroscopy (SD-IR) and two-dimensional correlation infrared spectroscopy (2DCOS-IR), was employed to characterize and discriminate nine China sponges. Sponges from different classes and different orders had respective unique IR macro-fingerprints. Their IR spectra suggested that the prime ingredient of calcareous sponges was calcium carbonate in calcite and/or aragonite forms, but that of demosponges was protein. Particularly, the sponges from the same genus which could not be identified by traditional spicule identification have been definitely discriminated. For sponges having highly similar chemical profile (IR spectral profile), SD-IR and 2DCOS-IR have been applied to enhance the spectral resolution to distinguish the sponges convincingly.

  2. [Studies on normal and mildewy Auricularia auricular by Fourier transform infrared spectroscopy].

    PubMed

    Shi, You-ming; Liu, Gang; Sun, Yan-lin; Wei, Sheng-xian; Yan, Cui-qiong

    2011-03-01

    In order to verify the capability of Fourier transform infrared spectroscopy in food safety, Fourier transform infrared spectroscopy (FTIR) was used to obtain the spectra of normal and mildewy auricularia auricula, The result showed the frequency of hydroxyl and aliphatic absorption band in their spectra had evident differentia, with the dispersion being 23.31 and 13.41 cm(-1) respectively. The curve-fitting analysis was used for the fold peaks of hydroxyl and amido, and it presented that the content of hydroxyl and amido had evident change. The substances in the auricularia auricula generated chemical change, and Fourier transform infrared spectroscopy could show the differentia easily. The results show that Fourier transform infrared spectroscopy can provide valuable information about the auricularia auricula. It could be used as a reference method for identification of the normal and mildewy auricularia auricula.

  3. A study of infrared spectroscopy de-noising based on LMS adaptive filter

    NASA Astrophysics Data System (ADS)

    Mo, Jia-qing; Lv, Xiao-yi; Yu, Xiao

    2015-12-01

    Infrared spectroscopy has been widely used, but which often contains a lot of noise, so the spectral characteristic of the sample is seriously affected. Therefore the de-noising is very important in the spectrum analysis and processing. In the study of infrared spectroscopy, the least mean square (LMS) adaptive filter was applied in the field firstly. LMS adaptive filter algorithm can reserve the detail and envelope of the effective signal when the method was applied to infrared spectroscopy of breast cancer which signal-to-noise ratio (SNR) is lower than 10 dB, contrast and analysis the result with result of wavelet transform and ensemble empirical mode decomposition (EEMD). The three evaluation standards (SNR, root mean square error (RMSE) and the correlation coefficient (ρ)) fully proved de-noising advantages of LMS adaptive filter in infrared spectroscopy of breast cancer.

  4. Toward Precision Mid-Infrared Spectroscopy on the OH Radical

    NASA Astrophysics Data System (ADS)

    Fast, Arthur; Furneaux, John; Meek, Samuel

    2016-06-01

    Measurements of vibrational transitions in small molecules can be used to test for a possible time variation of the electron-proton mass ratio. In our experiments, our goal is to measure two-photon v = 2 ← v = 0 vibrational transitions in the hydroxyl (OH) radical near 2 × 3500 wn with a relative accuracy of 10-14. Reaching this level of accuracy requires a mid-infrared laser with a linewidth of much less than 1 kHz, as well as the ability to compare the frequency of this laser with an absolute frequency standard. To achieve the high short-term stability necessary for such a narrow linewidth, we are implementing a 532-nm CW reference laser by locking a frequency-doubled Nd:YAG laser to a molecular iodine transition using saturated absorption spectroscopy. Similar setups have demonstrated relative stabilities of around 10-14 at the one-second timescale. The stability of this reference laser will then be transfered onto the idler of a 1064-nm-pumped optical parametric oscillator (OPO) using an optical frequency comb as a transfer oscillator. The frequency comb will also be used to measure the absolute optical frequencies of the various lasers and compare them to a GPS-linked radio frequency reference, providing long-term stability and absolute accuracy for the spectroscopic measurements. J.-P. Uzan. Rev. Mod. Phys. 75, 403-455 (2003). Döringshoff, K., Mohle, K., Nagel, M., Kovalchuk, E. V., Peters, A: High performance iodine frequency reference for tests of the LISA laser system. EFTF-2010 24th European Frequency and Time Forum (2010)

  5. Human Milk Analysis Using Mid-Infrared Spectroscopy.

    PubMed

    Groh-Wargo, Sharon; Valentic, Jennifer; Khaira, Sharmeel; Super, Dennis M; Collin, Marc

    2016-04-01

    The composition of human milk is known to vary with length of gestation, stage of lactation, and other factors. Human milk contains all nutrients required for infant health but requires fortification to meet the needs of low-birth-weight infants. Without a known nutrient profile of the mother's milk or donor milk fed to a baby, the composition of the fortified product is only an estimate. Human milk analysis has the potential to improve the nutrition care of high-risk newborns by increasing the information about human milk composition. Equipment to analyze human milk is available, and the technology is rapidly evolving. This pilot study compares mid-infrared (MIR) spectroscopy to reference laboratory milk analysis. After obtaining informed consent, we collected human milk samples from mothers of infants weighing <2 kg at birth. Duplicate samples were analyzed for macronutrients by MIR and by reference laboratory analysis including Kjeldahl for protein, Mojonnier for fat, and high-pressure liquid chromatography for lactose. Intraclass correlation coefficients, Bland-Altman scatter plots, and paired t tests were used to compare the two methods. No significant differences were detected between the macronutrient content of human milk obtained by MIR vs reference laboratory analysis. MIR analysis appears to provide an accurate assessment of macronutrient content in expressed human milk from mothers of preterm infants. The small sample size of this study limits confidence in the results. Measurement of lactose is confounded by the presence of oligosaccharides. Human milk analysis is a potentially useful tool for establishing an individualized fortification plan. © 2015 American Society for Parenteral and Enteral Nutrition.

  6. Fetal oxygenation measurement using wireless near infrared spectroscopy

    NASA Astrophysics Data System (ADS)

    Macnab, Andrew; Shadgan, Babak; Janssen, Patricia; Rurak, Dan

    2012-03-01

    Background: Fetal well-being is determined in large part by how well the placenta is able to supply oxygen and nutrients, but current technology is unable to directly measure how well a placenta functions. Near-infrared spectroscopy (NIRS) utilizes optical methods to measure tissue oxygenation. This pilot project evaluated the feasibility of NIRS for fetal monitoring through the maternal abdominal wall using a sheep model. Methods: A miniature wireless 2-wavelength NIRS device was placed on the abdominal skin over the placenta of a pregnant ewe whose fetus had been chronically catheterized to allow arterial sampling for measurement of arterial oxygen saturation. The NIRS device has 3-paired light emitting diodes and a single photodiode detector; allowing measurement of an index of tissue oxygen saturation (TSI%). Fetal limb TSI% values were compared before and during fetal breathing movements. Correlation was made during these events between arterial values and placental TSI% monitored continuously in real time. Results: Serial measurements were obtained in a single experiment. The correlation between transcutaneous NIRS derived TSI% and direct arterial oxygen saturation was very high (R2=0.86). Measures of fetal limb TSI% were declined after episodes of fetal breathing (P<0.005). Conclusions: This correlation suggests that NIRS is sensitive enough to detect changes in fetal tissue oxygenation noninvasively through the maternal abdominal wall in real-time in a sheep model. NIRS data confirmed that fetal breathing movements decrease arterial oxygen saturation in fetal lambs. If validated by further study this optical methodology could be applied as means of monitoring fetal wellbeing in humans.

  7. MOS spectroscopy with the JWST Near-Infrared Spectrometer

    NASA Astrophysics Data System (ADS)

    Karakla, Diane M.; Beck, Tracy; Gilbert, Karoline; Pontoppidan, Klaus Martin; Curtis, Gary; Shyrokov, Alexander

    2015-08-01

    The James Webb Space Telescope's Near-Infrared Spectrograph (NIRSpec) will feature astronomy’s first space-based, multi-object spectroscopic (MOS) capability enabled by the instrument’s micro-shutter array (MSA). The MSA is a four-quadrant fixed grid of nearly 250,000 tiny shutters that can be configured into slits on multiple astronomical targets in a field. In MOS mode, NIRSpec can obtain spectra of more than 100 targets simultaneously in one of three spectral bands (1.0 - 1.8 μm, 1.7 - 3.0 μm, and 2.9 - 5.0 μm) at medium (R~1000) or high resolution (R~2700) with the gratings, or at lower resolution (R~100, 0.6 - 5.0 μm) with the PRISM. The NIRSpec team and software developers at the Space Telescope Science Institute (STScI) have developed an MSA Planning Tool (MPT) to facilitate the complex observation planning process for a variety of observing strategies. The purpose of the tool is to find optimal pointings on the sky where many sources (or many high-valued sources) can be observed at a given pointing, or through a set of telescope dithers, and to design the associated MSA configurations at each position. The MPT is available to the astronomical community as part of the Astronomer’s Proposal Tool (APT), an integrated software package developed by STScI for the preparation of observing proposals. We will summarize the operational concept for MOS spectroscopy with the instrument, describe the MSA Planning Tool and its algorithms, and highlight recent developments that extend the tool’s applicability to diverse science cases.

  8. Effect of Mechanical Optical Clearing on Near-infrared Spectroscopy

    PubMed Central

    Idelson, Christopher R.; Vogt, William C.; King-Casas, Brooks; LaConte, Stephen M.; Rylander, Christopher G.

    2015-01-01

    Near-infrared Spectroscopy (NIRS) is a broadly utilized technology with many emerging applications including clinical diagnostics, sports medicine, and functional neuroimaging, to name a few. For functional brain imaging NIR light is delivered at multiple wavelengths through the scalp and skull to the brain to enable spatial oximetry measurements. Dynamic changes in brain oxygenation are highly correlated with neural stimulation, activation, and function. Unfortunately, NIRS is currently limited by its low spatial resolution, shallow penetration depth, and, perhaps most importantly, signal corruption due to light interactions with superficial non-target tissues such as scalp and skull. In response to these issues, we have combined the non-invasive and rapidly reversible method of mechanical tissue optical clearing (MOC) with a commercially available NIRS system. MOC utilizes a compressive loading force on tissue, causing the lateral displacement of blood and water, while simultaneously thinning the tissue. A MOC-NIRS Breath Hold Test displayed a ∼3.5 fold decrease in the time-averaged standard deviation between channels, consequentially promoting greater channel agreement. A Skin Pinch Test was implemented to negate brain and muscle activity from affecting the recorded signal. These results displayed a 2.5-3.0 fold increase in raw signal amplitude. Existing NIRS instrumentation has been further integrated within a custom helmet device to provide a uniform force distribution across the NIRS sensor array. These results showed a gradual decrease in time-averaged standard deviation among channels with an increase in applied pressure. Through these experiments, and the development of the MOC-NIRS helmet device, MOC appears to provide enhancement of NIRS technology beyond its current limitations. PMID:26041069

  9. TATP and TNT detection by mid-infrared transmission spectroscopy

    NASA Astrophysics Data System (ADS)

    Herbst, Johannes; Hildenbrand, Jürgen; Wöllenstein, Jürgen; Lambrecht, Armin

    2009-05-01

    Sensitive and fast detection of explosives remains a challenge in many threat scenarios. Fraunhofer IPM works on two different detection methods using mid-infrared absorption spectroscopy in combination with quantum cascade lasers (QCL). 1. stand-off detection for a spatial distance of several meters and 2. contactless extractive sampling for short distance applications. The extractive method is based on a hollow fiber that works as gas cell and optical waveguide for the QCL light. The samples are membranes contaminated with the explosives and real background. The low vapor pressure of TNT requires a thermal desorbtion to introduce gaseous TNT and TATP into the heated fiber. The advantage of the hollow fiber setup is the resulting small sample volume. This enables a fast gas exchange rate and fast detection in the second range. The presented measurement setup achieves a detection limit of around 58 ng TNT and 26 ng TATP for 1 m hollow fiber. TATP - an explosive with a very high vapor pressure in comparison to TNT or other explosives - shows potential for an adequate concentration in gas phase under normal ambient conditions and thus the possibility of an explosive detection using open path absorption of TATP at 8 μm wavelength. In order to lower the cross sensitivities or interferents with substances with an absorption in the wavelength range of the TATP absorption the probe volume is checked synchronously by a second QCL emitting beside the target absorption wavelength. In laboratory measurements a detection limit of 5 ppm*m TATP are achieved.

  10. Infrared Spectroscopy of Ammonia - Hydrocarbon Ices Relevant to Jupiter's Clouds

    NASA Astrophysics Data System (ADS)

    Engel, P. A.; Kalogerakis, K. S.

    2005-12-01

    Observational evidence and thermochemical models indicate an abundance of ammonia ice clouds in Jupiter's atmosphere. However, spectrally identifiable ammonia ice clouds are found covering less than 1% of Jupiter's atmosphere, notably in turbulent areas.1,2 This discrepancy highlights an important gap in our understanding of ammonia and its spectral signatures in Jupiter's atmosphere. Current literature suggests two possible explanations: coating by a hydrocarbon haze and/or photochemical processing ("tanning").2,3 We are performing laboratory experiments that investigate the above hypotheses. Thin films of ammonia ices are deposited in a cryogenic apparatus, coated with hydrocarbons, and characterized by infrared spectroscopy. The ice films can be irradiated by ultraviolet light. These spectroscopic measurements aim to identify the photophysical and chemical processes that control the optical properties of the ice mixtures and quantify their dependence on the identity of the coating, the temperature, and the ice composition. Our current results indicate a consistent suppression of the ammonia absorption feature at 3 μm with coverage by thin layers of hexane, cyclohexane, and benzene. Furthermore, strongest suppression is observed in the case of benzene, followed in magnitude by hexane and cyclohexane. Funding from the NSF Planetary Astronomy Program under grant AST-0206270 is gratefully acknowledged. The participation of Patricia A. Engel was made possible by the NSF Research Experiences for Undergraduates Program under grant PHY-0353745. 1. S. K. Atreya, A.-S. Wong, K. H. Baines, M. H. Wong, T. C. Owen, Planet. Space Science 53, 498 (2005). 2. K. H. Baines, R. W. Carlson, and L. W. Kamp, Icarus 159, 74 (2002). 3. A.-S. Wong, Y. L. Yung, and A. J. Friedson, Geophys. Res. Lett. 30, 1447 (2003).

  11. The hydration of Concanavalin A studied by infrared spectroscopy

    NASA Astrophysics Data System (ADS)

    Novak, Urban; Grdadolnik, Jože

    2017-05-01

    The influence of a stepwise hydration on the secondary structure of Concanavalin A, a 273 amino acid residues long lectin protein, was monitored by infrared spectroscopy. An analysis of Amide I and Amide III bands, assignment of model bands and determination of the populations of secondary structure elements using computed integral intensity of particular amino bands, was used to determine the proportion of β-sheet in protein films recorded under various steps of hydration and solution in water. In dry protein film 53% of amino acid residues are in β-sheet conformation. The hydration increases a population of β-sheet to 57% determined in fully hydrated film which finally reached 61% in water solution. On the basis of characteristic differential spectra calculated from the various hydration levels, we established that in the initial stage of hydration water molecules bind through hydrogen bonds directly to the main and side chains of protein. Hydration of side chains mainly occupies COO- and COOH groups. The increase of β-sheet population induced by hydration rearranged the water molecules attached to COOH side chain groups. A parallel analysis of Amide III bands shows that the Amid III region provides more complete information regarding the protein structure. Contemporary analysis of this region is very supportive, because it offers additional structural parameters which significantly contribute to reliability of secondary structure analysis by applying Amide I mode. Moreover, besides the comparable information about the population of secondary structure elements, the analysis of the Amide III area provides also the distribution of conformations of amino acids which are found in unstructured parts of protein.

  12. Implanted near-infrared spectroscopy for cardiac monitoring

    NASA Astrophysics Data System (ADS)

    Bhunia, Sourav K.; Cinbis, Can

    2011-02-01

    Implanted Cardioverter Defibrillator (ICD) provides one of the most effective therapies for the prevention of sudden cardiac death, but also delivers some high voltage shocks inappropriately, causing morbidity and mortality. Implanted near-infrared spectroscopy (NIRS) may augment ICD arrhythmia detection by monitoring skeletal muscle perfusion. A two-wavelength, single-distance, continuous-wave implanted NIRS has been evaluated in-vivo. A weighted difference of the changes in attenuation at two wavelengths, across the isobestic point of the hemoglobin spectra, was taken to be the microvascular oxygenation trend indicator (O2 Index). Although the exact weight depends on the local vascular distribution and their oxygen levels, the hypothesis that a constant weight may be adequate for hemodynamic trending during short arrhythmic episodes, was tested. The sensor was implanted subcutaneously both on fresh tissue and inside scar tissue that formed around a pre-existing implant, in 3 animals each. Attenuations were recorded at 660 and 890 nm during normal sinus rhythm (NSR) and induced ventricular fibrillation (VF). The slope of the O2 Index over 10 seconds was computed for 7 NSR and 8 VF episodes in fresh and 13 NSR and 15 VF episodes in scar tissue pockets. The mean O2 Index slope was significantly different (p<0.0001) between NSR and VF rhythms for both the fresh and scar tissue pockets. Therefore implanted NIRS may be useful for preventing inappropriate detection of VF during electromagnetic interference, double counting of ECG T-wave as an R-wave, ICD lead failure, electrocardiographic aberrancy etc.

  13. Effect of mechanical optical clearing on near-infrared spectroscopy.

    PubMed

    Idelson, Christopher R; Vogt, William C; King-Casas, Brooks; LaConte, Stephen M; Rylander, Christopher G

    2015-08-01

    Near-infrared Spectroscopy (NIRS) is a broadly utilized technology with many emerging applications including clinical diagnostics, sports medicine, and functional neuroimaging, to name a few. For functional brain imaging NIR light is delivered at multiple wavelengths through the scalp and skull to the brain to enable spatial oximetry measurements. Dynamic changes in brain oxygenation are highly correlated with neural stimulation, activation, and function. Unfortunately, NIRS is currently limited by its low spatial resolution, shallow penetration depth, and, perhaps most importantly, signal corruption due to light interactions with superficial non-target tissues such as scalp and skull. In response to these issues, we have combined the non-invasive and rapidly reversible method of mechanical tissue optical clearing (MOC) with a commercially available NIRS system. MOC utilizes a compressive loading force on tissue, causing the lateral displacement of blood and water, while simultaneously thinning the tissue. A MOC-NIRS Breath Hold Test displayed a ∼3.5-fold decrease in the time-averaged standard deviation between channels, consequentially promoting greater channel agreement. A Skin Pinch Test was implemented to negate brain and muscle activity from affecting the recorded signal. These results displayed a 2.5-3.0 fold increase in raw signal amplitude. Existing NIRS instrumentation has been further integrated within a custom helmet device to provide a uniform force distribution across the NIRS sensor array. These results showed a gradual decrease in time-averaged standard deviation among channels with an increase in applied pressure. Through these experiments, and the development of the MOC-NIRS helmet device, MOC appears to provide enhancement of NIRS technology beyond its current limitations. © 2015 Wiley Periodicals, Inc.

  14. Evaluation of Phalaenopsis flowering quality using near infrared spectroscopy

    NASA Astrophysics Data System (ADS)

    Chen, Suming; Chuang, Yung-Kun; Tsai, Chao-Yin; Chang, Yao-Chien A.; Yang, I.-Chang; Chang, Yung-Huei; Tai, Chu-Chun; Hou, Jiunn-Yan

    2013-05-01

    Carbohydrate contents have been demonstrated as indicators for flowering quality of Phalaenopsis plants. In this study, near infrared reflectance (NIR) spectroscopy was employed for quantitative analysis of carbohydrate contents like fructose, glucose, sucrose, and starch in Phalaenopsis. The modified partial least squares regression (MPLSR) method was adopted for spectra analyses of 176 grown plant samples (88 shoots and 88 roots), over the full wavelength range (FWR, 400 to 2498 nm). For fructose concentrations, the smoothing 1st derivative model can produce the best effect (Rc = 0.961, SEC = 0.210% DW, SEV = 0.324% DW) in the wavelength ranges of 1400-1600, 1800-2000, and 2200-2300 nm. For glucose concentrations, the smoothing 1st derivative model can produce the best effect (Rc = 0.975, SEC = 0.196% DW, SEV = 0.264% DW) in the wavelength range of 1400-1600, 1800-2000, and 2100-2400 nm. For sucrose concentrations, the smoothing 1st derivative model can produce the best effect (Rc = 0.961, SEC = 0.237% DW, SEV = 0.322% DW) in the wavelength range of 1300-1400, 1500-1800, 2000-2100, and 2200-2300 nm. For starch concentrations, the smoothing 1st derivative model can produce the best effect (Rc = 0.873, SEC = 0.697% DW, SEV = 0.774% DW) in the wavelength ranges of 500-700, 1200-1300, 1700-1800, and 2200-2300 nm. This study successfully developed the calibration models for inspecting concentrations of carbohydrates to predict the flowering quality in different cultivation environments of Phalaenopsis. The specific wavelengths can be used to predict the quality of Phalaenopsis flowers and thus to adjust cultivation managements.

  15. [Proximate analysis of straw by near infrared spectroscopy (NIRS)].

    PubMed

    Huang, Cai-jin; Han, Lu-jia; Liu, Xian; Yang, Zeng-ling

    2009-04-01

    Proximate analysis is one of the routine analysis procedures in utilization of straw for biomass energy use. The present paper studied the applicability of rapid proximate analysis of straw by near infrared spectroscopy (NIRS) technology, in which the authors constructed the first NIRS models to predict volatile matter and fixed carbon contents of straw. NIRS models were developed using Foss 6500 spectrometer with spectra in the range of 1,108-2,492 nm to predict the contents of moisture, ash, volatile matter and fixed carbon in the directly cut straw samples; to predict ash, volatile matter and fixed carbon in the dried milled straw samples. For the models based on directly cut straw samples, the determination coefficient of independent validation (R2v) and standard error of prediction (SEP) were 0.92% and 0.76% for moisture, 0.94% and 0.84% for ash, 0.88% and 0.82% for volatile matter, and 0.75% and 0.65% for fixed carbon, respectively. For the models based on dried milled straw samples, the determination coefficient of independent validation (R2v) and standard error of prediction (SEP) were 0.98% and 0.54% for ash, 0.95% and 0.57% for volatile matter, and 0.78% and 0.61% for fixed carbon, respectively. It was concluded that NIRS models can predict accurately as an alternative analysis method, therefore rapid and simultaneous analysis of multicomponents can be achieved by NIRS technology, decreasing the cost of proximate analysis for straw.

  16. Methanogenic activity tests by Infrared Tunable Diode Laser Absorption Spectroscopy.

    PubMed

    Martinez-Cruz, Karla; Sepulveda-Jauregui, Armando; Escobar-Orozco, Nayeli; Thalasso, Frederic

    2012-10-01

    Methanogenic activity (MA) tests are commonly carried out to estimate the capability of anaerobic biomass to treat effluents, to evaluate anaerobic activity in bioreactors or natural ecosystems, or to quantify inhibitory effects on methanogenic activity. These activity tests are usually based on the measurement of the volume of biogas produced by volumetric, pressure increase or gas chromatography (GC) methods. In this study, we present an alternative method for non-invasive measurement of methane produced during activity tests in closed vials, based on Infrared Tunable Diode Laser Absorption Spectroscopy (MA-TDLAS). This new method was tested during model acetoclastic and hydrogenotrophic methanogenic activity tests and was compared to a more traditional method based on gas chromatography. From the results obtained, the CH(4) detection limit of the method was estimated to 60 ppm and the minimum measurable methane production rate was estimated to 1.09(.)10(-3) mg l(-1) h(-1), which is below CH(4) production rate usually reported in both anaerobic reactors and natural ecosystems. Additionally to sensitivity, the method has several potential interests compared to more traditional methods among which short measurements time allowing the measurement of a large number of MA test vials, non-invasive measurements avoiding leakage or external interferences and similar cost to GC based methods. It is concluded that MA-TDLAS is a promising method that could be of interest not only in the field of anaerobic digestion but also, in the field of environmental ecology where CH(4) production rates are usually very low. Copyright © 2012 Elsevier B.V. All rights reserved.

  17. Study of organo-hybrid layered double hydroxides by medium and near infrared spectroscopy

    NASA Astrophysics Data System (ADS)

    Mora, Manuel; López, M. Isabel; Jiménez-Sanchidrián, César; Ruiz, J. Rafael

    2011-03-01

    An Mg/Al layered double hydroxide (LDH) containing carbonate ion in its interlayer region was examined by medium infrared (MIR) and near infrared reflectance spectroscopy (NIRS). The MIR and NIR spectroscopy techniques was also used to study two organo-hybrid LDHs containing interlayer dodecylbenzenesulphonate (DBS) and dodecylsulphate (DS) ions, respectively. The NIR spectra for the latter solids were found to exhibit the overtone and combination bands for the hydroxyl groups in addition to those typical bands of the organic host functions.

  18. Electron-transfer acceleration investigated by time resolved infrared spectroscopy.

    PubMed

    Vlček, Antonín; Kvapilová, Hana; Towrie, Michael; Záliš, Stanislav

    2015-03-17

    Ultrafast electron transfer (ET) processes are important primary steps in natural and artificial photosynthesis, as well as in molecular electronic/photonic devices. In biological systems, ET often occurs surprisingly fast over long distances of several tens of angströms. Laser-pulse irradiation is conveniently used to generate strongly oxidizing (or reducing) excited states whose reactions are then studied by time-resolved spectroscopic techniques. While photoluminescence decay and UV-vis absorption supply precise kinetics data, time-resolved infrared absorption (TRIR) and Raman-based spectroscopies have the advantage of providing additional structural information and monitoring vibrational energy flows and dissipation, as well as medium relaxation, that accompany ultrafast ET. We will discuss three cases of photoinduced ET involving the Re(I)(CO)3(N,N) moiety (N,N = polypyridine) that occur much faster than would be expected from ET theories. [Re(4-N-methylpyridinium-pyridine)(CO)3(N,N)](2+) represents a case of excited-state picosecond ET between two different ligands that remains ultrafast even in slow-relaxing solvents, beating the adiabatic limit. This is caused by vibrational/solvational excitation of the precursor state and participation of high-frequency quantum modes in barrier crossing. The case of Re-tryptophan assemblies demonstrates that excited-state Trp → *Re(II) ET is accelerated from nanoseconds to picoseconds when the Re(I)(CO)3(N,N) chromophore is appended to a protein, close to a tryptophan residue. TRIR in combination with DFT calculations and structural studies reveals an interaction between the N,N ligand and the tryptophan indole. It results in partial electronic delocalization in the precursor excited state and likely contributes to the ultrafast ET rate. Long-lived vibrational/solvational excitation of the protein Re(I)(CO)3(N,N)···Trp moiety, documented by dynamic IR band shifts, could be another accelerating factor. The last

  19. Understanding ion association states and molecular dynamics using infrared spectroscopy

    NASA Astrophysics Data System (ADS)

    Masser, Hanqing

    A molecular level understanding of the ion transport mechanism within polymer electrolytes is crucial to the further development for advanced energy storage applications. This can be achieved by the identification and quantitative measurement of different ion species in the system and further relating them to the ion conductivity. In the first part of this thesis, research is presented towards understanding the ion association states (free ions, ion pairs and ion aggregates) in ionomer systems, and the correlation of ion association states, ion conduction, polymer dynamics, and morphology. Ion conductivity in ionomers can be improved by lowering glass transition temperature, increasing polymer ion solvation ability, and adjusting ionomer structural variables such as ion content, cation type and side chain structure. These effects are studied in three ionomer systems respectively, using a combination of characterization methods. Fourier Transform Infrared Spectroscopy (FTIR) identifies and quantifies the ion association states. Dielectric Spectroscopy (DRS) characterizes ion conductivity and polymer and ion dynamics. X-ray scattering reveals changes in morphology. The influence of a cation solvating plasticizer on a polyester ionomer is systematically investigated with respect to ion association states, ion and polymer dynamics and morphology. A decrease in the number ratio of ion aggregates with increased plasticizer content and a slight increase at elevated temperature are observed in FTIR. Similar results are also detected by X-ray scattering. As determined from dielectric spectroscopy, ion conductivity increases with plasticizer content, in accordance with the decrease in glass transition temperature. Research on copolymer of poly(ethylene oxide) (PEO) and poly(tetramethylene oxide) (PTMO) based ionomers further develops an understanding of the trade-off between ion solvation and segmental dynamics. Upon the incorporation of PTMO, the majority of the PTMO

  20. Development of a neurofeedback protocol targeting the frontal pole using near-infrared spectroscopy.

    PubMed

    Kinoshita, Akihide; Takizawa, Ryu; Yahata, Noriaki; Homae, Fumitaka; Hashimoto, Ryuichiro; Sakakibara, Eisuke; Kawasaki, Shingo; Nishimura, Yukika; Koike, Shinsuke; Kasai, Kiyoto

    2016-11-01

    Neurofeedback has been studied with the aim of controlling cerebral activity. Near-infrared spectroscopy is a non-invasive neuroimaging technique used for measuring hemoglobin concentration changes in cortical surface areas with high temporal resolution. Thus, near-infrared spectroscopy may be useful for neurofeedback, which requires real-time feedback of repeated brain activation measurements. However, no study has specifically targeted neurofeedback, using near-infrared spectroscopy, in the frontal pole cortex. We developed an original near-infrared spectroscopy neurofeedback system targeting the frontal pole cortex. Over a single day of testing, each healthy participant (n = 24) received either correct or incorrect (Sham) feedback from near-infrared spectroscopy signals, based on a crossover design. Under correct feedback conditions, significant activation was observed in the frontal pole cortex (P = 0.000073). Additionally, self-evaluation of control and metacognitive beliefs were associated with near-infrared spectroscopy signals (P = 0.006). The neurofeedback system developed in this study might be useful for developing control of frontal pole cortex activation. © 2016 The Authors. Psychiatry and Clinical Neurosciences © 2016 Japanese Society of Psychiatry and Neurology.

  1. Development of secondary cell wall in cotton fibers as examined with Fourier transform-infrared spectroscopy

    USDA-ARS?s Scientific Manuscript database

    Our presentation will focus on continuing efforts to examine secondary cell wall development in cotton fibers using infrared Spectroscopy. Cotton fibers harvested at 18, 20, 24, 28, 32, 36 and 40 days after flowering were examined using attenuated total reflection Fourier transform-infrared (ATR FT-...

  2. Discriminating oat and groat kernels from other grains using near infrared spectroscopy

    USDA-ARS?s Scientific Manuscript database

    Oat and groats can be discriminated from other grains such as barley, wheat, rye, and triticale (non-oats) using near infrared spectroscopy. The two instruments tested were the manual version of the ARS-USDA Single Kernel Near Infrared (SKNIR) and the automated QualySense QSorter Explorer high-speed...

  3. Studies of UV photochemistry of psoralen and angelicin by infrared spectroscopy

    NASA Astrophysics Data System (ADS)

    Laczkó, Zsuzsa; Harsányi, László; Dobos, Sándor

    1985-09-01

    The UV homodimerization reaction of psoralen and angelicin in crystalline thin layers has been investigated by means of transmission infrared and infrared ATR (attenuated total reflection) spectroscopy. In the case of psoralen layers isoorientation was found. Dichroic ratios for several vibrational bands have been obtained. After irradiation, cis-syn photodimers were found for both psoralen and angelicin.

  4. Discrimination of different red wine by Fourier-transform infrared and two-dimensional infrared correlation spectroscopy

    NASA Astrophysics Data System (ADS)

    Zhang, Yan-ling; Chen, Jian-bo; Lei, Yu; Zhou, Qun; Sun, Su-qin; Noda, Isao

    2010-06-01

    Fourier-transform infrared spectroscopy (FT-IR) and two-dimensional infrared (2D IR) correlation spectroscopy were applied to analyze main components of liquid red wine with different sugar contents and volatilization residues of dry red wine from different manufactures. The infrared spectra, second derivative spectra of dry red wine show the typical peaks of alcohol, while the spectra of sweet wine are composed of the peaks of both alcohol and sugar, and the contribution of sugar enhanced as the increase of sugar content. Using principal component analysis (PCA) method, dry and sweet wine can be readily classified. Analysis of the infrared spectra of the volatilization residues of dry red wine samples from five different manufactures indicates that dry red wine may be composed of glycerol, carboxylic acids or esters and carboxyl ate, at the same time, different dry red wine show different characteristic peaks in the second derivative spectra and 2D IR correlation spectra, which can be used to discriminate the different manufactures and evaluate the quality of wine samples. The results suggested that infrared spectroscopy is a direct and effective method for the analysis of principle components of different red wines and discrimination of different red wines.

  5. Analysis of Chuanxiong Rhizoma and its active components by Fourier transform infrared spectroscopy combined with two-dimensional correlation infrared spectroscopy.

    PubMed

    Guo, Yizhen; Lv, Beiran; Wang, Jingjuan; Liu, Yang; Sun, Suqin; Xiao, Yao; Lu, Lina; Xiang, Li; Yang, Yanfang; Qu, Lei; Meng, Qinghong

    2016-01-15

    As complicated mixture systems, active components of Chuanxiong Rhizoma are very difficult to identify and discriminate. In this paper, the macroscopic IR fingerprint method including Fourier transform infrared spectroscopy (FT-IR), the second derivative infrared spectroscopy (SD-IR) and two-dimensional correlation infrared spectroscopy (2DCOS-IR), was applied to study and identify Chuanxiong raw materials and its different segmented production of HPD-100 macroporous resin. Chuanxiong Rhizoma is rich in sucrose. In the FT-IR spectra, water eluate is more similar to sucrose than the powder and the decoction. Their second derivative spectra amplified the differences and revealed the potentially characteristic IR absorption bands and combined with the correlation coefficient, concluding that 50% ethanol eluate had more ligustilide than other eluates. Finally, it can be found from 2DCOS-IR spectra that proteins were extracted by ethanol from Chuanxiong decoction by HPD-100 macroporous resin. It was demonstrated that the above three-step infrared spectroscopy could be applicable for quick, non-destructive and effective analysis and identification of very complicated and similar mixture systems of traditional Chinese medicines.

  6. Chemical profiling and adulteration screening of Aquilariae Lignum Resinatum by Fourier transform infrared (FT-IR) spectroscopy and two-dimensional correlation infrared (2D-IR) spectroscopy

    NASA Astrophysics Data System (ADS)

    Qu, Lei; Chen, Jian-bo; Zhang, Gui-Jun; Sun, Su-qin; Zheng, Jing

    2017-03-01

    As a kind of expensive perfume and valuable herb, Aquilariae Lignum Resinatum (ALR) is often adulterated for economic motivations. In this research, Fourier transform infrared (FT-IR) spectroscopy is employed to establish a simple and quick method for the adulteration screening of ALR. First, the principal chemical constituents of ALR are characterized by FT-IR spectroscopy at room temperature and two-dimensional correlation infrared (2D-IR) spectroscopy with thermal perturbation. Besides the common cellulose and lignin compounds, a certain amount of resin is the characteristic constituent of ALR. Synchronous and asynchronous 2D-IR spectra indicate that the resin (an unstable secondary metabolite) is more sensitive than cellulose and lignin (stable structural constituents) to the thermal perturbation. Using a certified ALR sample as the reference, the infrared spectral correlation threshold is determined by 30 authentic samples and 6 adulterated samples. The spectral correlation coefficient of an authentic ALR sample to the standard reference should be not less than 0.9886 (p = 0.01). Three commercial adulterated ALR samples are identified by the correlation threshold. Further interpretation of the infrared spectra of the adulterated samples indicates the common adulterating methods - counterfeiting with other kind of wood, adding ingredient such as sand to increase the weight, and adding the cheap resin such as rosin to increase the content of resin compounds. Results of this research prove that FT-IR spectroscopy can be used as a simple and accurate quality control method of ALR.

  7. Discrimination of different genuine Danshen and their extracts by Fourier transform infrared spectroscopy combined with two-dimensional correlation infrared spectroscopy

    NASA Astrophysics Data System (ADS)

    Liu, Xin-hu; Xu, Chang-hua; Sun, Su-qin; Huang, Jian; Zhang, Ke; Li, Guo-yu; Zhu, Yun; Zhou, Qun; Zhang, Zhi-cheng; Wang, Jin-hui

    2012-11-01

    In this study, six varieties of Danshen from different populations and genuine ("Daodi" in Chinese transliteration) regions were discriminated and identified by a three-step infrared spectroscopy method (Fourier transform-infrared spectroscopy (FT-IR) coupled with second derivative infrared spectroscopy (SD-IR) and two dimensional correlation infrared spectroscopy (2D-IR)). Though only small differences were found among the FT-IR spectra of the six Danshen samples, the positions and intensities of peaks at 3393, 3371, 1613, 1050, and 1036 cm-1 could be considered as the key factors to discriminate them. More significant differences were exhibited in their SD-IR, particularly for the peaks around 1080, 1144, 695, 665, 800, 1610, 1510, 1450, 1117 and 1077 cm-1. The visual 2D-IR spectra provided dynamic chemical structure information of the six Danshen samples with presenting different particular auto-peak clusters, respectively. Moreover, the contents of salvianolic acid B in all samples were measured quantitatively by a validated ultra performance liquid chromatography (UPLC), which was consistent with the FT-IR findings. This study provides a promising method for characteristics and quality control of the complicated and extremely similar herbal medicine like Danshen, which is more cost effective and time saving.

  8. Analysis of Chuanxiong Rhizoma and its active components by Fourier transform infrared spectroscopy combined with two-dimensional correlation infrared spectroscopy

    NASA Astrophysics Data System (ADS)

    Guo, Yizhen; Lv, Beiran; Wang, Jingjuan; Liu, Yang; Sun, Suqin; Xiao, Yao; Lu, Lina; Xiang, Li; Yang, Yanfang; Qu, Lei; Meng, Qinghong

    2016-01-01

    As complicated mixture systems, active components of Chuanxiong Rhizoma are very difficult to identify and discriminate. In this paper, the macroscopic IR fingerprint method including Fourier transform infrared spectroscopy (FT-IR), the second derivative infrared spectroscopy (SD-IR) and two-dimensional correlation infrared spectroscopy (2DCOS-IR), was applied to study and identify Chuanxiong raw materials and its different segmented production of HPD-100 macroporous resin. Chuanxiong Rhizoma is rich in sucrose. In the FT-IR spectra, water eluate is more similar to sucrose than the powder and the decoction. Their second derivative spectra amplified the differences and revealed the potentially characteristic IR absorption bands and combined with the correlation coefficient, concluding that 50% ethanol eluate had more ligustilide than other eluates. Finally, it can be found from 2DCOS-IR spectra that proteins were extracted by ethanol from Chuanxiong decoction by HPD-100 macroporous resin. It was demonstrated that the above three-step infrared spectroscopy could be applicable for quick, non-destructive and effective analysis and identification of very complicated and similar mixture systems of traditional Chinese medicines.

  9. Recent advances in the use of non-destructive near infrared spectroscopy on intact olive fruits

    USDA-ARS?s Scientific Manuscript database

    The objective of this review is to illustrate the state of the art in the use of non-destructive near infrared (NIR) spectroscopy for quality evaluation of intact fruit in the olive industry. First, the most recent studies regarding the application of non-destructive NIR spectroscopy methods to asse...

  10. An Inorganic Laboratory Experiment Involving Photochemistry, Liquid Chromatography, and Infrared Spectroscopy.

    ERIC Educational Resources Information Center

    Post, Elroy W.

    1980-01-01

    Presents an experiment involving photochemical legand displacement on a metal carbonyl, separation of the product mixture by chromotography, and identification of the components by use of infrared spectroscopy and group theory. The chromatography and spectroscopy are combined as complementary tools in this experiment. (Author/JN)

  11. An Inorganic Laboratory Experiment Involving Photochemistry, Liquid Chromatography, and Infrared Spectroscopy.

    ERIC Educational Resources Information Center

    Post, Elroy W.

    1980-01-01

    Presents an experiment involving photochemical legand displacement on a metal carbonyl, separation of the product mixture by chromotography, and identification of the components by use of infrared spectroscopy and group theory. The chromatography and spectroscopy are combined as complementary tools in this experiment. (Author/JN)

  12. Terahertz and Infrared Laboratory Spectroscopy in Support of NASA Missions

    NASA Astrophysics Data System (ADS)

    Yu, Shanshan

    2015-06-01

    The JPL molecular spectroscopy group supports NASA programs encompassing Astrophysics, Atmospheric Science, and Planetary Science. Ongoing activities include measurement and analysis of molecular spectra in the terahertz and infrared regions under conditions akin to the remote environments under study in NASA missions. This presentation will show the implementation of state-of-the-art spectroscopic techniques to fulfill spectroscopic demands of the Herschel Space Observatory and the Orbiting Carbon Observatory re-flight (OCO-2). A demonstrative example of the significantly improved frequency predictions for the H_3O^+ ground state high-J transitions will be given. This work was critical to Herschel's successful identification of highly excited metastable H_3O^+ Terahertz lines with J=K up to 11, one of the Herschel mission's many surprising observational results. The observation and subsequent laboratory work revealed that (1) these highly excited H_3O^+ lines had already been observed by European Southern Observatory's Atacama Pathfinder Experiment telescope a few years before but had been classified as U-lines; (2) the H_3O^+ number density was previously underestimated by an order of magnitude, due to ignorance of the population in the metastable states. A second example focuses on O_2, an important absorber from the microwave through the deep UV. This work is motivated by the challenge of developing an accurate and complete spectroscopic characterization of molecular oxygen across a wide frequency range for current and planned Earth atmospheric observations. Especially, OCO-2 utilizes the O_2 A-band for air mass calibration; extremely accurate O_2 molecular data, i.e., line positions with uncertainty on the order of MHz for the A-band around 13000 wn, are required to fulfill the demand of the proposed 0.25% precision for the carbon dioxide concentration retrievals. G. Pilbratt, J. Riedinger, T. Passvogel, G. Crone, D. Doyle, U. Gageur et al. A&A, 518, L1 (2010

  13. Identifying varnished rocks on Mars using thermal infrared spectroscopy

    NASA Astrophysics Data System (ADS)

    Hibbitts, C. A.; Gillespie, A.; Hansen, G. B.

    2004-12-01

    Thermal infrared (TIR) spectroscopy is widely implemented in attempts to determine the composition of the Mars's surface. Discoveries include basaltic rocks, possible andesites, and hematite-rich terrains associated with areas of probable hydrothermal alteration [Bandfield et al., 2000; Christensen et al., 2001; Glotch et al., 2004]. Some of the basaltic rocks appear to be covered by either a weathering rind or a varnish. The presence of a varnish would be interesting because it is believed to form through multiple wetting and drying events [reference]. The presence of these coatings can potentially be identified through unique nonlinear effects where both the substrate and varnish have strong spectral features. For example, varnished terrestrial quartz-rich rocks have a low-emissivity ~8.4-micron reststrahlan band diagnostic of a silicate-rich substrate which remains present while the longer wavelength reststrahlen band is obscured by the clay-rich varnish. In general, this non-linearity will conform to the Beer-Lambert Law, with additional reflection and scattering terms, so that the light emitted from the varnished stone will be similar to I=Io e-ax, where `Io' is the light emitted from a bare substrate, `a' is the absorption constant for the varnish coating, and `x' is the thickness of the coating. If the effect were linear, as expected for dusty surfaces [Johnson et al., 2002] or discrete patches of rock and clay, the emissivity of the emitted light would, at all wavelengths, possess equal contributions from the varnish and substrate; thus the clay feature would not completely dominate the longwave reststrahlan band without also erasing the shortwave reststrahlan band. After having theoretically determined a nonlinear at some wavelengths is probable, we have focused on laboratory spectral analyses of terrestrial varnished rocks. We have collected over 100 varnished stones from various pavements and unvarnished stones from other surfaces and have acquired over

  14. Bilateral near-infrared spectroscopy for detecting traumatic vascular injury.

    PubMed

    Van Haren, Robert M; Ryan, Mark L; Thorson, Chad M; Namias, Nicholas; Livingstone, Alan S; Proctor, Kenneth G

    2013-09-01

    Extremity wounds account for most battlefield injuries. Clinical examination may be unreliable by medics or first responders, and continuous assessment by experienced practitioners may not be possible on the frontline or during transport. Near-infrared spectroscopy (NIRS) provides continuous, noninvasive monitoring of tissue oxygen saturation (StO2), but its use is limited by inter-patient and intra-patient variability. We tested the hypothesis that bilateral NIRS partially addresses the variability problem and can reliably identify vascular injury after extremity trauma. This prospective study consisted of 30 subjects: 20 trauma patients with extremity injury and 10 healthy volunteers. Bilateral StO2 tissue sensors were placed on the thenar eminence or medial plantar surface. Injured and non-injured extremities within the same patient (ΔStO2) were compared using Wilcoxon signed ranks test. Receiver operating characteristic curves were generated and areas under the curve (AUCs) were calculated for ΔStO2 of 6, 10, and 15. Values are expressed as median (interquartile range). Trauma patients were age 31 y (23 y), 85% male, with injury severity score of 9 (5). There were seven arterial and three venous injuries. Most involved the lower extremity (n = 16; 80%) and resulted from a penetrating mechanism (n = 14; 70%). ΔStO2 between limbs was 20.4 (10.4) versus 2.4 (3.0) (P < 0.001) for all patients with vascular injury versus patients and volunteers with no vascular injury. ΔStO2 reliably identified any vascular injury (AUC, 0.975; P < 0.001), whereas pulse examination alone or in combination with Doppler exam could detect only arterial injury. A ΔStO2 of 6 had the greatest sensitivity and specificity (AUC, 0.900; P < 0.001). Continuous monitoring of bilateral limbs with NIRS detects changes in perfusion resulting from arterial or venous injury and may offer advantages over serial manual measurements of pulses or Doppler signals. This technique may be most

  15. Immersion Gratings for Infrared High-resolution Spectroscopy

    NASA Astrophysics Data System (ADS)

    Sarugaku, Yuki; Ikeda, Yuji; Kobayashi, Naoto; Kaji, Sayumi; Sukegawa, Takashi; Sugiyama, Shigeru; Nakagawa, Takao; Arasaki, Takayuki; Kondo, Sohei; Nakanishi, Kenshi; Yasui, Chikako; Kawakita, Hideyo

    2016-10-01

    High-resolution spectroscopy in the infrared wavelength range is essential for observations of minor isotopologues, such as HDO for water, and prebiotic organic molecules like hydrocarbons/P-bearing molecules because numerous vibrational molecular bands (including non-polar molecules) are located in this wavelength range. High spectral resolution enables us to detect weak lines without spectral line confusion. This technique has been widely used in planetary sciences, e.g., cometary coma (H2O, CO, and organic molecules), the martian atmosphere (CH4, CO2, H2O and HDO), and the upper atmosphere of gas giants (H3+ and organic molecules such as C2H6). Spectrographs with higher resolution (and higher sensitivity) still have a potential to provide a plenty of findings. However, because the size of spectrographs scales with the spectral resolution, it is difficult to realize it.Immersion grating (IG), which is a diffraction grating wherein the diffraction surface is immersed in a material with a high refractive index (n > 2), provides n times higher spectral resolution compared to a reflective grating of the same size. Because IG reduces the size of spectrograph to 1/n compared to the spectrograph with the same spectral resolution using a conventional reflective grating, it is widely acknowledged as a key optical device to realize compact spectrographs with high spectral resolution.Recently, we succeeded in fabricating a CdZnTe immersion grating with the theoretically predicted diffraction efficiency by machining process using an ultrahigh-precision five-axis processing machine developed by Canon Inc. Using the same technique, we completed a practical germanium (Ge) immersion grating with both a reflection coating on the grating surface and the an AR coating on the entrance surface. It is noteworthy that the wide wavelength range from 2 to 20 um can be covered by the two immersion gratings.In this paper, we present the performances and the applications of the immersion

  16. Determination of plant silicon content with near infrared reflectance spectroscopy

    PubMed Central

    Smis, Adriaan; Ancin Murguzur, Francisco Javier; Struyf, Eric; Soininen, Eeva M.; Herranz Jusdado, Juan G.; Meire, Patrick; Bråthen, Kari Anne

    2014-01-01

    Silicon (Si) is one of the most common elements in the earth bedrock, and its continental cycle is strongly biologically controlled. Yet, research on the biogeochemical cycle of Si in ecosystems is hampered by the time and cost associated with the currently used chemical analysis methods. Here, we assessed the suitability of Near Infrared Reflectance Spectroscopy (NIRS) for measuring Si content in plant tissues. NIR spectra depend on the characteristics of the present bonds between H and N, C and O, which can be calibrated against concentrations of various compounds. Because Si in plants always occurs as hydrated condensates of orthosilicic acid (Si(OH)4), linked to organic biomolecules, we hypothesized that NIRS is suitable for measuring Si content in plants across a range of plant species. We based our testing on 442 samples of 29 plant species belonging to a range of growth forms. We calibrated the NIRS method against a well-established plant Si analysis method by using partial least-squares regression. Si concentrations ranged from detection limit (0.24 ppmSi) to 7.8% Si on dry weight and were well predicted by NIRS. The model fit with validation data was good across all plant species (n = 141, R2 = 0.90, RMSEP = 0.24), but improved when only graminoids were modeled (n = 66, R2 = 0.95, RMSEP = 0.10). A species specific model for the grass Deschampsia cespitosa showed even slightly better results than the model for all graminoids (n = 16, R2 = 0.93, RMSEP = 0.015). We show for the first time that NIRS is applicable for determining plant Si concentration across a range of plant species and growth forms, and represents a time- and cost-effective alternative to the chemical Si analysis methods. As NIRS can be applied concurrently to a range of plant organic constituents, it opens up unprecedented research possibilities for studying interrelations between Si and other plant compounds in vegetation, and for addressing the role of Si in ecosystems across a range of Si

  17. Infrared Spectroscopy and Physical Chemistry of Cryogenic Aerosols

    NASA Astrophysics Data System (ADS)

    Clapp, Mannie Lee

    1995-01-01

    Infrared spectroscopy has been used as a tool for elucidating the spectroscopic and physical properties of cryogenic aerosols. Ammonia and hydrazine aerosols have been studied using this technique under conditions designed to mimic those found in the atmosphere of Jupiter. Aerosols of water ice, nitric acid and water, and sulfuric acid and water were also studied under temperature conditions similar to those found in the Earth's stratosphere. Aerosols are generated in low temperature flow cells via homogeneous and heterogeneous nucleation of the gas phase. The technique affords information on the size, composition, number density, and in some cases shape, of the particles created. Both ammonia and hydrazine aerosols were studied over the temperature range from 180 K to 110 K. Mie theory can adequately describe the observed particle spectra in most cases. Under conditions designed to enhance particle aggregation, shape effects in the 9.4 mu m absorption band of the ammonia aerosols become apparent which can be modeled well using the Discrete Dipole Approximation. Both substances can exist as supercooled liquid droplets. Ammonia particles freeze distinctly at 155 K, while hydrazine particles freeze over the temperature range from 180 K to 170 K. Spectra of aerosols which are of mixtures of ammonia and hydrazine reveal that the inclusion of hydrazine into ammonia particles affects the spectrum of the ammonia very little, while the hydrazine absorptions are strongly perturbed. Hydrazine is not very soluble in the ammonia particles, even at very low concentrations. A new technique for determining complex refractive indices from aerosol spectra has been developed and applied to water ice and crystalline hydrazine. Comparisons with previous data indicate that the method is sound and accurate. The temperature dependence of the water ice complex refractive index has been quantified and compares well with previous results as a function of temperature. No temperature

  18. Infrared spectroscopy of aqueous ionic salt solutions at low concentrations

    NASA Astrophysics Data System (ADS)

    Max, Jean-Joseph; Gessinger, Véronique; van Driessche, Caroline; Larouche, Pascal; Chapados, Camille

    2007-05-01

    The analysis by infrared spectroscopy of aqueous solutions of the binary inorganic salts NaI and NaCl and the ternary salts CaCl2 and BaCl2 at concentrations from 1000to2mM was carried out to complement a previous study done at higher concentrations on nine binary salts (alkali halides) and one ternary salt (MgCl2) [J.-J. Max and C. Chapados, J. Chem. Phys. 115, 2664 (2001)]. These salts are completely ionized in aqueous solutions, forming monoatomic species that do not absorb IR but that perturb the surrounding water, modifying its spectrum. The factor analysis of the spectra revealed that all these salt solutions were composed of two water types: pure water and salt solvated water. The authors obtained pure salt solvated water spectra for all the salts using an extrapolation technique. The water types obtained are constant for the binary and ternary salts down to 2mM. For the binary salts, we determine that 5.0 and 4.0 water molecules are solvated to the Na +-Cl- and Na+-I- ion pairs, respectively. These numbers are the same as that obtained at higher concentrations. For the new ternary salts, we find that 6.0 and 8.0 water molecules are solvated to Ca++-(Cl-)2 and Ba++-(Cl-)2 ion pairs, respectively. These numbers are higher than the four water molecules solvated to Mg++-(Cl-)2 ion pairs determined previously, but show a progression that follows their atomic numbers. These results constitute new experimental results on "simple" systems whose molecular organization is still a matter of debate. The IR method that probes the system at the molecular level is a method different than the macroscopic ones that give the activity coefficients. The IR gives direct observation at the molecular level of the strong ion-water interactions that are often neglected and its water structure not considered in macroscopic methods. The present results and their analysis together with those obtained by other methods will facilitate the determination of the organization of these

  19. Mid-infrared optical parametric oscillators and frequency combs for molecular spectroscopy.

    PubMed

    Vainio, M; Halonen, L

    2016-02-14

    Nonlinear optical frequency conversion is one of the most versatile methods to generate wavelength-tunable laser light in the mid-infrared region. This spectral region is particularly important for trace gas detection and other applications of molecular spectroscopy, because it accommodates the fundamental vibrational bands of several interesting molecules. In this article, we review the progress of the most significant nonlinear optics instruments for widely tunable, high-resolution mid-infrared spectroscopy: continuous-wave optical parametric oscillators and difference frequency generators. We extend our discussion to mid-infrared optical frequency combs, which are becoming increasingly important spectroscopic tools, owing to their capability of highly sensitive and selective parallel detection of several molecular species. To illustrate the potential and limitations of mid-infrared sources based on nonlinear optics, we also review typical uses of these instruments in both applied and fundamental spectroscopy.

  20. Tethered bilayer lipid membranes studied by simultaneous attenuated total reflectance infrared spectroscopy and electrochemical impedance spectroscopy

    PubMed Central

    Erbe, Andreas; Bushby, Richard J.; Evans, Stephen D.; Jeuken, Lars J. C.

    2013-01-01

    The formation of tethered lipid bilayer membranes (tBLMs) from unilamelar vesicles of egg yolk phosphatidylcholine (EggPC) on mixed self–assembled monolayers (SAMs) from varying ratios of 6-mercaptohexanol and EO3Cholesteryl on gold has been monitored by simultaneous attenuated total reflectance fourier transform infrared (ATR–FTIR) spectroscopy and electrochemical impedance spectroscopy (EIS). The influence of the lipid orientation (and hence the anisotropy) of lipids on a gold film on the dichroic ratio was studied by simulations of spectra with a matrix method for anisotropic layers. It is shown that for certain tilt angles of the dielectric tensor of the adsorbed anisotropic layer dispersive and negative absorption bands are possible. The experimental data indicates that the structure of the assemblies obtained varies with varying SAM composition. On SAMs with a high content of EO3Cholesteryl, tBLMs with reduced fluidity are formed. For SAMs with high content of 6-mercaptohexanol, the results are consistent with the adsorption of flattened vesicles, while spherical vesicles have been found in a small range of surface compositions. The kinetics of the adsorption process is consistent with the assumption of spherical vesicles as long–living intermediates for surfaces of high 6-mercaptohexanol content. No long–living spherical vesicles have been detected for surfaces with large fraction of EO3Cholesteryl tethers. The observed differences between the surfaces suggest that for the formation of tBLMs (unlike supported BLMs) no critical surface coverage of vesicles is needed prior to lipid bilayer formation. PMID:17388505

  1. Protein Dynamics and Conformational Heterogeneity Characterized with Two-Dimensional Infrared Spectroscopy

    NASA Astrophysics Data System (ADS)

    Thielges, Megan; Basom, Edward; Spearman, James

    2014-06-01

    Conformational heterogeneity and dynamics impact protein function, but their investigation is limited by the availability of methods for characterizing rapidly fluctuating protein states with both high spatial and temporal resolution. Multidimensional infrared spectroscopy is emerging as a powerful technique that directly probes the structural dynamics on fast timescales. To overcome the spectral congestion inherent to protein spectra that restricts application of infrared spectroscopy to protein systems, we incorporate into proteins vibrational probes with spectrally isolated frequencies and local-mode character that make possible rigorous analysis of protein environments and dynamics with infrared spectroscopy. In particular, both heme-bound carbon monoxide and nitriles selectively incorporated as unnatural amino acids are used as probes of cytochrome P450. 2D IR spectroscopy is used to investigate the impact of protein dynamics and conformational heterogeneity on the selectivity of its catalytic activity. Comparative studies of mutants of cytochrome P450 are used to unravel the contribution of specific residues to the protein's dynamics.

  2. Infrared and near infrared transient absorption spectroscopy of molecular free radicals

    SciTech Connect

    Sears, T.J.; Wu, M.; Hall, G.E.; Chang, B.C.; Hansford, G.; Bloch, J.C.; Field, R.W.

    1994-12-31

    In this paper, the authors report the results of experiments designed to measure spectra of small free-radical species by direct absorption techniques in the mid and near infrared (IR). The radical of interest was generated by excimer laser photolysis of a chemically stable precursor molecule and detected by measuring the transient decrease in power of a continuous wave probe laser that traversed the photolyzed volume before being imaged on to a detector. In the mid-IR, the authors have used diode lasers to record the vibrational spectrum of the HOCO radical in the region of its {nu}{sub 2} (C{double_bond}O stretch) fundamental. These were originally designed to detect the cis isomer of the radical. Previous experimental and theoretical work confirmed that this is the higher energy isomer, but that it probably lies only 500--1000 cm{sup {minus}1} above the trans configuration. Infrared spectra of the radical trapped in a low temperature matrix determined that the {nu}{sub 2} fundamental of cis-HOCO lies some 60 cm{sup {minus}1} below that of trans-HOCO and this region was not searched in earlier experiments. The authors were not successful in detecting absorptions which could be attributed to the higher energy isomer, however a large number of new spectral lines have been measured and these considerably improve the precision with which the {nu}{sub 2}=1 level of trans-HOCO is known. For the measurement of spectra in the near-IR they recently built a new spectrometer based on a Ti:sapphire ring laser which oscillates in the 700--1000 nm wavelength region. The authors have obtained new spectra of the CH{sub 2} radical in its {tilde b}{sup 1}B{sub 1}-{tilde a}{sup 1}A{sub 1} band system around 850 nm and results of a preliminary analysis of some of these data are presented here. Finally, the authors describe the results of some very recent experiments that combine the transient absorption technique with frequency modulation spectroscopy.

  3. Studies of Arctic Middle Atmosphere Chemistry using Infrared Absorption Spectroscopy

    NASA Astrophysics Data System (ADS)

    Lindenmaier, Rodica

    The objective of this Ph.D. project is to investigate Arctic middle atmosphere chemistry using solar infrared absorption spectroscopy. These measurements were made at the Polar Environment Atmospheric Research Laboratory (PEARL) at Eureka, Nunavut, which is operated by the Canadian Network for the Detection of Atmospheric Change (CANDAC). This research is part of the CANDAC/PEARL Arctic Middle Atmosphere Chemistry theme and aims to improve our understanding of the processes controlling the stratospheric ozone budget using measurements of the concentrations of stratospheric constituents. The instrument, a Bruker IFS 125HR Fourier transform infrared (FTIR) spectrometer, has been specifically designed for high-resolution measurements over a broad spectral range and has been used to measure reactive species, source gases, reservoirs, and dynamical tracers at PEARL since August 2006. The first part of this research focuses on the optimization of ozone retrievals, for which 22 microwindows were studied and compared. The spectral region from 1000 to 1005 cm-1 was found to be the most sensitive in both the stratosphere and troposphere, giving the highest number of independent pieces of information and the smallest total error for retrievals at Eureka. Similar studies were performed in coordination with the Network for the Detection of Atmospheric Composition Change for nine other species, with the goal of improving and harmonizing the retrieval parameters among all Infrared Working Group sites. Previous satellite validation exercises have identified the highly variable polar conditions of the spring period to be a challenge. In this work, comparisons between the 125HR and ACE-FTS (Atmospheric Chemistry Experiment-Fourier transform spectrometer) from 2007 to 2010 have been used to develop strict criteria that allow the ground and satellite-based instruments to be confidently compared. After applying these criteria, the differences between the two instruments were generally

  4. A Student Operated Animated Infrared Spectroscopy Teaching Model

    ERIC Educational Resources Information Center

    Hartman, Karel

    1976-01-01

    Describes a teaching model that consists of a plywood box containing mechanisms that instruct the student about the technical aspects of an infrared spectrophotometer and how a spectrum is generated. (MLH)

  5. The infrared fingerprint signals of silica nanoparticles and its application in immunoassay

    NASA Astrophysics Data System (ADS)

    Ding, Yadan; Chu, Xueying; Hong, Xia; Zou, Peng; Liu, Yichun

    2012-01-01

    Infrared absorption properties of silica nanoparticles were studied. The transverse optical and the longitudinal optical phonon modes from the silica were proved to be the characteristic spectroscopic fingerprint signals. Based on this, a sandwich-structured immunoassay was performed, and the detection of the analyte (human IgG) was achieved by using biofunctional silica nanoparticles as infrared probes. The immunoassay based on Fourier transform infrared reflection absorption spectroscopy of silica nanoparticles shows significant value for potential applications in many areas, such as biomedicine, food safety, and waste treatment.

  6. Fourier Transform Infrared Spectroscopy (FTIS). Volume I. Technical Report.

    DTIC Science & Technology

    1979-12-01

    height of a peak is known. The entire scheme for using infrared data quantitatively depends upon the Beer - Lambert law which is expressed as follows...as A does. Spectra Normalization In order to have the infrared spectra quantitative, one must somehow iccount for all the variables in the Beer - Lambert ...reflectance, perty prediction, FTS-10 spectrophotometer , storage stability lhie of troe flnts. otrc o salshtereain %Ecuipment for measurement of

  7. Infrared Spectroscopy of Star Formation in Galactic and Extragalactic Regions

    NASA Technical Reports Server (NTRS)

    Frogel, Jay (Technical Monitor); Smith, Howard A.

    2004-01-01

    In this program we proposed to perform a series of spectroscopic studies, including data analysis and modeling, of star formation regions using an ensemble of archival space-based data from the Infrared Space Observatory's Long Wavelength Spectrometer and Short Wavelength Spectrometer, and to take advantage of other spectroscopic databases including the first results from SIRTF. Our empha- sis has been on star formation in external, bright IR galaxies, but other areas of research have in- cluded young, low or high mass pre-main sequence stars in star formation regions, and the galactic center. The OH lines in the far infrared were proposed as one key focus of this inquiry because the Principal Investigator (H. Smith) had a full set of OH IR lines from IS0 observations. It was planned that during the proposed 2-1/2 year timeframe of the proposal other data (including perhaps from SIRTF) would become available, and we intended to be responsive to these and other such spec- troscopic data sets. Three papers are included:The Infrared Lines of OH: Diagnostics of Molecular Cloud Conditions in Infrared Bright Galaxies; The Far-Infrared Spectrum of Arp 220; andThe Far-Infrared Emission Line and Continuum Spectrum of the Seyfert Galaxy NGC 1068.

  8. High resolution infrared spectroscopy: Some new approaches and applications to planetary atmospheres

    NASA Technical Reports Server (NTRS)

    Mumma, M. J.

    1978-01-01

    The principles of spectral line formation and of techniques for retrieval of atmospheric temperature and constituent profiles are discussed. Applications to the atmospheres of Earth, Mars, Venus, and Jupiter are illustrated by results obtained with Fourier transform and infrared heterodyne spectrometers at resolving powers (lambda/delta hyperon lambda of approximately 10,000 and approximately 10 to the seventh power), respectively, showing the high complementarity of spectroscopy at these two widely different resolving powers. The principles of heterodyne spectroscopy are presented and its applications to atmospheric probing and to laboratory spectroscopy are discussed. Direct absorption spectroscopy with tuneable semiconductor lasers is discussed in terms of precision frequency-and line strength-measurements, showing substantial advances in laboratory infrared spectroscopy.

  9. Infrared consequence spectroscopy of gaseous protonated and metal ion cationized complexes.

    PubMed

    Fridgen, Travis D

    2009-01-01

    In this article, the new and exciting techniques of infrared consequence spectroscopy (sometimes called action spectroscopy) of gaseous ions are reviewed. These techniques include vibrational predissociation spectroscopy and infrared multiple photon dissociation spectroscopy and they typically complement one another in the systems studied and the information gained. In recent years infrared consequence spectroscopy has provided long-awaited direct evidence into the structures of gaseous ions from organometallic species to strong ionic hydrogen bonded structures to large biomolecules. Much is being learned with respect to the structures of ions without their stabilizing solvent which can be used to better understand the effect of solvent on their structures. This review mainly covers the topics with which the author has been directly involved in research: structures of proton-bound dimers, protonated amino acids and DNA bases, amino acid and DNA bases bound to metal ions and, more recently, solvated ionic complexes. It is hoped that this review reveals the impact that infrared consequence spectroscopy has had on the field of gaseous ion chemistry.

  10. Identification of anisodamine tablets by Raman and near-infrared spectroscopy with chemometrics.

    PubMed

    Li, Lian; Zang, Hengchang; Li, Jun; Chen, Dejun; Li, Tao; Wang, Fengshan

    2014-06-05

    Vibrational spectroscopy including Raman and near-infrared (NIR) spectroscopy has become an attractive tool for pharmaceutical analysis. In this study, effective calibration models for the identification of anisodamine tablet and its counterfeit and the distinguishment of manufacturing plants, based on Raman and NIR spectroscopy, were built, respectively. Anisodamine counterfeit tablets were identified by Raman spectroscopy with correlation coefficient method, and the results showed that the predictive accuracy was 100%. The genuine anisodamine tablets from 5 different manufacturing plants were distinguished by NIR spectroscopy using partial least squares discriminant analysis (PLS-DA) models based on interval principal component analysis (iPCA) method. And the results showed the recognition rate and rejection rate were 100% respectively. In conclusion, Raman spectroscopy and NIR spectroscopy combined with chemometrics are feasible and potential tools for rapid pharmaceutical tablet discrimination.

  11. Infrared spectroscopy of interplanetary dust in the laboratory

    NASA Technical Reports Server (NTRS)

    Fraundorf, P.; Patel, R. I.; Freeman, J. J.

    1981-01-01

    A mount containing three crushed chondritic interplanetary dust particles (IDPs) collected in the earth's stratosphere and subjected to infrared spectroscopic measurements shows features near 1000 and 500/cm, suggesting crystalline pyroxene rather than crystalline olivine, amorphous olivine, or meteoritic clay minerals. Chondritic IDP structural diversity and atmospheric heating effects must be considered when comparing this spectrum with interplanetary and cometary dust astrophysical spectra. TEM and infrared observations of one member of the rare subset of IDPs resembling hydrated carbonaceous chondrite matrix material shows a close infrared spectrum resemblance between 4000 and 400/cm to the C2 meteorite Murchison. TEM observations suggest that this class of particles may be used as an atmospheric entry heating-process thermometer.

  12. Infrared spectroscopy of interplanetary dust in the laboratory

    NASA Technical Reports Server (NTRS)

    Fraundorf, P.; Patel, R. I.; Freeman, J. J.

    1981-01-01

    A mount containing three crushed chondritic interplanetary dust particles (IDPs) collected in the earth's stratosphere and subjected to infrared spectroscopic measurements shows features near 1000 and 500/cm, suggesting crystalline pyroxene rather than crystalline olivine, amorphous olivine, or meteoritic clay minerals. Chondritic IDP structural diversity and atmospheric heating effects must be considered when comparing this spectrum with interplanetary and cometary dust astrophysical spectra. TEM and infrared observations of one member of the rare subset of IDPs resembling hydrated carbonaceous chondrite matrix material shows a close infrared spectrum resemblance between 4000 and 400/cm to the C2 meteorite Murchison. TEM observations suggest that this class of particles may be used as an atmospheric entry heating-process thermometer.

  13. Infrared Spectroscopy of Star Formation in Galactic and Extragalactic Regions

    NASA Technical Reports Server (NTRS)

    Smith, Howard A.; Hasan, Hashima (Technical Monitor)

    2002-01-01

    This report details work done in a project involving spectroscopic studies, including data analysis and modeling, of star-formation regions using an ensemble of archival space-based data including some from the Infrared Space Observatory's Long Wavelength Spectrometer and Short Wavelength Spectrometer, and other spectroscopic databases. We will include four kinds of regions: (1) disks around more evolved objects; (2) young, low or high mass pre-main sequence stars in star-formation regions; (3) star formation in external, bright IR (infrared) galaxies; and (4) the galactic center. During this period, work proceeded fully on track and on time. Details on workshops and conferences attended and research results are presented. A preprint article entitled 'The Far Infrared Lines of OH as Molecular Cloud Diagnostics' is included as an appendix.

  14. Infrared spectroscopy of organics of planetological interest at low temperatures.

    PubMed

    Khanna, R K

    1995-01-01

    In the context of prebiotic chemistry in space, some of the outer planetary objects display H, C, N and O rich chemistry similar to the one in the biosphere of Earth. Of particular interest are Saturn's moon, Titan; Neptune's moon, Triton; and Pluto where extreme cold conditions prevail. Identifications of chemical species on these objects (surfaces and atmospheres) is essential to a better understanding of the radiation induced chemical reactions occurring thereon. There have been several ground based observations of these planetary objects in the infrared windows from 1 to 2.5 micrometers. Voyager also provided spectra in the thermal infrared (6 to 50 micrometers) region. Interpretation of these data require laboratory infrared spectra of relevant species under the temperature conditions appropriate to these objects. The results of some of these studies carried out in our laboratory and elsewhere and their impact on the analyses of the observed data will be summarized.

  15. Atomic force microscope infrared spectroscopy of griseofulvin nanocrystals

    PubMed Central

    Harrison, A. J.; Bilgili, E. A.; Beaudoin, S. P.

    2013-01-01

    The goal of this work was to evaluate the ability of photothermal induced resonance (PTIR) to measure the local infrared absorption spectra of crystalline organic drug nanoparticles embedded within solid matrices. Herein, the first reports of the chemical characterization of sub-100 nm organic crystals are described; infrared spectra of 90 nm griseofulvin particles were obtained, confirming the chemical resolution of PTIR beyond the diffraction limit. Additionally, particle size distributions via dynamic light scattering and PTIR image analysis were found to be similar, suggesting that the PTIR measurements are not significantly affected by inhomogeneous infrared absorptivity of this system. Thus as medical applications increasingly emphasize localized drug delivery via micro/nano-engineered structures, PTIR can be used to unambiguously chemically characterize drug formulations at these length scales. PMID:24171582

  16. High pressure far infrared spectroscopy of ionic solids

    NASA Technical Reports Server (NTRS)

    Lowndes, R. P.

    1974-01-01

    A high-pressure far-infrared cell operating at up to truly hydrostatic pressures of 8 kbar is described and used to determine the anharmonic self-energies associated with the transverse optic modes of ionic solids in which q approximately equals zero. The cell allows far-infrared studies in the spectral range below 120 reciprocal cm. The transverse optic modes were investigated to determine their mode Gruneisen constants and the pressure dependence of their inverse lifetimes in RbI, CsI, and TlCl.

  17. High sensitivity transient infrared spectroscopy: a UV/Visible transient grating spectrometer with a heterodyne detected infrared probe.

    PubMed

    Donaldson, Paul M; Strzalka, Halina; Hamm, Peter

    2012-06-04

    We describe here a high sensitivity means of performing time resolved UV/Visible pump, infrared probe spectroscopy using optically Heterodyne Detected UV-IR Transient Gratings. The experiment design employed is simple, robust and includes a novel means of generating phase locked pulse pairs that relies on only mirrors and a beamsplitter. A signal to noise ratio increase of 24 compared with a conventional pump-probe arrangement is demonstrated.

  18. Combined autofluorescence and Raman spectroscopy method for skin tumor detection in visible and near infrared regions

    NASA Astrophysics Data System (ADS)

    Zakharov, V. P.; Bratchenko, I. A.; Artemyev, D. N.; Myakinin, O. O.; Khristoforova, Y. A.; Kozlov, S. V.; Moryatov, A. A.

    2015-07-01

    The combined application of Raman and autofluorescence spectroscopy in visible and near infrared regions for the analysis of malignant neoplasms of human skin was demonstrated. Ex vivo experiments were performed for 130 skin tissue samples: 28 malignant melanomas, 19 basal cell carcinomas, 15 benign tumors, 9 nevi and 59 normal tissues. Proposed method of Raman spectra analysis allows for malignant melanoma differentiating from other skin tissues with accuracy of 84% (sensitivity of 97%, specificity of 72%). Autofluorescence analysis in near infrared and visible regions helped us to increase the diagnostic accuracy by 5-10%. Registration of autofluorescence in near infrared region is realized in one optical unit with Raman spectroscopy. Thus, the proposed method of combined skin tissues study makes possible simultaneous large skin area study with autofluorescence spectra analysis and precise neoplasm type determination with Raman spectroscopy.

  19. Stress degradation studies of nelfinavir mesylate by Fourier transform infrared spectroscopy.

    PubMed

    Singh, Parul; Mehrotra, Ranjana; Bakhshi, A K

    2010-11-02

    Nelfinavir mesylate is the first nonpeptidic protease inhibitor available in pediatric formulation. In the present paper the stability of nelfinavir mesylate under different stress conditions is evaluated using Fourier transform infrared spectroscopy. The drug is subjected to thermal degradation, photodegradation, acid hydrolysis, base hydrolysis and oxidation as per ICH guidelines. Differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), X-ray diffraction (XRD) and high performance liquid chromatography (HPLC) are carried out to support the implementation of infrared spectroscopy for the stability studies of nelfinavir mesylate. Significant changes are observed in the IR spectra collected after exposing the drug to thermal radiations, acid and base hydrolysis and oxidative degradation. No change is observed in the spectra of the drug after exposing it to sunlight indicating the good photostability of nelfinavir mesylate. The results of infrared spectroscopy agree well with that of other complementary techniques as DSC, TGA, XRD and HPLC. Copyright (c) 2010 Elsevier B.V. All rights reserved.

  20. Thermal Infrared Spectroscopy of Experimentally Shocked Anorthosite and Pyroxenite

    NASA Technical Reports Server (NTRS)

    Johnson, J. R.; Hoerz, F.; Christensen, P.; Lucey, P. G.

    2001-01-01

    We performed shock recovery experiments at JSC (17-63 GPa) on samples of Stillwater pyroxenite and anorthosite and acquired their thermal infrared spectra (3-50 micron) to investigate the degradation of spectral features at high pressures. Additional information is contained in the original extended abstract.

  1. Thermal Infrared Spectroscopy of Saturn and Titan from Cassini

    NASA Technical Reports Server (NTRS)

    Jennings, Donald E.; Brasunas, J. C.; Carlson, R. C.; Flasar, F. M.; Kunde, V. G.; Mamoutkine, A. A.; Nixon, A.; Pearl, J. C.; Romani, P. N.; Simon-Miller, A. A.; Bjoraker, G. L.

    2009-01-01

    The Cassini spacecraft completed its nominal mission at Saturn in 2008 and began its extended mission. Cassini carries the Composite Infrared Spectrometer (CIRS); a Fourier transform spectrometer that measures the composition, thermal structure and dynamics of the atmospheres of Saturn and Titan, and also the temperatures of other moons and the rings.

  2. Near-Infrared Spectroscopy of Himalia An Irregular Jovian Satellite

    NASA Technical Reports Server (NTRS)

    Brown, R. H.; Baines, K.; Bellucci, G.; Bibring, J.-P.; Buratti, B.; Capaccioni, F.; Cerroni, P.; Clark, R.; Coradini, A.; Cruikshank, D.

    2002-01-01

    Spectra of the irregular Jovian satellite Himalia were obtained with the Visual and Infrared Mapping Spectrometer (VIMS) onboard Cassini during the Jupiter Flyby on December 18-19, 2000. These are the first spectral data of an irregular satellite beyond 2.5 microns. Additional information is contained in the original extended abstract.

  3. International Halley Watch: Discipline specialists for infrared spectroscopy and radiometry

    NASA Technical Reports Server (NTRS)

    Knacke, R. F.; Encrenaz, T.

    1986-01-01

    The Infrared Net has been active in all areas of comet science in its domain. The more than 100 members of the net and 30 participating observatories are still engaged in observations, and only a preliminary discussion of the highlights of the program is possible at this time.

  4. Infrared spectroscopy of fullerene C60/anthracene adducts

    NASA Astrophysics Data System (ADS)

    García-Hernández, D. A.; Cataldo, F.; Manchado, A.

    2013-09-01

    Recent Spitzer Space Telescope observations of several astrophysical environments such as planetary nebulae, reflection nebulae and R Coronae Borealis stars show the simultaneous presence of mid-infrared features attributed to neutral fullerene molecules (i.e. C60) and polycyclic aromatic hydrocarbons (PAHs). If C60 fullerenes and PAHs coexist in fullerene-rich space environments, then C60 may easily form adducts with a number of different PAH molecules, at least with catacondensed PAHs. Here we present the laboratory infrared spectra (˜2-25 μm) of C60 fullerene and anthracene Diels-Alder mono- and bis-adducts as produced by sonochemical synthesis. We find that C60/anthracene Diels-Alder adducts display spectral features strikingly similar to those from C60 (and C70) fullerenes and other unidentified infrared emission features. Thus, fullerene adducts - if formed under astrophysical conditions and are stable/abundant enough - may contribute to the infrared emission features observed in fullerene-containing circumstellar/interstellar environments.

  5. Laboratory Infrared Spectroscopy of Gaseous Negatively Charged Polyaromatic Hydrocarbons

    NASA Astrophysics Data System (ADS)

    Gao, Juehan; Berden, Giel; Oomens, Jos

    2014-06-01

    Based largely on infrared spectroscopic evidence, polycyclic aromatic hydrocarbon (PAH) molecules are now widely accepted to occur abundantly in the interstellar medium. Laboratory infrared spectra have been obtained for a large variety of neutral and cationic PAHs, but data for anionic PAHs are scarce. Nonetheless, in regions with relatively high electron densities and low UV photon fluxes, PAHs have been suggested to occur predominantly as negatively charged ions (anions), having substantial influence on cloud chemistry. While some matrix spectra have been reported for radical anion PAHs, no data is available for even-electron anions, which are more stable against electron detachment. Here we present the first laboratory infrared spectra of deprotonated PAHs ([PAH-H]-) in the wavelength ranges between 6 and 16 μm and around 3 μm. Wavelength-dependent infrared multiple-photon electron detachment is employed to obtain spectra for deprotonated naphthalene, anthracene, and pyrene in the gas phase. Spectra are compared with theoretical spectra computed at the density functional theory level. We show that the relative band intensities in different ranges of the IR spectrum deviate significantly from those of neutral and positively charged PAHs, and moreover from those of radical anion PAHs. These relative band intensities are, however, well reproduced by theory. An analysis of the frontier molecular orbitals of the even- and odd-electron anions reveals a high degree of charge localization in the deprotonated systems, qualitatively explaining the observed differences and suggesting unusually high electric dipole moments for this class of PAH molecules.

  6. Applications of infrared photo-acoustic spectroscopy for wood samples

    Treesearch

    Mon-Lin Kuo; John F. McClelland; Siquan Luo; Po-Liang Chien; R.D. Walker; Chung-Yun Hse

    1988-01-01

    Various infrared (IR) spectroscopic techniques for the analysis of wood samples are briefly discussed. Theories and instrumentation of the newly developed photoacoustic spectroscopic (PAS) technique for measuring absorbance spectra of solids are presented. Some important applications of the PAS technique in wood science research are discussed. The application of the...

  7. High-pressure-low-temperature cryostat designed for use with fourier transform infrared spectrometers and time-resolved infrared spectroscopy.

    PubMed

    Calladine, James A; Love, Ashley; Fields, Peter A; Wilson, Richard G M; George, Michael W

    2014-01-01

    The design for a new high-pressure-low-temperature infrared (IR) cell for performing experiments using conventional Fourier transform infrared or fast laser-based time-resolved infrared spectroscopy, in a range of solvents, is described. The design builds upon a commercially available compressor and cold end (Polycold PCC(®) and CryoTiger(®)), which enables almost vibration-free operation, ideal for use with sensitive instrumentation. The design of our cell and cryostat allows for the study of systems at temperatures from 77 to 310 K and at pressures up to 250 bar. The CaF2 windows pass light from the mid-IR to the ultraviolet (UV), enabling a number of experiments to be performed, such as Raman, UV-visible absorption spectroscopy, and time-resolved techniques where sample excitation/probing using continuous wave or pulsed lasers is required. We demonstrate the capabilities of this cell by detailing two different applications: (i) the reactivity of a range of Group V-VII organometallic alkane complexes using time-resolved spectroscopy on the millisecond timescale and (ii) the gas-to-liquid phase transition of CO2 at low temperature, which is applicable to measurements associated with transportation issues related to carbon capture and storage.

  8. Chemical profiling and adulteration screening of Aquilariae Lignum Resinatum by Fourier transform infrared (FT-IR) spectroscopy and two-dimensional correlation infrared (2D-IR) spectroscopy.

    PubMed

    Qu, Lei; Chen, Jian-Bo; Zhang, Gui-Jun; Sun, Su-Qin; Zheng, Jing

    2017-03-05

    As a kind of expensive perfume and valuable herb, Aquilariae Lignum Resinatum (ALR) is often adulterated for economic motivations. In this research, Fourier transform infrared (FT-IR) spectroscopy is employed to establish a simple and quick method for the adulteration screening of ALR. First, the principal chemical constituents of ALR are characterized by FT-IR spectroscopy at room temperature and two-dimensional correlation infrared (2D-IR) spectroscopy with thermal perturbation. Besides the common cellulose and lignin compounds, a certain amount of resin is the characteristic constituent of ALR. Synchronous and asynchronous 2D-IR spectra indicate that the resin (an unstable secondary metabolite) is more sensitive than cellulose and lignin (stable structural constituents) to the thermal perturbation. Using a certified ALR sample as the reference, the infrared spectral correlation threshold is determined by 30 authentic samples and 6 adulterated samples. The spectral correlation coefficient of an authentic ALR sample to the standard reference should be not less than 0.9886 (p=0.01). Three commercial adulterated ALR samples are identified by the correlation threshold. Further interpretation of the infrared spectra of the adulterated samples indicates the common adulterating methods - counterfeiting with other kind of wood, adding ingredient such as sand to increase the weight, and adding the cheap resin such as rosin to increase the content of resin compounds. Results of this research prove that FT-IR spectroscopy can be used as a simple and accurate quality control method of ALR. Copyright © 2016 Elsevier B.V. All rights reserved.

  9. Infrared spectroscopy of the bent isomer of N 2O-HF

    NASA Astrophysics Data System (ADS)

    Dayton, D. C.; Miller, R. E.

    1988-02-01

    We report the infrared spectrum of the bent isomer of N 2O-HF in which the HF subnit is hydrogen bonded to the oxygen. This isomer was previously observed using microwave spectroscopy, while recent infrared measurements by Lovejoy and Nesbitt have shown that a linear (or slightly bent) ONNHF isomer also exists. We find that the linear ONNHF isomer is present under identical beam conditions to those used to record the spectrum of the bent isomer.

  10. Vibrational spectra of CO on Ni (100) studied by infrared emission spectroscopy

    SciTech Connect

    Not Available

    1984-02-01

    We have developed the technique of infrared emission spectroscopy in order to observe vibrational modes of molecules adsorbed on clean, single crystal metal surfaces. A novel apparatus has been constructed which measures the emission from a single crystal sample in thermal equilibrium at room temperature. The apparatus consists of a liquid helium cooled infrared grating spectrometer coupled to an ultrahigh vacuum system equipped with surface preparation and characterization facilities. 3 references, 3 figures.

  11. [Effects of spectral pretreatment on the prediction of crystallinity of wood cellulose using near infrared spectroscopy].

    PubMed

    Jiang, Ze-hui; Fei, Ben-hua; Yang, Zhong

    2007-03-01

    The crystallinity of wood has an important effect on the physical, mechanical and chemical properties of cellulose fibers. The aims of this study were to investigate the ability of near infrared spectroscopy (NIR) to predict the crystallinity of wood cellulose and the effect of spectral pretreatment on the prediction of crystallinity in wood cellulose using near infrared spectroscopy (NIR). Near infrared diffuse reflectance spectra were collected from wood powder with a fiber-optical probe and the crystallinity of wood was determined by X-ray diffractometer (XRD) in this experiment. The results showed that near infrared spectroscopy coupled with partial least square (PLS) regression could be correlated with the crystallinity of plantation wood, and the ability of NIR prediction based on original spectra was better than that based on the first derivative or second derivative treated spectra. There was a significant correlation between NIR spectra and XRD determined crystallinity with a correlationcoefficient of 0.950 and a low RMSEP. Near infrared spectroscopy coupled with multivariate data anlaysis has proven to be an accurate and fast method for rapid prediction of wood crystallinity.

  12. Infrared ion spectroscopy inside a mass-selective cryogenic 2D linear ion trap.

    PubMed

    Cismesia, Adam P; Tesler, Larry F; Bell, Matthew R; Bailey, Laura S; Polfer, Nicolas C

    2017-07-27

    We demonstrate operation of the first cryogenic 2D linear ion trap (LIT) with mass-selective capabilities. This trap presents a number of advantages for infrared ion "action" spectroscopy studies, particularly those employing the "tagging/messenger" spectroscopy approach. The high trapping efficiencies, trapping capacities, and low detection limits make 2D LITs a highly suitable choice for low-concentration analytes from scarce biological samples. In our trap, ions can be cooled down to cryogenic temperatures to achieve higher-resolution infrared spectra, and individual ions can be mass selected prior to irradiation for a background-free photodissociation scheme. Conveniently, multiple tagged analyte ions can be mass isolated and efficiently irradiated in the same experiment, allowing their infrared spectra to be recorded in parallel. This multiplexed approach is critical in terms of increasing the duty cycle of infrared ion spectroscopy, which is currently a key weakness of the technique. The compact design of this instrument, coupled with powerful mass selection capabilities, set the stage for making cryogenic infrared ion spectroscopy viable as a bioanalytical tool in small molecule identification. This article is protected by copyright. All rights reserved.

  13. Variable Temperature Infrared Spectroscopy Investigation of Benzoic Acid Interactions with Montmorillonite Clay Interlayer Water.

    PubMed

    Nickels, Tara M; Ingram, Audrey L; Maraoulaite, Dalia K; White, Robert L

    2015-07-01

    Molecular interactions between benzoic acid and cations and water contained in montmorillonite clay interlayer spaces are characterized by using variable temperature diffuse reflection infrared Fourier transform spectroscopy (VT-DRIFTS). Using sample perturbation and difference spectroscopy, infrared spectral changes resulting from removal of interlayer water and associated changes in local benzoic acid environments are identified. Difference spectra features can be correlated with changes in specific molecular vibrations that are characteristic of benzoic acid molecular orientation. Results suggest that the carboxylic acid functionality of benzoic acid interacts with interlayer cations through a bridging water molecule and that this interaction is affected by the nature of the cation present in the clay interlayer space.

  14. Communication: Evidence of structural phase transitions in silicalite-1 by infrared spectroscopy

    NASA Astrophysics Data System (ADS)

    Ballandras, Anthony; Weber, Guy; Paulin, Christian; Bellat, Jean-Pierre; Rotger, Maud

    2013-09-01

    The adsorption of trichloroethylene, perchloroethylene, and p-xylene on a MFI (Mobile-FIve) zeolite is studied using in situ FTIR spectroscopy at 298 K. Spectra of self-supported zeolites in contact with increasing pressures of pure gas were recorded at equilibrium in the mid-infrared domain. Analysis of the evolution of the shape and location of vibrational bands of the zeolite as a function of the amount adsorbed allowed the observation of structural modifications of the adsorbent for the first time by infrared spectroscopy.

  15. [Application of near-infrared diffuse reflectance spectroscopy to the detection and identification of transgenic corn].

    PubMed

    Rui, Yu-kui; Luo, Yun-bo; Huang, Kun-lun; Wang, Wei-min; Zhang, Lu-da

    2005-10-01

    With the rapid development of the GMO, more and more GMO food has been pouring into the market. Much attention has been paid to GMO labeling under the controversy of GMO safety. Transgenic corns and their parents were scanned by continuous wave of near infrared diffuse reflectance spectroscopy range of 12000-4000 cm(-1); the resolution was 4 cm(-1); scanning was carried out for 64 times; BP algorithm was applied for data processing. The GMO food was easily resolved. Near-infrared diffuse reflectance spectroscopy is unpolluted and inexpensive compared with PCR and ELISA, so it is a very promising detection method for GMO food.

  16. [Near Infrared Spectroscopy of the Cretaceous Red Beds in Inner Mongolia Dongshengmiao].

    PubMed

    Liao, Yi-peng; Cao, Jian-jin; Wu, Zheng-quan; Luo, Song-ying; Wang, Zheng-yang

    2015-09-01

    Take the cores and surface weathered soil from the Cretaceous red beds in the western of Dongshengmiao mine of Inner Mongolia and analysis with near-infrared spectroscopy. The result shows that near-infrared spectroscopy can identify mineral quickly through the characteristic absorption peaks of each group. The Cretaceous red beds in the western of Dongshengmiao mine is argillaceous cementation, it is mainly composed of quartz, feldspar, montmorillonite, illite, chlorite, muscovite etc, the mineral composition is mainly affected by the upstream source area. The clay mineral like montmorillonite water swelling and uneven drying shrinkage expands the original crack and creates new cracks, reduces its strength, which is the mainly reason of its disintegration. According to the composition of clay mineral, we speculate its weathering process is mainly physical weathering, the climate during the weathering is cold and dry. The results can not only improve the geological feature of the mining area, but also show that the near-infrared spectroscopy technology can analyze the mineral composition of soil and rock effectively on the basis of Mineral spectroscopy, which demonstrates the feasibility of the near-infrared spectroscopy can analyze minerals in soil and rock quickly, that shows the feasibility in geology study, provides new ideas for the future research of soil and rock.

  17. Thermal infrared spectroscopy on feldspars — Successes, limitations and their implications for remote sensing

    NASA Astrophysics Data System (ADS)

    Hecker, Christoph; der Meijde, Mark van; van der Meer, Freek D.

    2010-11-01

    Minerals of the feldspar group are the most common on earth. Feldspars are economically important in two ways: either as industrial minerals or as a vector-to-ore for mineral deposits. In order to use feldspars for classifying rock compositions or metasomatic conditions during rock alteration events, there is a need for analytical methods to identify and classify feldspars. Traditionally, feldspar composition and structure have been investigated using methods such as optical microscopy, electron microprobe analysis (EMPA), cathodoluminescence and X-ray diffraction (XRD) analysis. In this paper infrared techniques (0.7-25 μm)) are reviewed in detail and investigated in how far some of the traditional analytical methods can be replaced by infrared spectroscopy. Successes as well as limitations of infrared approaches are highlighted and existing work is scrutinized in terms of its applicability to remote sensing techniques. Even though numerous studies on mid-infrared (MIR) spectroscopy of feldspars exist, their results often cannot be directly related to remote sensing applications. Examples are the effects of feldspar twinning, exsolution textures and structural state on infrared spectra. The applicability of the results to emission remote sensing requires further research. It has been shown that linear unmixing of laboratory infrared spectra of rocks works fairly well. Detection limits for feldspar are around 5% and plagioclase composition can be determined within error margins of ± 4% anorthite component. Infrared spectroscopy can, however, not detect compositional zonation or different generations of feldspars. Infrared spectra represent the current average plagioclase and average alkali feldspar composition in the sample. With several new airborne instruments under development, it is opportune to focus upcoming research efforts on developing standardized processing techniques and spectral feldspar indices for thermal infrared imagery. Commercially interesting

  18. Applications of remote fiber optic spectroscopy using infrared fibers and Fourier transform infrared (FTIR) spectroscopy to environmental monitoring

    NASA Astrophysics Data System (ADS)

    Druy, Mark A.; Glatkowski, Paul J.; Bolduc, Roy A.; Stevenson, William A.; Thomas, Thomas C.

    1994-10-01

    This manuscript summarizes the effort to demonstrate the feasibility of developing a field-portable Fourier Transform Infrared (FTIR) instrument that can perform a quick and accurate chemical analysis of unknown waste materials at Air Force bases without removing a sample for analysis. We report that devices containing a tapered infrared fiber optic sensor can remotely detect and quantify the range of liquid hazardous waste typically found at Air Force bases. Partial Least Squares (PLS) calibration equations were formulated and shown to accurately predict the concentration of components in a mixture with an error or +/- 0.05% volume.

  19. Difference Between Far-Infrared Photoconductivity Spectroscopy and Absorption Spectroscopy: Theoretical Evidence of the Electron Reservoir Mechanism

    NASA Astrophysics Data System (ADS)

    Toyoda, Tadashi; Fujita, Maho; Uchida, Tomohisa; Hiraiwa, Nobuyoshi; Fukuda, Taturo; Koizumi, Hideki; Zhang, Chao

    2013-08-01

    The intriguing difference between far-infrared photoconductivity spectroscopy and absorption spectroscopy in the measurement of the magnetoplasmon frequency in GaAs quantum wells reported by Holland et al. [Phys. Rev. Lett. 93, 186804 (2004)] remains unexplained to date. This Letter provides a consistent mechanism to solve this puzzle. The mechanism is based on the electron reservoir model for the integer quantum Hall effect in graphene [Phys. Lett. A 376, 616 (2012)]. We predict sharp kinks to appear in the magnetic induction dependence of the magnetoplasmon frequency at very low temperatures such as 14 mK in the same GaAs quantum well sample used by Holland et al..

  20. Kinetic inductance detectors for far-infrared spectroscopy

    NASA Astrophysics Data System (ADS)

    Barlis, A.; Aguirre, J.; Stevenson, T.

    2016-07-01

    The star formation mechanisms at work in the early universe remain one of the major unsolved problems of modern astrophysics. Many of the luminous galaxies present during the period of peak star formation (at redshift of about 2.5) were heavily enshrouded in dust, which makes observing their properties difficult at optical wavelengths. However, many spectral lines exist at far-infrared wavelengths that serve as tracers of star formation. Here, we describe a detector system suitable for a balloon-borne spectroscopic intensity mapping experiment at far-infrared wavelengths. The system uses lumped-element kinetic inductance detectors (KIDs), which have the potential to achieve high sensitivity and low noise levels. KIDs consist of separate capacitive and inductive elements, and use the inductive element as the radiation absorber. We describe the design considerations, fabrication process, and readout scheme for a prototype LEKID array of 1600 pixels.

  1. Near infrared and optical spectroscopy of FSC10214+4724

    NASA Technical Reports Server (NTRS)

    Soifer, B. T.; Cohen, J. G.; Armus, L.; Matthews, K.; Neugebauer, G.; Oke, J. B.

    1995-01-01

    New infrared and optical spectroscopic observations, obtained with the W.M. Keck Telescope, are reported for the highly luminous infrared source FSC10214+4724. The rest frame optical spectrum shows new emission lines of (NeIII, (NeV), (OI), (OII), (SII), and He(+) while the rest frame ultraviolet spectrum shows new lines of OIV+SiIV, NII, NIV, SiII, NeIV and possibly NII and (NeIII), as well as clearly showing the L alpha is self-absorbed. The emission line spectrum is most characteristic of a Seyfert 2 nucleus. The preponderance of spectroscopic evidence strengthens the case of a dust enshrouded AGN powering much or most of the observed luminosity. The various spectral lines lead to a wide range in the inferred reddening and ionization parameter for this system, suggesting that we are viewing several environments through differing extinctions.

  2. Surface plasmon-based infrared spectroscopy for cell biosensing

    NASA Astrophysics Data System (ADS)

    Yashunsky, Victor; Lirtsman, Vladislav; Zilbershtein, Alexander; Bein, Amir; Schwartz, Betty; Aroeti, Benjamin; Golosovsky, Michael; Davidov, Dan

    2012-08-01

    Cell morphology is often used as a valuable indicator of the physical condition and general status of living cells. We demonstrate a noninvasive method for morphological characterization of adherent cells. We measure infrared reflectivity spectrum at oblique angle from living cells cultured on thin Au film, and utilize the unique properties of the confined infrared waves (i.e., surface plasmon and guided modes) traveling inside the cell layer. The propagation of these waves strongly depends on cell morphology and connectivity. By tracking the resonant wavelength and attenuation of the surface plasmon and guided modes we measure the kinetics of various cellular processes such as (i) cell attachment and spreading on different substrata, (ii) modulation of the outer cell membrane with chlorpromazine, and (iii) formation of intercellular junctions associated with progressive cell polarization. Our method enables monitoring of submicron variations in cell layer morphology in real-time, and in the label-free manner.

  3. Dirac charge dynamics in graphene by infrared spectroscopy

    SciTech Connect

    Martin, Michael C; Li, Z.Q.; Henriksen, E.A.; Jiang, Z.; Hao, Z.; Martin, Michael C; Kim, P.; Stormer, H.L.; Basov, Dimitri N.

    2008-04-29

    A remarkable manifestation of the quantum character of electrons in matter is offered by graphene, a single atomic layer of graphite. Unlike conventional solids where electrons are described with the Schrödinger equation, electronic excitations in graphene are governed by the Dirac hamiltonian. Some of the intriguing electronic properties of graphene, such as massless Dirac quasiparticles with linear energy-momentum dispersion, have been confirmed by recent observations. Here, we report an infrared spectromicroscopy study of charge dynamics in graphene integrated in gated devices. Our measurements verify the expected characteristics of graphene and, owing to the previously unattainable accuracy of infrared experiments, also uncover significant departures of the quasiparticle dynamics from predictions made for Dirac fermions in idealized, free-standing graphene. Several observations reported here indicate the relevance of many-body interactions to the electromagnetic response of graphene.

  4. Infrared spectroscopy for chemical agent detection using tailored hypersorbent materials

    NASA Astrophysics Data System (ADS)

    Kozak, Dmitry A.; McGill, R. Andrew; Stievater, Todd H.; Furstenberg, Robert; Pruessner, Marcel W.; Nguyen, Viet

    2015-06-01

    We report long-wave infrared (LWIR, 5-15 μm) and mid-wave infrared (MWIR, 2.5 - 5 μm) differential absorption spectra of different nerve agent simulants and common solutes sorbed to poly(methyldi(1,1,1-trifluoro-2-trifluoromethyl- 2-hydroxypent-4-enyl)silane, HCSFA2, an NRL developed hypersorbent polymer. HCSFA2 is a strong hydrogen-bond acidic polymer which exhibits large gas-polymer partitions for a variety of hazardous chemicals with hydrogen-bond basic properties such as the phosphonate ester G-nerve agents or their simulants. The measured ATR-FTIR differential absorption spectra show complex fingerprint signal changes in the resonances for the sorbent material itself, as well as new resonances arising from chemical bonding between the solute or analyte and the sorbent or the solute itself being present in the sorbent.

  5. Development of Kinetic Inductance Detectors for Far-Infrared Spectroscopy

    NASA Astrophysics Data System (ADS)

    Barlis, Alyssa; Aguirre, James E.; Stevenson, Thomas

    2016-01-01

    An instrument with high sensitivity and spectral resolution at far-infrared wavelengths could contribute significantly to several currently unanswered questions in astrophysics. Here, we describe a detector system suitable for a spectroscopic experiment at far-infrared wavelengths using kinetic inductance detectors (KIDs). KIDs have the potential to achieve high sensitivity and low noise levels. Specifically, the approach we take uses lumped-element KIDs, which consist of separate capacitive and inductive elements combined to form a microresonator. The inductive element serves as a direct radiation absorber. We describe the design considerations, fabrication process, and readout scheme for a prototype LEKID array of 1600 pixels, along with results from a prototype detector array.

  6. Infrared spectroscopy of low-mass X-ray binaries

    NASA Astrophysics Data System (ADS)

    Bandyopadhyay, R.; Shahbaz, T.; Charles, P. A.; van Kerkwijk, M. H.; Naylor, T.

    1997-03-01

    Using CGS4 on UKIRT, we have obtained the first 2.05-2.45 μm infrared spectra of the Galactic bulge low-mass X-ray binaries (LMXBs) GX1+4 and GX13+1. We report the detection of Brackett gamma emission from the accretion disc in both systems, confirming the identification of the IR counterpart to GX13+1. In addition, both spectra show CO molecular bands and metal lines in absorption, representing the first infrared spectroscopic detection of the secondary in a heavily obscured bulge source. We also present a JHK spectrum of the LMXB ScoX-1, which shows strong Hi, Hei and HeII emission.

  7. Mid-infrared photothermal heterodyne spectroscopy in a liquid crystal using a quantum cascade laser

    PubMed Central

    Mërtiri, Alket; Jeys, Thomas; Liberman, Vladimir; Hong, M. K.; Mertz, Jerome; Altug, Hatice; Erramilli, Shyamsunder

    2012-01-01

    We report a technique to measure the mid-infrared photothermal response induced by a tunable quantum cascade laser in the neat liquid crystal 4-octyl-4′-cyanobiphenyl (8CB), without any intercalated dye. Heterodyne detection using a Ti:sapphire laser of the response in the solid, smectic, nematic and isotropic liquid crystal phases allows direct detection of a weak mid-infrared normal mode absorption using an inexpensive photodetector. At high pump power in the nematic phase, we observe an interesting peak splitting in the photothermal response. Tunable lasers that can access still stronger modes will facilitate photothermal heterodyne mid-infrared vibrational spectroscopy. PMID:22912508

  8. Applications of infrared free electron lasers in picosecond and nonlinear spectroscopy

    NASA Astrophysics Data System (ADS)

    Fann, W. S.; Benson, S. V.; Madey, J. M. J.; Etemad, S.; Baker, G. L.; Rothberg, L.; Roberson, M.; Austin, R. H.

    1990-10-01

    In this paper we describe two different types of spectroscopic experiments that exploit the characteristics of the infrared FEL, Mark III, for studies of condensed matter: - the spectrum of χ(3)(-3ω; ω, ω, ω) in polyacetylene: an application of the free electron laser in nonlinear optical spectroscopy, and - a dynamical test of Davydov-like solitons in acetanilide using a picosecond free electron laser. These two studies highlight the unique contributions FELs can make to condensed-matter spectroscopy.

  9. THE INFRARED SPECTROSCOPY OF NEUTRAL POLYCYCLIC AROMATIC HYDROCARBON CLUSTERS

    SciTech Connect

    Ricca, Alessandra; Bauschlicher, Charles W. Jr.; Allamandola, Louis J. E-mail: Charles.W.Bauschlicher@nasa.gov

    2013-10-10

    The mid-infrared spectra of neutral homogeneous polycyclic aromatic hydrocarbon (PAH) clusters have been computed using density functional theory including an empirical correction for dispersion. The C-H out-of-plane bending modes are redshifted for all the clusters considered in this work. The magnitude of the redshift and the peak broadening are dependent on PAH size, shape, and on the PAH arrangement in the cluster.

  10. Infrared Spectroscopy of Polycyclic Aromatic Hydrocarbon Cations. 3; The Members

    NASA Technical Reports Server (NTRS)

    Hudgins, D. M.; Allamandola, L. J.; Wittebon, Fred C. (Technical Monitor)

    1994-01-01

    In spite of the fact that the infrared spectroscopic properties of only a few isolated ionized polycyclic aromatic hydrocarbons (PAHs) are known, gaseous, ionized PAHs are thought to be responsible for a very common family of infrared interstellar emission bands. In order to provide a data base to test this hypothesis and, if borne out, to use this emission band family as a probe of many different interstellar environments, we are carrying out a thorough study of the infrared spectroscopic properties of neutral and ionized PAHs in argon matrices. Here we present the near and mid-infrared spectra of the cations of the five most thermodynamically favored PAHs up to coronene: phenanthrene, pyrene, benzo[e]pyrene, benzo[ghilperylene, and coronene. The properties of naphthalene, the first member of the series, are given elsewhere. The spectra of perdeuterated phenanthrene and pyrene are also reported. For those molecules which have been previously studied (pyrene, d(10)-pyrene, and coronene), band positions and relative intensities are in agreement. In all cases we report additional features. Absolute integrated absorbance values are given for the phenanthrene, perdeutero-phenanthrene, pyrene, benzo[ghi]perylene, and coronene cations. With the exception of coronene,the cation bands corresponding to the CC modes are typically 2-5 times more intense than those of the CH out-of-plane bending vibrations. For the cations the CC stretching and CH in-plane bending modes give rise to bands which are an order of magnitude stronger than for the neutral species, and the CH out-of-plane bends produce bands which are 5-20 times weaker than in the neutral species. This behavior is similar to that found in most other PAH cations studied to date. The astronomical implications of these PAH cation spectra are also discussed.

  11. Infrared Spectroscopy of Polycyclic Aromatic Hydrocarbon Cations. 3; The Members

    NASA Technical Reports Server (NTRS)

    Hudgins, D. M.; Allamandola, L. J.; Wittebon, Fred C. (Technical Monitor)

    1994-01-01

    In spite of the fact that the infrared spectroscopic properties of only a few isolated ionized polycyclic aromatic hydrocarbons (PAHs) are known, gaseous, ionized PAHs are thought to be responsible for a very common family of infrared interstellar emission bands. In order to provide a data base to test this hypothesis and, if borne out, to use this emission band family as a probe of many different interstellar environments, we are carrying out a thorough study of the infrared spectroscopic properties of neutral and ionized PAHs in argon matrices. Here we present the near and mid-infrared spectra of the cations of the five most thermodynamically favored PAHs up to coronene: phenanthrene, pyrene, benzo[e]pyrene, benzo[ghilperylene, and coronene. The properties of naphthalene, the first member of the series, are given elsewhere. The spectra of perdeuterated phenanthrene and pyrene are also reported. For those molecules which have been previously studied (pyrene, d(10)-pyrene, and coronene), band positions and relative intensities are in agreement. In all cases we report additional features. Absolute integrated absorbance values are given for the phenanthrene, perdeutero-phenanthrene, pyrene, benzo[ghi]perylene, and coronene cations. With the exception of coronene,the cation bands corresponding to the CC modes are typically 2-5 times more intense than those of the CH out-of-plane bending vibrations. For the cations the CC stretching and CH in-plane bending modes give rise to bands which are an order of magnitude stronger than for the neutral species, and the CH out-of-plane bends produce bands which are 5-20 times weaker than in the neutral species. This behavior is similar to that found in most other PAH cations studied to date. The astronomical implications of these PAH cation spectra are also discussed.

  12. Laboratory infrared spectroscopy of gaseous negatively charged polyaromatic hydrocarbons

    SciTech Connect

    Gao, Juehan; Berden, Giel; Oomens, Jos

    2014-06-01

    Based largely on infrared spectroscopic evidence, polycyclic aromatic hydrocarbon (PAH) molecules are now widely accepted to occur abundantly in the interstellar medium. Laboratory infrared spectra have been obtained for a large variety of neutral and cationic PAHs, but data for anionic PAHs are scarce. Nonetheless, in regions with relatively high electron densities and low UV photon fluxes, PAHs have been suggested to occur predominantly as negatively charged ions (anions), having substantial influence on cloud chemistry. While some matrix spectra have been reported for radical anion PAHs, no data is available for even-electron anions, which are more stable against electron detachment. Here we present the first laboratory infrared spectra of deprotonated PAHs ([PAH-H]{sup –}) in the wavelength ranges between 6 and 16 μm and around 3 μm. Wavelength-dependent infrared multiple-photon electron detachment is employed to obtain spectra for deprotonated naphthalene, anthracene, and pyrene in the gas phase. Spectra are compared with theoretical spectra computed at the density functional theory level. We show that the relative band intensities in different ranges of the IR spectrum deviate significantly from those of neutral and positively charged PAHs, and moreover from those of radical anion PAHs. These relative band intensities are, however, well reproduced by theory. An analysis of the frontier molecular orbitals of the even- and odd-electron anions reveals a high degree of charge localization in the deprotonated systems, qualitatively explaining the observed differences and suggesting unusually high electric dipole moments for this class of PAH molecules.

  13. Infrared spectroscopy of a polyurethane elastomer under thermal stress

    SciTech Connect

    Marsh, A.L.; Schoonover, J.R.

    1998-07-01

    FTIR spectroscopy was used to study changes in hydrogen bonding in estane, a polyurethane elastomer used as a binding agent in high explosive systems, as a function of temperature. Hydrogen bonding in estane has been observed to decrease with an increase in temperature.

  14. Infrared Multiple Photon Dissociation Spectroscopy Of Metal Cluster-Adducts

    NASA Astrophysics Data System (ADS)

    Cox, D. M.; Kaldor, A.; Zakin, M. R.

    1987-01-01

    Recent development of the laser vaporization technique combined with mass-selective detection has made possible new studies of the fundamental chemical and physical properties of unsupported transition metal clusters as a function of the number of constituent atoms. A variety of experimental techniques have been developed in our laboratory to measure ionization threshold energies, magnetic moments, and gas phase reactivity of clusters. However, studies have so far been unable to determine the cluster structure or the chemical state of chemisorbed species on gas phase clusters. The application of infrared multiple photon dissociation IRMPD to obtain the IR absorption properties of metal cluster-adsorbate species in a molecular beam is described here. Specifically using a high power, pulsed CO2 laser as the infrared source, the IRMPD spectrum for methanol chemisorbed on small iron clusters is measured as a function of the number of both iron atoms and methanols in the complex for different methanol isotopes. Both the feasibility and potential utility of IRMPD for characterizing metal cluster-adsorbate interactions are demonstrated. The method is generally applicable to any cluster or cluster-adsorbate system dependent only upon the availability of appropriate high power infrared sources.

  15. Study on mechanism of selective chemical vapor deposition of tungsten using in situ infrared spectroscopy and Auger electron spectroscopy

    NASA Astrophysics Data System (ADS)

    Kobayashi, Nobuyoshi; Goto, Hidekazu; Suzuki, Masayuki

    1991-01-01

    Selective chemical vapor deposition (CVD) of tungsten (W) using tungsten hexafluoride (WF6) and monosilane (SiH4) is investigated by in situ infrared spectroscopy and Auger electron spectroscopy. The infrared spectra show that trifluorosilane (SiHF3) is the main by-product species, and that silicon-tetrafluoride (SiF4) is less than 20%-25% of SiHF3 in partial pressure. The main chemical reaction involved in selective W CVD can be expressed as WF6+2SiH4→W+2SiHF3+3H2. Based on our experimental results, a new mechanism of selective W CVD, which notes hydrogen dissociation having a central role in this process, is proposed. It disproves the widely accepted model, which is based on the assumption that SiF4 is the major reaction product.

  16. Evaluation of different grades of ginseng using Fourier-transform infrared and two-dimensional infrared correlation spectroscopy

    NASA Astrophysics Data System (ADS)

    Zhang, Yan-ling; Chen, Jian-bo; Lei, Yu; Zhou, Qun; Sun, Su-qin; Noda, Isao

    2010-06-01

    Ginseng is one of the most widely used herbal medicines which have many kinds of pharmaceutical values. The discrimination of grades of ginseng includes the cultivation types and the growth years herein. To evaluate the different grades of ginseng, the fibrous roots and rhizome roots of ginseng were analyzed by Fourier-transform infrared and two-dimensional infrared correlation spectroscopy in this paper. The fibrous root and rhizome root of ginseng have different content of starch, calcium oxalate and other components. For the fibrous roots of ginseng, mountain cultivation ginseng (MCG), garden cultivation ginseng (GCG) and transplanted cultivation ginseng (TCG) have clear difference in the infrared spectra and second derivative spectra in the range of 1800-400 cm -1, and clearer difference was observed in the range of 1045-1160 and 1410-1730 cm -1 in 2D synchronous correlation spectra. Three kinds of ginseng can be clustered very well by using SIMCA analysis on the basis of PCA as well. For the rhizome roots, the content of calcium oxalate and starch change with growth years in the IR spectra, and some useful procedure can be obtained by the analysis of 2D IR synchronous spectra in the range of 1050-1415 cm -1. Also, ginsengs cultivated in different growth years were clustered perfectly by using SIMCA analysis. The results suggested that different grades of ginseng can be well recognized using the mid-infrared spectroscopy assisted by 2D IR correlation spectroscopy, which provide the macro-fingerprint characteristics of ginseng in different parts and supplied a rapid, effective approach for the evaluation of the quality of ginseng.

  17. Study on Angelica and its different extracts by Fourier transform infrared spectroscopy and two-dimensional correlation IR spectroscopy

    NASA Astrophysics Data System (ADS)

    Liu, Hong-xia; Sun, Su-qin; Lv, Guang-hua; Chan, Kelvin K. C.

    2006-05-01

    In order to develop a rapid and effective analysis method for studying integrally the main constituents in the medicinal materials and their extracts, discriminating the extracts from different extraction process, comparing the categories of chemical constituents in the different extracts and monitoring the qualities of medicinal materials, we applied Fourier transform infrared spectroscopy (FT-IR) associated with second derivative infrared spectroscopy and two-dimensional correlation infrared spectroscopy (2D-IR) to study the main constituents in traditional Chinese medicine Angelica and its different extracts (extracted by petroleum ether, ethanol and water in turn). The findings indicated that FT-IR spectrum can provide many holistic variation rules of chemical constituents. Use of the macroscopical fingerprint characters of FT-IR and 2D-IR spectrum can not only identify the main chemical constituents in medicinal materials and their different extracts, but also compare the components differences among the similar samples. This analytical method is highly rapid, effective, visual and accurate for pharmaceutical research.

  18. Mid-infrared spectroscopy of the Andromeda galaxy

    NASA Astrophysics Data System (ADS)

    Hemachandra, D.; Barmby, P.; Peeters, E.; Willner, S. P.; Ashby, M. L. N.; Smith, H. A.; Gordon, K. D.; Smith, D. A.; Fazio, G. G.

    2015-11-01

    We present Spitzer/Infrared Spectrograph (IRS) 5-21 μm spectroscopic maps towards 12 regions in the Andromeda galaxy (M31). These regions include the nucleus, bulge, an active region in the star-forming ring and nine other regions chosen to cover a range of mid-to-far-infrared colours. In line with previous results, polycyclic aromatic hydrocarbon (PAH) feature ratios (6.2 and 7.7 μm features compared to the 11.2 μm feature) measured from our extracted M31 spectra, except the nucleus, strongly correlate. The equivalent widths of the main PAH features, as a function of metallicity and radiation hardness, are consistent with those observed for other nearby spiral and starburst galaxies. Reprocessed data from the ISOCAM instrument on the Infrared Space Observatory agree with the IRS data; early reports of suppressed 6-8 μm features and enhanced 11.3 μm feature intensity and full width at half-maximum apparently resulted from background-subtraction problems. The nucleus does not show any PAH emission but does show strong silicate emission at 9.7 μm. Furthermore, different spectral features (11.3 μm PAH emission, silicate emission and [Ne III] 15.5 μm line emission) have distinct spatial distributions in the nuclear region: the silicate emission is strongest towards the stellar nucleus, while the PAH emission peaks 15 arcsec north of the nucleus. The PAH feature ratios at this position are atypical with strong emission at 11.2 and 15-20 μm but weak emission at 6-8 μm. The nucleus itself is dominated by stellar light giving rise to a strong blue continuum and silicate emission.

  19. Thermal infrared spectroscopy and modeling of experimentally shocked plagioclase feldspars

    USGS Publications Warehouse

    Johnson, J. R.; Horz, F.; Staid, M.I.

    2003-01-01

    Thermal infrared emission and reflectance spectra (250-1400 cm-1; ???7???40 ??m) of experimentally shocked albite- and anorthite-rich rocks (17-56 GPa) demonstrate that plagioclase feldspars exhibit characteristic degradations in spectral features with increasing pressure. New measurements of albite (Ab98) presented here display major spectral absorptions between 1000-1250 cm-1 (8-10 ??m) (due to Si-O antisymmetric stretch motions of the silica tetrahedra) and weaker absorptions between 350-700 cm-1 (14-29 ??m) (due to Si-O-Si octahedral bending vibrations). Many of these features persist to higher pressures compared to similar features in measurements of shocked anorthite, consistent with previous thermal infrared absorption studies of shocked feldspars. A transparency feature at 855 cm-1 (11.7 ??m) observed in powdered albite spectra also degrades with increasing pressure, similar to the 830 cm-1 (12.0 ??m) transparency feature in spectra of powders of shocked anorthite. Linear deconvolution models demonstrate that combinations of common mineral and glass spectra can replicate the spectra of shocked anorthite relatively well until shock pressures of 20-25 GPa, above which model errors increase substantially, coincident with the onset of diaplectic glass formation. Albite deconvolutions exhibit higher errors overall but do not change significantly with pressure, likely because certain clay minerals selected by the model exhibit absorption features similar to those in highly shocked albite. The implication for deconvolution of thermal infrared spectra of planetary surfaces (or laboratory spectra of samples) is that the use of highly shocked anorthite spectra in end-member libraries could be helpful in identifying highly shocked calcic plagioclase feldspars.

  20. Infrared and NIR Raman spectroscopy in medical microbiology

    NASA Astrophysics Data System (ADS)

    Naumann, Dieter

    1998-04-01

    FTIR and FT-NIR Raman spectra of intact microbial cells are highly specific, fingerprint-like signatures which can be used to (i) discriminate between diverse microbial species and strains, (ii) detect in situ intracellular components or structures such as inclusion bodies, storage materials or endospores, (iii) detect and quantify metabolically released CO2 in response to various different substrate, and (iv) characterize growth-dependent phenomena and cell-drug interactions. The characteristic information is extracted from the spectral contours by applying resolution enhancement techniques, difference spectroscopy, and pattern recognition methods such as factor-, cluster-, linear discriminant analysis, and artificial neural networks. Particularly interesting applications arise by means of a light microscope coupled to the spectrometer. FTIR spectra of micro-colonies containing less than 103 cells can be obtained from colony replica by a stamping technique that transfers micro-colonies growing on culture plates to a special IR-sample holder. Using a computer controlled x, y- stage together with mapping and video techniques, the fundamental tasks of microbiological analysis, namely detection, enumeration, and differentiation of micro- organisms can be integrated in one single apparatus. FTIR and NIR-FT-Raman spectroscopy can also be used in tandem to characterize medically important microorganisms. Currently novel methodologies are tested to take advantage of the complementary information of IR and Raman spectra. Representative examples on medically important microorganisms will be given that highlight the new possibilities of vibrational spectroscopies.

  1. Breast tumor characterization using near-infrared spectroscopy

    NASA Astrophysics Data System (ADS)

    Kang, Kyung A.; Chance, Britton; Zhao, Shiyin; Srinivasan, Sudhakar; Patterson, E.; Troupin, R.

    1993-09-01

    NIR time resolved spectroscopy (TRS) is one of the most feasible methods which can be used for the characterization of biological systems, due to its non-invasive nature and safety features in measurement. Breast cancer is the leading cause of death in women ages 40 - 44 and accounts for 32% of all cancer diagnosis in women. The occurrence rate is as high as one out of nine women in the USA. Breast cancer is the most common form of cancer and the second leading cause of cancer death in North America. Therefore, it is natural for researchers in the field of NIR spectroscopy to have strong interest in optical properties of normal and abnormal breast tissue. One of the main interests of NIR spectroscopy in breast cancer is the localization of the tumor. Another important feature is to characterize an anomaly non- invasively since more than 75% of mammographical anomalies are found to be benign. This could reduce the anxiety that the patients would have, as well as lower the clinical expense for the biopsy and operation (approximately $4,000 per a case).

  2. Infrared laser spectroscopy of the linear C13 carbon cluster

    NASA Technical Reports Server (NTRS)

    Giesen, T. F.; Van Orden, A.; Hwang, H. J.; Fellers, R. S.; Provencal, R. A.; Saykally, R. J.

    1994-01-01

    The infrared absorption spectrum of a linear, 13-atom carbon cluster (C13) has been observed by using a supersonic cluster beam-diode laser spectrometer. Seventy-six rovibrational transitions were measured near 1809 wave numbers and assigned to an antisymmetric stretching fundamental in the 1 sigma g+ ground state of C13. This definitive structural characterization of a carbon cluster in the intermediate size range between C10 and C20 is in apparent conflict with theoretical calculations, which predict that clusters of this size should exist as planar monocyclic rings.

  3. Infrared spectroscopy for geologic interpretation of TIMS data

    NASA Technical Reports Server (NTRS)

    Bartholomew, Mary Jane

    1986-01-01

    The Portable Field Emission Spectrometer (PFES) was designed to collect meaningful spectra in the field under climatic, thermal, and sky conditions that approximate those at the time of the overflight. The specifications and procedures of PFES are discussed. Laboratory reflectance measurements of rocks and minerals were examined for the purpose of interpreting Thermal Infrared Multispectral Scanner (TIMS) data. The capability is currently being developed to perform direct laboratory measurement of the normal spectral radiance of Earth surface materials at low temperatures (20 to 30 C) at the Jet Propulsion Laboratory.

  4. Measuring moisture in cheese by near infrared absorption spectroscopy.

    PubMed

    McKenna, D

    2001-01-01

    Data in the literature indicate that the measurement of moisture in cheese by near infrared transmittance (NIT) is more accurate than by reflectance (NIR). The accuracy of the NIT measurement (SEP) was calculated for Edam, Gouda, Brie, Colby, and Cheddar. A range of SEP values (0.12-0.35) was obtained using different methods of calibration for different types of samples. There was close agreement between these results, as they related to the precision of the reference method. The calibration validation technique described as Standard Error of Cross Validation (SECV) generated results that compared very closely to the equivalent SEP values for independent sample sets.

  5. Near-infrared spectroscopy of comet Bradfield 1979l

    NASA Astrophysics Data System (ADS)

    Danks, A. C.; Dennefeld, M.

    1981-02-01

    Spectroscopic observations using an unintensified reticon detector are presented of comet Bradfield 1979l, covering the spectral region from 6100 to 11,000 A. The red CN 2-0, 3-1, and 1-0 bands are easily identified in the nuclear region and their intensity ratios are used to determine that the vibrational transition probability for the ground electronic state lies between 0.32 and 1/sec. The CN 2-0 and 1-0 bands are also present in the coma. The interest in simultaneous measurements of the near-infrared and space UV of future comets is pointed out.

  6. Identification of clay minerals by infrared spectroscopy and discriminant analysis.

    PubMed

    Ritz, Michal; Vaculíková, Lenka; Plevová, Eva

    2010-12-01

    Identification of clay minerals based on chemometric analysis of measured infrared (IR) spectra was suggested. IR spectra were collected using the diffuse reflection technique. Discriminant analysis and principal component analysis were used as chemometric methods. Four statistical models were created for separation and identification of clay minerals. More than 50 samples of various clay mineral standards from different localities were used for the creation of statistical models. The results of this study confirm that the discriminant analysis of IR spectra of clay minerals could provide a powerful tool for identification of clay minerals. Differentiation of muscovite from illite and identification of mixed structures of illite-smectite were achieved.

  7. Infrared laser spectroscopy of the linear C13 carbon cluster

    NASA Technical Reports Server (NTRS)

    Giesen, T. F.; Van Orden, A.; Hwang, H. J.; Fellers, R. S.; Provencal, R. A.; Saykally, R. J.

    1994-01-01

    The infrared absorption spectrum of a linear, 13-atom carbon cluster (C13) has been observed by using a supersonic cluster beam-diode laser spectrometer. Seventy-six rovibrational transitions were measured near 1809 wave numbers and assigned to an antisymmetric stretching fundamental in the 1 sigma g+ ground state of C13. This definitive structural characterization of a carbon cluster in the intermediate size range between C10 and C20 is in apparent conflict with theoretical calculations, which predict that clusters of this size should exist as planar monocyclic rings.

  8. [Near infrared reflectance spectroscopy (NIRS) and its application in the determination for the quality of animal feed and products].

    PubMed

    Wang, Li; Meng, Qing-Xiang; Ren, Li-Ping; Yang, Jian-Song

    2010-06-01

    Near-infrared reflectance spectroscopy (NIRS) has been the most rapidly developing and noticeable spectrographic analytical technique in recent years. The determining principle and progresses of near-infrared reflectance spectroscopy are presented briefly. It mainly includes the progresses in pre-processing technique and analyzing model of near-infrared reflectance spectroscopy. Two pre-processing techniques, including differential coefficient-dealt with technique, the signal-smoothing technique, and four analyzing models of near-infrared spectroscopy, including the multiplied lined regression (MLR), principal component analysis (PCA), partial least squares (PLS), and artificial nerve network (ANN). The application of near-infrared reflectance spectroscopy to the first time. The investigation of reviewed papers shows that the near-infrared reflectance spectroscopy is widely applied in feed analysis and animal products analysis because of its rapidness, non-destruction and non-pollution. The near infrared reflectance spectroscopy has been used to determine the feed common ingredient, such as dry matter, crude protein, crude fiber, crude fat and so on, micro-components including amino acid, vitamin, and noxious components, and to determine the physical and chemical properties of animal products which including egg, mutton, beef and pork. Details of the analytical characteristics of feed and animal products described in the reviewed papers are given. New trends and limits to the application of near-infrared reflectance spectroscopy in these fields are also discussed.

  9. Use of Mid- and Near-Infrared Spectroscopy to Track Degradation of Polyactide Eating Utensils and Containers During Composting

    USDA-ARS?s Scientific Manuscript database

    Near-infrared spectroscopy (NIRS) has been used for decades for quantitative analysis of many agricultural products including forages, grains and foods, and more recently has become a powerful tool in the analysis of pharmaceutical ingredients and products. Mid-infrared spectroscopy (MIRS) has been ...

  10. Examination of Bond Properties through Infrared Spectroscopy and Molecular Modeling in the General Chemistry Laboratory

    ERIC Educational Resources Information Center

    Csizmar, Clifford M.; Force, Dee Ann; Warner, Don L.

    2012-01-01

    A concerted effort has been made to increase the opportunities for undergraduate students to address scientific problems employing the processes used by practicing chemists. As part of this effort, an infrared (IR) spectroscopy and molecular modeling experiment was developed for the first-year general chemistry laboratory course. In the…

  11. Limitations and potential of spectral subtractions in fourier-transform infrared (FTIR) spectroscopy of soil samples

    USDA-ARS?s Scientific Manuscript database

    Soil science research is increasingly applying Fourier transform infrared (FTIR) spectroscopy for analysis of soil organic matter (SOM). However, the compositional complexity of soils and the dominance of the mineral component can limit spectroscopic resolution of SOM and other minor components. The...

  12. Analysis of Total Oil and Fatty Acids Composition by Near Infrared Reflectance Spectroscopy in Edible Nuts

    USDA-ARS?s Scientific Manuscript database

    Near Infrared (NIR) Reflectance spectroscopy has established itself as an important tool in quantifying water and oil present in various food materials. It is rapid and nondestructive, easier to use, and does not require processing the samples with corrosive chemicals that would render them non-edib...

  13. Visible/near-infrared spectroscopy for discrimination of HLB-infected citrus leaves from healthy leaves

    USDA-ARS?s Scientific Manuscript database

    Researchers have used various hyperspectral systems, covering several areas of the electromagnetic spectrum to investigate all types of disease/plant interactions. The purpose of this research was to investigate using visible and near-infrared (400-1100nm) spectroscopy to differentiate HLB infected...

  14. Short Report: The effect of preservation methods on predicting mosquito age by near-infrared spectroscopy

    USDA-ARS?s Scientific Manuscript database

    Determining mosquito age is important to evaluate vector control programs because the ability to transmit diseases is age-dependent. Current age-grading techniques require dissection or DNA extraction. Near-infrared spectroscopy has been used to rapidly and nondestructively determine the age of fr...

  15. Use of near infrared spectroscopy to measure the chemical and mechanical properties of solid wood

    Treesearch

    Stephen S. Kelley; Timothy G. Rials; Rebecca Snell; Leslie H. Groom; Amie Sluiter

    2004-01-01

    Near infrared (NIR) spectroscopy (500 nm-2400 nm), coupled with multivariate analytic (MVA) statistical techniques, have been used to predict the chemical and mechanical properties of solid loblolly pine wood. The samples were selected from different radial locations and heights of three loblolly pine trees grown in Arkansas. The chemical composition and mechanical...

  16. Abdominal near-infrared spectroscopy measurements are lower in preterm infants at risk for necrotizing enterocolitis

    USDA-ARS?s Scientific Manuscript database

    Near-infrared spectroscopy is a noninvasive method of measuring local tissue oxygenation (StO[2]). Abdominal StO[2] measurements in preterm piglets are directly correlated with changes in intestinal blood flow and markedly reduced by necrotizing enterocolitis. The objectives of this study were to us...

  17. Prefrontal Dysfunction in Attention-Deficit/Hyperactivity Disorder as Measured by Near-Infrared Spectroscopy

    ERIC Educational Resources Information Center

    Negoro, Hideki; Sawada, Masayuki; Iida, Junzo; Ota, Toyosaku; Tanaka, Shohei; Kishimoto, Toshifumi

    2010-01-01

    Recent developments in near-infrared spectroscopy (NIRS) have enabled non-invasive clarification of brain functions in psychiatric disorders with measurement of hemoglobin concentrations as cerebral blood volume. Twenty medication-naive children with attention-deficit/hyperactivity disorder (ADHD) and 20 age- and sex-matched healthy control…

  18. Measurement of soy contents in ground beef using near-infrared spectroscopy

    USDA-ARS?s Scientific Manuscript database

    Models for determining contents of soy products in ground beef were developed using near-infrared (NIR) spectroscopy. Samples were prepared by mixing four kinds of soybean protein products (Arconet, toasted soy grits, Profam and textured vegetable protein (TVP)) with ground beef (content from 0%–100...

  19. Visible and Near-Infrared Spectroscopy Detects Honey Bee Queen Insemination

    USDA-ARS?s Scientific Manuscript database

    The abdomens of honey bee queens, the heads of worker bees, and the ventriculi of worker bees were analyzed by visible and near-infrared spectroscopy. Mated honey bee queens could be distinguished from virgin queens by their spectra with 100% accuracy. Also, the heads of worker bees taken from the ...

  20. Visible and near-infrared spectroscopy detects queen honey bee insemination

    USDA-ARS?s Scientific Manuscript database

    The abdomens of honey bee queens, the heads of worker bees, and the ventriculi of worker bees were analyzed by visible and near-infrared spectroscopy. Mated honey bee queens could be distinguished from virgin queens by their spectra with 100% accuracy. Also, the heads of worker bees taken from the...