Showing papers on "Fourier transform spectroscopy published in 1980"
TL;DR: In this paper, the generation of nuclear magnetic double quantum echoes and their detection by two-dimensional Fourier transform spectroscopy was reported for partially aligned one-deuteron systems in a nematic liquid crystal.
393 citations
TL;DR: It is concluded that in the gel phase, at all temperatures below the main transition, the acyl chains are predominantly in all-trans conformations and that the temperature-dependent variations of spectral parameters result from changes in interchain interactions.
Abstract: Fourier transform infrared spectroscopy has been used to study the infrared-active acyl chain vibrational modes of fully hydrated multibilayers of 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (L-DPPC) over the temperature range 0-55 degrees C. Frequencies, bandwidths, and other spectral parameters were measured as a function of temperature for the methylene scissoring, rocking, and wagging modes, as well as for the C-H stretching modes, and they were used to monitor the packing of the acyl chains. Particular emphasis was placed on determining the nature of the pretransition event. It is shown that between 36 and 38 degrees C the spectral changes are indicative of a phase change in the acyl chain packing from an orthorhombid to a hexagonal subcell. It is also concluded that in the gel phase, at all temperatures below the main transition, the acyl chains are predominantly in all-trans conformations and that the temperature-dependent variations of spectral parameters result from changes in interchain interactions.
235 citations
TL;DR: In this paper, diffuse reflectance techniques enable increased sensitivity to be obtained for infrared micro-sampling compared with the use of KBr micropellets, when nonabsorbing matrices such as KCl are used, detection limits of less than 10 ng of samples are observed.
Abstract: It is shown that diffuse reflectance techniques enable increased sensitivity to be obtained for infrared microsampling compared with the use of KBr micropellets. When nonabsorbing matrices, such as KCl, are used, detection limits of less than 10 ng of samples are observed. Samples absorbed on graphitized substrates, which have a fairly strong general absorption but few intense absorption bands, may also be studied but at somewhat reduced sensitivity. Diffuse reflectance infrared Fourier transform spectrometry does not appear to be particularly useful for studying adsorbates on silica gel, which is not only a strong infrared absorber but also has a surface which is so active that small changes in the surface structure can change the spectrum significantly. Extraction of sample spots from thin layer chromatography plates followed by deposition onto KCl yields much better results than in situ measurements.
148 citations
142 citations
TL;DR: In this article, the advantages and disadvantages of photoacoustic detection are discussed, and comparisons of sample spectra obtained by different techniques, including photoacoustical detection, are presented and compared.
Abstract: Fourier transform infrared spectroscopy of solids and liquids using photoacoustic detection is reported here. The advantages and disadvantages of photoacoustic detection are discussed, and comparisons of sample spectra obtained by different techniques, including photoacoustic detection, are presented and compared. Photoacoustic Fourier transform infrared spectroscopy is a promising spectroscopic method for IR analysis in cases where sample preparation is difficult.
131 citations
100 citations
82 citations
TL;DR: In this article, the rotational spectra of XeH35Cl, 129XeH37Cl, 128XeD35Cl and 132XeCl van der Waals molecules were derived from a Fabry-Perot cavity with a pulsed supersonic nozzle.
Abstract: Rotational spectra have been assigned for the 129XeH35Cl, 129XeH37Cl, 129XeD35Cl, 131XeH35Cl and 132XeH35Cl van der Waals molecules by employing pulsed microwave Fourier transform spectroscopy in a Fabry–Perot cavity with a pulsed supersonic nozzle as the molecular source. The rotational constants, centrifugal distortion constants, and Cl nuclear quadrupole coupling constants obtained from the spectra are used to determine the structure of XeHCl and to gain information on the intermolecular potential binding of Xe to HCl. From the spectrum of 131XeH35Cl and an analysis of the centrifugal distortion in 129XeH35Cl, 131XeH35Cl, and 132XeH35Cl the 131Xe nuclear quadrupole coupling constant in XeHCl is found to be −4.9±0.2 MHz. Using the known nuclear quadrupole moment of 131Xe, the electric field gradient at the Xe nucleus is calculated. The observed field gradient is discussed in terms of Sternheimer shielding and formation of the weak Xe–HCl van der Waals bond.
66 citations
TL;DR: The sensitivity of gas chromatography/Fourier transform infrared spectroscopy (GC/FT-IR) may be improved by use of small bore gold-coated glass gas cells.
Abstract: The sensitivity of gas chromatography/Fourier transform infrared spectroscopy (GC/FT-IR) may be significantly improved by use of small bore gold-coated glass gas cells. This note describes the method of preparing internally gold-coated glass or quartz tubes for GC-IR applications.
54 citations
TL;DR: In this article, a wide selection of infrared absorption spectra of opaque samples is presented to show the versatility of Fourier-transformed infrared photoacoustic spectroscopy, and a method for correcting these spectra for incident radiant power variations with respect to wavelength is also demonstrated.
Abstract: A wide selection of infrared absorption spectra of opaque samples is presented to show the versatility of Fourier-transformed infrared photoacoustic spectroscopy. A method for correcting these spectra for incident radiant power variations with respect to wavelength is also demonstrated.
52 citations
TL;DR: The first observation of the 4ν2 band of H2 16O is reported in this article, where a hot water vapor Fourier transform spectrum between 5 930 and 6 400 cm-1 has been used for this purpose.
Abstract: The first observation of the 4ν2 band of H2 16O is reported. A hot water vapor Fourier transform spectrum between 5 930 and 6 400 cm-1 has been used for this purpose. About 30 lines of the 4ν2 band have been assigned leading to the band center 4ν2 = 6 134.030 ± 0.412 cm-1. Rotational constants for the (040) vibrational state have been determined and an estimation of the total band intensity is : Sv(4 ν2) = 0.189 x 10-22 cm-1/molecule.cm -2 at 296 K .
TL;DR: In this paper, the vibration-rotation emission spectrum of the nitric oxide molecule has been recorded with a high-resolution Fourier transform interferometer (resolution 10 −2 cm −1 ) in the spectral range 2900 − 3810 cm − 1.
TL;DR: The rotational constants, centrifugal distortion constants, Br nuclear-quadrupole-coupling constants, and Br spin-rotation constants were determined and from them, the vibrationally averaged structure of OCHBr was derived, consistent with a linear geometry at equilibrium and an atomic arrangement.
Abstract: Rotational spectra have been assigned for five isotopic species of the OC···HBr hydrogen-bonded molecular complex by using pulsed microwave Fourier transform spectroscopy in a Fabry-Perot cavity and a pulsed supersonic nozzle as the molecular source. The rotational constants, centrifugal distortion constants, Br nuclear-quadrupole-coupling constants, and Br spin-rotation constants were determined and from them, the vibrationally averaged structure of OCHBr was derived. This structure is consistent with a linear geometry at equilibrium and an atomic arrangement as written above. The intermolecular potential binding CO to HBr is discussed.
TL;DR: In this article, the authors present the state-of-the-art of FTIR spectroscopy in the characterization of polymeric structure, which they call FTIR-VQA.
TL;DR: The results of experiments designed to study the infrared spectra of transient species produced by ultraviolet photolysis of acetaldehyde are reported and analyzed in this article, and the consequences of poor control are described and a qualitative explanation is offered.
Abstract: The results of experiments designed to study the infrared spectra of transient species produced by ultraviolet photolysis of acetaldehyde are reported and analyzed. Spectra obtained in similar work [A. W. Mantz, Appl. Opt. 17, 1347 (1978)] are critically reinterpreted. The evidence presented demonstrates that insufficient attention has been given to the necessary stringent control of experimental conditions. The consequences of poor control are described and a qualitative explanation is offered. This paper discusses, in particular, the production of spectral artifacts consisting of displaced (not folded) bands and their previous erroneous assignments. Other practical aspects of time resolved Fourier transform spectroscopy with a rapid scanning Michelson interferometer are outlined.
TL;DR: In this paper, a Fourier transform spectrometer was used to obtain high-resolution spectra of a 234UI4/238UI4 electrodeless discharge lamp and level isotope shifts were determined by least squares for 183 odd and 518 even levels of U i with an overall standard deviation of 0.0036 cm−1.
Abstract: A Fourier transform spectrometer was used to obtain high-resolution spectra of a 234UI4/238UI4 electrodeless discharge lamp. Over 2000 uranium isotope shifts were measured in the visible and near-infrared regions. Level isotope shifts were determined by least squares for 183 odd and 518 even levels of U i with an overall standard deviation of 0.0036 cm−1.
TL;DR: In this article, a Michelson interferometer with step-and-integrate mirror motion is described for use in Fourier transform photoacoustic spectrometry (FTPAS) at visible wavelengths.
Abstract: A Michelson interferometer with step‐and‐integrate mirror motion is described for use in Fourier transform photoacoustic spectrometry (FTPAS) at visible wavelengths. An overview of mechanical and software construction is supplied and the advantages of FTPAS are illustrated with a spectrum of powdered erbium oxide at visible wavelengths. The relative merits of step‐and‐integrate and rapid scan mirror motion for FTPAS are considered.
TL;DR: In this article, a high-resolution Fourier transform spectrometer was used to record the I2 B O+u state, excited by the 514.5 and 501.7 nm cw Ar+ laser lines, using both multimode (6 GHz) and single mode (<100 MHz) Ar+ lasers.
Abstract: Fluorescence from the I2 B O+u state, excited by the 514.5 and 501.7 nm cw Ar+ laser lines, is recorded using a high resolution Fourier transform spectrometer. Spectra are obtained with both multimode (6 GHz) and single mode (<100 MHz) Ar+ lasers, the latter spectra exhibiting reduced Doppler width. B O+u−X 1Σ+g fluorescence is recorded at 1 mK precision for v″=10–100, eQq″ quadrupole constants are obtained (±5%) from measured linewidths, broadening of quasibound X 1Σ+g rotational levels above the rotationless X 1Σ+g dissociation limit is observed, and perturbations of X 1Σ+ v″⩾92 by two previously unobserved long range I2 molecular states are detected. These two states, 0+g and 1g, which dissociate into two 2P3/2 I atoms, are also observed directly in the fluorescence spectrum. This paper presents illustrative examples; constants and a complete analysis will appear subsequently.
TL;DR: Fourier transform photoacoustic spectroscopy (FTPAS) can be carried out in the visible using either a piezoelectric crystal or a microphone to detect the interferogram produced in a sample when the latter is illuminated by white light passed through a Michelson interferometer as discussed by the authors.
Abstract: Fourier transform photoacoustic spectroscopy (FTPAS) can be carried out in the visible using either a piezoelectric crystal or a microphone to detect the interferogram produced in a sample when the latter is illuminated by white light passed through a Michelson interferometer. Spectra of lanthanide oxides and whole human blood are reported that illustrate benefits and limitations of visible FTPAS.
TL;DR: In this paper, a method is presented for the direct analysis of interferometric data from gas chromatography Fourier transform infrared spectroscopy (GC/FTIR) data, where a synthetic interferogram is initially produced which represents the characteristic absorption features of a particular functional group or compound class.
Abstract: A method is presented for the direct analysis of interferometric data from gas chromatography Fourier transform infrared spectroscopy (GC/FTIR). A synthetic interferogram is initially produced which represents the characteristic absorption features of a particular functional group or compound class. A zero displacement correlation is performed between this test interferogram and each sample interferogram from the GC data. The presence of the desired functionality in the GC effluent is indicated by a small value of the resulting cumulative sum. A "correlogram" which emulates the response from a chemically specific GC detector is obtained by plotting the cumulative sum from each sample correlation. Synthetic interferograms representing infrared absorption bands which are truly specific for a particular functionality yield the best results.
TL;DR: In this paper, Fourier transform infrared, transmission spectroscopy is presented as a technique with great potential for the study of aqueous membrane preparations and the methodology of spectra acquisition and data reduction is outlined.
TL;DR: The advantages of Fourier transform infrared spectroscopy (FT-IR) over dispersive IR are by now quite well known as mentioned in this paper, including high signal throughout, even when operating at high resolution, much greater data gathering speed, inherent line shape and wavenumber accuracy, and the digital nature of the data, which facilitates multiscan averaging, data storage, and spectral manipulation.
Abstract: The advantages of Fourier transform infrared spectroscopy (FT-IR) over dispersive spectroscopy are by now quite well known. These include high signal throughout, even when operating at high resolution, much greater data gathering speed, inherent line shape and wavenumber accuracy, and the digital nature of the data, which facilitates multiscan averaging, data storage, and spectral manipulation. However, despite their many advantages, FT-IR instruments have not dominated the IR market, and, in fact, accounted for only about 10% of the IR spectrometers sold in 1978. This is a direct result of the one disadvantage of FTIR ... high cost.
TL;DR: The applicability of transmission or attenuated total reflectance (ATR) techniques is often limited by the scattering of the radiation as discussed by the authors, which can be spectrally analyzed, if the diffuse reflected radiation can be collected and transfered to the infrared detector.
Abstract: Investigations of solids, especially of powders, are of great interest in infrared spectroscopy. The applicability of transmission or attenuated total reflectance (ATR) techniques is often limited by the scattering of the radiation. This scattering can be spectrally analyzed, if the diffuse reflected radiation can be collected and transfered to the infrared detector.
TL;DR: In this paper, room temperature Fourier transform infrared measurements on some contaminated silicon wafers are presented, using subtractive techniques readily allow both carbon and oxygen concentrations of about 0.1 ppm atomic to be obtained in relatively short measurement times (about 1 min).
Abstract: Room temperature Fourier transform infrared measurements on some contaminated silicon wafers are presented. Use of subtractive techniques readily allows both carbon and oxygen concentrations of about 0.1 ppm atomic to be obtained in relatively short measurement times (about 1 min), providing an adequate