Showing papers on "Fourier transform spectroscopy published in 1977"
TL;DR: Fourier Transform NMR Spectroscopy as mentioned in this paper is a well-known technique in NMR spectroscopy and has been used extensively in the field of computer vision. Pp. xvi + 357.
Abstract: Fourier Transform NMR Spectroscopy. By D. Shaw. Pp. xvi + 357. (Elsevier Scientific: Amsterdam, Oxford and New York, 1976.) Dfl. 129; $49.75.
144 citations
TL;DR: In this paper, a method for least-squares curvefitting of Fourier transform infrared spectra is presented for the analysis of several polymer systems by digital subtraction of spectra and a demonstration of the determination of xylene solution compositions illustrates the accuracy of the method.
Abstract: A method is presented for least-squares curve-fitting of Fourier transform infrared spectra. A demonstration of the determination of xylene solution compositions illustrates the accuracy of the method. Least-squares coefficients are shown to be valuable for the analysis of several polymer systems by digital subtraction of spectra.
119 citations
TL;DR: In this article, the authors compared the performance of infrared Fourier transform spectroscopy with conventional infrared spectrograms with reference to spectra of paper, egg yolk, albumin, madder, Indian yellow, purpurin, alizarin, indigo, and linseed oil.
Abstract: Though infrared spectroscopy is the single most powerful technique for the characterization of materials and though it is widely used in the chemical industries, its application to conservation has been severely limited due to the complexity and limited sample size of the materials presented for examination. In the past decade, the development of infrared Fourier transform spectroscopy has made possible the study of small samples and complex mixtures. The technique of infrared Fourier transform spectroscopy is compared to conventional infrared spectroscopy with reference to spectra of paper, egg yolk, albumin, madder, Indian yellow, purpurin, alizarin, indigo, and linseed oil.
47 citations
TL;DR: In this article, the authors propose to deconvolute a set of spectra taken at different angles into spectra corresponding to successive depth invervals, which is done by a new technique that measures spectra twice at each angle with different prism materials to give the necessary data sets.
Abstract: In total reflection spectroscopy the effective sampled depth increases as the angle of incidence approaches the critical one. At each angle of incidence, successive layers within the sample are weighed differently in the overall spectrum, and the manner of this weighing changes with angle. It is thus possible in principle to deconvolute a set of spectra taken at different angles into spectra corresponding to successive depth invervals. As this angular effect is particularly marked near the critical angle, where attenuated total reflection spectra are severely distorted, the spectra usually require inversion into optical constant spectra. This has been done by a new technique that measures spectra twice at each angle with different prism materials to give the necessary data sets. Examples of such subsurface spectra are shown.
44 citations
TL;DR: In this article, a dual-beam Fourier transform infrared (FT-IR) spectrometer was used for GC-IR measurements from less than 100 ng of material, and a method for removing the solvent from the effluent from a high performance liquid chromatograph was proposed, together with a device for on-line LC-ir at the submicrogram level.
Abstract: Several different applications of Fourier transform infrared (FT-ir) spectrometry being developed at Ohio University are described. A dual-beam FT-ir system which enables identifiable GC-ir spectra to be measured from less than 100 ng of material is described. A method for removing the solvent from the effluent from a high performance liquid chromatograph is proposed, together with a device for on-line LC-ir at the submicrogram level. Calculations showing the effect of the instrument line shape function of an FT-ir spectrometer used with or without apodization on Lorentzian absorption bands are described, and the implications of the results of these calculations on spectral subtraction and remote sensing experiments are discussed.
42 citations
39 citations
32 citations
TL;DR: The use of tunable uv laser systems to monitor OH radicals by their resonance fluorescence, the use of laser magnetic resonance in kinetic studies of OH, HO/sub 2/ε, and other free radicals was discussed in this article.
Abstract: Application of tunable lasers and infrared Fourier transform spectroscopy to atmospherically important systems has led to the identification and quantification of a number of species in smog chambers, in laboratory experiments, and in the polluted troposphere. Many of these are labile molecules or free radicals whose presence had been previously postulated on sound kinetics and mechanistic grounds, but not directly observed. Others had not even been suspected to exist in atmospheric systems. Additionally, the development of tunable lasers has greatly aided elucidation of the mechanisms of certain important atmospheric reactions, including primary photodecomposition processes. The paper discusses recent studies with tunable lasers and Fourier transform infrared spectroscopy in which certain free radical and labile molecular species present in ambient and simulated atmospheres were directly identified and measured. These species are significant in oxidant control either because of their mechanistic role in establishing kinetic computer models, or alternatively, because of their potential effects on health and visibility, or both. These studies include the use of tunable uv laser systems to monitor OH radicals by their resonance fluorescence, the use of laser magnetic resonance in kinetic studies of OH, HO/sub 2/, and other free radicals, the use of lasers in studying themore » modes of photodecomposition of primary and secondary pollutants, the use of tunable lasers in elucidating the photochemistry of formaldehyde, the use of long pathlength optical systems, and Fourier transform infrared (FT-IR) spectrometers with interferometers.« less
29 citations
TL;DR: In this article, the rotational lines in the P and R branches were measured to J = 165 with reference to uranium standards emitted by a hollow cathode, and the differences between the two sets of measurements were less than 0.001 cm −1, and the standard deviation between the observed wavenumbers and those calculated with the spectroscopic constants B v, D v, and H v is 0.0007 cm − 1.
29 citations
TL;DR: In this paper, the T1's, linewidths, and chemical shifts of 119Sn nuclei in a variety of tin compounds have been surveyed using pulse Fourier transform techniques, indicating that apart from a large scalar contribution in Sn(IV) iodides and bromides, the dominant 119Sn T1 mechanism is spin rotation interaction.
Abstract: The T1's, linewidths (T2's), and chemical shifts of 119Sn nuclei in a variety of tin compounds have been surveyed using pulse Fourier transform techniques. The results span the very large chemical shift range for tin-119 (∼2000 ppm), and indicate rather short T1 values with widely varied T2 relaxation times. Possible mechanisms are discussed for both T1 and T2 relaxation times. Our results show an approximate correlation between T1 (119Sn) and the paramagnetic contribution to the observed shielding of the 119Sn nucleus, indicating that apart from a large scalar contribution in Sn(IV) iodides and bromides, the dominant 119Sn T1 mechanism is spin rotation interaction.
26 citations
TL;DR: In this paper, the authors reported precise determination of wavenumbers corresponding to transitions observed in the infrared region of the arc spectrum of 202Hg, with an accuracy of about 0.005 cm-1.
Abstract: We report precise determination of wavenumbers corresponding to transitions observed in the infrared region of the arc spectrum of 202Hg, with an accuracy of about 0.005 cm-1. Isotope shifts of the seven stable isotopes and hyperfine structures (for both odd 199 and 201 isotopes) for excited levels in 6snl (with n≤10, l=0, 1, 2, 3) and d9s2p(6p') configurations are given with a relative precision of about 0.5%.
TL;DR: In this paper, the NMR signals of 207Pb have been observed in powder samples of Pb (NO3)2, PbCO3, PbCrO4,PbMoO4 and PbWO4 using a Fourier transform apparatus.
Abstract: Abstract The NMR signals of 207Pb have been observed in powder samples of Pb (NO3)2, PbCO3 , PbCrO4 , PbMoO4 and PbWO4 using a Fourier transform apparatus. All the observed signals are asymmetrical, indicating anisotropics of the magnetic shielding σ33- σ11 with values between - 56ppm for Pb(NO3)2 and - 884 ppm for PbCrO4 . The principal elements of the shielding ten sors σ11 , σ22 , σ33 are given relative to the Pb2+ ion at infinite dilution in H2O and can be referred to the free lead atom with the known shielding constant of earlier measurements.
Journal Article•
TL;DR: 13C FTNMR spectroscopy is found to provide an efflcient assay technique for connective tissue in meat, by analysis of Lhydroxyproline in defatted, hydrolyzed meat.
Abstract: 13C FTNMR spectroscopy is found to provide an efflcient assay technique for connective tissue in meat, by analysis of Lhydroxyproline in defatted, hydrolyzed meat. The sensitivity of 13C FTNMR spectroscopy is increased by rapid pulsing of highly concentrated vlscous solutions, and quantttative analysis is achieved by comparlng the peak height of C-4 in Lhydroxyproline with that d an internal standard. The technique has dlstinct advantages over exlsting colorimetric and amino-acld analysis prwedures. Most meats and processed meats contain 1 to 2% by weight Lhydroxyproiine of the dry, defatted meat; a quantltative analysis taking 29 mln is found to have a standard deviation of 0.16% at a level of 3.0% w/w Lhydroxyproline using a commercially available spectrometer with 10mm 0.d. NMR tubes and a crystal fitter. Survey spectra of Increased sensitivity are obtalned by shorter or longer observatlon as desired.
TL;DR: The three basic methods of linear laser spectroscopy are reviewed: absorption, opto-acoustic, and fluorescence as discussed by the authors, and the characteristics of each method and their areas of application are presented and compared.
Abstract: The three basic methods of linear laser spectroscopy are reviewed: absorption, opto-acoustic, and fluorescence spectroscopy The characteristics of each method and their areas of application are presented and compared
TL;DR: A phenomenon akin to higher order spectra in grating spectroscopy has been found in Fourier transform spectroscopic, while its relative intensity is orders of magnitude down from similar effects in gratings.
Abstract: A phenomenon akin to higher order spectra in grating spectroscopy has been found in Fourier transform spectroscopy. While its relative intensity is orders of magnitude down from similar effects in gratings, the high sensitivity of Fourier transform ir allows this perturbation to be detected.
TL;DR: In this article, the Michelson interferometer was used to achieve a resolution better than 0.05cm−1, the theoretical resolution being 0.03 cm−1.
TL;DR: The typical Fourier transform infrared (FT-ir) spectrometer has a huge light gathering power advantage over grating spectrometers of similar resolution as discussed by the authors, which is called the Jacquinot advantage.
Abstract: The typical Fourier transform infrared (FT-ir) spectrometer has a huge light gathering power advantage over grating spectrometers of similar resolution. This advantage, called the throughput or Jacquinot advantage, is given by TFT/TG = 2πF/l where TFT and TG are the FT-ir and grating instrument throughput, and F and l are the focal length and slit height of the latter. For practical instruments TFT/TG a 100 to 200. Here we have TFT = 2πAM/R = π2/2 dB2/R where AM is the interferometer beamsplitter area, dB its diameter, and R the resolution. At first glance it would appear that TFT can be enlarged for any given R by taking dB up to its technological limit. Even higher throughputs are possible in field-widened FTS spectrometers.
TL;DR: In this paper, the complex dielectric response associated with the q ≈ 0 transverse-optical mode in NaCl at 105 and 300 K is reported from measurements using dispersive Fourier transform spectroscopy, and the frequency dependence of the mode anharmonic self-energy.
Abstract: The complex dielectric response associated with the q ≈ 0 transverse-optical mode in NaCl at 105 and 300 K is reported from measurements using dispersive Fourier-transform spectroscopy, and is used to discuss the frequency dependence of the mode anharmonic self-energy.
TL;DR: In the spectroscopy of highly irregular samples, the spectral distortions introduced by absorbance averaging over nonuniform samples are further compounded by refractive and scattering beam distortion effects as mentioned in this paper.
Abstract: In the spectroscopy of highly irregular samples, the spectral distortions introduced by absorbance averaging over nonuniform samples are further compounded by refractive and scattering beam distortion effects
TL;DR: In this article, the basic physical principles of Fourier transform spectroscopy are described and explained, in addition to technical and mathematical details, as for instance error correction, examples are presented with spectra obtained by this method.
Abstract: Starting with the basic physical principles, the method of Fourier transform spectroscopy is described and explained. In addition to the technical and mathematical details, as for instance error correction, examples are presented with spectra obtained by this method. Advantages and disadvantages are discussed. New special developments in Fourier spectroscopy are briefly mentioned, e.g., phase modulation, compensative mode, and amplitude spectroscopy. Finally, some problems in analytical chemistry which have been studied by means of Fourier transform spectroscopy are summarized (155 references).
TL;DR: In this article, it was shown that the position of the uniquely bright fringe of the specimen interferogram for use as the displaced origin of computation is not important for the determination of refractive indices.
TL;DR: In this paper, it was shown that the multiplex advantage cannot be realized to a numerical extent equal to the square root of the number of independent spectral elements in broad featureless spectra such as are used to measure specimen transmission.
TL;DR: In this paper, the effective transmission, neglecting sample reflectance, and for not too strong absorption, is given by Te = T + (1 - T)QFΩE/4π where Te and T are the effective and actual transmission, respectively; QF is the fluorescent quantum efficiency, Ω the solid angle of light collection following the sample, and E is the collection efficiency of the interferometer.
Abstract: For samples showing appreciable fluorescence emission spectra, the effective transmission, neglecting sample reflectance, and for not too strong absorption, is given by Te = T + (1 - T)QFΩE/4π where Te and T are the effective and actual transmission, respectively; QF is the fluorescent quantum efficiency, Ω the solid angle of light collection following the sample, and E is the collection efficiency of the interferometer.
TL;DR: In this paper, the authors discuss the signal/noise ratios attainable in Fourier transform infrared (FT-IR) spectroscopy, including the magnitude of the multiplex and throughput advantages.
Abstract: There has been considerable discussion about the signal/noise ratios attainable in Fourier transform infrared (FT-ir) spectroscopy. This involves not only the magnitude of the multiplex and throughput advantages of FT-ir, but also several other features of this technology.