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Showing papers on "Fourier transform spectroscopy published in 1989"


Journal ArticleDOI
TL;DR: By analyzing the propagation of terahertz electromagnetic pulses through water vapor, this work has made what it is believed are the most accurate measurements to date of the absorption cross sections of the water molecule for the nine strongest lines.
Abstract: We describe the application of a new high-brightness, terahertz-beam system to time-domain spectroscopy. By analyzing the propagation of terahertz electromagnetic pulses through water vapor, we have made what we believe are the most accurate measurements to date of the absorption cross sections of the water molecule for the nine strongest lines in the frequency range from 0.2 to 1.45 THz.

830 citations


Journal ArticleDOI
TL;DR: In this article, two dilute solutions are prepared by using a reference compound in pure solvent, and the solution of the paramagnetic species whose susceptibility is to be determined is incorporated in an inner narrow-bore tube while the solvent containing the reference compound is placed in the NMR sample tube or vice versa.

436 citations


Book
28 Dec 1989
TL;DR: In this paper, Fourier Transform Spectrometry (FT-Spectrometry) is used to derive the line shape derived from the motion of a Damped Mass on a Spring, which is then used for spectral line shape estimation.
Abstract: 1. Spectral Line Shape Derived from the Motion of a Damped Mass on a Spring. 2. Fourier Transforms for Analog (Continuous) Waveforms. 3. Fourier Transforms of Digital (Discrete) Waveforms. 4. Fourier Transform Spectrometry: Common Features. 5. Noise. 6. Non-FT Methods for Proceeding from Time- to Frequency-Domain. 7. Fourier Transform Ion Cyclotron Resonance Mass Spectrometry. 8. FT/NMR. 9. FT/Interferometry. 10. Epilog: Fourier Transforms in Other Types of Spectroscopy. References. Problems (at the end of each chapter). Solutions to problems. Appendices. Index.

223 citations


Book
01 Jan 1989
TL;DR: In this article, a femtosecond vibrational dephasing measured by coherent Raman scattering and libration relaxation by degenerate four-wave mixing using temporally incoherent light is presented.
Abstract: Picosecond transient thermal phase grating spectroscopy - applications to the study of non-radiative energy relaxation, R.J.Dwayne Miller resonance rotational Raman and hyper-Raman scattering - a probe of sub-picosecond dynamics, L.D.Ziegler et al sub-picosecond vibrational dephasing measured by coherent Raman scattering and libration relaxation by degenerate four-wave mixing using temporally incoherent light, T.Kobayashi et al time resolved resonance Raman spectroscopy of chemical reaction intermediates in solution, G.N.R.Tripathi time-resolved Fourier transform spectroscopy, J.J.Sloan and E.J.Kruus picosecond coherent Raman spectroscopy of excited electronic states of multiatomic molecules in solutions, V.F.Kamalov et al vibrational spectroscopy of transient states in photosynthetic bacterial reaction centres, B.Robert et al picosecond and sub-picosecond vibrational spectroscopy of hemeproteins, J.W.Petrich and J.L.Martin new advances in femtosecond spectroscopy, C.V.Shank.

83 citations


Journal ArticleDOI
TL;DR: In this article, a Fourier transform infrared isotopic study of the products from the vacuum ultraviolet photolysis of diacetylene and 1,3 butadiene trapped in solid argon has enabled the identification of the 1543.4 cm−1 frequency as a vibration of the C4 molecule.
Abstract: A Fourier transform infrared isotopic study of the products from the vacuum ultraviolet photolysis of diacetylene and 1,3‐butadiene trapped in solid argon has enabled the identification of the 1543.4 cm−1 frequency as a vibration of the C4 molecule. The assignment is confirmed by the observation of the frequencies for seven carbon‐13 substituted isotopomers of the molecule.

79 citations


Book
11 Dec 1989
TL;DR: In this article, an up-to-date reference source for those familiar with chromatography/Fourier transform infrared spectroscopy (FT-IR) methods is provided.
Abstract: This book is intended to serve as an up-to-date reference source for those familiar with chromatography/Fourier transform infrared spectroscopy (FT-IR) methods and as an introduction to techniques and applications for those interested in future uses for chromatography/FT-IR.

62 citations



Journal ArticleDOI
01 Jan 1989-Analyst
TL;DR: A variety of applications of the technique of Fourier transform (FT) Raman spectroscopy using a near-infrared laser excitation source have now begun to emerge.
Abstract: A variety of applications of the technique of Fourier transform (FT) Raman spectroscopy using a near-infrared laser excitation source have now begun to emerge The design and construction of a bench-top, analytical-grade FT Raman spectrometer are described Its specifications are explained and its performance and convenience of use are reported A variety of analytical applications of the FT Raman technique have been surveyed to demonstrate the versatility of the spectrometer

53 citations


Journal ArticleDOI
TL;DR: In this article, the capabilities of a step-scan Fourier transform spectrometer for obtaining time-resolved spectra from a pulsed fluorescent lamp are reported. But the authors focus on the potential of the stepscan interferometry for time-resolution infrared measurements of a variety of transient phenomena.
Abstract: The capabilities of a step-scan Fourier transform spectrometer of obtaining time-resolved spectra are reported. As a demonstration of the method, time-resolved spectra from a pulsed fluorescent lamp are presented. The potential of step-scan interferometry for time-resolved infrared measurements of a variety of transient phenomena is discussed.

50 citations


Journal ArticleDOI
TL;DR: Fourier transform infrared (FTIR) spectra of nitrogen dioxide layers deposited at various rates and substrate temperatures, are reported in this article, where bands assignable to N2O4(D2h) (ordered and disordered layers), to O=N-O-NO2 ‘D’ and ‘ D’, to NO+NO−3 nitrosonium nitrate and to the NO2 monomer were observed.
Abstract: Fourier transform infrared (FTIR) spectra of nitrogen dioxide layers deposited at various rates and substrate temperatures, are reported. Bands assignable to N2O4(D2h) (ordered and disordered layers), to O=N–O–NO2 ‘‘D’’ and ‘‘D’’’ isomers, to NO+NO−3 nitrosonium nitrate and to the NO2 monomer were observed. The relative amounts of species depends upon deposition conditions. Temperature cycling effects were followed up to 205 K. Solid N2O4(D2h) behaves like a normal, stable molecular solid, its disordered layer exhibiting small frequency shifts, but also being stable with respect to temperature cycling. The observation of NO+NO−3 bands is related to the existence of the D’ isomer and of monomeric NO2. Raman experiments overemphasize the NO+NO−3 form due to resonant enhancement.

50 citations


Journal ArticleDOI
TL;DR: The dual-cell Fourier transform ion cyclotron resonance mass spectrometry (FTICRMS) has emerged as an ideal technique for synthesizing and studying interesting oinic species in the gas phase as mentioned in this paper.

Journal ArticleDOI
TL;DR: The ground-state rotational spectra of the symmetric top isotopomers of trimethylamine and hydrogen chloride have been observed in the vapor above heated samples of solid trimethyammonium chloride by pulsed-nozzle, Fourier transform, and microwave spectroscopy as mentioned in this paper.
Abstract: The ground‐state rotational spectra of the symmetric‐top isotopomers [(CH3)314N, H35Cl], [(CH3)314N, D35Cl], [(CH3)315N, H35Cl], and [(CH3)315N, H37Cl] of a dimer formed between trimethylamine and hydrogen chloride have been observed in the vapor above heated samples of solid trimethylammonium chloride by pulsed‐nozzle, Fourier‐transform, microwave spectroscopy. Spectroscopic constants have been determined in each case and for [(CH3)314N, H35Cl] the values are B0=1800.4605(2) MHz, DJ=0.320(10) kHz, DJK=13.59(11) kHz, χ(35Cl)=−21.625(5) MHz, and χ(14N)=−3.504(5) MHz. The observed rotational constants B0 indicate that the nuclei N, H, and Cl lie along the C3 symmetry axis of the molecule in the order N⋅⋅⋅H⋅⋅⋅Cl with the distance r(N⋅⋅⋅Cl)=2.8164(3) A. A comparison of the values of the nuclear quadrupole coupling constants χ(35Cl) and χ(14N) with those in related dimers and molecules leads to the evocation of some ionic character (CH3)3N +H Cl arising from a significant extent of proton transfer from Cl to ...

Journal ArticleDOI
01 Sep 1989
TL;DR: In this paper, the absorption frequencies of K-feldspar were characterized using X-ray methods, transmission electron microscopy, and Fourier transform infrared spectroscopy and the experimental results were discussed within the framework of Hard Mode Infrared Spectroscopy (HMIS).
Abstract: Natural samples of K-feldspar representing various states of Al, Si order were characterised using X-ray methods, transmission electron microscopy, and Fourier transform infrared spectroscopy. Line profiles of infrared absorption bands were observed to show strong correlation with the degree of Al, Si order present. In particular, the absorption frequencies of the 540 cm−1 and 640 cm−1 bands were seen to vary by ca. 10 cm−1 between sanidine and microcline, with modulated samples respresenting intermediate behaviour. Linewidths of these modes also decrease by ca. 50% in this series. The experimental results are discussed within the framework of Hard Mode Infrared Spectroscopy (HMIS), and it is shown that the absorption frequencies vary with the short range order parameter τ = (4t1-1)2 and the symmetry breaking order parameter describing Al, Si order, Q od=(t1 0−t1 m)/Q od=(t1 0+t1 m), where t1 is the average Al occupancy on the T1 sites and t1 o and t1 m are the individual site occupancies of the T1 o and T1 m sites, respectively. The structural state of orthoclase is characterised by strain-induced modulations with large spatial variations of the modulation wavelength. No such modulations were observed in the degree of local Al, Si order. Sanidine shows mode hardening in excess of the extrapolated effect of symmetry breaking Al, Si order, which is presumably related to nonsymmetry breaking ordering between T1 and T2 sites and/or as yet unobserved short range order of the symmetry breaking ordering scheme. The possibility of an additional phase transition in K-feldspar at temperatures above 1300 K is discussed.

Journal ArticleDOI
TL;DR: In this paper, the spectrum of a weakly bound dimer (CO2, CO) formed in a pulsed jet of CO2 and CO seeded in argon was observed at Doppler-limited resolution.
Abstract: Two techniques have been used to observe the spectrum of a weakly bound dimer (CO2, CO) formed in a pulsed jet of CO2 and CO seeded in argon. The v=1←0 vibrational transition in the modified asymmetric stretching mode of the CO2 subunit was first observed at Doppler‐limited resolution by investigating the pulsed jet with an infrared diode‐laser spectrometer. Then the ground‐state pure rotational spectrum was detected by applying Fourier‐transform microwave spectroscopy to such a jet. A combined fit of the two spectra of the parent isotopomer gave the following set of ground‐state (v=0) and excited‐state (v=1) spectroscopic constants: A0=11 863.48(56) MHz, B0=1883.915(4) MHz, C0=1613.297(4) MHz, A1=11 772.17(37) MHz, B1=1882.76(6) MHz, C1=1611.44(5) MHz, ΔJ =8.145(2) kHz, ΔJK =339.42(1) kHz, δJ =1.26(1) kHz, and δK =309.8(4) kHz when the centrifugal distortion constants were constrained to be equal in both states. Spectroscopic constants for the isotopomers (CO2, 13CO) and (CO2, C18O) have also been determ...

Journal ArticleDOI
TL;DR: In this paper, the infrared spectrum of CH 3 OH between 950 and HOOcm −1 has been measured by a high resolution Fourier transform spectrometer, and a catalog of 3410 assigned lines is presented, as well as the Taylor development tables for evaluating the energies of the upper levels of the corresponding transitions.

Journal ArticleDOI
TL;DR: In this article, a segmented Fourier transform (SEFT) was proposed to analyze quantitatively the frequency components of digitized time-domain signals, which enables accurate ion abundance and mass measurements to be made.

Journal ArticleDOI
TL;DR: In this article, the authors report the results of some initial exploratory experiments which indicate that significant fluorescence rejection can be achieved using a modified FT-IR spectrometer, which opens up new areas of application for Raman spectroscopy.
Abstract: In the past, the usefulness of laser Raman spectroscopy as an analytical technique in industrial laboratories has been greatly reduced by problems of laser-induced fluorescence. One method of circumventing this problem is to use near-infrared excitation coupled with a modified FT-IR spectrometer. In this paper, we report the results of some initial exploratory experiments which indicate that significant fluorescence rejection can be achieved. This fluorescence rejection opens up new areas of application for Raman spectroscopy. The advantages and limitations of FT-Raman spectroscopy are discussed. In addition, some initial experiments are outlined on Fourier transform Raman microscopy using a conventional microscope.

Journal ArticleDOI
TL;DR: In this paper, two techniques designed to facilitate the extraction of spontaneous radiative spectrum are discussed and compared, and two techniques for the identification of the photoluminescence peak are compared.
Abstract: Semiconductor materials commonly used in mid‐ and long‐wavelength infrared sensing applications generally have a low radiative efficiency, and the ambient blackbody radiation spectrum often dominates and interferes with the identification of the photoluminescence peak. Two techniques designed to facilitate the extraction of the spontaneous radiative spectrum are discussed and compared.

Journal ArticleDOI
TL;DR: In this paper, the laser-induced fluorescence of the and transitions of Na2 were analyzed using high-resolution Fourier transform spectroscopy, using high resolution Fourier Transform Spectroscopy (FTS).
Abstract: The laser-induced fluorescence of the and transitions of Na2 are analysed, using high resolution Fourier transform spectroscopy. Fixed-frequency ion-laser lines (4880 and 4765 A (1 A = 10−10 m) from Ar+ and 6471 and 4762 A from Kr+) together with laser frequencies from a ring dye laser, using rhodamine 6 G with λ = 5781.22 and 5796.80 A, were used to excite Na dimer in the gas phase. Twenty-eight series of and systems have been assigned and analysed, and the strong transitions are accompanied by numerous rotational relaxation lines. Molecular constants of the state were calculated with high precision from simultaneous least-squares fits to 1410 lines assigned to the A–X and B–X systems. These constants have been used to determine the Rydberg–Klein–Rees potential curve of the X ground state for vibrational levels up to ν = 62.

Patent
31 Jan 1989
TL;DR: In this article, two correction factors are calculated from this Fourier transform and these correction factors were then used to calculate a corrected interferogram, and these two corrections factors are then used in calculating a second order approximation to a corrected Interferogram.
Abstract: An interferogram is formed as in the prior art by dividing a beam of radiation from the source into two beams and interfering these beams so as to form an interferogram on the detector. A Fourier transform is then made of this interferogram. This transform has a signal spectrum above the cutoff frequency of the detector; and because of non-linearities in the detector and in the electronic signal processing circuitry, this transform also has a spectrum below the cutoff frequency of the detector. In accordance with the invention, two correction factors are calculated from this Fourier transform and these correction factors are then used to calculate a corrected interferogram. The first correction factor is evaluated by determining from the portion of the spectrum below the cutoff frequency a valve for the spectral signal at zero frequency. In addition, the integral of the square of the spectrum signal above the cutoff frequency is determined and the correction factor is found by dividing the signal at zero frequency by the integral of the square of the spectrum above the cutoff. The second correction factor is a function of the first correction factor and the integral of the spectrum signal above cutoff. These two corrections factors are then used in calculating a second order approximation to a corrected interferogram. Finally to produce the corrected Fourier transform, a Fourier transformation is made.

Journal ArticleDOI
TL;DR: In this article, a spatial Sagnac triangular common path (SGP) interferometer was used for obtaining spectra in the 200-950 nm wavelength region, where a linear CCD was employed as the detector, allowing spectra to be simultaneously acquired.
Abstract: A spatial (Sagnac triangular common path) interferometer is described and evaluated for obtaining spectra in the 200-950 nm wavelength region. The interferometer has no moving parts, requires no entrance or exit slits, and is easy to align. A linear CCD is employed as the detector, allowing spectra to be simultaneously acquired. The performance of the interferometer is demonstrated for atomic emission and solution absorbance spectra. A method to remove the fixed-pattern response of the detector and optical system is demonstrated which effectively increases the dynamic range of the resulting spectra.


Journal ArticleDOI
TL;DR: In this article, Fourier transform Raman spectroscopy has been used to acquire spectra of polysilane derivatives in the absence of resonance effects arising from electronic absorptions of these materials between 320 and 370 nm.
Abstract: Fourier transform Raman (FT‐Raman) spectroscopy has been used to acquire spectra of polysilane derivatives in the absence of resonance effects arising from electronic absorptions of these materials between 320 and 370 nm. The nonresonant FT‐Raman spectra allow detailed analysis of the conformation of and lateral interactions between alkyl side groups. Comparison of spectra for the series of unsymmetrically substituted compounds poly(n‐pentyl,n‐hexylsilane), poly(n‐heptyl,n‐hexylsilane), and poly(n‐octyl,n‐hexylsilane) with the symmetrically substituted analog poly(di‐n‐hexylsilane) reveals various degrees of intra‐ and intermolecular disorder due to mismatch of side chain length. The induced disorder is well correlated with transition temperatures and UV‐vis absorption maxima.

Journal ArticleDOI
TL;DR: In this paper, a theoretical model based on the Lorentz equations for ion motion and the mass action law was developed for two-dimensional Fourier transform mass spectrometry known as 2D FT-ICR or 2DFTMS.
Abstract: A theoretical model, based on the Lorentz equations for ion motion and the mass action law, is developed for two‐dimensional Fourier‐transform mass spectrometry known as 2D FT–ICR or 2D FTMS. The theory illustrates that the modulation of 2D FT–ICR ion signals in the additional time dimension comes from the modulation of the primary ion speed by the 2D excitation pulses. The modulation of the primary ion speed is found not to be sinusoidal and the modulation of the ion signals in 2D FT–ICR spectra is found to be complicated even in the simplest chemical system. The complex modulation creates higher harmonic components in the spectra. Based on the model, a data processing algorithm is proposed. The results show that the Fourier transformation should be performed stepwise in order to obtain complete information, and that the phase portion of the frequency domain generated by the second Fourier transformation should not be discarded since it contains useful information.

Journal ArticleDOI
TL;DR: In this paper, a method to generate the phase continuity necessary to perform broad-band two-dimensional Fourier transform ion cyclotron resonance (2D FT/ICR) spectroscopy is proposed.

Journal ArticleDOI
TL;DR: In this article, the infrared spectra of the ν3, ν4, and ν6 bands of formaldehyde in the region from 890 cm−1 to 1580 cm −1 have been obtained at high resolution using tunable diode laser (TDL) and Fourier transform-infrared (FT-IR) spectroscopy.
Abstract: The infrared spectra of the ν3, ν4, and ν6 bands of formaldehyde in the region from 890 cm−1 to 1580 cm−1 have been obtained at high resolution using tunable diode laser (TDL) and Fourier transform‐infrared (FT‐IR) spectroscopy. The transition frequencies have been analyzed using a Hamiltonian including terms through sextic in centrifugal distortion and including five interstate vibration–rotation coupling terms. Excited state pure rotational transitions are also included in the data, and their frequencies are reproduced well. Individual measured line intensities are used to determine dipole derivatives and band strengths using the fully coupled, asymmetric top eigenvectors.

Journal ArticleDOI
Joachim Oelichmann1
TL;DR: In this article, photoacoustic spectroscopy (PAS) is used to study layers at various depths below the surface of a sample, and this technique allows depth profile analysis, so that PAS reveals itself as a complementary method to attenuated total reflectance (ATR).
Abstract: The introduction of Fourier Transform techniques and the increasing use of computers in infrared spectroscopy has made new techniques of investigation available to the spectroscopist, such as photoacoustic spectroscopy (PAS) and IR microscopy. These methods now complement the techniques of specular reflectance and attenuated total reflectance. Thin films on metals, sometimes with a thickness of much less than a micron, can be studied by various specular reflectance methods. The physical basis of the attenuated total reflectance technique (ATR) leads to a penetration of the radiation in the order of a few microns. It is, therefore, especially suitable for the investigation of surfaces and of layers close to the surface. By changing the modulation frequency of the IR radiation, i.e. the mirror velocity of the FTIR spectrometer, photoacoustic spectroscopy (PAS) can be employed to study layers at various depths below the surface of a sample. Therefore, this technique allows depth-profile analysis, so that PAS reveals itself as a complementary method to attenuated total reflectance spectroscopy. Samples with inhomogeneous profiles, e.g. laminated polymer films, can often be prepared as microtome slices perpendicular to the layered structure. Using infrared microscopy it is now possible to investigate different regions of the cross-section easily. The size of the regions that can be studied in this way may be as small as a few microns.


Journal ArticleDOI
TL;DR: In this paper, the authors investigated the contribution of background gas to the FTIR spectrum and to the nonlinearity of Boltzmann plots in the 8-9 μm region at high resolutions of 0.004 and 0.0024 cm−1 (fwhm).

Journal ArticleDOI
TL;DR: In this paper, it was shown that n+ and/or p+ contacts on p−i−n diodes can function as solid-state photoemitters at temperatures ≲20 K.
Abstract: It is shown that n+ and/or p+ contacts on p‐i‐n diodes can function as solid‐state photoemitters at temperatures ≲20 K. Infrared radiation can excite electrons or holes over small n‐i or p‐i interfacial barriers and into the intrinsic region when the diode is forward biased. Photoelectric thresholds in the far infrared corresponding to 37 and 61 μm cutoffs have been observed for silicon devices using a Fourier transform spectrometer. Suggestions are made to tailor the cutoff wavelengths using different concentrations of various impurities near the metal‐insulator transition. Epitaxially grown multilayered (superlattice) detectors are proposed.