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Showing papers on "Fourier transform spectroscopy published in 1975"




Journal ArticleDOI
TL;DR: In this article, a method is developed for recording two dimensionally resolved undecoupled 13C NMR spectra, which is related to 2 D Fourier transform spectroscopy.
Abstract: A method is developed for recording two dimensionally resolved undecoupled 13C NMR spectra. The technique, which is related to 2 D Fourier transform spectroscopy, permits analysis for inspection even for large molecules. (AIP)

159 citations


Journal ArticleDOI
TL;DR: In this paper, Fourier transform infrared spectroscopy (FTIR) is used to improve the quality of the spectra of the desired components and the role of FTIR in analytical chemical laboratory.
Abstract: The advantages of Fourier transform infrared spectroscopy (FTIR) over dispersive infrared spectroscopy are outlined. The use of data processing with specific reference to difference spectroscopy is discussed in light of these advantages. Applications of FTIR to identification, quality control, and quantitative infrared analysis are indicated. The use of difference spectroscopy to improve the quality of the spectra of the desired components is illustrated for a variety of chemical systems. The role of FTIR is thus illustrated in the analytical chemical laboratory.

156 citations





Journal ArticleDOI
TL;DR: The construction and the performance of a double-beam Michelson-type Fourier spectrometer are described and the pure rotational spectra of H(2)O and CO have been recorded.
Abstract: The construction and the performance of a double-beam Michelson-type Fourier spectrometer are described. The instrument covers a wavenumber range from 10 cm−1 to 450 cm−1 with a maximum resolution of 0.025 cm−1 and an accuracy of frequency within ±0.001 cm−1. The optical path difference is measured by means of an He–Ne gas laser. To illustrate the general performance of the instrument, the pure rotational spectra of H2O and CO have been recorded.

69 citations


Journal ArticleDOI
TL;DR: Infrared absorption bands due to sulfhydryl groups (VSH) of alpha-104(G11) and beta-112 (G14) cysteine residues of human carboxyhemoglobin (HbCO) have been observed near 2560 cm- minus 1 by use of Fourier transform infrared (FTIR) spectroscopy.
Abstract: Infrared absorption bands due to sulfhydryl groups (VSH) of alpha-104(G11) and beta-112 (G14) cysteine residues of human carboxyhemoglobin (HbCO) have been observed near 2560 cm- minus 1 by use of Fourier transform infrared (FTIR) spectroscopy. The beta-93 cysteine SH groups absorb infrared radiation so weakly that they are not distinguished from background. Only single SH absorption bands due to the alpha-104 cysteines of pig and horse hemoglobin are observed. The SH absorption bands from human HbCO disappear in alkali, are broadened by detergent or guanidinium chloride, and show a complex titration curve, and an isotopic frequency shift (VSD/VSH equals to 0.7267) virtually identical with that reported for methanethiol. The integrated absorption coefficient (epsilonmM(area)) for 0.1 M ethanetiol increased with H-bond acceptor solvents in the order: CCl4 (0.07), water (0.21), acetone (0.43), and N,N-dimethyl-acetamide (1.35 mM- minus 1 cm- minus 2). Comparison of the integrated absorption coefficients for the alpha-104 cysteine SH (2.43), and the beta-112 SH (0.80), of human HbCO with those of ethanetiol solutions suggested specifically H-bonded structures with peptide carbonyl groups 4 (or 3) residues back in the G helices. This was found to agree with a molecular model of the alpha-chain G helix of horse HbO2 built to coordinates from M. F. Perutz.

60 citations


Journal ArticleDOI
TL;DR: In this paper, a series of LnNi(CO)o-n derivatives (n = 0-3) were obtained f0r.13C N M R spectra and analyzed in terms of the electron donor-acceptor abilities of the ligands.
Abstract: 13C N M R spectra have been obtained f0r.a series of LnNi(CO)o-n derivatives (n = 0-3) where L = PR3, PPhzY, PPhY2, P(OR')3, and Pc13 (R = Me, Et, Bu, Ph; R' = Me, Et, l-Pr, Ph; Y = C1, Me, OMe, OPh). The effect upon the carbonyl chemical shift of the replacement of X by Y substituents in X3-nYnPNi(C0)3 derivatives appears to be additive, as is the effect of the sequential replacement of carbonyl by phosphorus ligands. An excellent correlation is observed between the carbonyl chemical shifts and either the infrared stretching force constants or Kabachnik's a parameters. These data are analyzed in terms of the electron donor-acceptor abilities of the ligands.

50 citations


Journal ArticleDOI
TL;DR: In this article, the combination of double irradiation and a simple two-pulse spin echo sequence is used for detecting homonuclear decoupling in a complex spectrum, which is a powerful and sensitive method.
Abstract: It is shown that the combination of double irradiation and a simple two-pulse spin echo sequence is a powerful and sensitive method for detecting homonuclear decoupling in a complex spectrum.



Journal ArticleDOI
TL;DR: In this article, the aero-filled interferogram is apodized to prevent the generation of artifacts in the spectrum (of a similar origin to the sine x side-lobes formed when a non-zero-filled spectrum is computed with a box-ear truncation function).
Abstract: Digitally recorded spectra containing lines of width less than or equal to the resolution at which the measurement has been made are observed to show some photometric error. In spectra measured by Fourier transform spectroscopy, this error may be substantially reduced if the interferogram is aero-filled. To prevent the generation of artifacts in the spectrum (of a similar origin to the sine x side-lobes formed when a non-zero-filled spectrum is computed with a box-ear truncation function), the aero-filled interferogram must be suitably apodized.

Journal ArticleDOI
TL;DR: The optical constants of liquid chloroform and bromoform have been measured at 20°C by dispersive Fourier transform spectroscopy in the wavenumber range 20-350 cm −1.



Journal ArticleDOI
TL;DR: In this paper, the symbiosis of the Fourier transform spectrometer with the computer permits the development of novel procedures for handling spectroscopic data, and two such procedures are described.
Abstract: The symbiosis of the Fourier transform spectrometer with the computer permits the development of novel procedures for handling spectroscopic data. Two such procedures are here described. The first one produces directly the spectrum of the intermolecular interaction perturbation in solutions, while the second obtains the spectrum of pressure broadening coefficients of a gas sample. The interpretation of these techniques are discussed in the light of experimental results and shown to be critically dependent on a constant, well defined slit function and on nearly perfect spectral and intensity registration.


Journal ArticleDOI
TL;DR: An attachment for a commercial pulse Fourier transform nuclear magnetic resonance spectrometer is described in this article, which enables two solutions to be rapidly and efficiently mixed inside a spinning 5 mm diameter NMR tube.
Abstract: An attachment for a commercial pulse Fourier transform nuclear magnetic resonance spectrometer is described, which enables two solutions to be rapidly and efficiently mixed inside a spinning 5 mm diameter NMR tube. Complete high resolution 1H NMR spectra can be obtained with 0.2 s of mixing, and at a repetition rate of ca. 0.6 s per spectrum in favourable cases. The technique is illustrated by rapid reactions involving the base-catalysed hydrogen-deuterium exchange between methanol-d4 and the nitromethane anion ((CH2NO2)-), and by the chlorination of tris-(2,4-pentanedione)cobalt(III) ((Co(acac)3)) by N-chlorosuccinimide.





Journal ArticleDOI
TL;DR: For quantitative analysis by NMR spectroscopy with Fourier transform, the usual experimental conditions have to be partly modified as mentioned in this paper, and careful regulation of the delays between the different phases of the process is particularly important.
Abstract: For quantitative analysis by NMR spectroscopy with Fourier transform, the usual experimental conditions have to be partly modified. Careful regulation of the delays between the different phases of the process is particularly important. The filters of the spectrometer and the calculations on the free induction decay are important causes of error. Precise results are given.

Journal ArticleDOI
TL;DR: In this article, the properties of a rapid scanning Fourier transform infrared spectrometer (FT-IR) which permit its effective utilization in acquiring kinetics information are described, and experiments which would be lengthy and difficult to perform by conventional infrared procedures can be performed quickly and more reliably with an FT-IR system.
Abstract: The properties of a rapid scanning Fourier transform infrared spectrometer (FT-IR) which permit its effective utilization in acquiring kinetics information are described. Experiments which would be lengthy and difficult to perform by conventional infrared procedures can be performed quickly and more reliably with an FT-IR system. The detection of all spectral frequencies simultaneously, inherent to the interferometer spectrometer, enables these advances to be achieved. The computer, which is essential for Fourier transformation, can also be utilized to provide absorbance profiles, differential profiles, and other display formats which can simplify the analysis and improve the reliability of kinetic measurements. Spectra and profiles obtained for a gas-solid adsorption process and a gas phase reaction of butadiene with an NO2-N2O4 mixture are presented to illustrate the potentials of an FT-IR system.

Journal ArticleDOI
TL;DR: In this paper, the ratios of the Larmor frequencies of 25Mg and 37Cl and of 43Ca and37Cl have been measured in aqueous solutions and nuclear magnetic moments are given for these nuclei in the hydrated ions.
Abstract: The ratios of the Larmor frequencies of 25Mg and 37Cl and of 43Ca and 37Cl have been measured in aqueous solutions and nuclear magnetic moments are given for these nuclei in the hydrated ions. 25Mg and 43Ca chemical shifts have been investigated at natural abundance of these isotopes in solutions of the chlorides, bromides, nitrates, Perchlorates in H2O and D2O. The signal intensities are large enough to study within reasonable time these nuclei at natural abundance down to low concentrated solutions, e.g. 8 millimolal for 25Mg. For 25Mg very small chemical shifts have been observed whereas for 43Ca remarkable shifts to higher frequencies are found for halide solutions and to lower frequencies for the oxyanion solutions. Linewidths of only some Hz have been observed for both isotopes

Journal ArticleDOI
TL;DR: In this paper, the authors discuss the widening of the dipolar splittings of phenylene protons due to terminal proton groups, which results in incorrect measurements of the degree of order.
Abstract: Proton and deuteron Fourier transform magnetic resonance spectra are reported for a variety of nematic liquid crystals. We discuss the widening of the dipolar splittings of phenylene protons due to terminal proton groups, which results in the incorrect measurements of the degree of order. 'Fine structure' in the proton spectra is related to the rotating methyl groups.

Journal ArticleDOI
TL;DR: In this article, the theory for off resonance measurements of the nuclear spin-lattice relaxation time in the rotating coordinate frame (T1ϱ) is developed to facilitate measurements of this parameter by Fourier transform (FT) NMR.

Journal ArticleDOI
TL;DR: In this article, illustrative spectral lineshapes and experimental examples from Fourier transform ion cyclotron resonance spectroscopy were presented for the Fourier Transform ion resonance spectra.
Abstract: Presents illustrative spectral lineshapes and draws an experimental example from Fourier transform ion cyclotron resonance spectroscopy.