Showing papers on "Fourier transform spectroscopy published in 1971"
TL;DR: F fourier transform spectroscopy is used which is capable of giving more precise values for the relative vibrational populations at low intensities, by recording emission down to lower background pressures (1 x 10(-4) Torr), and by treating the vessel walls so as to remove OHdagger more effectively.
Abstract: Vibrationally excited hydroxyl formation by atomic hydrogen reaction with ozone, using Fourier transform spectroscopy
129 citations
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TL;DR: In this article, the authors proposed a pulse Fourier transform NMR spectroscopy 13C resonance method for elucidating the structures of organic compounds having the natural 13C abundance, which is facilitated by broad-band and off-resonance proton decoupling and knowledge of longitudinal relaxation times.
Abstract: As a result of the development of pulse Fourier transform NMR spectroscopy 13C resonance has become accepted as a means of elucidating the structures of organic compounds having the natural 13C abundance. Assignment of the signals is facilitated by broad-band and off resonance proton decoupling and by knowledge of longitudinal relaxation times. The pulse Fourier technique, which is more sensitive and faster than conventional NMR spectroscopy because of multi-channel excitation, allows 13C measurements within a short time even on dilute samples of high molecular weight compounds without prior enrichment in 13C.
61 citations
TL;DR: Two methods are described to attain high resolution holographic spectroscopy using an interferometer construction to record the localized interference fringes on the photographic plate directly and the application of heterodyning techniques to holographicSpectroscopy.
Abstract: Two methods are described to attain high resolution holographic spectroscopy. One is an interferometer construction to record the localized interference fringes on the photographic plate directly. The limitation due to the use of an imaging lens is removed. The other is the application of heterodyning techniques to holographic spectroscopy. By this method, a hologram with high resolving power is recorded on relatively low resolution photographic film.
51 citations
TL;DR: Partially relaxed (13)C Fourier transform NMR spectra, which yield spin-lattice relaxation times of each resolved resonance, were found to be a very useful addition to the arsenal of NMR techniques.
Abstract: High-resolution Fourier transform NMR at 15.08 MHz was used to observe the proton-decoupled natural-abundance (13)C spectra of aqueous solutions of cobinamide dicyanide (0.067 M), cyanocobalamin (0.024 M), dicyanocobalamin (0.14 M), and coenzyme B(12) (0.038 M). Assignments were made with the aid of chemical shift comparisons, off-resonance single-frequency proton decoupling, partially-relaxed Fourier transform spectra, and splittings arising from (13)C-(31)P coupling. As expected, the (13)C spectra of the coronoids were appreciably more informative than the corresponding proton spectra. Nearly all the lines in the (13)C spectra of the corrinoids were well-resolved single-carbon resonances, in spite of the structural complexity. Partially relaxed (13)C Fourier transform NMR spectra, which yield spin-lattice relaxation times of each resolved resonance, were found to be a very useful addition to the arsenal of NMR techniques.
44 citations
TL;DR: The reaction of vibrationally excited Hydroxyl with ozone was studied in a fast-flow system by observing the effect of ozone concentration on the intensity of hydroxyl emission bands in the 1.4-micro to 2.2-micro wavelength region.
Abstract: Reaction rate of vibrationally excited hydroxyl with ozone, obtaining hydroxyl emission spectra by Fourier transform spectroscopy
42 citations
TL;DR: In this article, Fourier transform spectroscopy has been used to measure the mixing ratio of water vapour in the stratosphere, and a value of (2.1 ± 0.3) × 10−6 g/g is derived above an altitude of 12.2 km.
Abstract: Observations have been made of the submillimetre wavelength radiation emitted by the lower stratosphere, using techniques of Fourier transform spectroscopy, while flying in a Comet 2E aircraft. Using the method of phase-modulation high quality spectra have been obtained at several altitudes over the spectral range 20 to 66 cm−1, and these have enabled identification of many emission lines due to O2 and O3, in addition to those of H2O. Also several unidentified emission lines have been observed. The meteorological applications of this spectroscopic technique are considered. In particular, a direct method of comparing the emission of ‘strong’ water-vapour and oxygen lines enables a calculation of mixing ratio of water vapour in the stratosphere to be made, and a value of (2.1 ± 0.3) × 10−6 g/g is derived above an altitude of 12.2 km. A similar comparison for ozone has given an integrated concentration of 0.35 ± 0.10 cm atm in the vertical path above the observer. The merits of these observations in measuring stratospheric mixing ratios are discussed with respect to alternative techniques, in particular with reference to balloon-borne studies.
TL;DR: The carbon-13 nuclear magnetic resonance spectra of several small peptides have been obtained at 25.1 MHz and natural abundance of 13C using the Fourier transform technique with proton noise decoupling and chemical shift values have been studied as a function of pH.
TL;DR: In this article, a modified Fourier spectroscopy technique was proposed for the direct measurement of difference frequencies in nuclear magnetic resonance, which is based on a nonlinear detector to form the desired difference frequencies.
TL;DR: The first natural abundance 13C NMR spectrum of an enzyme is reported, which is a simple and elegant spectral analysis of ‘Gramicidin S-A’, a decapeptide.
Abstract: NUCLEAR magnetic resonance (NMR) studies of biopolymers have so far been limited to proton resonances. On the other hand, 13C NMR analysis is potentially a more powerful technique because of the larger range of chemical shifts (300 p.p.m. compared with 10 p.p.m. for XH NMR), and because the chemical shift of 13C NMR is more sensitive to the nature of the chemical bonds. The chief limitations of 13C NMR are low natural abundance (1·1%), low relative sensitivity (1·59% of proton), and long relaxation times (˜1 min). These can be largely overcome, however, by the combined techniques of nuclear Overhauser enhancement and fourier transform spectroscopy. Thus, Gibbons et al.1 obtained a simple and elegant spectral analysis of ‘Gramicidin S-A’, a decapeptide. We report here the first natural abundance 13C NMR spectrum of an enzyme. Lysozyme was chosen because its primary structure is known2,3 and because its 1H NMR spectrum has already been described4.
TL;DR: In this paper, a 20 pass, 10 m cell was used, and IR spectra in the 8 to 12 μ region of 70 ppm by weight of Freon-12 and 10 ppm of methanol were obtained.
Abstract: Bar-Lev (1967) described an instrument incorporating a dual detector, dual beam Michelson interferometer, and presented experimental results on the detection of gases in air. A 20 pass, 10 m cell was used, and IR spectra in the 8 to 12 μ region of 70 ppm by weight of Freon-12 and 10 ppm by weight of methanol were obtained. Single 1 s scans were used and emphasis was apparently placed on speed. It seemed to us that such instrumentation should be capable of detecting gas at concentrations lower than those reported, and we consequently carried out the measurements described below.
TL;DR: In this paper, the construction and operation of a Connes-type Fourier spectrometer was discussed in an astronomical context with a sample of the type of spectra obtained with the system.
Abstract: The construction and operation of a Connes‐type Fourier spectrometer are discussed in an astronomical context with a sample of the type of spectra obtained with the system.
TL;DR: In this article, the advantages and disadvantages of apodization in submillimetre Fourier transform spectroscopy were discussed in terms of experimental results obtained observing emission of the stratosphere from an aircraft.
TL;DR: In this article, the condition derived by Nelson and Dowling concerning the resolution needed in Fourier transform spectroscopy in order to reproduce a Lorentzian line shape is extended to absorption spectra.
TL;DR: In this paper, the video response of superconducting point contacts to high microwave frequencies has been measured by Fourier transform spectroscopy and the signal polarity was observed to reverse at the Josephson frequency.
TL;DR: In this paper, a modification of Fourier difference spectroscopy is described which does not require a digital computer and may provide a possibility for the construction of inexpensive nuclear magnetic resonance instruments with resolution and sensitivity comparable to conventional continuous wave spectrometers.
TL;DR: In this paper, the spectra of aqueous solutions of aquocyanocobyric acid and dicyanocobric acid were recorded at 15·08 MHz: the spectrum of the first compound showed the presence of two isomers, and many of the carbon atoms showed large chemical shift variations between the two different isomers.
Abstract: Proton-decoupled natural-abundance carbon-13 Fourier transform n.m.r. spectra of aqueous solutions of aquocyanocobyric acid and dicyanocobyric acid were recorded at 15·08 MHz: the spectrum of the first compound showed the presence of two isomers, and many of the carbon atoms showed large chemical shift variations between the two isomers.
TL;DR: The fourier transform formulation is used for the spectral image formation of a point source in a concave grating mounting (in-plane) and the resolving power is discussed.
Abstract: The fourier transform formulation is used for the spectral image formation of a point source in a concave grating mounting (in-plane). In applying this formulation to an extended source, consideration is given to the condition of slit illumination. This formulation is applied to the Monk-Gillieson mounting, and the resolving power is discussed.
TL;DR: In this paper, the 13C satellites in the proton spectrum as well as the undecoupled 13C resonance spectrum of β-1,2,3,4,5,6-hexachlorocyclohexane were observed by the Fourier transform sensitivity enhancement technique.