Showing papers on "Fluorescence spectrometry published in 1972"
TL;DR: In this article, the inter-element relationships between various elements in howardites, particularly refractory elements, are interpreted in the light of the mixing model, whereby howardsites are considered to be mixtures of eucritic and diogenitic material.
65 citations
TL;DR: The use of fluorescence spectrometry as a qualitative analytical technique in the characterization of high-boiling petroleum distillates is reported in this article, where the authors used ion exchange chromatography, gel permeation chromatography and thin-layer chromatography to obtain fluorescence and excitation peak maxima of 35 aromatic model compounds.
Abstract: Use of fluorescence spectrometry as a qualitative analytical technique in the characterization of high-boiling petroleum distillates is reported. Examples of fluorescence emission and fluorescence excitation spectra obtained from compound types in 400 to 500/sup 0/C distillates are shown. Among the compound types identified were carbazoles, 11H-benzo(a)carbazoles, 7H-benzo(c)carbazoles, perylenes, coronenes, benzo(ghi)perylenes, and chrysenes. Fluorescence and excitation peak maxima of 35 aromatic model compounds are reported. The separation scheme which produced samples suitable for fluorescence analysis involved the use of ion exchange chromatography, gel permeation chromatography, and thin-layer chromatography.
53 citations
TL;DR: In this paper, the authors describe the application of pulsed X-ray excitation to Xray fluorescence spectrometry as a method for increasing the output counting rate of the system by a substantial factor.
Abstract: We describe the application of pulsed X-ray excitation to X-ray fluorescence spectrometry as a method for increasing the output counting rate of the system by a substantial factor. Using a pulsed X-ray tube that is immediately turned off when a signal is detected, and held off during the pulse processing time, it is possible to eliminate the need for a pulse pile-up rejection. We have achieved output counting rates significantly greater than with conventional operation for equivalent shaping networks. No significant degradation in spectrometer resolution was observed at the increased counting rates.
46 citations
39 citations
38 citations
TL;DR: In this paper, eight HL or Type III carbonaceous chondrites have been analysed for Si, Mg, Al, Ca, Ti, Mn, Na, K and P by X-ray fluorescence spectrometry.
27 citations
TL;DR: A detailed examination of the geographical location, external appearance, microstructure and chemical composition of the Loongana Station, Mundrabilla and Premier Downs siderites has led to the conclusion that they are all members of the one meteorite shower as discussed by the authors.
Abstract: A detailed examination of the geographical location, external appearance, microstructure and chemical composition of the Loongana Station, Mundrabilla and Premier Downs siderites has led to the conclusion that they are all members of the one meteorite shower. The cobalt, nickel, gallium and germanium contents of four of these meteorites have been measured by X-ray fluorescence spectrometry and this data enables them to be classified as anomalous, but probably related to Chemical Group I
16 citations
TL;DR: Analysis of the pyridoxal-P-phosphorylase b derivative shows that the major changes in enzymic characteristics are primarily due to modification of one group per monomer at a specific site on the enzyme.
14 citations
TL;DR: The net counts for each element can be converted to concentration using any of a variety of mathematical models for interelement effects for X-ray fluorescence spectrometry as discussed by the authors.
Abstract: Energy dispersive analysis of X-rays is a relatively new but rapidly growing technique for X-ray fluorescence spectrometry offering simultaneous analyses of many elements with sensitivities to a few p.p.m. The digitally recorded spectra lend themselves to processing to remove background and interfering peaks. The net counts for each element can be converted to concentration using any of a variety of mathematical models for interelement effects. When proper specimen preparation is used, final accuracies of better than 1 per cent can be realised over much of the analytical range.
12 citations
TL;DR: In this article, an accurate X-ray fluorescence spectrometric method was described for the determination of lead, zirconium and titanium in lead-zirconate-titanate ceramics.
10 citations
TL;DR: The problems of line broadening in microwave-excited electrodeless discharge lamps for the more volatile elements, P, S, I, Se, Zn, Cd and Hg are discussed in relation to their use in atomic-absorption and fluorescence spectrometry.
TL;DR: In this paper, the quenching of atomic fluorescence emitted by the excited Br atoms has been studied in a flow system at 298 K, in which the steady state concentration of ground state Br 4p52P was less than 1010 atom cm-3.
Abstract: Vacuum ultraviolet photolysis of Br2 was shown to form excited Br 5s4P5/2 and 4P atoms by independent primary processes. The quenching of atomic fluorescence emitted by the excited Br atoms has been studied in a flow system at 298 K, in which the steady state concentration of ground state Br 4p52P was less than 1010 atom cm–3. Although Br 5s4P atoms have too short a radiative lifetime to show quenching at pressures up to 3 kN m–2, quenching cross sections σM(10–20 m2) were determined for the more metastable Br 5s4P5/2 atoms: σHe < 0.02; σAr < 0.04; σH2= 0.27; σN2= 1.8; σCO= 2.9; σSF6= 28; σBr2= 146. These quenching cross sections are compared with those for quenching of metastable Br 4p52P½ atoms.
TL;DR: In this article, the authors obtained uncorrelated ultraviolet-visible fluorescence spectra of a coal-hydrogenation asphaltene, a coaltar pitch, a neutral oil from coal carbonization and pyridine extracts of vitrains from five coals as part of a comprehensive spectral investigation of coal and related materials.
Abstract: WE have obtained uncorrelated ultraviolet-visible fluorescence spectra of a coal-hydrogenation asphaltene, a coal-tar pitch, a neutral oil from coal carbonization and pyridine extracts of vitrains from five coals as part of a comprehensive spectral investigation of the chemical structure of coal and related materials. Although light-induced chemiluminescence in the visible has been detected in solutions of coal derivatives1 and infrared fluorescence has been observed for coals and a few related materials2, the technique of ultraviolet-visible fluorescence spectrometry has not been previously applied to studies of the structure of coal.
TL;DR: In this paper, a spectrochemical method was developed for the determination of potassium in graphite covering the concentration range between 0.1 and 10% with a standard deviation < 1% (rel.).
Abstract: A spectrochemical method has been developed for the determination of potassium in graphite covering the concentration range between 0.1 and 10%. After wet combustion of about a 100-mg sample, potassium could be analyzed by x-ray fluorescence spectrometry with a standard deviation <1% (rel.).