Source and Multiplier Modifications of a Time-of-Flight Mass Spectrometer to Increase SensitivityRohwedder, W. K.; Selke, E.; Bitner, E. D.
doi: 10.1366/000370264789620367pmid: N/A
The usefulness of a gas chromatograph and a mass spectrometer in tandem to analyze odor constituents is limited by the sensitivity of the mass spectrometer and by the large amount of helium carrier gas compared with the amount of sample A time-of-flight mass spectrometer was fitted with a tightly enclosed source and operated in a continuous ionization mode to increase instrument sensitivity A gate pulse was applied to the front end of the magnetic electron multiplier to eliminate the electrons due to the helium pulse before they reached the multiplier dynode strips This procedure prevented saturation of the multiplier by the helium carrier gas.
Spectrographic Analysis of High Purity Gold PlateShubin, Lester D.; Chaudet, Julian H.
doi: 10.1366/000370264789620385pmid: N/A
Determinations of trace impurities in high purity gold plate were made by emission spectroscopy at concentration levels of 0 001 to 0 1% Trace contaminants included Al, Cu, Si, Mg, Ni, Fe, Pb, and Ag. Contamination problems related to the handling of the gold plate were minimized by electrolytically depositing the gold on graphite electrodes followed by dissolution of the plate in a suitable solvent. Emission spectra were obtained on the resultant solution using high voltage ac arc excitation and vacuum cup electrodes
Molecular Structure Studies of 1,1,1-Triethylhydrazinium ChlorideHarvey, Mack C.; Kramm, David E.
doi: 10.1366/000370264789620411pmid: N/A
Infrared, nuclear magnetic resonance and ion exchange methods have been used to establish the molecular structure of 1,1,1-triethylhydrazimum chloride. Using stoichiometric ion exchange techniques, a general method for preparing 1,1,1-tnalkylhydrazinium salts has been developed and used to prepare compounds of the 1,1,1-tnethylhydrazimum cation and fourteen other anions. Infrared spectral studies on these compounds have shown that there is a strong hydrogen-bond between the -NH2 group and the anion and that the stretching-vibration frequency appears to be related to mass, charge, and geometry of the anion. Nuclear magnetic resonance and molecular weight studies on 1,1,1-tnethylhydrazinmm chloride show that the compound exists as a dimer when dissolved in chloroform. The molecule is partially dissociated when acetonitrile is used as a solvent
Mechanisms of Interactions of Alkali and Alkaline Earth Elements in Flame PhotometryJohnson, Russell W.; Schrenk, W. G.
doi: 10.1366/000370264789620394pmid: N/A
Cationic interactions in flame photometry were investigated to study some of the factors that cause enhancements of spectral lines. Interactions of the alkali and alkaline earth metals in an oxygen-acetylene flame have indicated that several mechanisms may be responsible for enhancement Where conditions are proper, enhancements of emissions of cations may be a combination of at least three factors a) the effect of electron concentration from an easily ionized extraneous element on the ground state population of the test element, b) the effect of transfer of energy by radiation and c) the effect of transfer of energy due to collisions with excited atomsThe effect of the electron concentration on the suppression of the ionization of the test element was the predominant mechanism by which enhancement occurred in most systems studied. However, in the study of the effect of potassium on rubidium direct evidence was obtained of excitation by transfer of radiant energy Indirect evidence of enhancement due to transfer of energy by collision also was observed in the same system.
Absorption Spectral Studies of Complexes of 8-Aminoquinoline with Metal HalidesCoakley, Mary P.
doi: 10.1366/000370264789620466pmid: N/A
Ultraviolet measurements in potassium bromide disks of the 2:1 complexes of 8-aminoquinoline with the chlorides of Mg, Ni(II) and Pd(II), and the 1.1 complexes with the chlorides of Zn, Cd and Cu(II) show a shift toward shorter wavelengths from that of the 8-aminoquinohne in the 300 millimicron region. The extent of the shift is almost identical for the Mg, Zn, Cd, Ni(II) and Cu(II) chelates, indicating that the metals are equally effective in blocking the resonance between the amino group and the quinohne ring by the nitrogen-to-metal bond formation. The ultraviolet spectra of the complexes of 8-aminoquinoline in dioxane do reveal differences in the values of the long wavelength maxima. Absorption patterns in the 3 micron region reveal the expected decrease in the frequencies of the N-H stretching vibration on chelation.
An Investigation into the Analysis of Nitrogen for Hydrogen by Emission SpectroscopyDickinson, G. W.; Wheeler, G. V.
doi: 10.1366/000370264789620402pmid: N/A
Continuous monitoring of hydrogen in flowing nitrogen gas was needed in connection with experimental work at the USAEC's National Reactor Testing Station. One of the methods investigated was emission spectroscopy, using quartz envelope electrodeless discharge tube excitation. The sample gas was passed through a cold trap to eliminate water vapor and hydrocarbon vapors before entering the discharge tube at a pressure of two mm Hg. Using a grating monochromator with photomultiplier detection set at 4861.3A hydrogen can be determined down to about 0.05% (v/v).