Spectrophotometric studies on technetium and rhenium

Low-temperature secondary positive ion mass spectrometry of neat and argon-diluted organic solids

“…If the fragmentation were excessive or strongly dependent on the experimental conditions, the value of the method as an analytical tool would be sharply decreased. Previous room-temperature SIMS data on organic solids coated on metals reported either relatively little fragmentation initially, but quite rapid decay of the sample with time (15, 161, or a n extent of fragmentation which was higher than in ordinary electron impact mass spect ra, but not prohibitive (13,14,17,18). Our experience with the four molecules chosen for this study parallels the latter results: fragmentation is stronger than in electron impact mass spectra but is not prohibitive, and the fragment ion m,' e values which emerge are those which have already proved to be useful in organic structure determination.…”

“…Our secondary aim is to assess the usefulness of low-temperature SIMS for analysis of neat organic samples. Room-temperature measurements of this latter type have been reported both for selected low-molecular weight organic solids (13)(14)(15)(16)(17)(18) and for several polymers (8)(9)(10)(11)(12), but little attention has been paid to the possible overheating and ion-molecule reactions in the neat solids. These dangers are minimized when very low primary ion current densities are used (static SIMS) (15,16) but this then does not permit depth profiling which may be of considerable interest in analytical applications.…”

“…Since in these instances the species of interest cannot be easily transferred to the gas phase without change, standard mass spectrometry is of little direct use and methods such as field desorption ( I ) have been investigated. In recent years, a limited amount of exploratory work on organic solids using plasma desorption mass spectrometry (PDMS) (2, 3) and secondary ion mass spectrometry (SIMS) (4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14)(15)(16)(17)(18) has been performed in several laboratories and appears t o show considerable promise. Even at the higher temperatures, there is no evidence that any of the observed SIMS signal originated in the gas phase (see Discussion).…”

Microbial and Monosaccharide Composition of Biofilms Developing on Sandy Loams from an Aquifer Contaminated with Liquid Radioactive Waste

“…The absolute configurations of the monosaccharides were determined using GLC of the acetylated (S)-2-octyl glycosides as described [ 44 ]. The reduction of technetium and chromium was determined using diphenylcarbazide [ 45 ], while that of uranium was determined using arsenazo III, after liquid extraction of the reduced form with 1-(2-thenoyl)-3,3,3-trifluoroacetone (TTA) [ 46 ].…”