Abstract
Cf-252 plasma desorption mass spectrometry (PDMS) has been applied to the characterization of compounds which are difficult to analyze by conventional mass spectrometry. These included organic dyes (individual and mixtures) and inorganic materials (asbestos and silica gel). Ion formation and fragmentation patterns of a series of organic dyes were studied, and the results were compared with those from laser desorption mass spectrometry (LMMS). For single component samples, spectra from the two techniques were qualitatively similar. Many different modes of ionization were represented (e.g., cationization, electron capture and hydrogen ionization). For multicomponent dye samples, PDMS proved to be more useful than LMMS due to the mixture inhomogeneity in the microvolume sampled by LMMS. The applicability of PDMS to the characterization of insulating inorganic materials was demonstrated in the analysis of Chrysotile asbestos and silica gel samples. Analysis of the samples showed ionic clustering of the major constituents. PDMS was also used to follow the modification of the asbestos surface with organosilane compounds. The spectra showed uptake of the organosilane represented by increases in Si+ and SiOH+. By monitoring the changes in PDMS peak area ratios, information about the structure and coverage of the modifier was obtained. As a reference point, spectra obtained from well characterized modified silica gel samples were compared with the asbestos data. The results show a build-up of siloxane polymers at the fiber surface. Comparison of x-ray photoelectron and Auger electron spectroscopy data with the SiOH+/Si+ values for a series of silicon-oxygen containing compounds suggests that small changes in the electronic environment around the Si atom strongly affect its ionization efficiency.
Bennett, Joseph Alden (1989). Characterization of organic species on solid surfaces using ²⁵²cf plasma desorption mass spectrometry. Texas A&M University. Texas A&M University. Libraries. Available electronically from
https : / /hdl .handle .net /1969 .1 /DISSERTATIONS -1017710.