The Spark Source Mass Spectra of Organic Solids

Abstract

Spark source mass spectra of organic solids, obtained on an A.E.I. M.S. 7 spectrometer, have been compared with the conventional mass spectra produced by electron impact ionization of the vapours of these same solids. Although fragmentation in the spark is very high, many more spectral lines being produced than by electron impact, the spark spectrum contains many features, including meta-stable peaks, that point to a similarity between the two ionization methods. It is suggested that electron impact of vaporised species is an important ionization process within the spark. This hypothesis is reinforced by the fact that those materials that could not be vaporised without thermal degradation for electron impact study also gave no spark spectra characteristic of their structure. Improvements in the design of spark source spectrometers would permit identification, by means of accurate mass measurement, of the numerous ions, many of which do not occur in electron impact mass spectra. This might provide an insight into the processes of fragmentation, re-arrange-ment and ion-molecule reactions occuring in the spark.