Internal Energy Distribution of Ions Emitted in Secondary Ion Mass Spectrometry

Abstract

In secondary ion mass spectrometry, the extent of fragmentation is reduced when taking the spectra from solutions instead of using solid supports (1,2). Consequently, the internal energy of the ejected ions could either be different according to the physical state of the sample or be dissipated in another manner. In general, spectra obtained from solutions present peaks corresponding to both intact and fragmented species. An estimation of the internal energy of the sputtered ions could be made by the examination of their fragmentation in order to enlight the ion formation mechanism and the so-called matrix effect. In previous works (3,4,5), the extent of fragmentation for a given family of molecules has been related to substitution. The correlations found were explained in terms of the quasi-equilibrium theory and thermochemical considerations or in terms of mechanistic organic chemistry, using free energy relationships. The differences in fragment abundances were related to differences in the decomposition kinetics.