Ion kinetic energy losses and excited state population in ion—molecule reactions

Abstract

Kinetic energy loss spectra are reported for some organic ions undergoing high energy ion—molecule reactions accompanied by scattering. The translational energy losses are associated with excitation of the ions in inelastic collisions on rare gas targets. The measured energy losses are compared with values for states in photoelectron spectra and this has allowed electronic transitions to stable excited states of the ions to be identified. The energy loss spectra of scattered ethylene and acetonitrile molecular ions show some evidence for the formation of stable ions in excited electronic states lying above the thermochemical threshold for fragmentation. The method used in this work is unusual in that a conventional mass spectrometry is employed to study ions scattered through appreciable angles.