A Mass Spectrometric Photoionization Study of CH3F. The CH2+, CH3+ and CH2F+ Ion Formation.

The decay of CH3F+ in the CH2+, CH3+ and CH2F+ dissociation channels has been investigated by photoionization mass spectrometry using synchrotron radiation in the energy range 10-25 eV. The photoabsorption curve of CH3F and the ionization efficiency curves of CH2+, CH3+ and CH2F+ as well as the kinetic energy-versus-appearance energy diagram for CH3+ were recorded. For the three fragment ions dissociative autoionization is a prominent formation process. Direct dissociative ionization is observed for the same ions through the decomposition of the CH3F+(A2A1+B2E) states at 16.1 eV as well as presumably of the C2A1 state at about 22.5 eV.