Electron transfer during the dissociation of CH3F+ produced by resonant photoemission following F 1s excitation

We present experimental evidence for pronounced electron transfer from C to F+ happening during the breakup of CH3F+ ions in gas phase produced by resonant photoemission following F 1s -> 6a(1)(*) core excitation of CH3F. We measured the momentum of the ionic fragments in coincidence with the F KVV Auger electrons that show a Doppler shift reflecting the motion of the F nucleus. The correlation between Doppler shift and ion momentum is opposite for the F+ and the CH2+ fragments, indicating that CH2+ is produced by electron transfer from C to F+, after the Auger electron emission from excited moving F. This finding is rationalized by calculations of the potential energy curves of the main states involved in the excitation and decay processes.