ChemInform Abstract: Dissociative Single and Double Photoionization of CH3F in the Region 20-110 eV Studied by Mass Spectrometry and the Photoion-Photoion Coincidence Method.

Abstract

Dissociative single and double photoionization of methyl fluoride (CH3F) has been studied in the photon energy region of 20–110 eV by use of synchrotron radiation, a time‐of‐flight (TOF) mass spectrometer, and the photoion–photoion coincidence (PIPICO) method. The TOF mass spectrometer facilitates relatively efficient extraction of energetic ions, which is essential for quantitative measurements. Photoion branching ratios are reported for the observed 11 singly charged ions, H+, H+2, CH+n (n=0–3), F+, CHnF+ (n=0–3). Stable CH3F2+ is not observed in all of the energy region studied in a μs time scale. The double photoionization threshold is measured to be 35.0±0.5 eV. PIPICO spectra measured at higher photon energies show the following five types of dissociation processes:(1) CH3F2+→H++CHnF+ (n=0–2), (2) H+2+CHnF+ (n=0–1), (3) H++CH+n (n=0–2), (4) H+2+CH+, (5) H++F+, with ten total dissociation channels. These processes are characteristic in regard to bond breakage involved, whether a rearrangement reactio...