Dissociative photoionization of m-Xylene: experiments and calculations

The study of m-Xylene photoionization and dissociation photoionization using synchrotron vacuum ultraviolet (VUV) light and supersonic expanding molecular beam reflection time-of-flight mass spectrometer system. Photoionization efficiency curves (PIEs) of molecule ion C8H10+ and fragment ions C8H9+ and C7H7+ were observed, and the ionization energy (IE) and the appearance energies (AEs) of the fragment ions C8H10+, C8H9+ and C7H7+ are obtained to be 8.59eV, 11.74eV and 11.89eV, respectively. Optimized structures of transitional states, intermediates, and product ions were characterized at the B3LYP/6-311++ G (d, p) basis sets, and the energies were calculated using the G3 method. Based on the results, two major dissociative photoionization channels, C7H7++CH3 and C8H9++H have been calculated at the B3LYP/6-311++ G (d, p) level. With the combination of theoretical and experimental results, the dissociative photoionization pathways of m-Xylene are proposed. The predominant m-Xylene cleavage mechanism is hydrogen migration.