Photoionization and dissociation study of p-nitrotoluene: Experimental and theoretical insights

Photoionization and dissociation of p-nitrotoluene in a region of 8.5–16.0 eV have been investigated by tunable vacuum ultraviolet (VUV) synchrotron radiation. The ionization energy (IE) of p-nitrotoluene and the appearance energies (AEs) for major fragments, C7H7O+, C 7 H 7 + , C 6 H 7 + , C 6 H 5 + , and C 5 H 5 + , are determined respectively to be 9.54, 10.95, 11.46, 11.04, 12.45, and 14.25 eV, by measurements of photoionization efficiency (PIE) curves. Five dissociative photoionization channels are proposed: C7H7O+ + NO, C 7 H 7 + + NO2, C 6 H 7 + + NO + CO, C 6 H 5 + + NO + CO + H2, and C 5 H 5 + + C2H2 + NO2. Additionally, the possible formation ways for the major fragments are predicted by ab initio calculations at G3B3 level and compared with the experimental results. All of these channels occur via isomerization prior to dissociation except for C 7 H 7 + + NO2. Transition structures and intermediates for those isomerization are also determined in this work.