Experimental study on photoionization of 1,3,5-trimethylbenzene

The photoionization and dissociation of 1,3,5-trimethylbenzene (TMB, C₉H₁₂) have been obtained using supersonic molecule beam, synchrotron radiation and photoionization mass spectrometry (PIMS). The photoionization efficiency (PIE) curves of the parent ion and some fragment ions were measured. The ionization energy (IE) of TMB and the appearance energies (AEs) of C₉H₁₁⁺ and C₈H₉⁺ were measured to be (8.32±0.03), (11.71±0.03) and (11.59±0.03) eV respectively. The dissociation energies (E_d) to produce C₉H₁₁⁺ and C₈H₉⁺ were deduced to be (3.39±0.06) and (3.27±0.06) eV respectively. The formation enthalpies of C₉H₁₂⁺, C₉H₁₁⁺ and C₈H₉⁺ were also deduced to be 786.87, 897.93 and 956.68 kJ/mol respectively.