Dissociation pathways of benzene trication

Density functional B3LYP calculations have been performed to investigate dissociation pathways of benzene trication in order to understand the mechanism of dissociative ionization of benzene after irradiation in intense laser fields. Numerous decomposition products can be formed: H2CCCH2++C3H3+ (with the activation barrier of 38.4 kcal/mol), cyclobutadiene dication C4H42++C2H2+ (53.0 kcal/mol), C6H52++H+ (64–65 kcal/mol), etc. The C2H2+ detachment channels have the highest exothermicity (−131 to −138 kcal/mol), followed by C3H3+ detachment (−125.7) and finally H+ detachment (−83.7). The fragments are expected to be produced with high-translational energy due to high Coulomb repulsion energy barriers.