Photodissociation Dynamics of Nitrobenzene Molecular Ion on a Nanosecond Time Scale

Photodissociation dynamics of nitrobenzene molecular ion has been investigated on a nanosecond time scale by mass-analyzed ion kinetic energy spectrometry. Photodissociation has been found to occur through various reaction channels. Three dissociation channels to C₅H₆O⁺, C₆H₅⁺, and NO⁺ have been observed together with a consecutive dissociation to C₅H₅⁺ via C₆H₅O⁺. The photodissociation rate constant of the molecular ion and the kinetic energy release distributions in each channel have been determined. The rate constant of the second step of the consecutive reaction has been determined in real time also. It has been found that the direct bond cleavage to C₆H₅⁺ occurs in competition with the rearrangement processes to C₆H₅O⁺ and NO⁺ on a nanosecond time scale. Statistical theories have been used to gain insight into the dynamics of the reactions.