Outer-Valence Intermolecular Coulombic Decay and Fragmentation Dynamics of p-Xylene•••Trimethylamine Complex

Resonant two-color two-photon excitation of p-xylene with a total energy of 8.33 eV, below its adiabatic ionization energy of 8.45 eV, in the p-xylene•••trimethylamine (PX•••TMA) cluster results in ionization of TMA due to the outer-valence Intermolecular Coulombic Decay (ICD) mechanism. The dynamics of the PX•••TMA cluster cation, created due to the ICD process, results in fragmentation of the cluster with the appearance of the TMA cation, whose translational energy was measured using the velocity-mapped imaging method. The Born-Oppenheimer molecular dynamics (BOMD) simulations establish that the translational energy distribution profile of the TMA cation originates primarily from the {Ar}C-H•••N hydrogen-bonded structure in the neutral ground electronic state of the PX•••TMA cluster. It is also demonstrated that the translational energy distribution profile of the fragment cation, following ICD, can be exploited to differentiate the structures of the binary complexes.