Exploring wavepacket dynamics behind strong-field momentum-dependent photodissociation in CH2BrI+

Abstract

The ultrafast photodissociation dynamics of CH₂BrI⁺ into CH₂Br⁺ + I is studied using high level ab initio electronic structure calculations in conjunction with integration of the time-dependent Schrödinger equation and compared with measured pump–probe signals. These pump–probe measurements provide evidence for momentum-dependent dissociation, which is interpreted using two theoretical models. The first is based on DFT and TD-DFT calculations neglecting spin–orbit coupling, while the other, more rigorous model employs a larger number of coupled multi-configurational potentials obtained by means of CASSCF calculations. The latter model highlights the role of spin–orbit coupling between ionic electronic states as well as the effect of strong fields in the quantum dynamics including Stark-shifts and multi-photon excitation.