Photoelectron imaging spectroscopy and photodynamics of m-xylene cations

Abstract

The delayed photofragmentation and photoelectron spectroscopy coupled with DFT calculations were employed for the investigation of the relaxation dynamics of m-xylene cations. The multiphoton ionization induced by the pump pulse was used for the preparation of the m-xylene cations, and the population was characterized by the technique of photoelectron imaging. A time-delayed probe pulse was used to excite the prepared m-xylene cations to energetically higher electronic states, which undergo fragmentation. The relaxation dynamics of the m-xylene cations was tracked by monitoring the depletion of excited parent-ion and the formation of the fragment-ion. Two relaxation time constants are determined by monitoring the depletion of the excited parent-ion and the formation of the fragment-ion with the delay time. The first component of τ1 = 764 (±25) fs is attributed to an intramolecular vibrational redistribution process within the D0 state and the slow one of τ2 > 440 ns is ascribed to the long lifetime of the cations.