Ultrafast Imaging of Electronic Relaxation in Ortho-xylene: New Features from Fragmentation-Ion Spectroscopy

As a continuous work of tracking electronic relaxation of the S₂ state in o-xylene by photoelectron imaging Y. Liu et al., Phys. Chem. Chem. Phys. 15 (2013) 18101, we report another contribution from the view of fragment-ion spectroscopy. Three components with time constants of τ₁?60 fs, τ₂=55(±20) fs and τ₃=6.99(±0.25) ps are observed for the only fragment-ion C₆H₄CH₃⁺. The velocity map image of the fragment-ion against the delay time are also measured. Transient information about the kinetic energy of the fragment-ion and angular distribution are analyzed and discussed. New features for competing ultrafast internal conversion and intersystem crossing are obtained.