Photofragment Spectroscopy and Predissociation Dynamics ofWeakly Bound Molecules

摘要

Photofragment spectroscopy is combined with imaging techniques and timeresolved measurements of photoions and photoelectrons to explore the predissociation dynamics of weakly bound molecules. Recent experimental advances include measurements of pair-correlated distributions, in which energy disposal in one cofragment is correlated with a state-selected level of the other fragment, and femtosecond pump-probe experiments, in some cases with coincidence detection. An application in which coincident measurements are carried out in the molecular frame is also described. To illustrate these state-selective and time-resolved techniques, we review two recent applications: (a) the photoinitiated dissociation of the covalently bound NO dimer on the ground and excited electronic states and the role of state couplings and (b) the state-selected vibrational predissociation of hydrogen-bonded acetylene dimers with HCl (acid) and ammonia (base) and the importance of angular momentum constraints. We highlight the crucial role of theoretical models in interpreting results.