Probing vibrational wave packets in molecular excited states

A time-dependent theoretical method is used to describe a UV pump?CUV probe strategy to trace, at a femtosecond time scale, the motion of vibrational wave packets created in excited states of the hydrogen molecule by measuring single ionization probabilities. We use a spectral method to solve the time-dependent Schr?dinger equation in full dimensionality, including correlation and all electronic and vibrational degrees of freedom. A pump pulse initially creates a vibrational wave packet in the intermediate electronic excited states of $\hbox{H}_2$ . The frequency of the probe is chosen to ionize the target leaving the ion in a bound vibrational state. By varying the time delay between pulses, non-dissociative single ionization is enhanced or suppressed. Energy differential ionization probabilities are reported and compared with a model based on the Franck?CCondon approximation.