Time-resolved photoelectron spectroscopy of molecular dissociation:: Classical trajectory versus quantum wave-packet calculations

We present a simulation of ultrafast pump probe photoelectron spectroscopy based on a classical treatment of the nuclear motion. A comparison with quantum mechanical wave-packet results shows that in the case of the direct dissociation of H2O in its (A) over tilde B-1(1) electronic state this method produces extremely accurate results. The energy distribution of the photoelectrons recorded as a function of the pump probe delay reflects the dissociation process, which takes place within only a few femtoseconds.