Femtosecond time-resolved photoelectron spectroscopy with high frequency probe pulses

The interaction of an intense 2 eV femtosecond pulse with the Na2 molecule prepares vibrational wavepackets in several electronic states. Subsequent ionization with a time-delayed probe pulse produces photoelectron kinetic energy distributions which depend on the pump–probe delay and reflect the vibrational dynamics in the various electronic states. We compare the resulting spectra with others obtained by direct one-photon ionization and show that in the latter case the contributions from different electronic states can be separated.