We study numerically the ability of time-resolved photoelectron angular distributions to provide useful information regarding the alignment of wave packets and hence a new view on excited state dynamics. The calculations employ a recently developed theory of pump-probe photoelectron spectroscopy [J. Chem. Phys. 107, 7859 (1997)] which treats both laser pulses nonperturbatively. Taking the NO system as a prototypical example, we first describe the alignment dynamics in the course of the perpendicular Π→Σ transition. The observation of alignment perpendicular to the field polarization which converts upon turn-off of the pulse to alignment parallel to the field is explained in terms of the phase relation between the wave packet components. Considering next the ionization stage, we find only weak dependence of the photoelectron angular distribution on the field intensity in the range typically employed in gas-phase femtosecond experiments. Our results illustrate the utility of time-resolved photoelectron angular distributions as a probe in pump-probe studies.
ASJC Scopus subject areas
- Physics and Astronomy(all)
- Physical and Theoretical Chemistry