Photoelectron angular distributions from resonantly enhanced multiphoton ionization of xenon via the 6s[3/2]1∘ and 6s^′[1/2]1∘ states: experiment and theory

Photoelectron energy and angular distributions are reported for resonantly enhanced multiphoton ionization (REMPI) through the three-photon-allowed $6s{[3/2]}_1^{\circ }$ and $6s^{\prime }{[1/2]}_1^{\circ }$ states of xenon at laser-power densities of ~10⁹–10¹¹ W/cm². Ionization from three-photon resonance with the $6s{[3/2]}_1^{\circ }$ state gives two photoelectron peaks corresponding to leaving the ion in either the ²P_3/2 or the ²P_1/2 state. It is found that the two groups of photoelectrons have distinctly different angular distributions. Calculations indicate that configuration mixing in the 6s manifold is important in describing the observed angular distributions. REMPI via the $6s^{\prime }{[1/2]}_1^{\circ }$ state gives one main photoelectron peak resulting from autoionization to the ²P_3/2 state of the ion. Two additional peaks of higher-energy photoelectrons are seen, which are due to the absorption of an additional photon before ionization. Strong core-changing processes are evident in the spectra.