Abstract
Three-photon resonance enhanced four-photon ionization of xenon shows preferential formation of ) when intermediate ns[3/2 Rydberg states are excited in the three-photon step. Here, the nl[K notation refers to l coupling, in which the angular momentum of the ion core, , is coupled to the orbital angular momentum of the Rydberg electron l to give K, which is then coupled to the Rydberg electron’s spin to give J. The primes following l denote states belonging to the core. Multichannel-quantum-defect theory identifies these intermediates as nearly pure Rydberg states belonging to the ) core. An equivalent behavior is found for the 7s’[1/2 intermediate state which preferentially produces ). On the other hand, for nd and nd’ resonances we observe final-state distributions which closely mirror the core character of the intermediate state. The suppression of the parent core channel for s-type Rydberg states is shown to be due to a Cooper minimum in the ns→ɛp transitio n amplitudes. As a consequence, minor components of the resonance state wave functions play a major role in the selection of the final ionization channel, in particular via the much larger amplitudes of nd’→ɛf’ transitions.
- Received 25 April 1994
DOI:https://doi.org/10.1103/PhysRevA.51.3726
©1995 American Physical Society