ELECTRIC-FIELD EFFECTS ON RESONANCE STRUCTURES IN NEGATIVE-ION PHOTODETACHMENT

The photodetachment of negative ions in a static electric field exhibits some new characteristic features and has been considered in various theoretical approaches. Most of them, however, neglect the short-range interaction between the escaping electron and the atomic core, and must be modified to describe various resonant effects. Experiments have shown very rich resonant structure in a dc-field, which can be attributed to the mixing of different excited states in the negative ion, to competition between elastic and inelastic decay channels, and to tunneling effects induced by the field. It is known that various resonant structures in photoprocesses can be successfully described within standard multichannel quantum defect theory (MQDT). We present a modified MQDT frame transformation approach to extend the standard method to long-range potentials with nonspherical symmetry. In our treatment both the electron-field and electron-atom interactions are treated nonperturbatively and on an equal footing. The resulting theoretical calculations are compared with experimental data on field-modified H- photodetachment in the vicinity of the n = 2 resonances. © 1991, Taylor & Francis Group, LLC. All rights reserved.