Analysis of doubly excited state resonances below the Li(5p) threshold in Li^- photodetachment

Authors

Chien-Nan Liu, University of Nebraska - Lincoln
Anthony F. Starace, University of Nebraska-LincolnFollow

Document Type

Article

Date of this Version

December 1998

Comments

Published by American Physical Society. Phys. Rev. A 58, 4997 (1998). http://pra.aps.org. Copyright © 1998 American Physical Society. Permission to use.

Abstract

Larger scale eigenchannel R-matrix calculations than those of Pan et al.  [Phys. Rev. A53, 840 (1996)] confirm the prediction of a 2-meV-wide resonance feature at a photon energy of 5.421 eV in the Li (3s) partial cross section resulting from photodetachment of Li^-. This resonance was neither clearly observed nor identified in measurements of Ljungblad et al. [Phys. Rev. Lett. 77, 3751 (1996)]. We identify this resonance as a _N{υ}_n^A=₅{1}₆^- state [having angular symmetry (K,T)^A=(2,0) ^- or (n _λ,n_μ,m)=(1,7,0)]. This state, which is forbidden by propensity rules in H^- photodetachment, is predicted to be prominent also in the Li(4l) partial cross sections, for l>~1. Besides the ₅{1}_6^- state, the Li(3s) partial cross section in the energy region 20–60 meV below the Li(5p) threshold is dominated by two other doubly excited states, which have been observed in H- photodetachment. Our calculations are in excellent agreement with the measurements of Ljungblad et al. in the energy region from the Li(5p) threshold to 20 meV below.