EVOLUTION OF BARIUM AUTOIONIZING STARK SPECTRA WITH ENERGY AND FIELD

Extensive calculations and measurements of barium autoionizing Stark spectra below the 5d ionization thresholds are presented. The theoretical description is based on a combination of R-matrix calculations in zero external field and a Harmin-Fano-type field-dependent frame transformation. In addition to verifying the basic validity of this approximation scheme, we examine the scaling of calculated resonance linewidths with energy. Under certain circumstances, the average linewidths are found to scale approximately as -4, with the relevant effective quantum number. Extreme departures from this scaling are observed for individual resonances, however, which could be important for the theoretical description of other processes in an electric field, such as dielectronic recombination. © 1994 The American Physical Society.