Potential barrier effects beyond the 4f photoionization thresholds in Pb I

Abstract

New Pb I absorption spectra show discrete structure due to excitation of the 4f subshell and continuous absorption beyond the 4f thresholds. The results are compared with those previously obtained in Tl I and Hg I, and the presence of additional maxima in the Pb I spectrum is accounted for by comparison with recent independent-particle non-relativistic central field calculations.