Generality and Systematics of Multiple Minima in Photoionization Cross Sections of Excited Atoms

Multiple zeros in the dipole matrix elements for photoionizing transitions in excited atomic d states are predicted over a broad range of Z for both l→l+1 and l→l-1 channels. The $3d$ (which is nodeless), $4d$, and $5d$ excited states show d→p zeros while the $5d$ also shows the two zeros in the d→f channel. The variation of the location of these minima with Z is discussed and analyzed in terms of quantum defect theory and some implications are pointed out.