First Angle-Resolved Photoelectron Measurements following Inner-Shell Resonant Excitation in a Singly Charged Ion

Abstract

We have measured the angular distribution of electrons emitted in the autoionization of the giant resonance ${3p}^{6}4s^{2}S\ensuremath{\rightarrow}[({3p}^{5}3d^{1}P)4s{]}^{2}P$ in ${\mathrm{Ca}}^{+}$ ions over the profile of the resonance. The absolute value of the asymmetry parameter we have determined at the top of the resonance is $\ensuremath{\beta}\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}1.89\ifmmode\pm\else\textpm\fi{}0.13$, suggesting that $\mathrm{LS}$ coupling remains a good approximation for the description of this ionic resonance.