Autoionizing resonance profiles in the photoelectron spectra of atomic cadmium

Photoelectron spectra have been taken of atomic Cd with synchrotron radiation between 19 and 27 eV using the double-angle time-of-flight method. Dramatically different energy dependences of the partial cross sections for producing the lowest ${}_{}{}^2{}_{}{}^{}D_{\frac{5}{2}}^{}{}_{}{}^{}$, ${}_{}{}^2{}_{}{}^{}D_{\frac{3}{2}}^{}{}_{}{}^{}$, ${}_{}{}^2{}_{}{}^{}S_{\frac{1}{2}}^{}{}_{}{}^{}$, and ${}_{}{}^2{}_{}{}^{}P_{\frac{3}{2},\frac{1}{2}}^{}{}_{}{}^{}$ ionic states of ${\mathrm{Cd}}^{+}$ were observed for photon energies in the neighborhood of the $\left[4d^9\right(5s5p{}_{}{}^3{}_{}{}^{}P\left)\right]{}_{}{}^2{}_{}{}^{}P_{\frac{3}{2}}^{}{}_{}{}^{}6s{}_{}{}^1{}_{}{}^{}P_1^{}{}_{}{}^{}$ autoionizing resonance at 588 Å. Partial decay widths from the excited resonance state have been determined by fitting the resonance line shapes to theoretical expressions for the partial cross sections. Resonance profiles in the photoelectron angular-distribution asymmetry parameter for the ${}_{}{}^2{}_{}{}^{}D_{\frac{5}{2}}^{}{}_{}{}^{}$ and ${}_{}{}^2{}_{}{}^{}D_{\frac{3}{2}}^{}{}_{}{}^{}$ channels are also reported. The ${}_{}{}^2{}_{}{}^{}P_{\frac{3}{2},\frac{1}{2}}^{}{}_{}{}^{}$ satellite is found to decrease slightly relative to the ${}_{}{}^2{}_{}{}^{}S_{\frac{1}{2}}^{}{}_{}{}^{}$ main line in the 19-25-eV range. Three new satellite peaks have been detected with intensities enhanced by autoionization.