Effects of Autoionization on the Alignment ofCd+(4d95s2D522) in the Range 680-710 Å

The alignment of the $4d^{9}5s^2{}_{}{}^2{}_{}{}^{}D_{\frac{5}{2}}^{}{}_{}{}^{}$ state of ${\mathrm{Cd}}^{+}$ is obtained from fluorescence polarization measurements using dispersed synchrotron radiation in the spectral region 680 to 710 Å. This region is dominated by strong autoionization features associated with the $nf\left({}_{}{}^1{}_{}{}^{}P_1^{}{}_{}{}^{}\right)$ and $np({}_{}{}^3{}_{}{}^{}P_1^{}{}_{}{}^{}, {}_{}{}^3{}_{}{}^{}D_1^{}{}_{}{}^{})$ Rydberg states converging to the $4d^{9}5s^2{}_{}{}^2{}_{}{}^{}D_{\frac{3}{2}}^{}{}_{}{}^{}$ fine-structure threshold. The polarization and alignment data show marked variations across the resonance profiles and are compared with recent calculations in the relativistic random-phase approximation in conjunction with multichannel quantum-defect theory.