Mg 3pnsand 3pnd(J=1) autoionizing series

The Mg 3pns (n=10–18) and 3pnd (n=9–40) doubly excited J=1 autoionizing states have been observed experimentally using an isolated-core excitation method with stepwise laser excitation. Linearly polarized laser light excites the 3pnd J=1 and J=3 states, as well as the 3pns J=1 states. Our previous study of the J=3 states enables the J=1 states in the 3pnd spectra to be identified. We have also calculated the spectra from a reaction matrix, and the agreement between theory and experiment is generally excellent. Differences between the J=1 and J=3 features are discussed and qualitatively explained in terms of semiclassical arguments. Additionally, energies of the 3sns ${}_{}{}^1{}_{}{}^{}$ ${\mathit{S}}_0$ (n=11–22) Rydberg levels are reported.