Mg 3pnd(J=3) autoionization spectra using isolated-core excitation

The Mg 3pnd J=3 autoionizing spectra have been studied for n values ranging from 9 to 40, using an isolated-core excitation technique with ion detection. The measured spectra are found to be in generally excellent agreement with results from a calculated reaction matrix. The observed spectra exhibit strong interseries interactions between the 3p1/2{nd}5/2$ and 3${p}3/2ndⱼ series, and, for n{≤}15, interferences between the amplitudes for excitation of the core electron to the 3P1/2 and 3P3/2 ion states. Classifications of states for n{≤}29 are tabulated. We discuss the difficulties in deducing autoionization rates for Mg from the experimental and theoretical data, the implications of which could have relevance to dielectronic recombination rate calculations.