Photoion-yield spectra of Xe2+ in the 4d-threshold energy region

Photoion yields from doubly charged Xe ions were measured in the 4d-threshold energy region. The experiment was performed by a photon-ion merged-beam technique with synchrotron radiation as a light source. The measured spectrum mainly consists of strong 4d --> 5p transition lines at around 57 eV, a very broad peak at around 100 eV, and the preceding strong discrete peaks lying between 79 and 90 eV. The peak position of the broad peak changes very little from that in Xe+ photoion-yield spectra of Sane et al. The enhancement of discrete peaks in the Xe2+ spectrum implies a further collapse of nf-wavefunctions than that of Xe+.