ASYMMETRY PARAMETERS FOR DOUBLE PHOTOIONIZATION OF NEON TO THE 2P(-2) (1)S STATE IN THE THRESHOLD REGION

A coincidence photoelectron spectrometer has been used to measure the asymmetry parameters for double photoionization of neon to the 2p-2 1S State up to 2 eV above threshold. The observations were made for the extreme situation of unequal energy partitioning between the two photoelectrons wherein one electron has near-zero energy and the other carries off all the excess energy. These measurements are in qualitative agreement with the findings of recent ab initio calculations and show that in this case of extreme unequal energy sharing, electron correlation still plays a dominant role.