Photoelectron spectrometry of mercury in the17–40-eV photon-energy range

Photoionization in the 5d and 6s subshells of atomic mercury has been studied in the 17–40-eV photon-energy range using the 1-m aluminum Seya monochromator on the Tantalus storage ring. The angular distribution parameter β has been obtained for the 5$d_{3/2}$, 5$d_{5/2}$, and 6s photolines (up to ∼32 eV in the latter case). The 6s β’s have been observed to decrease by ∼0.4 units between the 5$d_{3/2}$ threshold (16.71 eV) and 17 eV (to a value less than 1), then increase to near 2 by hν=35 eV. Somewhat better agreement has been found with 5d Dirac-Fock calculations than with relativistic random-phase approximation (RRPA) results, while the 6s β’s are predicted very well by RRPA except for the position of the Cooper minimum at ∼17 eV.