PHOTO-IONIZATION OF THE (NP)41S0 LEVEL OF THE GROUP-VI ATOMS VIA AUTO-IONIZING LEVELS

Calculations are presented for the effective photoionization cross section of the (ns)2 (np)4 S01 level in O, S, Se, and Te, via excitation to autoionizing levels. The eigenvalues and eigenfunctions of 67 odd-parity levels with J=1, both bound and autoionizing, are obtained via the diagonalization of a matrix including both configuration and spin-orbit interaction. The diagonal entries in the matrix are experimental values, where possible, as a constraint on the calculations was agreement between calculated and experimental energy levels to better than 200 cm-1. The (ns)1 (np)5 P13 and P11 levels are included, but do not satisfy the constraint for S, Se, and Te. The calculations on Te support the tentative level identifications of Bartelt, and suggest that the Te ionization potential in Moore's Tables in 800 cm-1 too low. The calculations indicate that while the effective photoionization cross section for (np)4 S1 is surprisingly large and broad for S, Se, and Te, there are windows in the spectrum for S and Se. These windows would permit efficient production of large S1 population densities via photodissociation of OCS or OCSe without substantial quenching of the S1 population via photoionization and secondary-electron superelastic scattering, e.g., Se at 1720. © 1979 The American Physical Society.