Angular Distributions of Photoelectrons and Partial Photoionization Cross-Sections

An experimental arrangement is given for measuring the angular distribution of photoelectrons. The asymmetry coefficient $\beta $ is found to be 0.3 for Ar, and 0.3 and 0.12 for N$_{2}$ at 584 angstrom when the residual ion core is left in its X$^{2}\Sigma $ and A$^{2}\Pi $ states, respectively. The partial photoionization cross-sections are given for O$_{2}$ at 186, 209, 247, 330, and 460 angstrom. New ionization potentials for O$_{2}$ are found at 23.5, 24.6 and 27.3 eV $\pm $ 0.3 eV. The effects of autoionizing transitions on the population of vibrational states of N$_{2}^{+}$ are illustrated.