Strong nondipole effects in low-energy photoionization of the 5s and 5p subshells of xenon - art. no. 022504

Large nondipole effects are predicted in the angular distribution of photoe lectrons from the 5s and 5p subshells of xenon for photon energies below 20 0 eV. The nondipore parameter gamma (5s) exhibits a dispersion-curve variat ion near the first minimum of the 5s cross section at 35 eV, reaching a min imum value of -0.8 near 40 eV. Rapid Variation of gamma (5s) is also found near the second minimum of the 5s cross section at 150 eV, where gamma (5s) reaches a maximum value of 1.2. Smaller, but significant, nondipole effect s are also found in the parameter zeta (5p) = gamma (5p) + 3 delta (5p), wh ich has a maximum value of 0.15 near 50 eV, and a second maximum value of 0 .18 near 160 eV. The higher energy maxima in gamma (5s) and zeta (5p) arise from correlation enhanced by shape resonances in the 4p --> f quadrupole p hotoionization channels. These predictions are based on relativistic random -phase approximation calculations in which excitations from 5p, 5s, 4d, 4p, and 4s subshells are coupled.