CORRELATION-EFFECTS IN THE PHOTOIONIZATION OF BA(6S6P P-1(1)) - DETERMINATION OF CROSS-SECTIONS FOR PRODUCTION OF SPECIFIC FINAL J STATES

Absolute cross sections for photoionization of isotropically populated Ba(6s6p 1P1) to each accessible final J state (0, 1, and 2) have been determined from threshold to 370 nm using spectra obtained with four different combinations of linear and circular polarizations of the exciting and ionizing radiation. The effects of dealignment due to hyperfine interaction of the nuclear spin I=3/2 isotopes of barium have been taken into account. The results are generally in good agreement with R-matrix predictions of shapes and positions of autoionizing resonances as well as the magnitudes of the background (nonresonance) cross sections, but there are some discrepancies with oscillator strengths of the autoionizing states. It is shown that, to obtain the correct magnitude of the background cross section theoretically, the inclusion of electron correlation effects in the wave functions of both initial and final states is required. Data are also presented that verify the equivalence of obtaining the total photoionization cross section by properly combining two sets of data, each acquired with a different angle between linear polarization vectors, e.g., parallel and perpendicular, or by making a single measurement with the angle set at the ''magic'' angle, 54.7°. © 1995 The American Physical Society.