Experimental and theoretical Auger and autoionization spectra for electronimpact on laser-excited Ba atoms

We present high-resolution experimental Auger and autoionization spectra in the energy range 5.6 to 17 eV for 5p ionization/excitation of Ba(6s(2)) an d of laser-excited Ba*(5d6s (SD2)-S-1,3) and Ba *(6s6p P-1(1)) by 1.5 keV e lectron impact. The wave-functions and energies of Auger states for 5p ioni zation of ground-state and laser-excited Ba are calculated by the many-conf iguration Hartree-Pock method with relaxed nonorthogonal radial orbitals fo r different configurations and including relativistic effects through the B reit-Pauli Hamiltonian. We have also evaluated the 5p ionization cross sect ions in sudden approximation and the decay rates of the Auger states. The e xperimental spectra in the energy range 5.6 to 11 eV are due to the Auger d ecay following 5p ionization and are well predicted by the present theory. The spectra in the energy range 11 to 17 eV, however, are mainly due to the autoionization decay following a 5p excitation. These spectra cannot be un derstood by the present calculation, which considers only 5p ionization.