CHANNEL MIXING IN 4FNG AUTOIONIZING SERIES OF BARIUM

Autoionizing 4fng J = 0-3 levels of barium in the energy range 88240-9 0460 cm(-1) have been studied, both experimentally and theoretically. Excitation spectra, recorded in a three-step pulsed laser experiment b ased on an isolated-core excitation scheme, are confronted with eigenc hannel R-matrix calculations. Series converging to the upper 4f(7/2) a nd lower 4f(5/2) thresholds are found to interact strongly, in particu lar for J = 1. As a result the observed 4fng resonances vary widely in width, shape and intensity. Although the complete R-matrix calculatio ns involve many interacting channels for each J (up to 49 for J = 3), good agreement is found between experiment and theory and all observed resonances can be unambiguously assigned.