Measurements and calculations of high-angular-momentum satellite transitions in Li 1s photoionization - art. no. 062509

Lithium is photoelectron spectra are reported in high electron and photon e nergy resolution, with resolved LS term structure of the Li+ 1 nl satellite transitions up to n = 6. Branching ratios and anisotropy parameters of ind ividual lints, determined over the 85-130 eV photon energy range, are compa red with R-matrix calculations and with previous works. The high-angular-mo mentum satellite lines (L greater than or equal to2) are found to contribut e significantly to the 1 snl satellite; cross sections for n=3 and 4, and t o become the dominant terms for n greater than or equal to5. The high-angul ar-momentum lines exhibit the same photon-energy-dependence as the P-lines, providing experimental evidence that the continuum-continuum state couplin g (equivalent to virtual electron collision processes) is responsible for t he L greater than or equal to1 terms in the satellite spectrum, in contrast to the electron relaxation (shake-up) mechanism responsible for the 5-term s. The angular distribution of the lines in the Li+ 1 snl, rt = 2-6 groups, determined at 110 eV photon energy, is in good agreement with calculations , showing more isotropic distributions for high-angular-momentum lines.