The core excitation of Li2 by low energy electron impact

Abstract

The electron impact excitation of the Li2 molecule was studied for the first time by measuring the autoionizing spectra of lithium vapour near the 1s-core excitation threshold. The broad line at 51.4 eV ejected-electron energy was observed in spectra at impact energies below 60 eV. It was tentatively assigned to the decay of the lowest triplet autoionizing state of Li2 with the excitation threshold of 56.5 ± 0.1 eV. The and singlet autoionizing states were also observed in spectra at impact energies above 70 eV. The excitation cross-sections for the observed molecular states were estimated to be of the order of magnitude of 10−17–10−16 cm2 at impact energies ⩽80 eV. These values are on average two orders of magnitude larger than the cross-sections for the 1s2snl lowest atomic autoionizing states.