New Photon-Induced Triply Excited Hollow Atom States of Lithium

Numerous new resonances of triply photoexcited hollow Li atoms have been found above the ${2s}^{2}2p{}^{2}{P}^{o}$ resonance at 142.3 eV. The main features are reproduced by multiconfiguration Dirac-Fock calculations. The spectrum lacks regular series structure and the pattern is found to manifest the effect of the hollow atomic nature of triply excited states. Fano parameters for the ${2s}^{2}2p{}^{2}{P}^{o}$ resonance were obtained. One-step double autoionization was observed for the first time in the decay from this resonance.