Double ionisation of Ba from 550 to 670 nm

Abstract

The authors have observed the spectra for the production of Ba⁺ and Ba²⁺ between 550 and 670 nm. They observe sharp resonances for the production of Ba²⁺ which generally do not coincide with peaks in the Ba⁺ production. While they can easily assign most of the resonances in the Ba⁺ spectra to two-photon resonances with bound states it is not possible to assign most of the Ba²⁺ peaks to two- or three-photon Ba⁺ transitions. This suggests that the production of Ba²⁺ proceeds both via Ba autoionising states and low-lying Ba⁺ states.