Multiple photoionisation of the rare gases in the XUV region

Abstract

The photoionisation cross sections for multiple ionisation produced by 2p-shell excitation of Ar, 3d-shell excitation of Kr, 4d-shell excitation of Xe and the two-electron excitation, 4d-15p-1nln'l', of Xe have been obtained by means of a time-of-flight mass spectrometer and synchrotron radiation. The formation of Ar+ is prominent in the 2p-1ns and 2p-1nd states of the Rydberg series and Ar2+ is dominant above the L-shell ionisation threshold. The post-collision interaction effect is discussed for photoionisation of Ar in connection with the structure above the L-shell ionisation threshold. Doubly charged ions of Kr and Xe are produced dominantly not only above the 3d- and 4d-shell ionisation thresholds but also through the 3d-1np and 4d-1np states of the Rydberg series, respectively. The formation of these doubly charged ions for Kr and Xe is considered to be due to the Auger process.