Photoionisation of atomic selenium

The photoionisation spectrum of atomic selenium, prepared by the reaction of H atoms with H 2 Se, is presented from its ionisation threshold to 600 AA. Autoionisation peaks assigned to quasidiscrete levels . . .( 2 D degrees )nd 3 p degrees are sharp, those assigned to . . .( 2 D degrees )ns 3 D degrees and . . .( 2 D degrees )nd 3 S degrees are somewhat broader, and others assigned to . . .( 3 D degrees )nd 3 D degrees are very broad. A few members of the series converging to Se + ( 2 P degrees ) are also observed. Two prominent peaks are tentatively assigned to 4s4p 5 3 P degrees 2,1 , and taken to be the first members of the series . . . 4s4p 4 np, the latter appearing as window resonances in this spectrum. The photoionisation spectrum of H 2 Se is also presented.