Post-collision interaction in the selenium L/sub 2/M/sub 4,5/M/sub 4,5/ Auger spectrum following photoionization

The L/sub 2,3/M/sub 4,5/M/sub 4,5/ Auger spectrum of selenium in a variety of compounds has been measured following near-threshold photoionization of the 2p/sub 1/2/ level by monochromatic Al K..cap alpha../sub 1,2/ radiation. The energy difference between the L/sub 2/M/sub 4,5/M/sub 4,5/ and the L/sub 3/M/sub 4,5/M/sub 4,5/ Auger peaks was observed to increase by as much as 1.1 +- 0.1 eV as the 2p/sub 1/2/ binding energy approached to within 1.1 eV of the ionization threshold. The energy shifts are compared with the predictions of a semiclassical analysis by Niehaus which takes into consideration the influence of the Coulomb field of the slow photoelectron on the Auger process.