2p Photoabsorption in amorphous,trigonal and monoclinic selenium

The 2p photoabsorption spectra of amorphous and polycrystalline trigonal and α-monoclinic selenium have been studied. Our experimental results, accounting for the transition probabilities and inner level broadening, are in qualitative agreement with Kramer's pseudo-potential formalism calculations of the density of unoccupied states. The amorphous selenium spectrum seems intermediate between the two crystalline form spectra and we deduce that both trigonal chains and monoclinic rings are randomly distributed in the amorphous phase.