KAbsorption Edge of Selenium

Use of thin unsupported selenium absorbers has permitted observation of significant structure in the $K$ absorption spectrum. Observations of the $K{\beta }_2$ emission and the fundamental optical absorption of similar samples have been made and used to assist in the interpretation of the $K$ edge structure. It is suggested that the prominent absorption maximum at the experimentally determined "edge" arises from transitions to an x-ray excitation state or states in the region of the forbidden energy gap. The following general absorption is attributed to transitions to the conduction band. The gap energy required in this interpretation is approximately 4 electron volts, indicating that the lower part of the conduction band contains little $p$-type symmetry.