  We investigate the crystallization of amorphous arsenic-selenium alloys with
0%, 0.5%, 2%, 6%, 10%, and 19% arsenic by atomic concentration using
synchrotron X-ray absorption spectroscopy. We identify crystalline order using
the extended X-ray absorption fine structure (EXAFS) spectra and correlate this
order to changes in features of the X-ray absorption near edge structure
(XANES) spectra. We find supporting evidence that the structure of amorphous
selenium is composed of disordered helical chains, and is therefore closer to
the trigonal crystalline phase than the monoclinic crystalline phase.
