A study of transferability of atomic background on EXAFS spectra of simple gaseous compounds of As

From EXAFS spectra of As and As2O3 vapors and arsine gas AsH3 the ab initio calculated structural signal is removed. The remainders comprise small absorption edges due to shake-up channels involving electrons from 3d or 3p subshell. With enhanced resolution, the edges reveal a fine splitting and a varying contribution of resonance channels, due to individual molecular energy-level structure of the samples. On the resolution level appropriate for routine EXAFS analysis the remainders coincide, representing a unique and transferable atomic absorption background for the range of As valence states spanned by the samples.