He(II) photoelectron spectra of esters

Intensities of X-ray photoelectron transitions from the As 3d level are theoretically analysed taking into account many-electron interactions. The latter interactions profoundly affect the relative intensities of the transitions as well as binding energies. Implications for the surface structure of GaAs are then discussed and in particular we show that As atoms having the same chemical environment are spread over distances into the surface comparable to the interatomic spacing. This supports a recently proposed layer model for the untreated surface of GaAs.