Photoelectron emission spectroscopy analyses of the arsenic bonding in the near-surface region of an initially arsenic-capped MnAs (1 (1) over bar 00) film grown on GaAs(001) have been carried out for progressive thermal decapping stages. Electronically distinct As-bonding states are identified and assigned to bulk MnAs phases, bulk arsenic, and interfacial environments. The arsenic coating imposes mechanical constraints to the MnAs film, in addition to those imposed by the GaAs substrate, which appear to alter the relative stability of the alpha and beta MnAs phases around room temperature. (C) 2008 American Vacuum Society.