Electron-Energy-Loss Spectroscopy of Semiconducting SmS(100): Evidence for a Surface Phase Transition

Abstract
The presence of trivalent Sm has been observed near the (100) surface of pure semiconducting SmS using electron-energy-loss spectroscopy with 100-eV electrons. This surface phase transition is interpreted as due to differential contraction of the surface cation lattice constant for NaCl-type (100) surfaces and helps to resolve reported differences in ultraviolet and x-ray photoemission experiments on SmS.