H2O-derived contamination of cleaved Si(111)-2×1 surfaces

A 100-meV electron-energy-loss feature found frequently on cleaved Si(111)-2×1 surfaces has been studied with high-resolution electron-energy-loss spectroscopy. Scattering conditions are chosen to enhance our sensitivity to detect OH stretching vibrations. A direct correlation between the strong 100-meV loss feature and the very weak OH stretching vibration is observed for coverages estimated to be above 0.03% of a monolayer. These results cast doubt but do not exclude a recent assignment of this 100-meV loss feature to a new H-derived state. © 1985 The American Physical Society.