Skin Bond Electron Relaxation Dynamics of Germanium Manipulated by Interactions with H2 , O2 , H2 O, H2 O2 , HF, and Au.

Although germanium performs amazingly well at sites surrounding hetero-coordinated impurities and under-coordinated defects or skins with unusual properties, having important impact on electronic and optical devices, understanding the behavior of the local bonds and electrons at such sites remains a great challenge. Here we show that a combination of density functional theory calculations, zone-resolved X-ray photoelectron spectroscopy, and bond order length strength correlation mechanism has enabled us to clarify the physical origin of the Ge 3d core-level shift for the under-coordinated (111) and (100) skin with and without hetero-coordinated H2 , O2 , H2 O, H2 O2 , HF impurities. The Ge 3d level shifts from 27.579 (for an isolated atom) by 1.381 to 28.960 eV upon bulk formation. Atomic under-coordination shifts the binding energy further to 29.823 eV for the (001) and to 29.713 eV for the (111) monolayer skin. Addition of O2 , HF, H2 O, H2 O2 and Au impurities results in quantum entrapment by different amounts, but H adsorption leads to polarization.