The Electronic and Adsorption Structures of 2-Mercaptoethanol and Thioglycolic Acid on the Ge(100) Surface

Abstract

The adsorption selectivity of 2-mercaptoethanol (2-ME) and thioglycolic acid (TGA) was studied on the Ge(100)-2x1 surface using high-resolution photoemission spectroscopy (HRPES) and the corresponding density functional theory (DFT) calculations. HRPES analysis results indicated that an OH dissociated SH dissociation bonded structure at low coverage and an O-dative bonded structure at high coverage are the stable adsorption structures of 2-ME on the Ge(100) surface. In addition, a SH dissociated O-B -dative bonded structure at low coverage and a S-dative bonded structure at high coverage are reasonable adsorption structures of TGA on the Ge(100) surface. Through work function measurements, we also confirmed that the forms of the adsorption structures of 2-ME and TGA can be determined by n-type (dissociation-bonded structure) and p-type (dative-bonded structure) properties. Moreover, the adsorption structures of 2-ME and TGA on the Ge(100)-2x1 surface were determined through DFT calculations, and the respective stable adsorption structures, transition-state energy, and reaction pathways were obtained.