Dissociative chemisorption of methanol on Ge(100)

The adsorption of methanol (CH3OH) on Ge(100) surface has been studied using ultrahigh vacuum scanning tunneling microscopy (UHV-STM) and density functional theory (DFT) calculations. At low coverages, high-resolution experimental STM shows that methanol undergoes O-H bond dissociative adsorption on a single Ge-Ge dimer. As the methanol coverage increases to saturation, a series of dissociative adsorptions of methanol results in the formation of dimer row-based chainlike arrays. The DFT calculations show that, at room temperature, O-H bond dissociative adsorption is kinetically more favorable than C-O bond dissociative adsorption, although the final product of C-O bond dissociative adsorption is more stable geometry thermodynamically. From the results of our STM experiments and DFT calculations, we conclude that the adsorption structure of methanol on Ge(100) at room temperature has a H-Ge-Ge-OCH3 geometry as a result of O-H bond dissociative adsorption on a single dimer.