Dissociative Adsorption of Diethyl Ether on Si(001) Studied by Means of Scanning Tunneling Microscopy and Photoelectron Spectroscopy

The adsorption of diethyl ether (Et2O) on Si(001) was studied by means of scanning tunneling microscopy (STM) and photoelectron spectroscopy. Et2O reacts on Si(001) via a datively bonded intermediate, which was isolated at surface temperatures below 100 K. At higher surface temperature, Et2O converts dissociatively into the final state by cleaving one O–C bond; the resulting −O–C2H5 and −C2H5 fragments are found to attach on two Si dimers of neighboring dimer rows. Tip-induced hopping of the −C2H5 fragment on one dimer was observed at positive sample bias. The results are discussed in the context of recent experiments on the reaction of tetrahydrofuran (THF) on Si(001) (Mette et al. ChemPhysChem 2014, 15, 3725) and allow a more general description of the reaction of ethers on Si(001).