Deposition of iron on MgO(100): Reaction of CO and H 2

Abstract

Ultraviolet photoelectron spectroscopy (UPS), electron energy loss spectroscopy (EELS) and surface extended energy loss fine structure (SEELFS) were used to study the deposition of Fe on MgO(100) and to identify the surface compounds formed after reaction of CO/H 2 (1:1). The clean MgO(100) surface was characterized using the above techniques and the effect of argon ion bombardment damage to the surface was investigated. With the deposition of iron, metallic characteristics appear in the photoemission spectrum; the electron energy loss peaks of the MgO(100) substrate diminish in intensity with no significant shifts in loss energies. Fine structure analysis of the oxygen K-edge of the MgO(100) surface with less than 2 monolayers (ML) of iron suggests that the iron atoms bond with the oxygen at the surface of the MgO(100) lattice. For less than 4 ML of iron, the EEL spectra show that the deposited iron is oxidized after reaction of CO/H 2. Higher iron coverages result in carburization of the surface. Carbon deposition was observed with CO for all Fe coverages. Measurement of the fine structure above the carbon K-edge suggests that the types of carbide formed depend on the iron coverage; one carbide has a short CFe distance of 1.78 Å and the other a distance of 2.06 Å (high metal coverage).