Transformation of the Electronic Characteristics of Ytterbium Nanofilms, Induced by Carbon-Monoxide Molecules Adsorbed on Their Surface

Abstract

The adsorption of carbon monoxide (CO) molecules on ytterbium nanofilms composed of 16–200 single layers (6.1–76 nm-thick) is studied. The films are grown on grain-oriented tungsten ribbons with the preferential surface orientation (100). It is shown that, prior to the adsorption of CO molecules, ytterbium is divalent, possessing the [Xe]4f¹⁴6s² electron configuration. The adsorption of gas molecules in the surface region of the film led to the formation of a layer with trivalent ytterbium (with the [Xe]4f¹³5d¹⁶s² electron configuration). The minimum thickness of the ytterbium layer modified by adsorbed CO molecules is found to be composed of 16 single layers, corresponding to a thickness of 6.1 nm, which is anomalously higher than the values reported in publications.