X-ray photoelectron spectra of oxygen molecules adsorbed on ytterbium nanofilms

Abstract

The adsorption of oxygen molecules on ytterbium nanofilms of various thicknesses has been studied by X-ray photoelectron spectroscopy and contact potential difference measurements. It has been established that the maximum number of O2 molecules that can be adsorbed on the films increases with the film thickness. Such behavior is observed at thicknesses less than 10 monolayers. This size effect is ultimately due to the fact that an indispensable condition for the adsorption process at high doses of oxygen is the electron transfer from the film to molecules, and that the maximum number of electrons that can participate in this process depends on the nanolayer thickness. Localization of a negative charge on O2 molecules occurring in at high doses of adsorbate, causes a weakening of the bonding of 1s-electrons in these molecules. In addition, it should lead to a weakening of the bond between oxygen atoms in O2 molecules. Keywords: oxygen, ytterbium, adsorbed molecules, nanofilms, X-ray photoelectron spectroscopy, work function.