Valence transition investigation in the О$_{2}$–Yb–Si(111) system by means of the angle-resolved photoelectron spectroscopy method

Investigations of the Yb–Si(111) and О$_{2}$–Yb–Si(111) structures are carried out by means of the angle-resolved photoelectron spectroscopy method, and data about distribution of two- and three-valence ions in ytterbium nanofilms are obtained in the case when an adsorbed molecules layer on their surface is not fully formed yet, and Yb$^{2+}$ $\to$ Yb$^{3+}$ valence transition is not completed. It is shown that distribution of Yb$^{2+}$ and Yb$^{3+}$ ions deep into the nanofilms is close to isotropic, and that its spread is 9 or more monolayers. The obtained results indicate that all atoms of the nanofilm participate in formation of the ytterbium 5$d$ band, stimulated by adsorbed molecules, confirming assumptions made in earlier publications.