Metals

Submonolayer sodium coverages on the surface of the gold film

P. A. Dementev^a, E. V. Dementevа^a, S. V. Masyukevich^a, S. N. Timoshnev<sup>ab

a</sup> Ioffe Institute, St. Petersburg, Russia
^b Alferov Federal State Budgetary Institution of Higher Education and Science Saint Petersburg National Research Academic University of the Russian Academy of Sciences, St. Petersburg, Russia

Abstract: Photoelectron spectroscopy studies of the electronic structure of a 2D-Au film deposited on a W surface with a natural oxide have been carried out in situ in ultrahigh vacuum, before and after adsorption of Na atoms. The photoemession spectra from the valence band and core levels of Au 4f, W $4f$ and Na $2p$ were studied under synchrotron excitation in the photon energy range of 120–300 eV. A 0.83 nm thick 2D gold film formed on the tungsten surface has a valence band close to the valence band of the bulk sample. The diffusion of Na atoms deep into the gold film was not detected, which indicates the layer-by-layer growth of the 2D-Au film. Two states have been found: Na$^{\delta+}$ and Na$^+$, which exist even with a 0.15 monolayer sodium coverage, that indicates the formation of Na islands and single adsorption of Na atoms. The density functional method is used to calculate the electronic structure of a 2D-Au layer without and with adsorbed Na. It is established that the adsorption of Na atoms in the hollow or bridge position is preferable. It is found that the Na adsorption leads to the surface reconstruction.

Keywords: adsorption, sodium, gold, surface reconstruction, photoemission, density functional method.

Received: 16.06.2023
Revised: 16.06.2023
Accepted: 17.06.2023

DOI: 10.21883/FTT.2023.09.56242.115

Bibliographic databases:

•