Quantum well states of [formula omitted] and d xz, yz orbital character in Pd nanofilms

Abstract

Quantum well states of quantised d-bands have been measured in the binding energy range from −4.8 to 0 eV with polarised and non-polarised ultraviolet photoelectron spectroscopy in 1–10 monolayer thick Pd films deposited on Nb(100) and on W(100). Using polarised ultraviolet photoelectron spectroscopy we could distinguish between quantum well states with d 3 z 2– r 2 and d xz, yz orbital character. Pd nanofilms grown on the two substrates have the (100)-oriented body centred tetragonal (i.e. pseudomorphic) structure up to the thickness of 2.5 monolayers. For larger thicknesses they have the ( 11 2 ¯ 0 ) -oriented hexagonal close packed structure, which is unusual for Pd. A partial coupling of Pd states to substrate ones and/or ferromagnetic order in the hexagonal-close packed Pd films can be responsible for the broad spectral shapes.