Quantum well states of and dxz,yz orbital character in Pd nanofilms

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 d3z2–r2 and dxz,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.