XPS characterisation of in situ treated lanthanum oxide and hydroxide using tailored charge referencing and peak fitting procedures

A technique is described for deposition of gold nanoparticles under vacuum, enabling consistent energy referencing of X-ray photoelectron spectra obtained from lanthanum hydroxide La(OH)(3) and in situ treated lanthanum oxide La2O3 powders. A method is also presented for the separation of the overlapping lanthanum 3d and MNN peaks in X-ray photoelectron spectra acquired with Al K alpha radiation. The lower satellite intensity in La(OH)(3) compared to La2O3 is related to the higher ionicity of the La-O bond in the former compared to the latter compound. The presence of an additional peak in the valence band spectrum of the hydroxide compared to the oxide is attributed to the O-H bond as indicated by density functional theory based calculations. A doublet in the O Is peak of lanthanum oxide is associated to the presence of two distinct oxygen sites in the crystal structure of this compound. (C) 2011 Elsevier B.V. All rights reserved.