Nature of oxygen at rocksalt and spinel oxide surfaces

Authors

Marjorie Langell, University of Nebraska - LincolnFollow
J.G. Kim, University of Nebraska - Lincoln
D. L. Pugmire, University of Nebraska-LincolnFollow
W. McCarroll, Rider University, Lawrenceville, New Jersey

Date of this Version

7-1-2001

Comments

Published by American Vacuum Society. J. Vac. Sci. Technol. A 19„(4), Jul-Aug 2001. ©2001 American Vacuum Society. Permission to use.

Abstract

The chemical environment of oxygen in cobalt-containing metal oxides with compositions M _xM′_{( x – 1)} O and M _xM′_{(3x – 1)} O₄ (M,M′ = Mn,Ni,Co) has been studied by Auger, x-ray and ultraviolet photoelectron, and high resolution electron energy loss spectroscopies. While there is a single type of lattice oxygen in the bulk structure of simple rocksalt and spinel oxides, the nature of oxygen at the surface of the spinel oxides is considerably more complex. Photoemission from core oxygen states in these materials often shows multiple peaks and satellite structure which have been attributed to a range of intrinsic and extrinsic oxygen states. All of these 3d transition metal oxides show a single, intense O 1s core photoemission peak at approximately 529.6 eV. In the spinel materials, a second state at 531.2 eV is also observed and is shown to be intrinsic to the spinel surface and not a result of hydroxylation or other surface contaminant. Similar photoemission features in Fe₃O₄ were previously attributed to final state effects; however, the nature of the multiple final states remains to be elucidated.