Determination of the characteristic interfacial electronic states of {111} Cu-MgO interfaces by ELNES

Issue		Eur. Phys. J. Appl. Phys. Volume 5, Number 1, January 1999


Page(s)		9 - 18
DOI		10.1051/epjap:1999107

DOI: 10.1051/epjap:1999107

Eur. Phys. J. AP 5, 9-18

Determination of the characteristic interfacial electronic states of {111} Cu-MgO interfaces by ELNES

D. Imhoff¹ - S. Laurent² - C. Colliex¹ - M. Backhaus-Ricoult²

¹ Laboratoire de Physique des Solides, CNRS, bâtiment 510, Université Paris-Sud, 91405 Orsay, France
² Centre d'Études de Chimie Métallurgique, CNRS, 15 rue G. Urbain, 94407 Vitry sur Seine, France
imhoff@lps.u-psud.fr

Received: 5 March 1998 / Revised: 4 May 1998 / Accepted: 1st December 1998

Abstract
The chemical bonding of different $\{111\}$ Cu-MgO interfaces obtained by internal oxidation of (Cu, Mg) alloys at $T = 900~^\circ{\rm C}$ and for an high oxygen activity of $a_{\rm o_2}=10^{-8}$ , is studied by transmission electron energy loss spectroscopy (EELS) at high spatial resolution. For polar $\{111\}$ interfaces (Cu and MgO in topotactical or pseudotwin orientation), it is shown that the terminating lattice plane in magnesia is occupied by oxygen atoms. An important charge transfer is identified at the interface, yielding Cu-L ELNES features corresponding to those of Cu¹⁺ (Cu(I)) in its oxide. O-K edge fine structures at the interface are also modified: an edge enlargement and the presence of a low energy shoulder confirm the bonding of oxygen to Cu¹⁺. Consistent with these results, the Mg-L edge is never modified compared to the MgO bulk phase. Specifically adapted to the heterophase interfaces, a spatial difference method, based on normalised spectra (NSD), is applied to estimate the relative contribution of the ELNES signal in the interface area. In the present case of high oxygen activity, the number of copper atoms in the Cu(I) oxidized state corresponds to a total occupancy of the outermost metal plane at the interface.

PACS
82.65.i Surface and interface chemistry - 82.80.Pv Electron spectroscopy - 73. Electronic structure and electrical properties of surfaces, interfaces

What is OpenURL?

The OpenURL standard is a protocol for transmission of metadata describing the resource that you wish to access. An OpenURL link contains article metadata and directs it to the OpenURL server of your choice. The OpenURL server can provide access to the resource and also offer complementary services (specific search engine, export of references...). The OpenURL link can be generated by different means.

If your librarian has set up your subscription with an OpenURL resolver, OpenURL links appear automatically on the abstract pages.
You can define your own OpenURL resolver with your EDPS Account. In this case your choice will be given priority over that of your library.
You can use an add-on for your browser (Firefox or I.E.) to display OpenURL links on a page (see http://www.openly.com/openurlref/). You should disable this module if you wish to use the OpenURL server that you or your library have defined.