Spin polarized photoelectron studies of magnetism in solids: Progress report for period June 1, 1986-May 31, 1987

The photoemission EXAFS (PEXAFS) technique has been applied to the early stages of the oxidation of aluminium. This work demonstrates the unique chemical sensitivity of PEXAFS. The near neighbor Al-O and Al-Al interatomic distances have been determined for the environments giving rise to unshifted and chemically shifted Al 2p photopeaks. Appreciable amounts of oxygen may be near an Al atom without shifting the electron binding energies and so previous measurements of others making use of the O ls extended fine structure have been misinterpreted. The first use of surface and bulk plasmon-loss electrons for EXAFS has been made. These losses are predominately by extrinsic plasmon production. An attempt was made to carry out the first PEXAFS experiment at the Berlin synchrotron radiation laboratory BESSY and this work will probably be continued. A procedure was developed for preparing thin, conducting films of MnO and spin polarized EXAFS (SPEXAFS) measurements were carried out at NSLS on MnO using the exchange split Mn 3s photopeaks and the 3p peaks. These data are being analyzed. We plan to soon put into operation facilities for MBE and for studying surface structure by means of electron energy loss extended fine structure