AVS 51st International Symposium
    Applied Surface Science Monday Sessions
       Session AS-MoP

Paper AS-MoP16
Electronic Structure of Rare-Earth Oxoborates: A Photoemission Investigation

Monday, November 15, 2004, 5:00 pm, Room Exhibit Hall B

Session: Poster Session
Presenter: A.J. Nelson, Lawrence Livermore National Laboratory
Authors: A.J. Nelson, Lawrence Livermore National Laboratory
J.J. Adams, Lawrence Livermore National Laboratory
K.I. Schaffers, Lawrence Livermore National Laboratory
Correspondent: Click to Email
Calcium's rare-earth (R) oxoborates are nonlinear optical materials with general composition Ca@sub 4@RO(BO@sub 3@)@sub 3@ (R@super 3+@ = La, Sm, Gd, Lu) that have potential for high-average power laser frequency conversion and intra-cavity doubling. X-ray photoemission was applied to study the valence band electronic structure and surface chemistry of these novel materials and their rare-earth oxide model compounds. Core-level and valence band results for the rare-earth oxides La@sub 2@O@sub 3@, Sm@sub 2@O@sub 3@, Gd@sub 2@O@sub 3@, and Lu@sub 2@O@sub 3@, were applied to the interpretation of the photoemission spectra of select oxoborate crystals. Specifically, high resolution photoemission measurements on the La and Gd 3d and 4d, Ca 2p, B 1s and O 1s core lines and valence band were used to evaluate the surface and near surface chemistry of lanthanum calcium oxoborate (LaCOB) and gadolinium calcium oxoborate (GdCOB). Results for these oxoborate crystals revealed that the occupied states exhibit a high degree of mixing between the p-f bonding-antibonding states. In addition, general treads in the 3d and 4d core-level line shapes and occupied 4f valence band states of the rare-earth oxide model compounds are best understood in terms of final state effects. This work was performed under the auspices of the U.S. Dept. of Energy by the University of California Lawrence Livermore National Laboratory under Contract No. W-7405-Eng-48.