AVS 52nd International Symposium
    Surface Science Monday Sessions
       Session SS-MoP

Paper SS-MoP24
LEED and XPS Study of the Oxidation Process on Cu(111)

Monday, October 31, 2005, 5:00 pm, Room Exhibit Hall C&D

Session: Surface Science Poster Session
Presenter: K. Moritani, JAERI, Japan
Authors: K. Moritani, JAERI, Japan
M. Okada, Osaka University, Japan
Y. Teraoka, JAERI, Japan
A. Yoshige, JAERI, Japan
T. Kasai, Osaka University, Japan
Correspondent: Click to Email
The oxidation of Cu has been of great interest because of the important role of Cu oxides in material science. Thus, many experimental and theoretical studies have been performed to understand the oxidation of Cu. However, the oxide-formation processes and the oxygen induced reconstruction on Cu(111) is far less clear. It is advantageous to control oxidation processes and structure in order to understand the chemical reactions and oxide formation processes on the nanoscale. In this work, we studied the oxidation of Cu(111) surface with a hyperthermal O@sub 2@ molecular beam (HOMB) and thermal O@sub 2@ gas using low energy electron diffraction (LEED) and high-resolution X-ray photoemission spectroscopy (XPS) in conjunction with a synchrotron radiation (SR) source. All experiments were performed with the surface reaction analysis apparatus (SUREAC 2000) constructed in BL23SU at SPring-8. The kinetic energy of incident O@sub 2@ can be controlled by changing the O@sub 2@, He and/or Ar gas mixing ratios and the nozzle temperature. After the irradiation of a proper amount of HOMB or thermal O@sub 2@ gas, high-resolution XPS spectra were measured at ~300 K using SR and then LEED pattern was observed. We measured O-uptake curves, determined from the integration of O-1s XPS on the surface, after the HOMB irradiation or the exposure to the oxygen atmosphere. The oxidation with under 0.23 eV HOMB at room temperature saturated at 0.3 ML, when only (1x1) and diffused background LEED pattern was observed. The additional incident energy above 0.5 eV promoted the further oxidation above 0.3 ML and induced the reconstruction to c(8x8) phase where the O-1s peak sifted the low binding energy side. This reconstruction and peak shift were observed after thermal gas exposure at the higher temperature. We discuss possible models of oxidation process on the basis of the incident-energy and temperature dependence of the O-1s XPS spectra and LEED pattern.