AVS 47th International Symposium
    Surface Science Wednesday Sessions
       Session SS-WeP

Paper SS-WeP32
Coadsorption of CO and O@sub 2@ on W(110) Surface

Wednesday, October 4, 2000, 11:00 am, Room Exhibit Hall C & D

Session: Poster Session
Presenter: T.S. Yang, Sungkyunkwan University, Korea
Authors: K.-H. Lee, Sungkyunkwan University, Korea
H.-S. Han, Sungkyunkwan University, Korea
H.-G. Yun, Sungkyunkwan University, Korea
T.S. Yang, Sungkyunkwan University, Korea
J.-H. Boo, Sungkyunkwan University, Korea
S.-B. Lee, Sungkyunkwan University, Korea
H.T. Kwak, Kookmin University, Korea
Correspondent: Click to Email
The coadsorption of CO and O@sub 2@ on W(110) surface was studied by LEED, TDS, and photoelectron spectroscopy. In the TDS for the coadsorption of CO at RT on O@sub 2@ precovered W(110) surface, two CO desorption states were observed at about 400 and 1150 K, called @alpha@ and @beta@, respectively. The @beta@-CO spectra with second order desorption kinetics were shifted to lower desorption temperature as increasing the amount of preadsorbed atomic oxygen on the W(110). Moreover, the @beta@-CO spectra were gradually increased with increasing the amount of preadsorbed oxygen to 0.5 ML. Even though a (2x1) LEED pattern appeared during oxygen adsorption at RT and 1-3 L oxygen exposures, we didn't observe any new pattern induced by CO in this study. Only the structure of c(11x5) was obtained at temperature in their range of 800-1100 K. These results indicated that there were interaction between CO and O and thereby the @beta@-CO might not be dissociated even at the higher temperature than 800 K. By using the XPS and UPS, it was also confirmed that the coadsorbed @beta@-CO at 950 K doesn't dissociate as the experimental results of the adsorption of pure CO on W(110) surface at the same temperature. According to the valence band spectra, two CO peaks at near 10.7 eV(4@sigma@) and 7.0 eV(5@sigma@+1@pi@) were observed, indicating molecular CO adsorption on the oxygen preadsorbed surface at RT. Even heating the coadsorbed surface to 950 K, we could also detect the CO 4@sigma@ peak that can be an important factor for identifying a contribution of the CO 4@sigma@ molecular orbital to the CO-metal bond. To our best knowledge, this is the first report and quite contradictory result to that reported previously.