LEED Observations of Oxygen Ordering on Copper(110)

• Published in: Surface science Vol. 151; no. 2-3; pp. 430 - 446
• Main Authors: Gruzalski, G R, Zehner, D M, Wendelken, J F, Hathcock, R S
• Format: Journal Article
• Language: English
• Published: 01.03.1985
• ISSN: 0039-6028

LEED observations were used to study oxygen adsorbed on Cu(110) and to follow changes in surface structure produced by 5 min anneals at up to 880K. Factors determining the surface structure include the surface temperature T sub s at exposure, the amount of exposure, and the maximum T sub s after exposure. For surfaces exposed at T sub s = 83 plus/minus 1K to between 0.3 and 100 langmuir (L) of room-temperature molecular oxygen, the LEED patterns upon exposure and after anneals are described for the first time in a detailed and systematic way. Upon exposure the surface exhibits a (1 x 1) pattern, although diffuse third-order reflections corresponding to an increase in the (110) dimension of the unit mesh are visible for coverages theta = > 0.50. A (3 x 1)pattern, which may be due to a molecular configuration, is seen after annealing at 180K. After annealing at 330K or higher, a simple relationship exists between oxygen coverage and surface structure, as inferred from LEED patterns; if theta < = 0.50, a (2 x 1) pattern is seen; if 0.50 < = theta < = 0.67, a superposition of a (2 x 1) and c(6 x 2) pattern is seen; if theta approx = 0.67, a c(6 x 2) pattern is seen; and if theta = > 0.67, a c(6 x 2) pattern with additional reflections is seen. For surfaces exposed at 300 < = T sub s < = 320K up to 10 exp 5 L oxygen, the LEED patterns are similar to those reported by others; here too, however, previously unreported behavior is presented. The observations are interpreted in the light of UPS and recent XPS data, which give information regarding the chemical state (atomic or molecular) and amount of the adsorbate. 14 ref.--AA