Probing the size-dependent properties of small Au clusters and CO chemisorbed Au clusters using photoelectron spectroscopy


Xi Li1, Jun Li,, Satya Bulusu3, Min Ji4, Xiao Gu4, Hua-Jin Zhai, hua-jin.zhai@pnl.gov1, Boggavarapu Kiran, krian@pnl.gov1, Bing Dai1, Xiao Cheng Zeng, xzeng1@unl.edu3, Xingao Gong,, and Lai-Sheng Wang, lsw@pnl.gov1. (1) Department of Physics, Washington State University, 2710 University Drive, Richland, WA 99354, (2) W. R. Wiley Environmental Molecular Sciences Laboratory, Pacific Northwest National Laboratory, P.O. Box 999, richland, WA 99352, (3) Department of Chemistry, University of Nebraska-Lincoln, Lincoln, NE 68588, (4) Surface Physics Laboratory and Department of Physics, Fudan University, Shanghai 200433, China
We report joint photoelectron spectroscopic and computational studies of the unique electronic and structural properties of small Au clusters and CO chemisorbed Au clusters. Specific topics to be covered are as follow: (1) The observation of the tetrahedral Au20 cluster; (2) Experimental and theoretical evidence for hollow gold cage clusters in Au16- through Au18-; (3) Combined experimental and theoretical characterization of the Au32- anion, which is shown to likely possesses a low symmetry structure controlled by vibrational entropy, in contrast to the Au32 neutral species predicted computationally to be a highly symmetric icosahedral cage; (4) Photoelectron spectroscopy of gold carbonyl complexes Aum(CO)n- (m = 2-5; n = 0-7), which reveals spectroscopic evidence for CO chemisorption sites on Au clusters, transitions from chemisorption to physisorption, and important activation mechanisms of Au clusters by CO chemisorption; (5) Unique CO chemisorption properties of the Au hexamer in Au6(CO)n- (n = 1-3).