Acta Phys. -Chim. Sin. ›› 1992, Vol. 8 ›› Issue (03): 376-382.doi: 10.3866/PKU.WHXB19920317

• ARTICLE • Previous Articles     Next Articles

Size-Dependence of Chemisorption on Aluminum Clusters and its Theoretical Model

Li Lin-Feng; Gu Xian-Zhang; Cao Xuan; Liao Mu-Zhen; Wu Guo-Shi   

  1. Department of Chemistry, Tsinghua University, Beijing 100084
  • Received:1991-03-20 Revised:1991-09-09 Published:1992-06-15
  • Contact: Wu Guo-Shi

Abstract: Theoretical investigations have been made on the monomolecular adsorption of carbon monoxide on aluminum clusters Al_n(n=1-10, 12, 13). The equilibrium adsorption positions and the binding energies of various CO sites have been evaluated by using the quantum chemical method of CNDO/2 with properly choosing the optimal geometries of aluminum clusters from the reported data. The results reveal that the adsorption of CO on Al_n remarkably depends upon the number of metal atoms in the cluster and exhibits a notable "magic number" behavior, viz. the adsorption energies on Al_2, Al_6 and Al_(12) appear in particularly large values, which are in encouraging agreement with the experimental observations and that predicted by our Extended Electron-Shell Model proposed previously. The analysis of the electronic structure of Al_(12) and Al_(13) puts the model on a still solid basis. It can also be seen that such a size-dependence goes down with the increasing cluster size and the behavior of cluster gradually approaches to that of bulk aluminum.

Key words: Microcluster, Aluminum cluster, Adsorption, Electron-Shell Model, Carbon monoxide