Paper SS1-ThA11
Substrate Effect on the Morphological Transition of Planar Magic Ag Nanoclusters

Thursday, November 12, 2009, 5:20 pm, Room M

Two-dimensional (2D) magic Ag nanoclusters have been demonstrated experimentally[1]. Experimental observations show that a template that originates from the electronic effect of quantum Pb islands grown on an Si(111) substrate can be used to develop Ag nanoclusters in planar feature with unusual size distributions, called a two-dimensional magic Ag nanocluster. Theoretically, the transition of Ag clusters from planar to 3D structures begins with Ag clusters of seven atoms without consideration of the substrate support [2]. However, utilizing the symmetry and size of the periodic pattern on the Pb islands, distinguishable planar hexagonal Ag clusters can be grown even for Ag clusters of 127 atoms [3]. How the substrate has influence on the morphological transition of Ag clusters from planar to 3D is of our interest and motivates the present work. To elucidate the effect of the substrate on the growth behavior of Ag clusters, highly oriented pyrolytic graphite (HOPG) is adopted as a template in the work. STM is used to characterize and analyze the growth behavior of Ag nanoclusters on HOPG. The process of the transition of Ag nanoclusters from planar to 3D and the onset of the formation of three-dimensional Ag clusters are also elucidated. A thorough analysis of the energetic optimization of Ag clusters not only yields information on the growth of Ag clusters on HOPG, but also elucidates how the substrate influences the formation of magic Ag clusters.

References

[1] Y.P. Chiu, L.W. Huang, C.M. Wei, C.S. Chang, and T.T. Tsong, Phys. Rev. Lett. 97, 165504 (2006).

[2] Eva M. Fernández, José M. Soler, Ignacio L. Garzón, and Luis C. Balbás, Phys. Rev. B 70, 165403 (2004).

[3] Y.P. Chiu, C.M. Wei, and C.S. Chang, Phys. Rev. B Vol. 78, 115402 (2008).