Nanoclustering of vacancies in thin metal films revealed by x-ray diffuse scattering

doi:10.1063/1.2779097 http://scitation.aip.org/getpdf/servlet/GetPDFServlet?filetype=pdf&id=APPLAB000091000009093131000001&idtype=cvips&prog=normal&doi=10.1063/1.2779097The authors report the incorporation of unexpectedly large vacancy clusters into homoepitaxial Ag(001) films. These results, which are for a simple noble metal system, have important implications for understanding the atomic-scale kinetics of surfaces where current models have mostly ignored the role of vacancies. For films grown at 150 K, an average vacancy cluster exhibits a local dilatation volume of 750 Å3, which leads to a 1% compressive strain of the film. Vacancy clusters are observed even for films grown near room temperature. These in situ diffuse x-ray scattering experiments measure the local deformation around the cluster and, therefore, provide conclusive evidence of vacancy clusters.Financial support is gratefully acknowledged from the University of Missouri Research Board, the National Science Foundation under Grant No. DMR0706278, the Petroleum Research Fund under Grant No. 41792-AC10 P.F.M. and C.K. , the Canim Scientific Group E.H.C. and R.F. , and the Seoul Research and Business Development Program under Grant No. 10583 C.K. . The Advanced Photon Source is supported by the DOE Office of Basic Energy Sciences under Contract No. W-31-109-Eng-38. The CAT beam line is supported through Ames Laboratory, operated for the U.S. DOE by Iowa State University under Contract No. W-7405-Eng-82