Bibliographical noteFunding Information:
This work is supported primarily by the Nanoscale Science and Engineering Initiative of the NSF EEC-0117770 and NYSTAR C020071. The sample preparation facilities and STEM are supported by NSF through the CCMR DMR 9632275. We would also like to acknowledge M. Thomas for technical support.
Copyright 2008 Elsevier B.V., All rights reserved.