1 F.X. Campos, G.C. Weaver, C.J. Waltman, and S.R. Leone, Journal of Vacuum Science \& Technology B: Microelectronics and Nanometer Structures 10, (1992).
1 C.P. Lauenstein, M.J. Bastian, V.M. Bierbaum, S.D. Penn, and S.R. Leone, The Journal of Chemical Physics 94, (1991).