Scanning tunneling microscopy study of the adsorption of toluene on Si(001)

Scanning tunneling microscopy is used to investigate the adsorption of tolu ene on the Si(001)-2X1 surface. At room temperature, adsorption occurs excl usively on top of dimer rows and results in several binding geometries. A m etastable and weakly bound state is observed initially upon adsorption. Thi s state converts to a more stable geometry. Conversions between the dominan t adsorbed states are observed and can be induced by the scanning tunneling microscopy (STM) tip. These states closely resemble those of benzene on Si (001). Evidence that toluene interacts with more surface dimers than benzen e is found in the bias dependence of the adsorbed states in STM images. Tol uene decomposes upon annealing, leaving carbon on the surface. (C) 1999 Ame rican Vacuum Society. [S0734-211X(99)03001-2].