MULTIPLE BONDING GEOMETRIES AND BINDING STATE CONVERSION OF BENZENE SI(100)/

Scanning tunneling microscopy (STM), Fourier-transform infrared spectr oscopy and semiempirical quantum cluster calculations have been used t o investigate the chemisorption of benzene on the Si(100)(2X1) surface . Room temperature adsorption results in the occupation of multiple bo nding configurations including on-top of a single Si dimer and two dif ferent bridging geometries involving interaction with two Si dimers. W hile the single dimer state is populated preferentially upon adsorptio n, it is observed to be metastable with respect to the bridging config uration. The single dimer to bridge conversion is activated, with a ba rrier of 0.94 eV. The single dimer geometry can be repopulated via a p rocess assisted by the STM tip. (C) 1998 American Vacuum Society.