Hamburg 2001 – wissenschaftliches Programm
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O: Oberflächenphysik
O 38: Adsorption an Oberfl
ächen (IV)
O 38.5: Vortrag
Freitag, 30. März 2001, 12:15–12:30, C
HREELS Study of Benzene on Si(001)-(2×1): Identification of a Step Species — •B. Naydenov, K.L. Kostov, and W. Widdra — Physik-Department E20, Technische Universität München, D-85747 Garching
Using high resolution vibrational spectroscopy (HREELS) and thermal desorption the adsorption of C6H6 and C6D6 on vicinal Si(100)-(2x1) surfaces has been studied. Two different adsorbed benzene species are found: A dominant 1,4-cyclohexadiene like butterfly adsorption complex in agreement with previous ARUPS studies and a similarly bound step species. By annealing and preadsorption of atomic hydrogen a separation of both species is possible. For the terrace species 20 eigenmodes have been identified. All frequencies and isotopic shifts agree well with the results of density functional cluster calculations [1]. For the energetically favored benzene step adsorption the vibrational structure indicates small strain-induced modifications of the butterfly benzene adsorption complex. Additionally, time and temperature dependent conversions between different adsorption sites (except diffusion to step sites) which have been proposed previously can be ruled out.
[1] M. Staufer et al., J. Chem. Phys. 112, 2498 (2000).