Polarization and angle-resolved NEXAFS of benzene adsorbed on oriented single-domain Si(100)-2x1 sur face, N. Witkowski(France), F. Hennies, A. Pietzsch, S. Mattsson, A. Fohlisch, and W. Wurth (Germany) M. Nagasono(Kyoto U., Japan), M. N. Piancastelli(Italy), Phys. Rev. B 68, 115408 (2003).
Polarization and angle-resolved NEXAFS of benzene adsorbed on oriented single-domain Si(100)-2x1 surface, N. Witkowski(France), F. Hennies, A. Pietzsch, S. Mattsson, A. Fohlisch, and W. Wurth (Germany) M. Nagasono(Kyoto U., Japan), M. N. Piancastelli(Italy), - PowerPoint PPT Presentation
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Polarization and angle-resolved NEXAFS of benzene adsorbed on oriented single-domain Si(100)-2x1 surface,
N. Witkowski(France), F. Hennies, A. Pietzsch, S. Mattsson, A. Fohlisch, and W. Wurth (Germany)
M. Nagasono(Kyoto U., Japan), M. N. Piancastelli(Italy),
• Overall decrease of the peak at 248.8 eV compared with Fig. 2 -> molecule is close to in-plane (but, not parallel to the surface)
• Apparent difference between Fig. 3 and Fig. 4 -> π* resonance has an in-plane component normal to the dimers
• No asymmetric shape (contrary to the previous NEXAFS results (Tong, SS 1998)) -> Not a metastable species ! (Also, no change after further annealing)
• σC-H* resonance appears all in Fig. 2-4. -> C-H is tilted away from in-plane or out-of plane
• No 289 eV peak (due to conjugated benzene ring) -> aromatic ring is broken.
• ---- > Butterfly rather than tilted geometry !!!!
• From Fig. 5, adsorbed benzene has a mirror plane perpendicular to the dimer.
• From Fig. 6, adsorbed benzene has a mirror plane parallel to the dimer.
• Small difference in the CH* resonance -> a slight distortion on each side -> step edge effect(?)
• Major conclusions that can be drawn from the above results are,
Summary
• Still, π-bond is preserved. (OK) • No other bonding structure other than “butterfly” is observe (?) - in conflict with previous STM, NEXAFS results
• From Fig. 3-4, butterfly rather than tilted ----- ?
• butterfly still comply with the results of Fig. 5-6.