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Polarized near-edge x-ray-absorption fine structure spectroscopy of C-60-functionalized 11-amino-1-undecane thiol self-assembled monolayer: Molecular orientation and evidence for C-60 aggregation

Patnaik, A. and Okudaira , K. K. and Kera, S. and Setoyama , H. and Mase , K. and Ueno , N. (2005) Polarized near-edge x-ray-absorption fine structure spectroscopy of C-60-functionalized 11-amino-1-undecane thiol self-assembled monolayer: Molecular orientation and evidence for C-60 aggregation. JOURNAL OF CHEMICAL PHYSICS , 122 (15). p. 154703. ISSN 0021-9606

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Abstract

Near-edge x-ray-absorption fine structure (NEXAFS) spectroscopy was adopted to probe the unoccupied electronic states of C-60 anchored onto an organized assembly of 11-amino-1-undecane thiol on Au(111). The polarization dependence of the intensity of p* resonance associated with C-60 p network revealed the self-assembled monolayer (SAM) system to be oriented with an average molecular tilt angle of 57 with respect to the surface normal. Invoking the absence of solid-state band dispersion effects and in comparison to solid C-60 and/or 1-ML C-60/Au(111), the electronic structure of the resulting assembly was found dominated by spectral position shift and linewidth and intensity changes of the lowest unoccupied molecular orbital (LUMO), LUMO+1, and LUMO +2 orbitals. The latter implied hybridization between N P-z of -NH2 group of thiolate SAM and p levels of C60, resulting in a nucleophilic addition with a change in the symmetry of C-60 from I-h to C1 in the SAM. Occurrence of a new feature at 285.3 eV in the NEXAFS spectrum, assigned previously to p* graphitic LUMO, signified the formation of aggregated clusters, (C-60)(n) of C-60 monomer. Low tunneling current scanning tunneling microscopy confirmed them to be spherical and stable aggregates with n similar to 5. 2005 American Institute of Physics.

Item Type:Article
Subjects:Physical Science > Nanophysics
Physical Science > Nano objects
Material Science > Nanochemistry
Material Science > Nanostructured materials
Divisions:Faculty of Engineering, Science and Mathematics > School of Physics
Faculty of Engineering, Science and Mathematics > School of Chemistry
ID Code:7117
Deposited By:JNCASR
Deposited On:09 Sep 2009 06:16
Last Modified:09 Sep 2009 06:16

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