COLL 160 |
| We report on first principles density functional theory calculations of the electronic structure and tunneling properties of alkane molecules with different anchoring (NH2, COOH) and terminal groups (COOH, NH2, OH, SH, and CH3) on Au(111). The molecules are adsorbed on the surface through a gold adatom, as it is likely the case in a mechanical break junction; for the NH2-anchored molecules, however, adsorption on the flat surface is also considered for comparison. For molecules with the same terminal group, the computed tunneling currents through NH2-anchored molecules are orders of magnitude larger than the currents for molecules with COOH headgroups. The influence of the terminal group on the tunneling current is found to depend on the anchoring group. For NH2-anchored molecules, the tunneling current for the different terminals decreases according to OH > NH2 > SH > CH3 > COOH, whereas for the molecules with COOH-anchoring groups the order become SH >CH3 >OH >NH2 > COOH. Analysis of the molecular and interface electronic structure (level alignments) is performed to rationalize these results. |
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Fundamental Research in Colloid and Surface Chemistry
6:00 PM-8:00 PM, Monday, August 20, 2007 BCEC -- East Registration, Poster
Division of Colloid & Surface Chemistry |