Regensburg 2002 – wissenschaftliches Programm
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O: Oberflächenphysik
O 34: Organische Dünnschichten
O 34.9: Vortrag
Donnerstag, 14. März 2002, 17:30–17:45, H45
Self-assembled monolayers of nitrile-functionalized alkanethiols on gold and silver substrates — •Michael Zharnikov1, Stefan Frey1, David Allara2, Karin Heister1, and Michael Grunze1 — 1Angewandte Physikalische Chemie, Universität Heidelberg, 69120 Heidelberg — 2Departments of Chemistry and Materials Science, Pennsylvania State University, University Park, PA 16802, USA
Self-assembled monolayers (SAMs) formed on (111) gold and silver substrates from nitrile-functionalized alkanethiols (AT) CN(CH2)16SH (CN-C16) were characterized by X-ray photoelectron spectroscopy and near-edge X-ray absorption fine structure spectroscopy at the C1s and N1s absorption edges. The results imply that the substitution of the weakly interacting methyl groups by the nitrile entities has a strong influence on the molecular orientation, packing, and the structure of AT SAMs on both Au and Ag substrates. A strong dipole-dipole interaction between the polar nitrile groups is assumed to disturb a balance between the headgroup-substrate and interchain interactions, which is responsible for the SAM structure and packing density. In contrast to the methyl-functionalized AT SAMs, only a slight difference in the orientation of the alkyl chains in CN-C16/Au and CN-C16/Ag is observed. The nitrile groups in both CN-C16/Au and CN-C16/Ag are oriented almost parallel to the film surface, which is beneficial to minimize the dipole-dipole interaction between these moieties, but different from the standard orientation of the functional groups in AT SAMs of the same chain length.