Regensburg 2002 – wissenschaftliches Programm

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O: Oberflächenphysik

O 34: Organische Dünnschichten

O 34.6: Vortrag

Donnerstag, 14. März 2002, 16:45–17:00, H45

The effect of the substrate on response of thiol-derived self-assembled monolayers to free radical-dominant plasma — •Michael Zharnikov¹, Stefan Frey¹, Michael Grunze¹, M.-C. Wang², J.-D. Liao², C.-C. Weng², and Ruth Klauser³ — ¹Angewandte Physikalische Chemie, Universität Heidelberg, 69120 Heidelberg — ²Department of Biomedical Engineering, Chung Yuan Christian University, Chung-Li, Taoyuan 32023, Taiwan (ROC) — ³Synchrotron Radiation Research Center, Hsinchu 300, Taiwan (ROC)

Synchrotron-based high-resolution photoelectron spectroscopy was applied to study the modification of aliphatic and aromatic thiol-derived self-assembled monolayers (SAMs) on (111) gold and silver substrates by a nitrogen-oxygen downstream microwave plasma and the attachment of acrylic acid to the plasma-modified SAMs. The plasma treatment resulted in massive damage and disordering of the SAMs, with the extent and character being similar for the aliphatic and aromatic films, but being noticeably different for the SAMs on Au and Ag. These findings imply that in the case of the plasma treatment (and, presumably, in the case of UV photooxidation), not the character of the long chain spacer, but the defect density and the strength of the headgroup-substrate bond are of significance. The differences in the response of the SAMs on Au and Ag toward the plasma treatment are assumed to be predominantly related to the different strengths of the thiolate-substrate bond for these substrates. The extent of acrylic acid attachment to the plasma-treated SAMs on Ag was essentially larger than that to the plasma-treated SAMs on Au.