Regensburg 2004 – scientific programme

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CPP: Chemische Physik und Polymerphysik

CPP 16: POSTER: Computational Physics, Complex Systems

CPP 16.18: Poster

Tuesday, March 9, 2004, 17:00–19:00, B

The Interaction of Water with Oligo(Ethylene Glycol)-Terminated Self-Assembled Monolayers on Gold and Silver Investigated by IR and Vibrational Sum-Frequency Spectroscopy — •Rong-Yao Wang, Jörg Fick, Sascha Herrwerth, Wolfgang Eck, Michael Himmelhaus, and Michael Grunze — Lehrstuhl für Angewandte Physikalische Chemie, Universität Heidelberg, Im Neuenheimer Feld 253, 69120 Heidelberg

Due their unique protein repulsion properties, self-assembled monolayers of oligo(ethylene glycol)-terminated alkanethiols have been intensively studied throughout the last decade. Particularly the structure of the films in contact to aqueous solutions has been at the focus of interest, recently.[1]

In the study presented here, we applied infrared reflection absorption spectroscopy (IRRAS) and vibrational sum frequency generation spectroscopy (VSFS) to investigate water-induced structural changes in methyl (1-mercaptoundec-11-yl) hexa (ethylene glycol)-terminated alkanethiols (EG6) formed on thin Au and Ag films. Spectra were recorded right after preparation of the monolayers as well as after their exposure to water. In the case of gold as a substrate, the films were also investigated during water contact. The spectra indicate that water causes pronounced disorder effects in the EG6 layers, which are only partially reversible after drying of the films. Further, VSFS turns out to be more sensitive than IRRAS in particular to subtle changes induced by bound water molecules.

[1] Langmuir, 16, 5849, 2000; Langmuir 19, 2284, 2003