Abstract
The effects of high pressure up to 10 GPa on organic molecules in the form of a solid or a self-assembled monolayer (SAM) on a metal surface are investigated by Raman spectroscopy. The SAMs studied are benzenethiol (BT) and benzenemethylthiol (BMT) on polycrystalline Ag(111). Raman spectra of the SAMs are obtained using a periodically nanostructured Ag surface that provides surface-enhanced Raman scattering (SERS), All the vibrational modes studied show a pressure-dependent blue-shift. These blue-shifts are remarkably similar for the SAMs and solids. There are some minor differences between the SAM and solid-state spectra in the v 18asymmetric in-plane CH-bend and in the v Cs CS-stretch. The v 18 mode in BT blue-shifts more in the SAM than in the solid, but in BMT it blue-shifts less in the SAM than in the solid. The greater blue-shift for the BT SAM is attributed to the much lower surface coverage of BT, causing greater compressibility. In the SAM, v CS blue-shifts slower in BT than in the solid, but in BMT the blue-shifts are the same in the SAM and in the solid. It is noted that strain is more easily transmitted from phenyl to the C-S linkage in BT than in BMT.
Original language | English (US) |
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Pages (from-to) | 5751-5757 |
Number of pages | 7 |
Journal | Journal of Physical Chemistry C |
Volume | 113 |
Issue number | 14 |
DOIs | |
State | Published - Apr 9 2009 |
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Energy(all)
- Physical and Theoretical Chemistry
- Surfaces, Coatings and Films