Chain-length-dependent change in the structure of self-assembled monolayers ofn-alkanethiols on Au(111) probed by broad-bandwidth sum frequency generation spectroscopy
| Autor: | Masahiro Yamamoto, Takashi Kakiuchi, Daisuke Hobara, Naoya Nishi |
|---|---|
| Rok vydání: | 2003 |
| Předmět: |
chemistry.chemical_classification
Analytical chemistry General Physics and Astronomy Infrared spectroscopy Self-assembled monolayer chemistry.chemical_compound Crystallography chemistry Molecular vibration Monolayer Self-assembly Physical and Theoretical Chemistry Alkyl Methyl group Sum frequency generation spectroscopy |
| Zdroj: | The Journal of Chemical Physics. 118:1904-1911 |
| ISSN: | 1089-7690 0021-9606 |
| Popis: | The structure of the self-assembled monolayers (SAMs) of n-alkanethiols [CH3(CH2)nSH, n=3–11, 13–15, 17] on Au(111) has been studied using broad-bandwidth sum frequency generation spectroscopy. Sum-frequency vibrational spectra show three pronounced CH3 vibrational modes for all alkanethiol investigated, indicating that the commonly accepted picture that the alkyl chain for the long-chain alkanethiol SAMs has the all-trans conformation applies even to the short chain SAMs. The chain-length dependence of the ratio of the intensity for the CH3 symmetric vibrational mode to that for the CH3 asymmetric mode clearly shows the odd–even effect due to the difference in the direction of methyl group for SAMs with odd and even n, also supporting that the alkyl chain of SAMs has the all-trans conformation. An analysis of the vibrational intensities with respect to the angle between the main axis of the methyl group and the surface normal reveals that the structure of the alkanethiol SAMs gradually changes with n. |
| Databáze: | OpenAIRE |
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