Evidence for Epitaxial Arrangement and High Conformational Order of an Organic Monolayer on Si(111) by Sum Frequency Generation Spectroscopy

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• 作者：Satoshi Nihonyanagi ; Dai Miyamoto ; Satoru Idojiri ; and Kohei Uosaki
• 刊名：Journal of the American Chemical Society
• 出版年：2004
• 出版时间：June 9, 2004
• 年：2004
• 卷：126
• 期：22
• 页码：7034 - 7040
• 全文大小：179K
• 年卷期：v.126,no.22(June 9, 2004)
• ISSN：1520-5126

文摘

The structure of an octadecyl monolayer formed on a hydrogen-terminated Si(111) surface inneat octadecene was studied by infrared-visible sum frequency generation (SFG) spectroscopy. The SFGspectra in the CH vibration region were dominated by peaks corresponding to those of the methyl group,confirming that the monolayer is essentially in the all-trans conformation. The shapes of the spectra werestrongly dependent on the azimuthal angle, and the strength of the asymmetric vibration mode obtainedfrom the theoretical fitting shows threefold symmetry with respect to the azimuthal angle, suggesting theepitaxial arrangement of the monolayer with the Si(111) substrate. The orientation angle of the methylgroup estimated from SFG anisotropy was in good agreement with the theoretical prediction.