Structure of Thioaromatic Self-Assembled Monolayers on Gold and Silver

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• 作者：S. Frey ; V. Stadler ; K. Heister ; W. Eck ; M. Zharnikov ; M. Grunze ; B. Zeysing ; and A. Terfort
• 刊名：Langmuir
• 出版年：2001
• 出版时间：April 17, 2001
• 年：2001
• 卷：17
• 期：8
• 页码：2408 - 2415
• 全文大小：117K
• 年卷期：v.17,no.8(April 17, 2001)
• ISSN：1520-5827

文摘

Self-assembled monolayers (SAMs) formed from thiophenol, 1,1'-biphenyl-4-thiol, 1,1';4',1' '-terphenyl-4-thiol, and anthracene-2-thiol on polycrystalline Au and Ag were characterized by X-ray photoelectronspectroscopy and angle-resolved near-edge X-ray absorption fine structure spectroscopy. With the exceptionof the poorly defined thiophenol film on Au, all thioaromatic molecules were found to form highly orientedand densely packed SAMs on both substrates. The molecular orientation and orientational order of theadsorbed thioaromatic molecules depends on the number of aromatic rings, the substrate, and the rigidityof the aromatic system. The molecules, which on average are slightly inclined with respect to the surfacenormal, show a less tilted orientation with increasing length of the aromatic chain, and as observed foraliphatic SAMs, they exhibit smaller tilt angles on Ag than on Au. However, the difference in the tilt anglesfor aromatic SAMs on Au and Ag is smaller than that observed in the aliphatic films. A comparison of themonolayers formed from p-terphenylthiol and anthracenethiol films suggests that a higher molecularrigidity has only a slight effect on the final molecular orientation within the respective SAMs.