Sandhyarani N, Skanth G, Berchmans S, Yegnaraman V, Pradeep T
Regional Sophisticated Instrumentation Centre, Indian Institute of Technology, Madras, 600 036, India
J Colloid Interface Sci. 1999 Jan 1;209(1):154-161. doi: 10.1006/jcis.1998.5882.
The monolayers of 2-mercaptobenzothiazole (MBT) on polycrystalline Au and Ag films have been studied by surface-enhanced Raman (SERS) and X-ray photoelectron (XPS) spectroscopies. Whereas MBT adsorbs with its molecular plane flat on Ag, its plane is perpendicular on Au. This difference in adsorbate geometry is manifested as differences in the intensities of certain vibrational peaks in the Raman spectra. Ab initio molecular orbital (MO) calculations suggest that MBT adsorbs on Au in the thione form and on Ag in the thiol form. The monolayers are stable up to a temperature of 473 K, much higher than most of the self-assembled monolayers (SAMs) studied so far. The adsorption geometry does not undergo any significant change when the monolayers are heated, although minor changes are observed in the SER spectra of the Ag monolayer. Raman intensities of all the bands increase with heating, and the enhanced intensity is preserved even after cooling. This is attributed to monolayer-induced coalescence of gold islands leading to the formation of an extended self-assembly. XPS studies confirm chemisorption, although structural details are not manifested. Copyright 1999 Academic Press.
通过表面增强拉曼光谱（SERS）和X射线光电子能谱（XPS）对多晶金膜和银膜上的2-巯基苯并噻唑（MBT）单分子层进行了研究。MBT以其分子平面平躺的方式吸附在银上，而在金上其平面是垂直的。吸附质几何结构的这种差异表现为拉曼光谱中某些振动峰强度的差异。从头算分子轨道（MO）计算表明，MBT以硫酮形式吸附在金上，以硫醇形式吸附在银上。这些单分子层在高达473 K的温度下都是稳定的，这比迄今为止研究的大多数自组装单分子层（SAMs）要高得多。当单分子层受热时，吸附几何结构没有发生任何显著变化，尽管在银单分子层的SERS光谱中观察到了微小变化。所有谱带的拉曼强度都随加热而增加，即使冷却后增强强度仍得以保留。这归因于单分子层诱导的金岛聚结，导致形成扩展的自组装结构。XPS研究证实了化学吸附，尽管没有体现出结构细节。版权所有1999年学术出版社。
