SURFACE PLASMON POLARITON-AIDED RAMAN SPECTROSCOPIC STUDY ON FILM GROWTH MECHANISMS

1)为了研究对氨基苯硫酚（PATP）在银表面的吸附行为，利用表面等离子体激元激发银岛膜，进行了拉曼散射实验。用真空蒸发法在BaF_2基片上制备了质量厚度为5 nm的银薄膜。将板浸入含有1 mM PATP的乙醇溶液中，测量拉曼光谱随浸泡时间的变化。PATP在Ag上吸附的初始阶段，PATP的拉曼信号与吸附时间的平方根成正比，表明吸附速率受PATP在溶液中扩散的制约。由于Ag-S伸缩振动的拉曼带也在220 cm-2附近被检测到<-1>，这表明S原子与Ag直接接触。2）在120 K真空条件下，测量了五羰基铁（IPC）在平整和粗糙Ag膜表面的拉曼散射光谱。在升高的温度下，IPC从表面分子解吸。用低压汞灯的紫外光照射IPC使拉曼信号降低，但在光谱中没有观察到显著变化。在UV照射下加热衬底至200 K时，2000 cm-2区域中的两个C-O伸缩带<-1>消失，而是出现两个新的带。这些光谱变化被认为是由IPC的结构变化或其转化为其他Fe-羰基物质引起的。在260 K附近发现了紫外光照射下的另一个光谱变化。应该注意的是，拉曼信号在粗糙的银表面上比在平坦表面上更强。这种增强的拉曼信号从粗糙的表面解释的SPP激发银。因此，通过这些研究，我们可以证明SPP辅助的拉曼光谱在获得表面反应和沉积过程的信息，其中大部分是模糊的有用性。

1) In order to investigate the adsorption of p-aminothiophenol (PATP) on silver, Raman scattering experiments were performed by exciting surface plasmon polaritons on Ag island films. The silver films were prepared by vacuum evaporation as a mass thickness of 5nm on BaF_2 plates. The plates were dipped into ethanol solutions containing 1 mM PATP.The Raman spectra were measured as a function of dipping time. At the initial stages of the adsorption of PATP on Ag, the Raman signals from PATP increased in proprtion to the square root of dipping time, suggesting that the adsorption rate was conditioned by the diffusion of PATP in the solution. The Raman band due to the Ag-S stretching vibration was also detected at near 220cm^<-1>, which demonstrates a direct contact of the S atom with Ag. These results were supported by our FT-IR experiments.2) Raman scattering was measured for iron pentacarbonyl (IPC) deposited in vacuum at 120K on flat and rough Ag film surfaces. At elevated temperatures IPC was molecularly desorbed from the surface. Illumination of IPC with UV light from a low pressure Hg lamp decreased the Raman signals, but no significant changes were observed in the spectra. Upon heating the substrate up to 200K under UV irradiation, the two C-O stretch bands in the 2000 cm^<-1> region disappeared and, instead, two novel bands appeared. These spectral changes are thought to arise from a structural change of IPC or its conversion into other Fe-carbonyl species. Another spectral change was found near 260K under UV illumination. It should be noted that the Raman signals were more intense on rough silver surfaces than on flat ones. This enhancement of Raman signals from the rough surfaces are explained by the SPP excitations of Ag. Thus, through these investigations, we could demonstrate the usefulness of the SPP-aided Raman spectroscopy in getting information on surface reactions and deposition processes, most of which had been ambiguous.