A Raman cell suitable for the study of solid/liquid/gas three-phase systems and that can work very efficiently onconfocal microprobe Raman systems was introduced. The influence of the environment on the adsorption behavior ofmodel molecule CO on Pt was investigated and different behaviors were observed in the aqueous solution compared tothe gas phase. A preliminary Raman measurement on the three-phase system was performed using methanol as a testingsolution. The diffusion of CO, a dissociate product of methanol, on the Pt electrode from the solution side to the gasside was observed.

A detailed surface Raman study of the effect of the bulk concentration of cyanide (CN-), electrode potential.and immersion potential on the adsorption behavior of CN- on the Pt electrode surface was performed on aconfocal microprobe Raman system. The notable change of the C-N frequency and the Pt-C intensity at ca.-0.7 V(vs SCE) indicates a subtle change of the adsorption behavior of CN- on the platinum electrode insolutions with concentration of about 10-4M or lower. The concentration of cyanide in the bulk solutionaffects the adsorption behavior. The surface Raman signal can still be observed at concentrations as low as10-6M. When the CN-concentration is higher than 10-3M, the potential for immersing the platinum electrodein the CN-solution has a remarkable effect on the adsorption behavior of CN-With the high-quality surfaceRaman spectra, the surface enhancement factor for the adsorbed CN- was estimated to be about 150.

By using the previously developed roughening method for producing SERS-active Rh electrode, and assistedby the highly sensitive confocal microprobe Raman system, we carried out a detailed SERS study on thedissociation and electrooxidation of C1 molecules on a Rh surface. The SERS spectra obtained in a widefrequency region provide not only the vibrations reflecting the internal bonding of CO (at ca. 2000cm-1) butalso the bonding between CO or O with Rh (at ca. 450cm-1). A complementary electrochemical study wasalso performed on the roughened Rh surface in order to correlate the electrochemical and vibrationalinformation. Both electrochemical and SERS studies show that Rh has no discernible activity toward theelectrooxidation or dissociation of methanol in acidic solutions. Rh becomes active and its activity increaseswith the decrease of the solution acidity. For HCHO and HCOOH, the electrooxidation activity of Rh increaseswith increasing pH. On the basis of the result of the model CO system, discussion on the dissociation orelectrooxidation mechanisms was presented for C1 molecules on Rh.

We describe a method of preparing gold scanning tunneling microscopy STM tips by direct currentelectrochemical etching in concentrated HCl and ethanol solution. Gold tips with tip apex radiuslower than 30nm can be reproducibly prepared by this method. The influence of the solutioncomposition, etching voltage on the surface structure, and sharpness has been investigated. Thesetips can be efficiently used for STM imaging, tip-enhanced Raman spectroscopy, and light emissioninvestigations on the same sample.