The Interfacial Versatility of Surface-Enhanced Raman Spectroscopy: New Applications in Urface Chemistry and Materials Science

摘要

Over the last twenty years, surface-enhanced Raman scattering (SERS) has become an increasingly improtant means of chanacterizing adsorbates in ambitent, especially electrochemical, environments, While the unique surfae selectrivity. sensitivity, and liberal selectio rules of SERS enable remarkably rich (and chemically informative) vibrational spectra to be obtained for a mayriad of adsorbates, its apparent restriction largely to "coinage metals" (Cu, Ag, & Au) has until recently limited the breadth of interfacial chemical applications. Probably the most useful (and reliable) means of extending the SERS sffect to interfacial materials, and to adsorbates thereon, which do not in thermselves exhibit Raman surface-enhancement is to deposit them as ultra-thin films on a suitable SERS-active substrate. Starting in 1986, we have extensively exploited this strategy to explore surface chemstry in ambient electrochemical and gas-phase enviroments Most of these applications have along with its deisrable electrochemcial propertis and chemical interness, Particular emphasis has been placed on Pt-ground transition-metal overlayers, given the central important of these materials as heterogeneous catalysts. While the deposition of thicker films yields an attenuation of the Rman enhancement factors for adsorbates bound to theoverlayers due to electromagnetic effects. these strategies coupled with the recent marked improvements inthe sensitivity of Rman instrumentation offer exciting new vistas in surface analytical chemistry.