2-DIMENSIONAL SURFACE-ENHANCED RAMAN IMAGING OF A ROUGHENED SILVER ELECTRODE SURFACE WITH ADSORBED PYRIDINE AND COMPARISON WITH AFM IMAGES

Raman scattered light from pyridine adsorbed on an electrochemically r oughened silver electrode surface was used to image the two-dimensiona l surface morphology with a spatial resolution of 1 mu m. The images s howed that the spatial distribution and intensity of the surface-enhan ced Raman scattered (SERS) light intensity varied to a significant ext ent over the electrode surface and revealed apparent surface features, specifically, ridges and domes with dimensions on the order of 10 mu m. Atomic force microscopic images also showed similar structures. In addition, the AFM images showed that smaller surface features, on the order of 1-3 mu m, were associated with brighter areas in the SERS ima ges. However, the difference in SERS intensities for bright vs dark ar eas was at most a factor of similar to 6, indicating that, even in the dark areas, there was significant surface enhancement. Consistent wit h this result is the fact that, at still higher magnification, the AFM images in different areas of the electrode showed very similar surfac e structure, consisting of silver particles with diameters in the rang e 50-400 nm.