Fig. 6.

Raman images of a single area on selected fractal and nonfractal surfaces for different excitation wavelengths. (Upper) The Raman images of immersion oil on the 100-nm-thick silver film. (Lower) The Raman images of 4-mercaptopyridine adsorbed on cluster–cluster aggregated films. The size of each image is 5 μm × 5 μm. Note that each image is internally normalized to its maximum so that relative intensities between images cannot be compared. In particular, the hot spots on fractal surfaces have orders of magnitude more Raman scattering than counterparts of similar color on nonfractal surfaces.