Silver-Molecule Separation Dependence of Surface-Enhanced Raman Scattering

Surface-enhanced Raman scattering from a layer of organic molecules adsorbed on aluminum oxide and covered by a controlled-roughness silver film has been studied. The molecule-silver distance dependence of the Raman-scattering enhancement by the surface was measured in four separate experiments. Large enhancements ({~}10³) persist in our samples for molecule-silver separation as large as 100 {}, and thus the use of surface-enhanced Raman scattering is shown to be a viable technique for vibrational spectroscopy of a large variety of interface systems.