Raman scattering cross section of adsorbed pyridine molecules on a smooth silver surface

We have determined the Raman scattering cross section of pyridine molecules adsorbed on a "smooth" surface of silver prepared and characterized in an ultrahigh-vacuum chamber. The Raman intensity of the 1004-${\mathrm{cm}}^{-1\mathrm{}}$ line of adsorbed pyridine was calibrated against the scattering intensity of the same mode from gaseous pyridine and liquid pyridine. The cross section for pyridine molecules adsorbed on a "smooth" silver (100) surface is 4.4 × ${10}^2$ times greater than that of gaseous and liquid pyridine molecules. This measured cross section is an upper limit for that on a theoretically perfect, flat plane of silver atoms.