Raman intensity interpretation of pyridine liquid and its adsorption on the Ag electrode via bond polarizabilities

The temporal bond polarizabilities of pyridine adsorbed on the Ag electrode under various applied voltages are obtained from their surface enhanced Raman intensities. In so doing, the delicate bond behaviors of pyridine molecule in the surface enhanced Raman process are well demonstrated, including the effects by the charge transfer and electromagnetic mechanisms. Furthermore, the adsorption effect is well reflected by the bond polarizabilities after relaxation as contrasted with the calculated bond electronic densities in the ground state. The work of pyridine liquid is also shown because its comparison with that under adsorption deepens our understanding of the Raman process. Though the method is semi-classical and simple as contrasted with those based on the quantum chemistry, it indeed offers us a very clear physical picture. This work demonstrates that this approach is quite universal for the Raman active systems even under adsorption as far as their Raman profiles are well measured.