Molecular systems scattering cross sections

For a limited number of metal surfaces, adsorption of a molecular species in a thin (monomolecular layer) film results in a huge increase in the effective vibrational Raman scattering cross-section (again, as with RR scattering, up to ca. 106 times) of the adsorbate species. The SERS effect was discovered more than ten years ago for pyridine adsorbed at a silver electrode surface in contact with an aqueous electrolyte [1, 2]. In the intervening period, many hundreds of papers devoted to SERS phenomena have been published, extending the studies to other metals than silver, to non-aqueous as well as aqueous electrolytes, to colloidal dispersions of metals as well as metal electrodes, and even to vacuum-deposited thin film systems under UHV conditions. This review will concentrate on studies of metal-electrolyte interfaces. 

In Eq. (1.350 is the total emission intensity of the coupled molecule-metal system and it is measured after that the excitation signal has ended, while is the molecular scattering cross section near the metal. The excitation contribution is simply... 

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