A theory of light scattering from adsorbed molecules is presented based on the general formulation of second order optical processes. The molecularndash;solid interaction is assumed to be theshyphen;dinteraction, which leads to the shift and broadening of the molecular excited state. The physical origin of the anomalous enhancement of the Raman scattering from adsorbed molecules is explained by an effective resonant model so that the electronic resonant level of adsorbed molecule shifts towards lower energies and the effective resonant condition is realized even when the molecule is excited by the offhyphen;resonant energy of the isolated molecule. It is also shown that the Raman scattering includes an additional term, which gives rise to the continuum background on which the Raman spectra are superimposed.
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