Angular dispersion of ‘‘backward’’ Raman scattering: Weakly absorbing cubic materials (Si)

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Abstract
We have shown that the angular distribution of Raman scattering power from the surface of diamond-type opaque materials can be adequately described by use of classical optics. It turns out that within the commonly-used nearly backward scattering geometries there are significant variations of the scattered power due to purely geometrical factors. Only crystals with small extinction coefficients are considered. Families of curves for the scattered power are derived in terms of the angles of incidence and detection and of the index of refraction for three of the most widely-used crystal orientations. The analysis reveals the optimum scattering configuration for a given geometrical situation and provides a quantitative measure for the deviation from the selection rules when a ‘‘backward’’ geometry for forbidden scattering is less than exact. The importance of incidence and/or detection at the Brewster angle is examined. The experimental data obtained in Si are consistent with the theoretical predictions. The applicability of these results to other situations is discussed.