An Extension of the Polarizability Theory of Raman Effect

The polarizability theory of Raman effect has two defects: (a) The depolarization factor $\rho$ of Raman lines of totally symmetric oscillations of molecules can be given only by the indefinite statement $\rho <\frac{6}{7}$; additional utilization of the Silberstein model of optical anisotropy for a more precise prediction leads to wrong results. (b) The depolarization factor of the totally symmetric lines of calcite and aragonite should be zero for every orientation of the crystals, whereas finite values are observed for some orientations. The following cure is proposed. It is assumed that the atomic polarizability $\alpha$ is dependent on the exciting field strength $E(\alpha ={\alpha }_0+\beta E^2)$. In the crystals, it is furthermore assumed that a disturbing field exists which depends on crystal symmetry. With these assumptions, it is possible to account for the observed results without changing the fundaments of the polarizability theory.