Some remarks on the optical rotary dispersion of quartz

Summary

The quantum mechanical theory of rotary dispersion leads to the rule that the sum of the rotational strengths Σa _r of the various terms in a dispersion formula of the Drude type expressed in terms of the characteristic frequencies should be zero. It is shown in this paper that the rotary dispersion formulæ for quartz which had been proposed earlier do not satisfy this summation rule. On the other hand, the single-term formula of the formρ=Kλ²/(λ²−λ₀ ²)² suggested by the present author which fits the data along the optic axis accurately from the visible to the ultra-violet region of the spectrum, fulfils the summation condition. It is also shown that the data of Bruhat and Grivet for the rotary dispersion of quartz normal to the optic axis is fitted well by a formula of the same form as that given above if we put K=−3·56 and λ₀=0·111355µ.