Measurement of the LinearkTerm in a Polar Crystal (CdS) by Spin-Flip Raman Scattering

A large differnce in widths and intensities between Stokes and anti-Stokes spin-flip Raman scattering lines of donor electrons in $n$-CdS has been observed. This asymmetry arises from the linear $k$ term, $\lambda (\overrightarrow{\mathrm{k}}\times \overrightarrow{\mathrm{c}})·\overrightarrow{\mathrm{s}}$. In a diffusional linewidth, the term $\lambda$ appears as $D{(q\pm \frac{\lambda m^{*}}{{\hslash }^2})}^2$ from which we find $\lambda =1.6\mathrm{}\times {10}^{-10\mathrm{}}$ eV cm in good agreement with our theoretical estimate. A new effect called Doppler narrowing is implied.