Moment analysis of collision-induced light scattering from compressed CF4

The method of moments is used to determine a functional form of the induced polarizability increment $\beta$, which gives rise to collision-induced light scattering from compressed C${\mathrm{F}}_4$. Based upon the zeroth and second moments, two expressions are found to be acceptable: $\beta \mathrm{}\left(x\right)=6\mathrm{}{\alpha }^2{\sigma }^{-3\mathrm{}}(x^{-3\mathrm{}}-2.85\mathrm{}{x}^{-4.05\mathrm{}})$ and $\beta \mathrm{}\left(x\right)=6\mathrm{}{\alpha }^2{\sigma }^{-3\mathrm{}}(x^{-3\mathrm{}}+0.757\mathrm{}{x}^{-8.51\mathrm{}})$, where $x=\frac{r}{\sigma }$. Both expressions result in calculated fourth moments consistent with the experimental estimate. This is the first experimental evidence in which a positive non-dipole-induced-dipole term is shown to be a possibility. In other respects, however, the results are similar to those obtained from rare-gas spectra.