Raman scattering by hot polaritons in NaClO3

Summary By nonlinear mixing of IR and visible radiation,i.e. coherent Raman scattering by polaritons driven by a CO₂ laser, it has been possible to get high-resolution spectra for theF-modes of a NaClO₃ crystal in the region (907÷957) cm⁻¹, where several isotopic modes are present. The obtained independent measurement of the refractive index and absorbance allows an accurate determination of the polariton dispersion curve and its width inq-space. The experimental data confirm the existence of a localized isotopic mode at 931 cm⁻¹ and a strongly damped isotopic mode near 960 cm⁻¹. Finally, an accurate measurement of the dispersion of the second-order nonlinear polarizability in the same energy region has been obtained for the first time. This work was supported by the Italian Consiglio Nazionale delle Ricerche and Ministero della Pubblica Istruzione.