Rayleigh-Brillouin spectra of gaseous ${\mathrm{N}}_2$ is measured for light scattered at 15° over a pressure range from 1 to 661 Torr. Spectral profiles are analyzed by means of an appropriate kinetic model. A least-${\chi }^2$ method determines the optimum values of the theory parameters: total collision frequency and rotational relaxation number. These parameters are compared with values obtained by other methods. Information provided by light-scattering measurements concerning rotational relaxation in dilute systems is discussed.

• Received 11 August 1975

DOI:https://doi.org/10.1103/PhysRevA.13.752