SMALL-ANGLE RAYLEIGH-SCATTERING FROM NONEQUILIBRIUM FLUCTUATIONS IN
                                                           LIQUIDS AND LIQUID-MIXTURES
 
                                                  LI WB, SEGRE PN, GAMMON RW, SENGERS JV
                                                                                PHYSICA A
                                                                  204: (1-4) 399-436 MAR 1 1994
 
                                                                                Abstract:
We have developed an improved experimental arrangement for measuring small-angle Rayleigh scattering in liquid
systems subjected to a stationary temperature gradient. This improved arrangement has enabled us to measure
nonequilibrium fluctuations with a simple helium-neon laser. We have used this technique to measure long-range
nonequilibrium fluctuations in n-hexane and in several mixtures of n-hexane with toluene, thus complementing
measurements for the equimolar mixture obtained previously. The experiments confirm that all diffusive
nonequilibrium fluctuations vary with (Grad T)²/k⁴, where Grad T is the imposed temperature gradient and where k is
the wave number of the fluctuations. A quantitative comparison of the strength of these nonequilibrium
fluctuations with the theoretical predictions is also presented.