DYNAMICS OF CONCENTRATION FLUCTUATIONS IN POLYMER-SOLUTIONS WITH SPATIOTEMPORAL CORRELATED NOISE

We study the problem of concentration fluctuations in polymer solution s under the influence of spatiotemporal correlated noise. We find that in contrast to the case of white noise, where the dynamic structure f unction is characterized by a single decay rate Gamma(k) which is give n in terms of the static structure function g(k) in the colored noise case, the decay rate takes a different form depending on a characteris tic wave vector kappa, given by the solution of the equation 1 + xi2ka ppa2-tauGAMMA(kappa)=0, with xi being the correlation length of the po lymers and tau being the correlation time of the colored noise. For th e wave vector k much less than kappa, the decay rate is GAMMA(kappa), just as in the white noise case. For k = kappa, the decay rate is GAMM A(kappa), but the decay is modified by an extra factor (i + GAMMA(kapp a)t) where t is the time. For k much greater than kappa, the decay rat e is (1 + xik2)/tau. Since our result should hold as long as the corre lation time tau is not exactly zero, it should lead to experimentally verifiable consequences in dynamic light scattering in polymer solutio ns in short time scales.