Conformational change of core particles studied by quasielastic light scattering

The diffusion translational coefficient Dt of core particles in monodisperse solutions has been measured by the quasielastic light scattering method in a large scale of salinities over the range 6.10(-4) to 2M Na+ or K+. The observed values of DT are independent of particle concentration in the range 0.1-2 mg/ml and do not vary with the scattering vector q corresponding to scattering angles between 40 degrees -120 degrees. When the salinity is progressively raised an increase of DT from 1.9.10(-7) cm2s-1 to 3.2.10(-7) cm2s-1 was observed at about 2.10(-3) M NaCl followed by a decrease of DT beyond 0.6 M NaCl.