Spectral structure of critical opalescence: Binary mixture

Th e linearized hydrod ynami c equations of irre vers ible thermodynami cs a re used to ob tain the t im e de pen dence of the kth Fourie r co mpon e nt of a co ncentra tion flu ctuati on in th e one-phase region of a binary mixture . Th e fr eque ncy of the light sc alle red by co nce ntration flu c tuati ons nea r the c riti ca l mixin g point is found to b e broadened into a Lorentzian di s tributi on with a ha lf-width propo rti ona l to the ma ss diffu s ion coe ffi c ient, D. The poss ibility of d e tecting s pace di spers ion in D is di sc u ssed .