Critical fluctuations of a binary fluid mixture confined in a porous medium

The have performed small angle neutron scattering experiments on the binary fluid mixture n-C6H14+n-C8F18 imbibed inside porous Vycor glass in the thermodynamic region corresponding to the bulk critical one. The resulting structure can be represented as the sum of a temperature dependent Lorentzian term and a term describing the interference between the porous matrix, a shell part richer in one component coating. the glass surface; and a core part richer in the other component. We observe critical fluctuations extending over distances markedly larger than the mean pore size.