Light scattering was used to study the time evolution of phase separation of a critical isobutyric acid and water mixture in the spinodal region. A shoulder is observed in the larger-scattering-angle region of the main dominant peak in the structure factor, and the time dependence of the position of shoulder is well scaled by the same characteristic wave number and interdiffusion coefficient as those for the main peak. The tail in the large-scattering-angle region of the structure factor is well expressed by the Porod law in the intermediate and late stages of spinodal decomposition.

• Received 10 December 1991

DOI:https://doi.org/10.1103/PhysRevA.45.R3377