Dynamic behavior of Brownian particles close to a wall is studied by photon correlation from an evanescent wave with variable penetration depth. Surface correlation spectra strongly differ from the bulk measurements and are completely interpreted in terms of the combined wall’s mirror effect and evanescent-wave geometry. Relevance of these new effects to the light-scattering study of surface dynamics is discussed.

• Received 27 December 1985

DOI:https://doi.org/10.1103/PhysRevLett.57.17