X-ray-scattering study of capillary-wave fluctuations at a liquid surface

Abstract

A study of the scattering of x rays from the liquid-vapor interface of ethanol at room temperature is reported and compared in detail to predictions based on standard continuum capillary-wave theory. Quantitative agreement is obtained and, in particular, the asymptotic power laws in the diffuse scattering characteristic of the algebraic decay of the density-fluctuation correlations at the surface are verified. The root-mean-square fluctuation of the liquid surface is obtained as 6.9\ifmmode\pm\else\textpm\fi{}0.2 \AA{}.