The possibilities to measure the diffuse X-ray reflectivity of interfaces and thin films are only being fully developed thanks to synchrotron sources. At BM32 during the experiment, we could determine the spectral dependence of the thermal fluctuations in freely-suspended smectic liquid crystalline films down to molecular dimensions. While at long wavelengths the top and bottom of such a film fluctuate in unison, at shorter wavelengths a cross-over to independent fluctuations could be observed.

ESRF Newsletter

de Jeu, W. H, Mol, E. A. L, Wong, G. C. L, Petit, J. -M, & Rieutord, F. (1997). Fluctuations of freely-suspended smectic films as observed by diffuse x-ray reflectivity. ESRF Newsletter, 29, 10–12.