Crystalline smectic-B films as fluctuating systems: Static and dynamic x-ray scattering - art. no. 020601

Static and dynamic x-ray scattering has been used to characterize thermal f luctuations in free-standing smectic films in the crystalline-B phase. The results are remarkably similar to those in smectic-A films, in spite of the three-dimensional positional order in the crystalline-B phase. The main di fference is the disappearance of the characteristic Landau-Peierls instabil ity of the smectic-A phase. The dynamic nature of the fluctuations is expli citly demonstrated by x-ray photon correlation spectroscopy. This fluctuati on behavior of crystalline-B films can be attributed to the small value of the shear elastic constant C-44.