Smectic Membranes in Motion: Approaching the Fast Limits of X-Ray Photon Correlation Spectroscopy

Abstract

The dynamics of the layer-displacement fluctuations in smectic membranes have been studied by x-ray photon correlation spectroscopy (XPCS). We report transitions from an oscillatory damping regime to simple exponential decay of the fluctuations, both as a function of membrane thickness and upon changing from specular to off-specular scattering. This behavior is in agreement with recent theories. Employing avalanche photodiode detectors and the uniform filling mode of the synchrotron storage ring, the fast limits of XPCS have been explored down to 50 ns.

Beyond simple exponential correlation functions and equilibrium dynamics in x-ray photon correlation spectroscopy

“…Pronounced viscoelastic behavior may affect the dispersion relations of capillary waves, and behavior of this kind has been studied with XPCS in a variety of systems ranging from viscous free surfaces to thin polymer films and liquidcrystalline membranes [12]- [17].…”

Surface and Bulk Elasticity Determined Fluctuation Regimes in Smectic Membranes

“…The thickness can vary from two layers (about 5 nm) up to thousands of layers (tens of m) for surface areas as large as several cm 2 . X-ray photon correlation spectroscopy (XPCS) -the x-ray implementation of classical dynamic light scattering [4] -has been used to probe the fluctuation dynamics in smectic membranes [5][6][7]. In addition to simple exponential relaxation of surfacedominated overdamped fluctuations, oscillatory relaxation of the fluctuations due to inertial effects has also been observed.…”

Effects of partial coherence on correlation functions measured by x-ray photon correlation spectroscopy

“…[1][2][3][4][5][6][7][8][9][10][11] At third-generation synchrotrons it is nowadays possible to produce intense x-ray beam with a high degree of coherence. The scattered intensity distribution of such an x-ray beam coming from a rough surface provides a speckle pattern due to destructive and constructive interference.…”