Coherent x-ray scattering and dynamics of fluctuations in smectic-Aand crystal-Bfilms: Continuous model

Abstract

We present a theoretical study of the dynamic displacement-displacement and intensity-intensity (for coherent soft x-ray scattering) correlations in Sm-A as well as Cr-B free-standing films. The work is based on a continuous hydrodynamic model that allows one to calculate efficiently the dynamic correlation functions and considerably simplifies earlier analyses of finite-size and surface effects in Sm-A films. The model is extended to Cr-B films. We show that despite the crystalline order, the Cr-B film is a strongly fluctuating system, which is due to an abnormally small shear elastic constant. An easy-shear approximation is developed to describe the fluctuations in the Cr-B phase. We predict nonmonotonic behavior of the intensity-intensity correlation function in both Sm-A and Cr-B films. The analysis can be applied to either coherent x-ray or conventional laser dynamic light scattering experiments.

Surface and Bulk Elasticity Determined Fluctuation Regimes in Smectic Membranes

“…3. Several theoretical models are available using a continuum description of the static [13] as well as the dynamic [14,15] properties of the fluctuations in smectic membranes. Following Ref.…”

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

“…Significant progress has been made in both the static [10] and the dynamic [11,12] description of fluctuations in smectic membranes by extending the Landau -de Gennes theory of smectic-A (Sm-A) with surface terms. Because of the finite film thickness the continuous bulk response spectrum changes into discrete response modes.…”

“…The results will be compared with the theory of fluctuations in Sm-A membranes [11]. The calculations are based on the solution of the equation of motion for such membranes:…”

Dynamic properties of smectic films

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