Surface and bulk elasticity determined fluctuation regimes in smectic membranes.
نویسندگان
چکیده
We report combined x-ray photon correlation spectroscopy (XPCS) and neutron spin echo (NSE) measurements of the layer-displacement fluctuations in smectic liquid-crystal membranes in the range from 10 ns to 10 micros. NSE reveals a new regime, determined by bulk elasticity, in which relaxation times decrease with the wave vector of the fluctuations. XPCS probes slower surface-tension-dominated relaxation times, independent of the wave vector. XPCS gives a difference in correlation times at specular and off-specular positions that can be related to different detection schemes.
منابع مشابه
Annihilation of edge dislocations in smectic-A liquid crystals.
This paper presents a theoretical study of the annihilation of edge dislocations in the same smectic plane in a bulk smectic-A phase. We use a time-dependent Landau-Ginzburg approach where the smectic ordering is described by the complex order parameter psi( r--> ,t) =eta e(iphi) . This quantity allows both the degree of layering and the position of the layers to be monitored. We are able to fo...
متن کاملSmall membranes under negative surface tension.
We use computer simulations and a simple free energy model to study the response of a bilayer membrane to the application of a negative (compressive) mechanical tension. Such a tension destabilizes the long wavelength undulation modes of giant vesicles, but it can be sustained when small membranes and vesicles are considered. Our negative tension simulation results reveal two regimes-(i) a weak...
متن کاملSurface Effects on Phases Transitions in Smectic Membranes
In liquid crystal materials, frustration between competing interactions and thermal fluctuation results in the observation of many different phases (up to 5) in a relatively narrow temperature window (usually about 30K). Identifying the interactions as well as finding out the nature of those interactions that stabilize those phases is a very important and interesting question. In this thesis, w...
متن کاملSurface Dynamics of a Freely Standing Smectic-A Film
A theoretical analysis of surface fluctuations of a freely standing thermotropic smectic-A liquid crystal film is provided, including the effects of viscous hydrodynamics. We find two surface dynamic modes (undulation and peristaltic). For long wavelengths and small frequencies in a thin film, the undulation mode is the dominant mode. Permeation enters the theory only through the boundary condi...
متن کاملSurface-induced effects in fluctuation-based measurements of single-polymer elasticity: A direct probe of the radius of gyration.
Single-molecule measurements of polymer elasticity are powerful, direct probes of both biomolecular structure and principles of polymer physics. Recent work has revealed low-force regimes in which biopolymer elasticity is understood through blob-based scaling models. However, the small tensions required to observe these regimes have the potential to create measurement biases, particularly due t...
متن کاملذخیره در منابع من
با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید
عنوان ژورنال:
- Physical review letters
دوره 91 16 شماره
صفحات -
تاریخ انتشار 2003