title: Dispersion relation of lipid membrane shape fluctuations by neutron spin-echo spectrometry.
abstract: We have studied the mesoscopic shape fluctuations in aligned multilamellar stacks of 1,2-dimyristoyl-sn-glycero-3-phoshatidylcholine bilayers using the neutron spin-echo technique. The corresponding in plane dispersion relation tau-1(q//) at different temperatures in the gel (ripple, Pbeta') and the fluid (Lalpha) phase of this model system has been determined. Two relaxation processes, one at about 10 ns and a second, slower process at about 100 ns can be quantified. The dispersion relation in the fluid phase is fitted to a smectic hydrodynamic theory, with a correction for finite qz resolution. We extract values for the bilayer bending rigidity kappa, the compressional modulus of the stacks B, and the effective sliding viscosity eta3. The softening of a mode which can be associated with the formation of the ripple structure is observed close to the main phase transition.
authors.affiliation: Institut Laue-Langevin, 6 rue Jules Horowitz, BP 156, 38042 Grenoble Cedex 9, France. rheinstaedter@ill.fr
authors.forename: Maikel C
authors.initials: MC
authors.lastname: Rheinstädter
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Häussler
authors.forename: Tim
authors.initials: T
authors.lastname: Salditt
mesh_terms: D003198:Computer Simulation; D004134:Dimyristoylphosphatidylcholine / Q000737:chemistry*; D008560:Membrane Fluidity; D008563:Membrane Lipids / Q000737:chemistry*; D008956:Models, Chemical; D008958:Models, Molecular; D008968:Molecular Conformation; D033363:Neutron Diffraction; D013057:Spectrum Analysis; D013696:Temperature
chemical_list: D008563:Membrane Lipids; D004134:Dimyristoylphosphatidylcholine