Regensburg 2004 – scientific programme
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AKB: Biologische Physik
AKB 50: Poster Session "Biological Physics"
AKB 50.62: Poster
Friday, March 12, 2004, 10:30–13:00, B
Collective dynamics of lipid membranes studied by inelastic neutron scattering — •Maikel C. Rheinstädter1,2, Christoph Ollinger3, Giovanna Fragneto1, and Tim Salditt3 — 1Institut Laue-Langevin, 6 rue Jules Horowitz, 38042 Grenoble, France — 2IFF, FZ-Jülich, 52425 Jülich, Germany — 3Institut für Röntgenphysik, Georg-August-Universität Göttingen, Geiststr. 11, 37073 Göttingen, Germany
The collective dynamics of lipid molecules are believed to affect significantly the physical properties of phospholipid membranes. In the context of more complex biological membranes, collective molecular motions may play a significant role for different biological functions [1]. We present a first time inelastic neutron scattering study on the collective dynamics of the lipid acyl chains in the model system DMPC -d54. We have measured the dynamical structure factor S(Qr,ω) in the gel (Lβ) and the fluid (Lα) phase of the lipid bilayer. The dispersion relation we find is similar to those found in liquids, with a distinct minimum at Q0, the maximum of the static structure factor S(Qr), and can be compared to recent Molecular Dynamics simulations [2]. Furthermore, we investigated the temperature dependence of the excitations in the minimum in the vicinity of the main phase transition. Our discussion may shed light on the gel-fluid phase transition and coexistence of the two phases. By combining neutron diffraction and inelastic measurements, we gain information about structure and (collective) dynamics of model membranes on a molecular length scale. [1] R. Lipowsky and E. Sackmann, Handbook of Biological Physics, vol. 1, Elsevier (1995); [2] M. Tarek et al., Phys. Rev. Lett. 87, 238101 (2001).