The slow short-time motions of phospholipid molecules with a focus on the influence of multiple scattering and fitting artifacts

Abstract

Quasielastic neutron scattering is a powerful tool for the study of non-periodic motions in condensed matter as a detailed line shape analysis can give information about the geometry and rate of the scatterers' displacements. Unfortunately, there are also a number of artifacts which can masquerade as signatures of motions and can therefore lead to erroneous results. Their influence on the evaluation of the motions of the phospholipid dimyristoylphosphatidylcholine (DMPC) is discussed. On a 60 ps time scale, the long-range motion of the molecules has a flow-like character with similar velocities above and below the main phase transition. It is proposed that the concepts of dynamical heterogeneities and "floppy modes" developed in glass physics provide a framework to explain the observed behaviour.

This is an author-created, un-copyedited version of an article accepted for publication in Journal of Physics: Condensed Matter. IOP Publishing Ltd is not responsible for any errors or omissions in this version of the manuscript or any version derived from it. The definitive publisher authenticated version will soon be available