  We report a high energy-resolution neutron backscattering study to
investigate slow motions on nanosecond time scales in highly oriented solid
supported phospholipid bilayers of the model system DMPC -d54 (deuterated
1,2-dimyristoyl-sn-glycero-3-phoshatidylcholine), hydrated with heavy water.
This technique allows to discriminate the onset of mobility at different length
scales for the different molecular components, as e.g.\@ the lipid acyl-chains
and the hydration water in between the membrane stacks, respectively, and
provides a benchmark test regarding the feasibility of neutron backscattering
investigations on these sample systems. We discuss freezing of the lipid
acyl-chains, as observed by this technique, and observe a second freezing
transition which we attribute to the hydration water.
