Dynamics of dioleoyl phosphatidylcholine by muon spin relaxation

Muon spin relaxation has been used to study the dynamics of the hydrocarbon chains in methyl oleate and dioleoyl phosphatidylcholine (DOPC) as a funct ion of temperature. Repolarisation of the radical muonium spin shows that t he muons implant in the C-9-C-10 double bond. Dynamic processes involving t he hydrocarbon chains are evident from the increases observed in the muon s pin relaxation rate as the ester and DOPC are heated from 100 to 400 K. Sim ilar increases in muon spin relaxation are observed before the melting poin t in methyl oleate and the chain melting temperature in DOPC indicative of fast segmental motions occurring in the chains before the phase change take s place.