The static 2 H NMR spectra measured from membranes containing 5 vol% of C30d in DMPC are shown in Fig. . The high-temperature spectrum was acquired above the melting point of C30d (approx. 62 • C ) and originates from a superposition of Pake patterns. In the middle of this spectrum a narrow peak is visible. This peak likely originates from a separate, isotropic n-alkane phase, i.e. C30d that didn't enter the lipid membrane. A quantification of this alkane fraction will be provided only in the following section. Upon cooling the mixtures to 30 • C the complete signal seems to vanish. However, closer inspection reveals that the spectrum broadens considerably (Figure ). For comparison, the spectrum of crystalline bulk C30d obtained at 30 • C is included in the figure. The spectra of both C30d in DMPC and bulk C30d feature horns at about ±17-18 kHz and ±60 kHz. Comparison with a simulated spectrum shows that both these horns represent the quadrupolar splittings for a 90 • orientation of C30d crystallites with respect to the main magnetic field. The position of the outer splittings indeed corresponds to a rigid quadrupolar coupling of 167 kHz, as expected for the static limit . Similar splittings have been measured in short nalkane solids . Therefore, at 30 • C, C30d molecules that were mixed with the acyl chains at high temperature must (mostly) be part of a crystalline structure. We have also performed experiments on samples containing C30d in POPC bilayers and the 2 H spectra obtained mirror the results for C30d in DMPC (Fig. ).