Amplitude of Rippling in the Pβ Phase of Dipalmitoylphosphatidylcholine Bilayers

We present x-ray diffraction results of dipalmitoylphosphatidylcholine (DPPC) multilayers in three structural phases. Using pure DPPC, precision temperature control, and high angular resolution methods, we have discovered splitting of the first diffraction order due to multilayering in the P_β phase. This splitting permits us to calculate the amplitude of ripples in this phase. The amplitude is large enough to suggest a structural mechanism for rippling.