FIGURE 3.

Phase diagram of lipid DPhPC as a function of temperature and the level of hydration measured by the ambient relative humidity (RH). The symbols circle, diamond, and square correspond to the x-ray diffraction patterns A, B, and C, respectively, shown on the right-hand side. Symbols Δ and ∇ indicate changeover regions where two phases were detected. The range of the changeover region depended on the direction of hydration change and the speed of the change. The x-ray diffraction patterns were recorded by reflection on an area detector (see Data collection and Fig. 2), where the ordinate was normal to the substrate surface. (The incident angle was 0.7° relative to the substrate.) The abscissa was proportional to the magnitude of the in-plane component of the reciprocal vector (approximately). (A) Diffraction pattern of a lamellar structure corresponding to the L_α phase. (B) Diffraction pattern of a rhombohedral structure (space group R). (C) Diffraction pattern of a two-dimensional hexagonal structure (space group p6) corresponding to the inverted hexagonal (H_II) phase.