Background subtracted GIXD data on a water subphase at 30°C for DPPC, GM1, and various binary mixtures displaying Bragg peaks. (A) 100:0 (squares), 95:5 (sideways triangles), 75:25 (triangles), 6:4 (inverted triangles), and 0:100 DPPC/GM1 (diamonds) at 15 mN/m. For clarity, the data have been offset vertically. Note the two pure components have no Bragg peaks, indicating a lack of in-plane order in the tail region. (B) Comparison of DPPC (open triangles) and 75:25 DPPC/GM1 (squares) at 23 (lower panel) and 30 mN/m (upper panel) to show the difference in type and degree of ordering. For clarity, the data at the two pressures have been offset vertically.