Membranes of cells are the physical barrier between the inside and outside of the cell. Transport and signaling is control by transport and signaling proteins but their ability to function depends critically on the lipid environment available to them. One mechanism for these proteins to be turned off and on is the existence of a differing of lipid environments with in the membrane. The last decade has seen the concept of lipid rafts be strengthen by model membrane mixtures which mimic the cell membrane and exhibit phase separation. However, in cells, this has not been seen as they are believed to be nanometer in size. In an effort to ultimately measure these domains in cells, new techniques are being sought. SERGIS has this potential. This proposal seeks to study a well known lipid mixture: DPPC/DLPC to study domain organization in several configurations as a function of temperature.