Phase determination of x-ray reflections for membrane-type systems with constant fluid density.

A new technique for phase determination of X-ray reflections from symmetric structures is presented. This method, involving comparison of intensity data from structures with variable fluid layer thickness and constant fluid electron density, permits computation of phase angles, scaling factors, and origin reflection values independently. Possible sources of error inherent in other methods of phase determination are thereby eliminated. Results of the application of this method to model structures and to myelin data are reported. Advantages of the technique, which tests all possible phase angle combinations in a rapid fashion, are discussed.