We discuss the possibility of using the standing waves created in a perfect crystal by Bragg reflection to measure the phase of the structure factor, utilizing a technique similar to that used by Materlik et al. [Phys. Rev. Lett. 52, 441 (1984)] to solve the surface registration problem. The phase information would be obtained by observing the fluorescence radiation emitted either by a monolayer of atoms adsorbed onto the crystal surface or by atoms isomorphically replaced in the top few layers of the crystal. While analysis shows this technique to be equivalent to obtaining phase information by Kossel-line analysis, several potential difficulties with that method should be eliminated.

• Received 16 November 1984

DOI:https://doi.org/10.1103/PhysRevB.31.6420