COHERENT QUASI-ELASTIC BRAGG SCATTERING FROM SINGLE-CRYSTALS CONTAINING FAST DIFFUSERS

Recent developments in the nuclear resonant (Mossbauer) scattering of synchrotron radiation (NRSR) allowed one to observe successfully diffu sive quasielastically scattered radiation from intermediate nonresonan t amorphous targets, e.g., glycerin, in a time domain. Hence, there is a real chance to observe such a radiation scattered coherently at Bra gg angles from single crystals containing fast diffusing atoms. Quasie lasticity of the latter radiation is solely caused by jumps between va rious Bravais lattices due to the peculiarity of the Bragg conditions. On the other hand, an energy resolution could be easily increased by two orders of magnitude in comparison with the incoherent quasielastic scattering of the cold neutrons (QNS) at much higher momentum transfe r to the crystal than in the case of QNS. The paper is devoted to a di scussion of the physics underlying scattering of NRSR beams from fast diffusers in single crystals under Bragg conditions. [S0163-1829(98)07 741-8].