Atomic resolution neutron holography (principles and realization)

Abstract

Atomic resolution neutron holography constitutes a novel technique to obtain structural information. It is based on the recording of the interference of neutron waves coherently scattered by atoms located on a crystal lattice with a suitable reference wave. This process can be accomplished by two complementary schemes. In the frame of the first approach, a point-like source of spherical neutron waves is required inside a single crystal. Such a source can be realized owing to the extremely large value of the incoherent neutron scattering cross section of the proton. Hydrogen atoms imbedded in a sample which is placed in a monochromatic beam of slow neutrons will emit spherical neutron waves as a result of an incoherent scattering process. The interference between the undisturbed wave field and that part of the wave which is scattered by neighboring atoms can be recorded, thereby producing a hologram. The second approach utilizes a source of plane neutron waves outside the sample. The interference between the undisturbed and the scattered parts of the neutron wave field is recorded by point-like detectors, i.e. strongly neutron-absorbing nuclei, which are placed inside the crystal lattice that is to be imaged. The experimental feasibility of these two techniques is demonstrated.