Nuclear resonant scattering of synchrotron radiation from thin films

Abstract

The optical properties of thin films containing Mossbauer isotopes undergo dramatic changes in the vicinity of a nuclear resonance. Remarkable phenomena are observed in the energetic and temporal response of X-rays resonantly scattered in grazing incidence geometry. These properties allow an effective discrimination of the resonantly scattered radiation from the nonresonant electronic charge scattering. In contrast to Bragg scattering from single crystals, the reflectivity of film systems can be tailored by their design and the way of preparation. As a result, several optical elements have been developed for ultra-narrow bandpass filtering of synchrotron radiation: Grazing-Incidence Antireflection (GIAR) films, nuclear resonant multilayers and reflection gratings. Moreover, resonant scattering in grazing incidence geometry is a very attractive tool to study properties of thin films themselves. This has led to applications, e.g., in the study of surface magnetism and the determination of vibrational properties of thin films. Such investigations benefit from the outstanding brilliance of third-generation synchrotron radiation sources, extending the sensitivity of the method into the monolayer regime.