Nuclear resonant scattering of synchrotron radiation from thin films

The optical properties of thin films containing Mossbauer isotopes undergo dramatic changes in the vicinity of a nuclear resonance. Remarkable phenome na are observed in the energetic and temporal response of X-rays resonantly scattered in grazing incidence geometry. These properties allow an effecti ve discrimination of the resonantly scattered radiation from the nonresonan t 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 bee n developed for ultra-narrow bandpass filtering of synchrotron radiation: G razing-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 thems elves. This has led to applications, e.g., in the study of surface magnetis m and the determination of vibrational properties of thin films. Such inves tigations benefit from the outstanding brilliance of third-generation synch rotron radiation sources, extending the sensitivity of the method into the monolayer regime.