In-beam Mössbauer spectroscopy at heavy-ion accelerators

Abstract

The method of “in-beam Mossbauer spectroscopy (IBMS)” as presently performed at heavy-ion accelerators is presented and reviewed. Experimental aspects are outlined and special features of this technique in comparison with more conventional radioactive ion implantation are stressed. The review is centered on the fate of57Fe atoms implanted in metals and semi-conductors in which very limited or vanishing solubility for Fe exists. Under these conditions Fe takes up to a rather large extent interstitial positions. These can be characterized by the Mossbauer parameters, in particular by the isomer shift. Already at rather low temperatures one observes in several materials a dynamic behaviour of the Fe interstitial which can be described in some cases as localized motion and in others as onset of long-range interstitial diffusion. Additional information on the dynamic behaviour and the electronic structure in some of the systems presented comes from Perturbed Angular Distribution of γ-rays (PAD). which also is an “in-beam” technique working with a 10+ isomeric state of54Fe.