HYPERFINE SPECTROSCOPY OF RADIOACTIVE ATOMS

The interaction between the nucleus and the electrons and its effects on atomic spectra are first recalled and the relevance of the parameters deduced from these hyperfine effects to nuclear structure is emphasised. Special attention is paid to effects which are now observable in long isotopic chains. The production and handling of these radioactive atoms is studied in some detail, including the production of nuclei far from stability by means of nuclear reactions with particle beams coming from accelerators, and the use of on-line isotope separators. The experimental methods of radiofrequency are explained at an introductory level with the different means of producing and detecting nuclear orientation, some of which are specific to radioactive atoms, being described. Methods of optical hyperfine spectroscopy are reviewed and the dramatic increase in sensitivity offered by the use of tunable lasers and by new methods of non-optical detection of optical resonances is explained. Finally, an account is given of the main results obtained in three cases: light alkalis, heavy alkalis and mercury. These results are interpreted in terms of nuclear structure.