On the hyperfine structure and isotope shift of radium

K. Wendt, S. A. Ahmad, W. Klempt, R. Neugart, E. W. Otten, H. H. Stroke

    Research output: Contribution to journalArticlepeer-review


    The hyperfine structure and isotope shift of the heaviest known alkaline earth element radium (Z=88) have been studied in both the atomic Ra I and ionic Ra II spectra. The measurements, carried out by on-line collinear fast-beam laser spectroscopy, yield the hyperfine constants A and B of the 7 s and 7 p1/2 states in Ra II, of all states of the excited 7 s 7 p configuration and the 7 s 7 d3D3 state in Ra I. The data allow a consistent evaluation of the nuclear moments for eight odd-A radium isotopes. In particular, a complete analysis of the hyperfine structure of the sp configuration in the two-electron system provides a stringent test of the validity of the semi-empirical modified Breit-Wills theory. It is shown that the effective operator formalism is equivalent, if relativistic correction functions are used to reduce the number of parameters. The semi-empirical hyperfine fields are evaluated and found to agree generally with those from ab-initio calculations. The isotope shifts in the s-p, s2-sp, sp-sd transitions are analysed semi-empirically and compared with ab-initio calculations. The consistency of the different analyses proves their validity and classifies the spectrum of Ra I as a model case for a simple and clean two-electron spectrum.

    Original languageEnglish (US)
    Pages (from-to)227-241
    Number of pages15
    JournalZeitschrift für Physik D Atoms, Molecules and Clusters
    Issue number3
    StatePublished - Sep 1987


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    ASJC Scopus subject areas

    • Atomic and Molecular Physics, and Optics


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