Results of relativistic multiconfiguration Dirac-Fock calculations with an extended nucleus are used to analyze the volume isotope shifts of the resonance transitions in the group-11a and-11 b elements as well as in Vb. This is done together with a review of the isotope shift theory, including a critical evaluation and comparison of the semiempirical calculation of volume isotope shifts commonly used today. Electronic factors F;, proportional to differences of electronic densities over the nuclear volume, are discussed within various approximations and compared with experimental results. r" over the nuclear charge distribution of the two nuclei. Expression (6) can be written in various ways:4,4Z-44

Relativistic multi-configuration Dirac Fock (MCDF) wavefunctions coupled to good angular momentum J have been ca1culated for low lying states of Ba I and Ba 11. These wavefunctions are compared with semiempirical ones derived from experimental atomic energy levels. It is found that significantly better agreement is obtained when close configurations are included in the MCDF wavefunctions. Ca1culations of the electronic part of the field isotope shift lead to very good agreement with electronic factors derived from experimental data. Furthermore, the slopes of the lines in a King plot analysis of many of the optical lines are predicted accurately by these ca1culations. However, the MCDF wavefunctions seem not to be of sufficient accuracy to give agreement with the experimental magnetic dipole and electric quadrupole hyperfine structure constants.

Relativistic multi-configuration Dirac-Fock wavefunctions, coupled to good angular mornentum J, have been calculated for low lying states of Ba I and Ba 11. The resulting electronic factors show good agreement with data derived from recent high-resolution laser spectroscopy experiments and results from a cornparison of muonic and optical data.

Electronic factors in the volume isotope shift have been calculated in an ab initio way with the relativistic Dirac-Fock method for a number of different optical single/and two-photon transitions in Au I. The agreement with a semi-empirical method is within 10 % for the resonance transition. For this one and a few other transitions the effect of core excitation has been analyzed with the Multi-configuration Dirac-Fock method as well, and it was found to reduce the electronic factor in the order of 5 %.Programs for measurements of nuclear spins, hyperfine structure constants, and isotope shifts (IS) for series of neutron-deficient as well as neutron-rich isotopes have been going on during the last years at the ISOLDE facility at CERN [1][2][3][4][5]. The objective of these investigations is to get information on the single particle structure of the investigated nuclei, to follow trends of nuclear properties for series of isotopes, and isotones as well as to test the validity of different nuclear models [6]. The measurements give the nuclear spins directly, while the evaluation of nuclear moments for a certain isotope, and change of nuclear charge radii between isotopes, requires knowledge of the electronic factor for that particular interaction [7]. The magnetic ground state hyperfine structure, and the nuclear spins have been determined for a number of radioactive Au-isotopes [8][9][10] by the atomicbeam magnetic-resonance method. Information about the quadrupole moment exists only for the stable isotope 197Au [11]. Recently [12][13][14] IS have been measured in the resonance line between 19VAu (stable), and 19SAu (T1/2 = 183d) isotopes at Mainz as a pilot project of systematic IS-measurements for a series of short-lived Au-isotopes at the ISOLDE facility. In this project measurements are planned also for some 6s-ns two-photon transitions. Nuclear data properties, derived from these measurements, then are planned to be used for comparison with data for neighbouring isotopes of Os, Ir, Pt, Hg, TI, and Pb [5,6].Recently, relativistic Multi-configuration Dirac-Fock (MCDF) wave functions, coupled to good angular momentum J, have been obtained for low lying states of Ba I and Ba II [15]. Good agreement was achieved with an electronic factor for the volume isotope shift, evaluated from isotope shifts in muonic X-rays [16], although there is some discrepancy to more recently published muonic X-ray data [17]. The reason for this discrepancy is at present not understood. Further, a comparison of experimental slopes of lines, obtained by a King plot analysis, was found to be reproduced well by these wave functions. Also the J-dependence of the volume IS of the resonance transitions in BaII was found to be in complete agreement with the experimental values [18,19]. These calculations are extended at present to all elements in group IIa and IIb of the periodic table [20]. As a continuation of those calculations we present in this paper electronic factors for a number of transitions within the AuI spectrum, which will be usef...