ISOTOPE SHIFT AND HYPERFINE-STRUCTURE IN THE ATOMIC SPECTRUM OF HAFNIUM BY LASER SPECTROSCOPY

The isotope shift and the hyperfine structure of 14 spectral lines of Hf I were investigated using high-resolution laser spectroscopy of a well-collimated beam of Hf atoms. The hyperfine splitting constants A and B of the electronic states 5G5,..., 5G2, F-5(3) of the excited configuration 5d(2)6s6p and of some electronic states of 5d6s(2)6p were obtained for the two stable odd isotopes Hf-179 and Hf-178. From these data one-electron hyperfine splitting parameters could be deduced, e.g., a6s, = 3.08(15) GHz for the magnetic dipole part in the case of Hf-177. Our accurate experimental values of the isotope shifts between the stable Hf isotopes 174,176-180 allow a reliable separation of the effect of the specific mass shift and of the field shift for all observed spectral lines. Using the field shift of the 545.29-nm line, which corresponds to an almost pure 5d(2)6s2-5d(2)6s6p transition, the change in mean-square nuclear charge radius between Hf-178 and Hf-180 was determined to be delta[r2]=0.098(13) fm2. Values of delta[r2] for the Hf isotopes 174, 176, 177, and 179 referred to Hf-178 are also available from the present work.