ISOTOPE SHIFTS FOR THE 5D(5)6S7S AND 5D(5)6S6D CONFIGURATIONS OF RE-I

The isotope shift and hyperfine structure in a rhenium hollow cathode discharge was studied for transitions of the type 5d(5)6s7s --> 5d(5)6s6p and 5d(5)6s6d --> 5d(5)6s6p through Doppler-free saturation absorption laserspectroscopy and high resolution interferometry. Taking configuration mixing in the lower levels of 5d(5)6s6p under consideration, we obtain average configuration isotope shift values for 5d(5)6s7s of -1760(100) MHz and for 5d(5)6s6d of -1930(200) MHz. These experimental values compare extremely well with the theoretically predicted configuration isotope shifts in rhenium, based on pseudo-relativistic Hartree-Fock calculations, of -1710 MHz and -1940 MHz, resp. In addition hyperfine structure constants for rhenium levels of 5d(5)6s6d are reported here for the first time