Hyperfine and Zeeman studies of low-lying atomic levels of 181Ta and the nuclear electric quadrupole moment

The hyperfine structure of the atomic levels 5d36s24F7sub(/)2, 9sub(/)2 and 4 P1sub(/)2 in 181Ta has been studied by atomic-beam magnetic-resonance. Using intermediate coupling wave functions derived for the configurations (5d + 6s)5 the hyperfine structure data of six low-lying metastable states have been analyzed with respect to the effective operator formalism. The effective radial paramters for the magnetic dipole and electric quadrupole interactions are determined from these measurements and compared with relativistic calculations. The value obtained for the spectroscopic quadrupole moment of the 181Ta nuclear ground state is Qsub(h)sub(f)sub(s) = 3.44(17) barn (uncorrected for configuration interaction effects). (orig.)