HYPERFINE-STRUCTURE STUDIES OF NB-93 BY 3-STEP RESONANCE IONIZATION SPECTROSCOPY

The hyperfine structure of Nb-93 is studied by three-step resonance io nization spectroscopy with electric field ionization. The atomic beam is produced by thermal evaporation. The hyperfine splitting of eight J = 1/2 states, namely the ground state, five odd-parity states belongi ng to the configurations 4d(4)5p and 4d(3)5s5p, and two high-lying eve n-parity states belonging to the configurations 4d(4)6s and 4d(3)5s6s, is reported. The convergence limit of a Rydberg series obtained by ex citing one of the even-parity states is determined. The possibility of isomer (Nb-93m) selective laser excitation and ionization of niobium is discussed in relation to fast-neutron fluence monitoring by an acti vation reaction of niobium.