Fine and hyperfine interactions of PbF studied by laser-induced fluorescence spectroscopy

The fine and hyperfine interactions in PbF have been studied using the laser-induced fluorescence (LIF) spectroscopy method. Cold PbF molecular beam was produced by laser-ablating a Pb rod under jet-cooled conditions, followed by the reaction with SF₆. The LIF excitation spectrum of the (0, 0) band in the B²Σ⁺-X²Π_1/2 system of the ²⁰⁸PbF, ²⁰⁷PbF, and ²⁰⁶PbF isotopologues has been recorded with rotational, fine structure, and hyperfine-structure resolution. Transitions in the LIF spectrum were assigned and combined with the previous X²Π_3/2-X²Π_1/2 emission spectrum in the near-infrared region [Ziebarth et al., J. Mol. Spectrosc. 191, 108-116 (1998)] and the X²Π_1/2 state pure rotational spectrum of PbF [Mawhorter et al., Phys. Rev. A 84, 022508 (2011)] in a global fit to derive the rotational, spin-orbit, spin-rotation, and hyperfine interaction parameters of the ground (X²Π_1/2) and the excited (B²Σ⁺) electronic states. Molecular constants determined in the present work are compared with previously reported values. Particularly, the significance of the hyperfine parameters, A_⊥ and A_‖, of ²⁰⁷Pb is discussed.