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 SF. The LIF excitation spectrum of the (0, 0) band in the BΣ-XΠ system of the PbF, PbF, and PbF isotopologues has been recorded with rotational, fine structure, and hyperfine-structure resolution. Transitions in the LIF spectrum were assigned and combined with the previous XΠ-XΠ emission spectrum in the near-infrared region [Ziebarth et al., J. Mol. Spectrosc. 191, 108-116 (1998)] and the XΠ 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 (XΠ) and the excited (BΣ) 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 Pb is discussed.