Laser-rf double resonance spectroscopy of 174YbF in theX 2Σ+ state: Spin-rotation, hyperfine interactions, and the electric dipole moment

Abstract

We report the first laser-radio-frequency double resonance spectrum of a simple lanthanide compound, the paramagnetic radical 174YbF. Measurements of the rf intervals as a function of the rotational quantum number N allow us to determine precise spin-rotation and fluorine hyperfine interaction coupling constants for the X 2Σ+(v=0 and v=1) ground states of 174YbF. The results for v=0 are γ0=−13.424 00(16) MHz, γ1=3.982 3(11) kHz, γ2=−25(1) mHz, b0=141.795 6(5) MHz, b1=−0.510(11) kHz, c=85.402 6(14) MHz, C=20.38(13) kHz. For v=1 they are γ0=−33.811 8(7) MHz, γ1=4.323(6) kHz, γ2=−28(9) mHz, b0=139.89(4) MHz, b1=−0.7(4) kHz, c=86.75(5) MHz, C=18.3(1) kHz. A direct microwave measurement of the first rotational interval in X 2Σ+(v=0) gives the rotational constant B0=0.241 292 7(7) cm−1. Finally, the Stark shift of hyperfine transitions in the first two rotational states of X 2Σ+(v=0) are analyzed to determine the electric dipole moment μe=3.91(4) D. We find that although the gross structure of YbF in its ground state resembles that of an alkaline earth monofluoride, the 4f shell is evidently important even in the low-lying excited states and leads to unusual behavior in the ground-state magnetic structure.