Laser-rf Double-Resonance Spectroscopy

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 X2∑+(v =0 and v = 1) ground states of 174YbF. The results for v=0 are γ0=-13.424 00(16) MHz, γ1=3.9823(11) kHz, γ2=-25(1) mHz, b0= 141.795 6(5) MHz, b1, = -0.510(11) kHz, c = 85.4026(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 X2∑+(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 X2∑+(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 monofiuoride, the 4f shell is evidently important even in the low-lying excited states and leads to unusual behavior in the ground-state magnetic structure. © 1996 American Institute of Physics.