Optical-Radio-Frequency Double Resonance

German, K.R., Bergman, T.H., Weinstock, E.M. and Zare, R.N. (1973). Zero-field level crossing and optical radio-frequency double resonance studies of the A2E+ states of OH and OD, J. Chem. Phys., 58, 4304-4318. 

Fig. 5.7 Optical-radio frequency double resonance for lower and upper level of the optical transition...

H.G. Weber, P. Brucat, W. Demtrbder, R.N. Zare, Measurement of N02 B2 state g-values by optical radio frequency double-resonance. J. Mol. Spectrosc. 75, 58 (1979)... 

Figure 11.8. Hyperfine levels in OH and OD in the excited A2E+ state studied by radio frequency/ optical double resonance. The splittings are not to scale.

Figure 11.40. Hyperfine and spin-rotation splitting of atypicalrotational level intheX2E+ state of YO, and the magnetic dipole transitions observed by radio frequency/optical double resonance.

Figure 11.52. Energy level diagram for typical even-/V and odd-/V rotational levels of the X 2 + state of 14Nj. The principal P-branch optical pumping transitions to the B 2 + excited state, Pi (IV) and P2(Ar)> are shown, as well as the principal radio frequency double resonance transitions in the ground state. The I = 0, F = J levels are not shown, but lie close to the I = 2, F = J levels [99].

RFODR radio frequency optical double resonance... 

This change ANi of the population density can be probed by a second EM wave, which may be a radio frequency (RE) field, a microwave, or another laser beam. If this probe wave is tuned into resonance with a molecular transition sharing one of the two levels /) or A ) with the pump transition, the pump laser and the probe wave are simultaneously in resonance with the coupled atomic or molecular transitions (Fig. 5.1). This situation is therefore called optical-RF, optical-microwave or optical-optical double resonance. 

Even this double-resonance spectroscopy has already been applied to the study of atomic transitions before lasers were available. In these pre-laser experiments incoherent atomic resonance lamps served as pump sources and a radio frequency field provided probe transitions between Zeeman levels of optically excited atomic states [509]. However, with tunable lasers as pump sources, these techniques are no longer restricted to some special favorable cases, and the achievable signal-to-noise ratio of the double-resonance signals may be increased by several orders of magnitude [510]. 

Figure 8.31 illustrates the concept of optical-rf double resonance. The sample is placed in a radio frequency field produced by an rf current through a coil. 

---