Optical pumping magnetic resonance

Fig,17.9. Schematic diagram of the apparatus required for optical pumping magnetic resonance experiments. 

It is also found that the position of the centre Oi. tne resonance depends on the intensity of the pumping radiation for reasons which are discussed in section 17.9.7. Consequently it is necessary to make a series of measurements at different light intensities and to extrapolate the results to zero intensity in order to find the position of the unperturbed resonance. Although all of the g-factor ratios included in Table 17.3 are of interest since they provide tests of the theoretical calculation of atomic g-factors, the ratio for the free electron is of particular importance in the determination of fundamental atomic constants (Problem 17.6). The application of the optical pumping magnetic resonance technique to the determination of atomic hyperfine structures is equally important and is described in Chapter 18. 

Gupta, R., Happer, W., Moe, G. and Park, W. (1974). Nuclear magnetic resonance of diatomic molecules in optically pumped alkali vapors, Phys. Rev. Lett., 32, 574-577. 

Kamke, W. (1975). Nuclear magnetic resonance of K2 in optically pumped potassium vapor, Phys. Lett. A, 55, 15-16. 

Miller, et al., (1974) used MOMRIE (Microwave Optical Magnetic Resonance Induced by Electrons) complementarily with anticrossing spectroscopy in experiments on He, H2, and other molecules. Small differences in electron bombardment excitation cross-sections combined with different radiative lifetimes lead to steady-state population differences between initial and final levels of the microwave transition. By monitoring fluorescence from one of the two involved electronic states, a change in fluorescence intensity signals a microwave resonance. Electron bombardment excitation tends to produce smaller population differences than the chemical pumping scheme exploited in the CN experiments, but the MOMRIE technique is more generally applicable. 

Millimeter wave spectroscopy with a free space cell such as a Broida oven is more sensitive than lower frequency microwave spectroscopy. However, the higher J transitions monitored by millimeter wave spectroscopy often do not show the effects of hyperfine structure. In the case of CaOH and SrOH, the proton hyperfine structure was measured in beautiful pump-probe microwave optical double resonance experiments in the Steimle group [24,68], They adapted the classic atomic beam magnetic resonance experiments to work with a pulsed laser vaporization source and replaced the microwave fields in the A and C regions by optical fields (Fig. 15). These sensitive, high-precision measurements yielded a very small value for the proton Fermi contact parameter (bF), consistent with ionic bonding and a... 

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