Optical Double-Resonance and Level-Crossing Experiments with Laser Excitation

3 Optical Double-Resonance and Level-Crossing Experiments with Laser Excitation 

In Fig.9.16 a fluorescence light spectrum for Cs is given as recorded with the apparatus shown in Fig.9.I5. The 12 Dg/2 state is populated by step-wise excitation. In cascade decays, as illustrated in Fig.9.1, lower-lying P and F levels are populated and fluorescence lines are obtained in the blue and UV, and in the red spectral regions, respectively. 

If the primary excitation is performed, e.g., with tt light (Fig.4.9) the magnetic sublevels of the Dg/2 state will be non-uniformly populated. The 

In Chap. 7 we have discussed how hyperfine structure can be determined by level-crossing spectroscopy. Clearly, alkali atom states can readily be studied using this technique after step-wise excitation. We will here instead choose an example illustrating fine-structure measurements. In Fig.9.17 the example of the inverted sodium 4d 05/2,3/2 given. 

From the measured level-crossing positions the fine-structure splitting can be calculated using the Breit-Rabi formula for the fine structure, (2.31). 

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