Microwave/optical double resonance polarisation

Figure 11.1. (a) Principles of the microwave/optical double resonance method, (b) Change of polarisation of fluorescent light resulting from AM= 1 radiofrequency transitions. 

An important development in microwave/optical double resonance, called microwave/optical polarisation spectroscopy, was described by Ernst and Torring [42], The principles of this technique are illustrated in figure 11.22. A linearly polarised probe beam from a tunable laser is sent through the gas sample and a nearly crossed linear polariser, before its final detection. Polarised microwave radiation resonant with a rotational transition in the gas sample is introduced via a microwave horn as shown, and resonant absorption results in a partial change in polarisation of... 

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