Phase optical-microwave system

Solvent-free conditions can be employed according to three main methods (a) using only neat reactants (b) reactants adsorbed onto solid supports or (c) reactants in the presence of phase transfer catalysts (in the case of anionic reactions). Besides the apparent potential benefits in solvent usage, reactions can be conducted conveniently and rapidly, often without temperature measurement in domestic microwave ovens. However, they now are often carried out under more precisely controlled conditions using monomode reactors initially introduced by the former French manufacturer Prolabo. Nowadays, several systems are available that provide facilities for the accurate measurement and monitoring of temperature throughout the reaction by modulation of emitted power with an infrared detector or an optical fibre. 

Field splitting of energy levels (see Fig. 2.8) can also be observed in transitions from level 1 or 2 to some third level. As a result, of this sphtting, the spectral line of the 2 —> 3 transition is split into two hnes (Fig. 2.8(b)). This phenomenon was first observed in microwave spectroscopy (the Autler-Townes effect (Autler and Townes 1955)). In the optical region of the spectrum and in the presence of phase relaxation, such a splitting can apparently be observed only if condition (2.62) is satisfied, that is, when the response of the two-level system to the laser-light field is truly oscillatory. 

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