Observables in CPL spectroscopy

The measured quantities in CPL spectroscopy are the difference of intensity (A/) of the left handed (/l) and right handed (7r) circularly polarized components of the emitted light, and the total luminescence intensity (I) emitted by the sample  

As discussed in the previous section, if CPL occurs the values 4(A) and 4( l) are different and the total luminescence shows a partial circular polarization (the emitted light is elliptically polarized). In a CPL experiment one can either measure directly A/(A) or determine Ii (X) and 4(- ) separately. In both cases the key problem of the experiment is to make a reliable measurement, because the difference between 4( ) and 4( ) is usually very small. 

The emission dissymmetry factor, gem( ) can be calculated from these quantities  

The experimental determination of the emission intensity in absolute units is quite complex as it commonly happens in luminescence measurements, /(A) and A/(A) are often measured in arbitrary units, which are dependent on the equipment and the experimental conditions adopted. The dissymmetry factor gem(- ) is a significant quantity because it is a ratio of emission intensities and is therefore unaffected by the instrumental and experimental parameters. Its value gives an absolute quantification of the chirality of the emitting excited state. 

293 K) [33], The CPL signal is noisy because it is very weak. The lower part of the figure shows the values of the absorption and emission dissymmetry factors measured at specific frequencies 

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