Circular Polarization - Circularly Polarized Luminescence

Circularly polarized luminescence (CPL) can occur when either a luminophore or an ensemble of luminophores is chiral. The extent to which emissions are polarized is quantified in the same way it is for circular dichroism, in terms of the dissymmetry factor, also sometimes referred to as the anisotropy factor. This value is given by

where corresponds to the quantum yield of left-handed circularly polarized light, and to that of right-handed light. The maximum absolute value of g_em, corresponding to purely left- or right-handed circular polarization, is therefore 2. Meanwhile the smallest absolute value that g_em can achieve, corresponding to linearly polarized or unpolarized light, is zero.