Abstract
This chapter refers to the measurement of the net circular polarization in the luminescence as Circularly Polarized Luminescence (CPL) and the use of the acronym CPL. This is now the most widely used term to describe spectroscopic technique, but in the older literature one finds circularly polarized emission (CPE), emission circular intensity differentials (ECID), or the somewhat more specific terms of circularly polarized fluorescence (CPF) or circularly polarized phosphorescence (CPP). All these terms, refer to the spontaneous emission of circularly polarized light by chiral or so-called “optically active” systems. A chiral molecule is one, in which the mirror image isomers are not superimposable. From a molecular symmetry point of view, molecules belonging to point groups that do not contain mirror planes or an inversion center are chiral. All interactions involving light with chiral molecules, discriminate between the two possible circular polarizations (left = L and right = R). In the absence of a perturbing static electric or magnetic field, the light emitted by a molecular chromophore will be partially circularly polarized only if the emitting species are chiral. CPL is becoming increasingly useful as a probe of the existence of chiral lanthanide structures and as an indicator of the changes in chiral structure.
Published Version
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