The expression for TPCD, defined as, \ Delta \ delta ( \ lambda ) = \ delta _ L ^ { TPA } ( \ lambda )-\ delta _ R ^ { TPA } ( \ lambda ), was obtained by Tinoco in his 1975 paper as a semiclassical extension of the TPA formulae . and, in a series of papers, by Meath and Power who were able to generalize the approach to the case of " n " photons, and considered also the modifications occurring in the formulae when elliptical polarization is assumed.
