A quantum electrodynamic theory of two-centre two-photon circular dichroism

Abstract

Expressions for the rate of two-phot on circular dichroism occurring at two identical oriented or completely randomly oriented centres are calculated using perturbation theory and the Fermi golden rule within the framework of non-relativistic quant um electrodynamics. Circular differential absorption in the two-group model arises from the relative dissymmetric juxtaposition of two inherently achiral functional groups. Inter-chromophore coupling is included through the exchange of virtual photons. Absorption of two circularly polarized photons takes place at each centre, and the interference between the two amplitudes depends on the chromophore separation and on the handedness of the incident radiation. In the near zone, the two-centre two-phot on circular dichroism rate is found to depend linearly upon the inter-group separation distance.