Fig. 8. (a) The split excited states of two degenerate exciton-coupled chromophores. (b) The excitonic components (green, red) to the absorption (top) and CD (bottom) spectra and their overall observable spectra (purple). The CD spectra reveals the bisignate couplet (often referred to as a Cotton effect) typical of such coupling.55 (c) Schematic diagram of two chromophores highlighting the key quantities that determine the rotational strength R. The terms μ1, μ2 and r12 describe the two electric transition dipoles and their mutual distance.
