Screening hypochromism in molecular aggregates and biopolymers.

An improved model of the screening effect is suggested. Mutual ≪shielding≫ of chromophores from light due to competition for the incident photon can take place in molecular aggregates and macromolecules. From a common point of view, it could be interpreted as in ≪interaction≫ of the absorption dipol moment transitions. Screening leads to a decrease in the extinction coefficient. The largest decrease is observed in the maximum of the absorption band. This is demonstrated with chromophores of adenine, tyrosine, tryptophan, retinol, porphyrin and anthracene. The model enables prediction of hypochromic spectra or evaluation of the quantity of chromophores in an aggregate or macromolecule.