Interplay between "neutral" and "charge-transfer"excimers rules the excited state decay in adenine-rich polynucleotides

The excited states of (dA)4 oligonucleotides (A=adenine), including the phosphoribose backbone, were studied in water at a fully quantum mechanical level, providing an atomistic description of the main decay paths and a comprehensive interpretation of the experimental data (see picture). After absorption to exciton states delocalized over multiple A bases, the behavior of the excited state is ruled by the interplay of a number of species responsible for different spectral features.