Both intra- and interstrand charge-transfer excited states in aqueous B-DNA are present at energies comparable to, or just above, the [super 1][pi][pi]* excitonic bright states

Vertical electronic excitations in model systems representing single- and double-stranded B-DNA are characterized by using electronic structure theory and are compared to the optically bright [super 1][pi][pi]* states. The studies have shown that a single Watson-Crick base pair is an inadequate model of the photophysics of B-DNA.