Abstract: Absorption, Fluorescence and Phosphorescence Spectra of uracil, 1,3-dimethyl uracil, thymine, 1,3-dimethylthymine, 6-aza-uracil, 1,3-dimethyl-6-aza-uracil, 6-aza-thymine, 1,3-dimethy-6-aza-thymine, guanine and 8-aza-guanine were determined. Relationship of molecular structure with photophysics and excited state was discussed.
The conclusion is that the singlet state of these compounds is neither pure ~1(n, π~*) nor pure ~1(π, π~*). It is suitable when the mixing state was used to describe the singlet state of the compounds.