Excited States of Nucleotides and Singlet Energy Transfer in Polynucleotides

摘要: We have measured the absorption, fluorescence, and phosphorescence spectra of nucleotides at 77°K. The order decreasing energies is A, U, T, G, C for singlet, U−, C, T−, T triplet. Besides quantum yields fluorescence phosphorescence, we also determined yield intersystem crossing to triplet, using amplitude Δm=2 triplet ESR signal. find internal conversion occurring from both singlet states. From excitation in neutral ionized molecules, stability ionizable proton excited states can be compared that ground state, results are applied question transfer A DNA.From a discussion various cases intermolecular energy singlets, considering broadband nucleotides, it shown Forster's ``very weak case'' applicable. emphasize two subcases must distinguished, depending on whether occu...