Charge separation and charge delocalization identified in long-living states of photoexcited DNA.

ABSTRACT: Base stacking in DNA is related to long-living excited states whose molecular nature is still under debate. To elucidate the molecular background we study well-defined oligonucleotides with natural bases, which allow selective UV excitation of one single base in the strand. IR probing in the picosecond regime enables us to dissect the contribution of different single bases to the excited state. All investigated oligonucleotides show long-living states on the 100-ps time scale, which are not observable in a mixture of single bases. The fraction of these states is well correlated with the stacking probabilities and reaches values up to 0.4. The long-living states show characteristic absorbance bands that can be assigned to charge-transfer states by comparing them to marker bands of radical c

SUBMITTER: Bucher DB 

PROVIDER: S-EPMC3970531 | biostudies-literature | 2014 Mar

REPOSITORIES: biostudies-literature