Influence of triplet states on single donor-acceptor pair fluorescence

Single donor-acceptor (D-A) pairs whose molecules have both singlet and triplet states are considered. Fluorescence of such D-A pair has two types of fluctuations: fluctuations due to singlet-triplet transitions and fluctuations because of energy transfer in D-A pair. Both types of fluctuations mani...

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Bibliographic Details
Published in:Chemical physics 2019-09, Vol.525, p.110401, Article 110401
Main Author: Osad'ko, I.S
Format: Article
Language:English
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Summary:Single donor-acceptor (D-A) pairs whose molecules have both singlet and triplet states are considered. Fluorescence of such D-A pair has two types of fluctuations: fluctuations due to singlet-triplet transitions and fluctuations because of energy transfer in D-A pair. Both types of fluctuations manifest themselves in the duration of on/off intervals in fluorescence trajectories. Triplet state in the donor molecule creates off-intervals in D- and A-fluorescence. However, it does not influence FRET efficiency E. Another picture we will observe if we take into account triplet state in the acceptor molecule. This state influences FRET efficiency distribution S(E) considerable. 1) Acceptor triplet state hampers energy transfer in D-A pair and changes expression for S(E). 2) Acceptor triplet state is responsible for appearance off-intervals in A-fluorescence and dual d-fluorescence: bright and moderate. Fluctuating D- and A-fluorescence are simulated with the help of Monte Carlo method. Dual d-fluorescence of single D-A pair creates FRET efficiency distribution S(E) with two maxima.
ISSN:0301-0104
DOI:10.1016/j.chemphys.2019.110401