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Nanofabrication of Gate-defined GaAs/AlGaAs Lateral Quantum Dots
Published on: November 1, 2013
Manipulating photogenerated radical ion pair lifetimes in wirelike molecules using microwave pulses: molecular
Tomoaki Miura1, Michael R Wasielewski
1Department of Chemistry and Argonne-Northwestern Solar Energy Research (ANSER) Center, Northwestern University, Evanston, Illinois 60208-3113, USA.
Abstract:
We have studied spin-dependent charge transfer dynamics in wirelike donor-bridge-acceptor (D-B-A) molecules comprising a phenothiazine (PTZ) donor, an oligo(2,7-fluorene) (FL(n)) bridge, and a perylene-3,4:9,10-bis(dicarboximide) (PDI) acceptor, PTZ-FL(3)-PDI (1) and PTZ-FL(4)-PDI (2), dissolved in the magnetic field-aligned nematic phase of 4-cyano-4'-n-pentylbiphenyl (5CB) at 295 K. Time-resolved EPR spectroscopy using both continuous wave and pulsed microwaves shows that the photogenerated radical pairs (RPs), PTZ(+•)-FL(3)-PDI(-•) and PTZ(+•)-FL(4)-PDI(-•), recombine much faster from the singlet RP manifold than the triplet RP manifold. When a strong resonant microwave π pulse is applied following RP photogeneration in 1 and 2, the RP lifetimes increase about 50-fold as indicated by electron spin-echo detection. This result shows that the RP lifetime can be greatly extended by rapidly switching off fast triplet RP recombination.
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