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Published on: October 18, 2018
Ultrafast spectroscopy of even-parity states in pi-conjugated polymers
Frolov1, Bao, Wohlgenannt
1Bell Laboratories, Lucent Technologies, 600 Mountain Avenue, Murray Hill, New Jersey 07974, USA.
Abstract:
Relaxation dynamics of even parity ( A(g)) states in poly( p-phenylene vinylene) derivatives are studied using a novel fsec transient spectroscopy, in which two different excitation pulses successively generate odd parity ( 1 (1)B(u)) excitons at 2.2 eV and then reexcite them to higher A(g) states. For reexcitation energies Planck's over 2piomega<1.1 eV ultrafast internal conversion back to 1 (1)B(u) takes place in accordance with Vavilov-Kasha's rule. However, for Planck's over 2piomega>1.1 eV the decay occurs in a nonemissive state identified as a polaron pair, showing that the A(g) states above 3.3 eV mediate charge transfer.
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