SPIN RELAXATION AND STRUCTURE OF LIGHT-INDUCED SPIN-CORRELATED PCBM
-/P3HT
+ RADICAL PAIRS
M.N. Uvarov1, A.G. Popov1,2, E.A. Lukina1,2, L.V. Kulik1,2
1Voevodskii Institute of Chemical Kinetics and Combustion, Siberian Branch, Russian Academy of Sciences, Novosibirsk, Russia
2Novosibirsk State University, Russia
Keywords: спин-коррелированная радикальная пара, фуллерены, проводящие полимеры, электронный парамагнитный резонанс, электронное спиновое эхо, spin-correlated radical pair, fullerenes, conducting polymers, electron paramagnetic resonance, electron spin echo
Abstract
The electron spin echo (ESE) method is applied to determine the spin relaxation times of long-term light-induced radicals and short-term spin-correlated radical pairs (SCRPs) formed during pulse laser irradiation of a composite consisting of phenyl-С
61-butyric acid methyl ether (PCBM) and poly-(3-hexylthiophene) (P3HT) at 80 K. Dependences of the ESE signal recorded to measure the longitudinal relaxation times of P3HT
+/PCBM
- SCRPs and the free P3HT
+ radical are found to be approximated by the dependence of the form exp(-(
t/
T
1)
0
.
6) with parameters
Т
1 lying in the microsecond range. By means of the instantaneous diffusion model the difference in the transverse spin relaxation times of the P3HT
+/PCBM
- radical pair at complete and incomplete microwave pulse excitation of the echo-detected EPR spectrum is explained. Based on it, the magnetic interaction energy between the electron spins in P3HT
+/PCBM
- SCRPs is estimated;
E/
ћ ~ 10
6 s
-1.
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