Research output: Contribution to journal › Article › peer-review
The Quantum Dynamical Basis of a Classical Kinetic Scheme Describing Coherent and Incoherent Regimes of Radical Pair Recombination. / Lukzen, Nikita N.; Klein, Johannes H.; Lambert, Christoph et al.
In: Zeitschrift fur Physikalische Chemie, Vol. 231, No. 2, 01.02.2017, p. 197-223.Research output: Contribution to journal › Article › peer-review
}
TY - JOUR
T1 - The Quantum Dynamical Basis of a Classical Kinetic Scheme Describing Coherent and Incoherent Regimes of Radical Pair Recombination
AU - Lukzen, Nikita N.
AU - Klein, Johannes H.
AU - Lambert, Christoph
AU - Steiner, Ulrich E.
N1 - Publisher Copyright: © 2017 Walter de Gruyter GmbH, Berlin/Boston 2017.
PY - 2017/2/1
Y1 - 2017/2/1
N2 - In recent work from this group (J. H. Klein et al. J. Am. Chem. Soc. 2015, 137, 11011), the magnetic field dependent charge recombination kinetics in donor/Ir-complex/acceptor triads has been determined with outstanding accuracy and reproducibility. The field-dependent kinetics has been analyzed in terms of a classical reaction scheme including the field-independent rate parameters of singlet recombination (rate constant kS) and S/T0 mixing (rate constant kST0) and the field-dependent rate constant k±(B) connecting central and outer Zeeman levels. In the present work, the extraction of k± from the experimental data is more precisely defined and the appearance of a "coherent" and "incoherent" regime of spin motion in a double log plot of k± vs. B is confirmed. The experimental decay curves have been reproduced by a full quantum dynamical model based on the stochastic Liouville equation, which was solved numerically, taking into account isotropic hyperfine coupling with five nuclear spins (1 N on donor radical, 4 H on acceptor radical) and anisotropic hyperfine coupling with the nitrogen nucleus at the donor radical. The results of the quantum calculations serve as a rigorous basis of interpreting the classical parameter k±. Furthermore, it is demonstrated that the incoherent part of spin motion is essential for a full understanding of the charge recombination kinetics even in the "coherent" regime.
AB - In recent work from this group (J. H. Klein et al. J. Am. Chem. Soc. 2015, 137, 11011), the magnetic field dependent charge recombination kinetics in donor/Ir-complex/acceptor triads has been determined with outstanding accuracy and reproducibility. The field-dependent kinetics has been analyzed in terms of a classical reaction scheme including the field-independent rate parameters of singlet recombination (rate constant kS) and S/T0 mixing (rate constant kST0) and the field-dependent rate constant k±(B) connecting central and outer Zeeman levels. In the present work, the extraction of k± from the experimental data is more precisely defined and the appearance of a "coherent" and "incoherent" regime of spin motion in a double log plot of k± vs. B is confirmed. The experimental decay curves have been reproduced by a full quantum dynamical model based on the stochastic Liouville equation, which was solved numerically, taking into account isotropic hyperfine coupling with five nuclear spins (1 N on donor radical, 4 H on acceptor radical) and anisotropic hyperfine coupling with the nitrogen nucleus at the donor radical. The results of the quantum calculations serve as a rigorous basis of interpreting the classical parameter k±. Furthermore, it is demonstrated that the incoherent part of spin motion is essential for a full understanding of the charge recombination kinetics even in the "coherent" regime.
KW - charge recombination
KW - linked radical pairs
KW - spin chemistry
KW - spin relaxation
UR - http://www.scopus.com/inward/record.url?scp=85012196178&partnerID=8YFLogxK
U2 - 10.1515/zpch-2016-0833
DO - 10.1515/zpch-2016-0833
M3 - Article
AN - SCOPUS:85012196178
VL - 231
SP - 197
EP - 223
JO - Zeitschrift fur Physikalische Chemie
JF - Zeitschrift fur Physikalische Chemie
SN - 0942-9352
IS - 2
ER -
ID: 18177068