Asymmetric recombination and electron spin relaxation in the semiclassical theory of radical pair reactions.

We describe how the semiclassical theory of radical pair recombination reactions recently introduced by two of us [D. E. Manolopoulos and P. J. Hore, J. Chem. Phys. 139, 124106 (2013)] can be generalised to allow for different singlet and triplet recombination rates. This is a non-trivial generalisa...

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मुख्य लेखकों: Lewis, A, Manolopoulos, D, Hore, P
स्वरूप: Journal article
भाषा:English
प्रकाशित: 2014
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author Lewis, A
Manolopoulos, D
Hore, P
author_facet Lewis, A
Manolopoulos, D
Hore, P
author_sort Lewis, A
collection OXFORD
description We describe how the semiclassical theory of radical pair recombination reactions recently introduced by two of us [D. E. Manolopoulos and P. J. Hore, J. Chem. Phys. 139, 124106 (2013)] can be generalised to allow for different singlet and triplet recombination rates. This is a non-trivial generalisation because when the recombination rates are different the recombination process is dynamically coupled to the coherent electron spin dynamics of the radical pair. Furthermore, because the recombination operator is a two-electron operator, it is no longer sufficient simply to consider the two electrons as classical vectors: one has to consider the complete set of 16 two-electron spin operators as independent classical variables. The resulting semiclassical theory is first validated by comparison with exact quantum mechanical results for a model radical pair containing 12 nuclear spins. It is then used to shed light on the spin dynamics of a carotenoid-porphyrin-fullerene triad containing considerably more nuclear spins which has recently been used to establish a "proof of principle" for the operation of a chemical compass [K. Maeda, K. B. Henbest, F. Cintolesi, I. Kuprov, C. T. Rodgers, P. A. Liddell, D. Gust, C. R. Timmel, and P. J. Hore, Nature (London) 453, 387 (2008)]. We find in particular that the intriguing biphasic behaviour that has been observed in the effect of an Earth-strength magnetic field on the time-dependent survival probability of the photo-excited C(·+)PF(·-) radical pair arises from a delicate balance between its asymmetric recombination and the relaxation of the electron spin in the carotenoid radical.
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spelling oxford-uuid:851433ed-f94d-4a4d-82dd-bfe28f3efd2a2022-03-26T21:55:05ZAsymmetric recombination and electron spin relaxation in the semiclassical theory of radical pair reactions.Journal articlehttp://purl.org/coar/resource_type/c_dcae04bcuuid:851433ed-f94d-4a4d-82dd-bfe28f3efd2aEnglishSymplectic Elements at Oxford2014Lewis, AManolopoulos, DHore, PWe describe how the semiclassical theory of radical pair recombination reactions recently introduced by two of us [D. E. Manolopoulos and P. J. Hore, J. Chem. Phys. 139, 124106 (2013)] can be generalised to allow for different singlet and triplet recombination rates. This is a non-trivial generalisation because when the recombination rates are different the recombination process is dynamically coupled to the coherent electron spin dynamics of the radical pair. Furthermore, because the recombination operator is a two-electron operator, it is no longer sufficient simply to consider the two electrons as classical vectors: one has to consider the complete set of 16 two-electron spin operators as independent classical variables. The resulting semiclassical theory is first validated by comparison with exact quantum mechanical results for a model radical pair containing 12 nuclear spins. It is then used to shed light on the spin dynamics of a carotenoid-porphyrin-fullerene triad containing considerably more nuclear spins which has recently been used to establish a "proof of principle" for the operation of a chemical compass [K. Maeda, K. B. Henbest, F. Cintolesi, I. Kuprov, C. T. Rodgers, P. A. Liddell, D. Gust, C. R. Timmel, and P. J. Hore, Nature (London) 453, 387 (2008)]. We find in particular that the intriguing biphasic behaviour that has been observed in the effect of an Earth-strength magnetic field on the time-dependent survival probability of the photo-excited C(·+)PF(·-) radical pair arises from a delicate balance between its asymmetric recombination and the relaxation of the electron spin in the carotenoid radical.
spellingShingle Lewis, A
Manolopoulos, D
Hore, P
Asymmetric recombination and electron spin relaxation in the semiclassical theory of radical pair reactions.
title Asymmetric recombination and electron spin relaxation in the semiclassical theory of radical pair reactions.
title_full Asymmetric recombination and electron spin relaxation in the semiclassical theory of radical pair reactions.
title_fullStr Asymmetric recombination and electron spin relaxation in the semiclassical theory of radical pair reactions.
title_full_unstemmed Asymmetric recombination and electron spin relaxation in the semiclassical theory of radical pair reactions.
title_short Asymmetric recombination and electron spin relaxation in the semiclassical theory of radical pair reactions.
title_sort asymmetric recombination and electron spin relaxation in the semiclassical theory of radical pair reactions
work_keys_str_mv AT lewisa asymmetricrecombinationandelectronspinrelaxationinthesemiclassicaltheoryofradicalpairreactions
AT manolopoulosd asymmetricrecombinationandelectronspinrelaxationinthesemiclassicaltheoryofradicalpairreactions
AT horep asymmetricrecombinationandelectronspinrelaxationinthesemiclassicaltheoryofradicalpairreactions