Quantum beats in radical pairs

Bagryansky, V. A.; Borovkov, V. I.; Molin, Yuri N.

doi:10.1070/rc2007v076n06abeh003715

Cited by 54 publications

(70 citation statements)

References 14 publications

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“…The time dependence of the spin density operator in the absence of spin relaxation and chemical reactions was obtained from the von Neumann equation, and the chemical fate of the RP was modeled by means of separate first-order spin-selective reactions of the singlet and triplet pairs. Spin relaxation was introduced phenomenologically following Bagryansky et al [ 35 ]. The derivation of Eq 6 has been given below.…”

Section: Methodsmentioning

confidence: 99%

Radical pairs may explain reactive oxygen species-mediated effects of hypomagnetic field on neurogenesis

et al. 2022

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Exposures to a hypomagnetic field can affect biological processes. Recently, it has been observed that hypomagnetic field exposure can adversely affect adult hippocampal neurogenesis and hippocampus-dependent cognition in mice. In the same study, the role of reactive oxygen species (ROS) in hypomagnetic field effects has been demonstrated. However, the mechanistic reasons behind this effect are not clear. This study proposes a radical pair mechanism based on a flavin-superoxide radical pair to explain the modulation of ROS production and the attenuation of adult hippocampal neurogenesis in a hypomagnetic field. The results of our calculations favor a singlet-born radical pair over a triplet-born radical pair. Our model predicts hypomagnetic field effects on the triplet/singlet yield of comparable strength as the effects observed in experimental studies on adult hippocampal neurogenesis. Our predictions are in qualitative agreement with experimental results on superoxide concentration and other observed ROS effects. We also predict the effects of applied magnetic fields and oxygen isotopic substitution on adult hippocampal neurogenesis.

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Section: Methodsmentioning

confidence: 99%

Radical pairs may explain reactive oxygen species-mediated effects of hypomagnetic field on neurogenesis

et al. 2022

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“…For example, a bimolecular electron transfer reaction between an excited triplet electron donor and a closed shell acceptor would produce a pair of ion radicals in a triplet state. However, singlet and triplet are rarely eigenstates of the spin Hamiltonian, with the consequence that the spin state of the radical pair evolves coherently at frequencies and with amplitudes determined by the internal and external magnetic interactions of the electron spins [3]. Simultaneously, the singlet and triplet radical pairs react at different rates to form distinct reaction products.…”

Section: Introductionmentioning

confidence: 99%

Spin-selective reactions of radical pairs act as quantum measurements

Jones

Hore

2010

Chemical Physics Letters

135

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Since the 1970s, spin-selective reactions of radical pairs have been modelled theoretically by adding phenomenological rate equations to the quantum mechanical equation of motion of the radical pair spin density matrix. Here, using a quantum measurement approach, we derive an alternative set of rate expressions which predict a faster decay of coherent superpositions of the singlet and triplet radical pair states. The difference between the two results, however, is not dramatic and would probably be difficult to distinguish experimentally from decoherence arising from other sources. The interactions that determine the coherent singlet-triplet interconversion of a radical

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“…Spin relaxation was introduced phenomenologically (compare equation (19) of Bagryansky et al, 2007) as:true0pT(t) = 34 + (pTnormal′(t)−34)exp⁡(−rt),where true0r is the relaxation rate constant.…”

Section: Methodsmentioning

confidence: 99%

Upper bound on the biological effects of 50/60 Hz magnetic fields mediated by radical pairs

Hore

2019

eLife

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Prolonged exposure to weak (~1 μT) extremely-low-frequency (ELF, 50/60 Hz) magnetic fields has been associated with an increased risk of childhood leukaemia. One of the few biophysical mechanisms that might account for this link involves short-lived chemical reaction intermediates known as radical pairs. In this report, we use spin dynamics simulations to derive an upper bound of 10 parts per million on the effect of a 1 μT ELF magnetic field on the yield of a radical pair reaction. By comparing this figure with the corresponding effects of changes in the strength of the Earth’s magnetic field, we conclude that if exposure to such weak 50/60 Hz magnetic fields has any effect on human biology, and results from a radical pair mechanism, then the risk should be no greater than travelling a few kilometres towards or away from the geomagnetic north or south pole.

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Quantum beats in radical pairs

Cited by 54 publications

References 14 publications

Radical pairs may explain reactive oxygen species-mediated effects of hypomagnetic field on neurogenesis

Radical pairs may explain reactive oxygen species-mediated effects of hypomagnetic field on neurogenesis

Spin-selective reactions of radical pairs act as quantum measurements

Upper bound on the biological effects of 50/60 Hz magnetic fields mediated by radical pairs

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