Magnetic Field Influence on Dynamics of Singlet‐Triplet Conversion

Makarov, Vladimir I.; Khmelinskii, Igor

doi:10.1002/9780470141786.ch2

Cited by 6 publications

(3 citation statements)

References 154 publications

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“…During the oxidation process of oxalate, both singlet and triplet radical pairs are generated. An applied magnetic field could facilitate the spin evolution from singlet to triplet in spin-correlated radical pairs ,− and largely raise the triplet yield. Because of the triplet radical pair owning larger dissociation probability than the singlet radical pair, the increase of triplet yield could promote the oxidation process of oxalate and enhance the oxidation current.…”

Section: Introductionmentioning

confidence: 99%

Large Magneto-Current Effect in the Electrochemical Detection of Oxalate in Aqueous Solution

et al. 2018

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Herein, we first report an interesting observation of a large magneto-current (MC) of nearly 30% based on the electrochemical oxidation of oxalate in aqueous solution at room temperature. The large MC is ascribed to spin-dependent oxidation of oxalate. Both singlet and triplet radical pairs are generated during the electrochemical oxidation of oxalate. An applied magnetic field could accelerate the spin evolution of a singlet radical pair into its triplet state. The triplet radical pair has a much larger dissociation probability than the singlet radical pair because of the Pauli exclusion principle. Thus, enhancing the triplet yield could largely increase the oxidation rate of oxalate and generate significant MC. The significant MC effect provides a new approach to study spin evolution of radical pairs in electrochemical cells. Furthermore, an effective analytical method for oxalate determination can be developed based on the significant MC effect.

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Section: Introductionmentioning

confidence: 99%

Large Magneto-Current Effect in the Electrochemical Detection of Oxalate in Aqueous Solution

et al. 2018

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“…The dehydrogenation process undergoes catalytic breaking of the N–H bond − and generates singlet radical pairs (N–H → [N • ↑···↓ • H] 1 ) due to Pauli exclusion principle . Second, an applied magnetic field can facilitate the spin flipping from singlet to triplet in spin-correlated radical pairs. − Furthermore, the singlet radical pairs can recombine to form new N–H bond and inhibit the oxidation process of hydrazine. However, the recombination of triplet radical pairs is spin-forbidden due to the Pauli exclusion principle .…”

mentioning

confidence: 99%

“…An applied magnetic field could disturb the dynamic balance and largely enhance the electrical current by facilitating singlet → triplet spin evolution ,, in spin-correlated radical pairs. Indeed, after an external magnetic field is applied, the singlet → triplet interconversion rate in radical pairs can be largely enhanced by magnetic field-perturbed spin precession. − In general, the precession of the electron spin vector in a radical can be controlled by both the internal magnetic field and the applied magnetic field B . The difference between precessional frequencies of the spin vectors in a radical pair is given by ,− where ΔgB arises from the Zeeman interaction for cases in which the g factors of the two electrons are different (Δ g mechanism) and Σa i m i arises from the difference in the hyperfine field experienced by electrons (hyperfine coupling mechanism).…”

mentioning

confidence: 99%

Generating Huge Magnetocurrent by Using Spin-Dependent Dehydrogenation Based on Electrochemical System

Pan

Xiao

et al. 2017

J. Phys. Chem. C

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Systems featuring large magnetocurrent (MC) at room temperature are attractive owing to their potential for application in magnetic field sensing. Usually, the magnetic materials are exploited to achieve large MC effect. Here, we report a huge MC of up to 150% in a nonmagnetic system based on the electrochemical oxidation of hydrazine at room temperature. The huge MC is ascribed to the spin-dependent N−H bond cleavage and reformation through dehydrogenation during the oxidation of hydrazine. Specifically, the N−H bond cleavage generates singlet radical pairs. An external magnetic field can accelerate the spin evolution from singlet to triplet in spin-correlated radical pairs by perturbing spin precessions. Increasing the amount of triplet radical pairs can largely reduce the N−H bond recovery and significantly enhance the oxidation current of hydrazine. As a consequence, the spin-dependent bond formation through dehydrogenation can provide a new approach to generate huge MC in electrochemical cells.

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Paramagnetic Relaxation of Long‐Lived Coherences in Solution NMR

et al. 2013

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Long-lived coherences (LLCs) are known to have lifetimes much longer than transverse magnetization or single quantum coherences (SQCs). The effect of paramagnetic ions on the relaxation of LLCs is not known. This is particularly important, as LLCs have potential applications in various fields like analytical NMR, in vivo NMR and MR imaging methods. We study here the behaviour of LLCs in the presence of paramagnetic relaxation agents. The stepwise increase in the concentration of the metal ion is followed by measuring various relaxation rates. The effect of paramagnetic ions is analysed in terms of the external random field's contribution to the relaxation of two coupled protons in 2,3,6-trichlorobenzaldehyde. The LLCs relax faster than ordinary SQCs in the presence of paramagnetic ions of varying character. This is explained on the basis of an increase in the contribution of the external random field to relaxation due to a paramagnetic relaxation mechanism. Comparison is also made with ordinary Zeeman relaxation rates like R1, R2, R1ρ and also with rate of relaxation of long-lived states RLLS which are known to be less sensitive to paramagnetically induced relaxation. Also, the extent of correlation of random fields at two proton sites is studied and is found to be strongly correlated with each other. The obtained correlation constant is found to be independent of the nature of added paramagnetic impurities.

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Magnetic Field Influence on Dynamics of Singlet‐Triplet Conversion

Cited by 6 publications

References 154 publications

Large Magneto-Current Effect in the Electrochemical Detection of Oxalate in Aqueous Solution

Large Magneto-Current Effect in the Electrochemical Detection of Oxalate in Aqueous Solution

Generating Huge Magnetocurrent by Using Spin-Dependent Dehydrogenation Based on Electrochemical System

Paramagnetic Relaxation of Long‐Lived Coherences in Solution NMR

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