Influence of dipolar interactions on radical pair recombination reactions subject to weak magnetic fields.

The journal of physical chemistry. A · 2005 · Unclear · Insufficient evidence

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UnclearInsufficient evidencePaper 3580

Study snapshot

PublicationThe journal of physical chemistry. A · 2005

Study typeother

Reported directionUnclear

Evidence ratingInsufficient

Abstract

Monte Carlo simulations of the effects of weak magnetic fields on the recombination of interacting radical pairs undergoing free diffusion in solution have been performed, with the aim of determining the influence on the low field effect of the magnetic dipolar coupling between the radicals. The suppression of singlet-triplet interconversion in the radical pair by the dipolar interaction is found to be pronounced at magnetic field strengths comparable to the hyperfine interactions in the radicals, to the extent that the low field effect is completely abolished. The averaging of the dipolar coupling by the translational diffusion of the radicals around one another is relatively efficient in the presence of strong magnetic fields but becomes ineffective in weak applied fields where the strength of the dipolar interaction is independent of the orientation of the inter-radical vector. Low field effects are only likely to be observed if the motion of the radical pair is restricted in some way so as to increase the likelihood that, having separated to the large distance required for the dipolar interaction to have a negligible effect, the radicals subsequently encounter and have the opportunity to recombine.

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AI evidence extraction

Structured fields below were generated from the paper’s abstract and metadata to make the evidence easier to inspect. Automated extraction may be incomplete or incorrect; verify important details against the original paper.

Study typeother

Effect directionunclear

PopulationNot supplied

Sample sizeNot supplied

ExposureNot supplied

Evidence strengthInsufficientConfidence: 74% · Peer reviewed: yes

Main findings

Monte Carlo simulations indicate that magnetic dipolar coupling between radicals can strongly suppress singlet-triplet interconversion at magnetic field strengths comparable to the radicals' hyperfine interactions, potentially abolishing the low field effect. Diffusion averages dipolar coupling efficiently in strong fields but not in weak applied fields; low field effects are suggested to be more likely when radical-pair motion is restricted to allow recombination after separation to distances where dipolar effects are negligible.

Outcomes measured

radical pair recombination
low field effect
singlet-triplet interconversion
influence of magnetic dipolar coupling
effects of translational diffusion on dipolar coupling averaging

Limitations

Simulation study (Monte Carlo) rather than empirical measurements
Specific radical pair system parameters (e.g., hyperfine interactions) not detailed in the abstract
No quantitative field strengths or exposure metrics provided in the abstract

View raw extracted JSON

{
  "study_type": "other",
  "exposure": {
    "band": null,
    "source": "weak magnetic fields (applied)",
    "frequency_mhz": null,
    "sar_wkg": null,
    "duration": null
  },
  "population": null,
  "sample_size": null,
  "outcomes": [
    "radical pair recombination",
    "low field effect",
    "singlet-triplet interconversion",
    "influence of magnetic dipolar coupling",
    "effects of translational diffusion on dipolar coupling averaging"
  ],
  "main_findings": "Monte Carlo simulations indicate that magnetic dipolar coupling between radicals can strongly suppress singlet-triplet interconversion at magnetic field strengths comparable to the radicals' hyperfine interactions, potentially abolishing the low field effect. Diffusion averages dipolar coupling efficiently in strong fields but not in weak applied fields; low field effects are suggested to be more likely when radical-pair motion is restricted to allow recombination after separation to distances where dipolar effects are negligible.",
  "effect_direction": "unclear",
  "limitations": [
    "Simulation study (Monte Carlo) rather than empirical measurements",
    "Specific radical pair system parameters (e.g., hyperfine interactions) not detailed in the abstract",
    "No quantitative field strengths or exposure metrics provided in the abstract"
  ],
  "evidence_strength": "insufficient",
  "confidence": 0.74,
  "peer_reviewed_likely": "yes",
  "keywords": [
    "radical pair",
    "recombination",
    "weak magnetic fields",
    "low field effect",
    "dipolar interaction",
    "hyperfine interaction",
    "singlet-triplet interconversion",
    "Monte Carlo simulation",
    "diffusion"
  ],
  "suggested_hubs": []
}

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AI-extracted fields are generated from the abstract and metadata and may be incomplete or incorrect. This material is for informational purposes and is not medical advice.

Identifiers and source

DOI: 10.1021/jp0456943
PubMed: 16838958

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