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Spin dynamics of the radical pair in a low magnetic field studied by the transient absorption detected magnetic field effect on the reaction yield and switched external magnetic field.

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

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MixedInsufficient evidencePaper 3581

In micellar solutions, a negative magnetic field effect on radical yield was observed at magnetic fields below 60 mT, while a positive effect was observed at higher magnetic fields. The low-field negative effect was attributed to the low field effect (LFE) me…

Study snapshot

PublicationThe journal of physical chemistry. A · 2005
Study typein_vitro
Reported directionMixed
Evidence ratingInsufficient

Abstract

The spin dynamics of the radical pair generated from the photocleavage reaction of (2,4,6-trimethylbenzoyl)diphenylphosphine oxide (TMDPO) in micellar solutions was studied by the time-resolved magnetic field effect (MFE) on the transient absorption (TA) and by a novel technique, absorption detected switched external magnetic field (AD-SEMF). Thanks to the large hyperfine coupling constant (A = 38 mT), a characteristic negative MFE on the radical yield was observed at a magnetic field lower than 60 mT whereas a positive effect due to the conventional hyperfine (HFM) and relaxation mechanisms (RM) was observed at higher magnetic field. The negative effect can be assigned to the mechanism "so-called" low field effect (LFE) mechanism and has been analyzed thoroughly using a model calculation incorporating a fast spin dephasing process. The time scale of the spin mixing process of LFE studied by AD-SEMF is shorter than the lifetime of the recombination kinetics of the radical pair. These results indicate that the LFE originates from the coherent spin motion. This can be interfered from the fast spin dephasing caused by electron spin interaction fluctuations.

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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 typein_vitro
Effect directionmixed
PopulationNot supplied
Sample sizeNot supplied
ExposureNot supplied
Evidence strengthInsufficientConfidence: 74% · Peer reviewed: yes

Main findings

In micellar solutions, a negative magnetic field effect on radical yield was observed at magnetic fields below 60 mT, while a positive effect was observed at higher magnetic fields. The low-field negative effect was attributed to the low field effect (LFE) mechanism and analyzed with a model including fast spin dephasing; results suggested the LFE originates from coherent spin motion that can be interfered with by fast spin dephasing.

Outcomes measured

  • Transient absorption detected magnetic field effect (MFE) on radical yield
  • Spin dynamics/spin mixing time scale in radical pair recombination
  • Low field effect (LFE) vs hyperfine/relaxation mechanisms at different magnetic field strengths

Limitations

  • Study is a chemical/photophysical in vitro system (radical pair in micellar solutions), not a biological or health outcome study
  • Exposure characterized by magnetic field strength (mT) without frequency information
  • Model-based interpretation (fast spin dephasing) described; details/validation not provided in abstract
View raw extracted JSON
{
  "study_type": "in_vitro",
  "exposure": {
    "band": null,
    "source": "switched external magnetic field",
    "frequency_mhz": null,
    "sar_wkg": null,
    "duration": null
  },
  "population": null,
  "sample_size": null,
  "outcomes": [
    "Transient absorption detected magnetic field effect (MFE) on radical yield",
    "Spin dynamics/spin mixing time scale in radical pair recombination",
    "Low field effect (LFE) vs hyperfine/relaxation mechanisms at different magnetic field strengths"
  ],
  "main_findings": "In micellar solutions, a negative magnetic field effect on radical yield was observed at magnetic fields below 60 mT, while a positive effect was observed at higher magnetic fields. The low-field negative effect was attributed to the low field effect (LFE) mechanism and analyzed with a model including fast spin dephasing; results suggested the LFE originates from coherent spin motion that can be interfered with by fast spin dephasing.",
  "effect_direction": "mixed",
  "limitations": [
    "Study is a chemical/photophysical in vitro system (radical pair in micellar solutions), not a biological or health outcome study",
    "Exposure characterized by magnetic field strength (mT) without frequency information",
    "Model-based interpretation (fast spin dephasing) described; details/validation not provided in abstract"
  ],
  "evidence_strength": "insufficient",
  "confidence": 0.74,
  "peer_reviewed_likely": "yes",
  "keywords": [
    "radical pair",
    "spin dynamics",
    "magnetic field effect",
    "transient absorption",
    "low field effect",
    "hyperfine coupling",
    "spin dephasing",
    "micellar solution",
    "switched external magnetic field"
  ],
  "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/jp053989q
PubMed: 16838907

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