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Yago T. Analytical model for spin dynamics in radical pairs under the spin-locking condition. J Chem Phys 2024; 160:244701. [PMID: 38912632 DOI: 10.1063/5.0210982] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2024] [Accepted: 06/04/2024] [Indexed: 06/25/2024] Open
Abstract
Spin dynamics in triplet radical pairs are theoretically studied under the spin-locking condition, where singlet-triplet mixing is blocked by the resonant microwave field. A key assumption in the theory is simultaneous excitations of T+-T0 and T--T0 transitions in triplet radical pairs. This assumption allows for the application of a three-state model [Yago, J. Chem. Phys. 151, 214501 (2019)] to describe the spin dynamics of triplet radical pairs. The analysis based on the three-state model shows that the triplet states are quantized along the direction of a microwave-induced magnetic field (B1) in the rotating frame under the spin-locking condition. This gives rise to a new spin-locking phenomenon where T+-T0 and T--T0 mixing are most enhanced at magnetic fields that deviate from the resonance by ±B1. It is also shown that the quantum beats observed under the spin-locking condition originate from the spin dynamics in triplet radical pairs.
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Affiliation(s)
- T Yago
- Department of Chemistry, Graduate School of Science and Engineering, Saitama University, 255 Shimo-ohkubo, Sakura-ku, Saitama 338-8570, Japan
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Abstract
Radical pairs (RPs) are important reaction intermediates generated whenever two radicals encounter one another, a bond is cleaved homolytically or electron transfer between non-radical species takes place. The concept of a radical pair as a reaction intermediate is introduced and developed through simple pictorial analogies, indicating how RP behaviour is governed by interplay of spin and spatial motion. Such analogies are then extended to describe the experimental consequences of RPs in magnetic resonance and magnetochemistry experiments, including reference to the relevance of RPs in biological systems. Finally experimental techniques by which RPs can be observed directly are introduced and described in the context of the developed models.
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Affiliation(s)
- J. R. Woodward
- Department of Chemistry, University of Leicester, University Road, Leicester LE1 7RH, UK
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Schnegg A, Behrends J, Fehr M, Lips K. Pulsed electrically detected magnetic resonance for thin film silicon and organic solar cells. Phys Chem Chem Phys 2012; 14:14418-38. [PMID: 22941053 DOI: 10.1039/c2cp41258f] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
In thin film solar cells based on non-crystalline thin film silicon or organic semiconductors structural disorder leads to localized states that induce device limiting charge recombination and trapping. Both processes frequently involve paramagnetic states and become spin-dependent. In the present perspectives article we report on advanced pulsed electrically detected magnetic resonance (pEDMR) experiments for the study of spin dependent transport processes in fully processed thin film solar cells. We reflect on recent advances in pEDMR spectroscopy and demonstrate its capabilities on two different state of the art thin film solar cell concepts based on microcrystalline silicon and organic MEH-PPV:PCBM blends, recently studied at HZB. Benefiting from the increased capabilities of novel pEDMR detection schemes we were able to ascertain spin-dependent transport processes and microscopically identify paramagnetic states and their role in the charge collection mechanism of solar cells.
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Affiliation(s)
- Alexander Schnegg
- Helmholtz-Zentrum Berlin für Materialien und Energie, Institute for Silicon Photovoltaics, Berlin, Germany.
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Miura T, Kageyama A, Torii S, Murai H. Photoreactions and Molecular Dynamics of Radical Pairs in a Reversed Micelle Studied by Time-Resolved Measurements of EPR and Magnetic Field Effect. J Phys Chem B 2010; 114:14550-8. [DOI: 10.1021/jp102300z] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Tomoaki Miura
- Graduate School of Science and Engineering and Department of Chemistry, Shizuoka University, 836 Oya, Shizuoka 422-8529, Japan, and Department of Chemistry, Graduate School of Science, Tohoku University, Sendai, Japan
| | - Atsushi Kageyama
- Graduate School of Science and Engineering and Department of Chemistry, Shizuoka University, 836 Oya, Shizuoka 422-8529, Japan, and Department of Chemistry, Graduate School of Science, Tohoku University, Sendai, Japan
| | - Sakiko Torii
- Graduate School of Science and Engineering and Department of Chemistry, Shizuoka University, 836 Oya, Shizuoka 422-8529, Japan, and Department of Chemistry, Graduate School of Science, Tohoku University, Sendai, Japan
| | - Hisao Murai
- Graduate School of Science and Engineering and Department of Chemistry, Shizuoka University, 836 Oya, Shizuoka 422-8529, Japan, and Department of Chemistry, Graduate School of Science, Tohoku University, Sendai, Japan
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Miura T, Murai H. Real-time observation of the spin-state mixing process of a micellized radical pair in weak magnetic fields by nanosecond fast field switching. J Phys Chem A 2008; 112:2526-32. [PMID: 18307324 DOI: 10.1021/jp077505x] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The singlet-triplet spin-state mixing process of a singlet-born radical pair confined in a sodium dodecyl sulfate (SDS) micelle was studied by observing the nanosecond switched external magnetic field (SEMF) effect on the transient absorption signals. A long-lived singlet radical pair is generated by the photoinduced bond cleavage reaction of tetraphenylhydrazine in an SDS micelle. Application of off-on type SEMF results in the increase of the free radical yield contrary to the decrease produced by an applied static magnetic field. The S-T mixing process in low magnetic field was observed by means of a delay-shift SEMF experiment. Observed incoherent mixing processes are explained in terms of the interplay between coherent hyperfine interaction and fast dephasing processes caused by the fluctuation of electron-spin interactions. Singlet-triplet and triplet-triplet dephasing rate constants are determined independently to be 2 x 10(8) and 0.2 x 10(8) s(-)1, respectively, by a simulation based on a modified single-site Liouville equation. This is the first direct observation of the incoherent spin-state mixing process at magnetic fields comparable to the hyperfine interactions of the radical pair.
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Affiliation(s)
- Tomoaki Miura
- Graduate School of Science and Engineering, Faculty of Science, Shizuoka University, 836 Oya, Surugaku, Shizuoka 422-8529, Japan
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Kitahama Y, Sakaguchi Y. Magnetic isotope effect on kinetic parameters and quantum beats of radical pairs in micellar solution studied by optically detected esr using pulsed microwave. J Phys Chem A 2008; 112:176-82. [PMID: 18081265 DOI: 10.1021/jp076611w] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
We investigated the quantum beats, the oscillation between singlet and triplet states of radical pairs induced by the microwave field resonant to one of the component radicals. They were observed as the alternation of the yields of the component radicals by a nanosecond time-resolved optical absorption with the X-band (9.15 GHz) resonant microwave pulse. This technique was applied to the photochemical reaction of benzophenone, benzophenone-d(10), and benzophenone-carbonyl-(13)C in a sodium dodecylsulfate micellar solution with a step-by-step increase of the resonant microwave pulse width. The yields of the component radicals showed alternation with an increase of the microwave pulse width. This indicates that the radical pair retains spin coherence in the micellar solution. The magnetic isotope effect on the amplitude of the quantum beat was observed. The MW effect on the quantum beat of BP-(13)C decreases from 80% to 60% of that of BP by irradiation of the pi-pulse MW due to spin-locking. The kinetic parameters were also determined using the X- or Ku-band (17.44 GHz) region. They are almost similar to each other except for the intersystem recombination rate in the system of BP-(13)C, which may be slightly higher than those in other systems.
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Affiliation(s)
- Yasutaka Kitahama
- RIKEN (The Institute of Physical and Chemical Research), 351-0198 Wako, Saitama, Japan
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Kitahama Y, Sakaguchi Y. Viscosity Dependence of the Kinetic Parameters of the Radical Ion Pair in Homogeneous Solution Determined by Optically Detected X- and Ku-Band Electron Spin Resonance. J Phys Chem A 2007; 112:347-52. [DOI: 10.1021/jp076582p] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Yasutaka Kitahama
- RIKEN (The Institute of Physical and Chemical Research), 351-0198 Wako, Saitama, Japan
| | - Yoshio Sakaguchi
- RIKEN (The Institute of Physical and Chemical Research), 351-0198 Wako, Saitama, Japan
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Miura T, Maeda K, Arai T. The spin mixing process of a radical pair in low magnetic field observed by transient absorption detected nanosecond pulsed magnetic field effect. J Phys Chem A 2007; 110:4151-6. [PMID: 16553365 DOI: 10.1021/jp056488d] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The spin mixing process of the radical pair in the sodium dodecyl sulfate (SDS) micelle is studied by using a novel technique nanosecond pulsed magnetic field effect on transient absorption. We have developed the equipment for a nanosecond pulsed magnetic field and observed its effect on the radical pair reaction. A decrease of the free radical yield by a reversely directed pulsed magnetic field that cancels static field is observed, and the dependence on its magnitude, which is called pulsed MARY (magnetic field effect on reaction yield) spectra, is studied. The observed spectra reflect the spin mixing in 50-200 ns and show clear time evolution. Theoretical simulation of pulsed MARY spectra based on a single site modified Liouville equation indicates that the fast spin dephasing processes induced by the modulation of electron-electron spin interaction by molecular reencounter affect to the coherent spin mixing by a hyperfine interaction in a low magnetic field.
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Affiliation(s)
- Tomoaki Miura
- Department of Chemistry, Faculty of Science, Shizuoka University, Ohya 836, Shizuoka City 422-8529, Japan
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Sakaguchi Y, Iwasaki Y, Okimi H, Fukuno K, Asahi M, Matsumura M. Magnetic field effect and RYDMR on the emission of an organic electroluminescent material, Alq3. Mol Phys 2006. [DOI: 10.1080/00268970600564828] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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Maeda K, Miura T, Arai T. A practical simulation and a novel insight to the magnetic field effect on a radical pair in a micelle. Mol Phys 2006. [DOI: 10.1080/14767050600588106] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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Spin-chemical approach to photochemistry: reaction control by spin quantum operation. JOURNAL OF PHOTOCHEMISTRY AND PHOTOBIOLOGY C-PHOTOCHEMISTRY REVIEWS 2003. [DOI: 10.1016/s1389-5567(02)00038-2] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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KITAHAMA YASUTAKA, SAKAGUCHI YOSHIO. Determination of the kinetic parameters of radical pairs with heavy atom substitutions in micellar solution by optical detected × and Ku band ESR. Mol Phys 2002. [DOI: 10.1080/00268970110118268] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/16/2022]
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SAKAGUCHI YOSHIO. Magnetic field dependence of spin dynamics of radical pairs studied by time-resolved RYDMR. Mol Phys 2002. [DOI: 10.1080/00268970110109772] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
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Matsuyama A, Murai H. Effect of the Spin Dephasing on the Photoconductivity-Detected Magnetic Resonance Spectra Observed in the Photolysis of Xanthone and N,N-Diethylaniline in 2-Propanol. J Phys Chem A 2001. [DOI: 10.1021/jp012563i] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Akihito Matsuyama
- Department of Chemistry, Graduate School of Science, Tohoku University, Sendai 980-8578, Japan
| | - Hisao Murai
- Department of Chemistry, Graduate School of Science, Tohoku University, Sendai 980-8578, Japan
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Sakaguchi Y. Application of a liquid chromatography detector to time-resolved RYDMR spectroscopy: a comparison of in situ and ex post facto measurements. Chem Phys Lett 2001. [DOI: 10.1016/s0009-2614(01)00837-5] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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Gorelik VR, Maeda K, Yashiro H, Murai H. Microwave-Induced Quantum Beats in Micellized Radical Pairs under Spin-Locking Conditions. J Phys Chem A 2001. [DOI: 10.1021/jp0109628] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Vitaly R. Gorelik
- Department of Chemistry, Graduated School of Science, Tohoku University, Sendai, 980-8578, Japan
| | - Kiminori Maeda
- Department of Chemistry, Graduated School of Science, Tohoku University, Sendai, 980-8578, Japan
| | - Haruhiko Yashiro
- Department of Chemistry, Graduated School of Science, Tohoku University, Sendai, 980-8578, Japan
| | - Hisao Murai
- Department of Chemistry, Graduated School of Science, Tohoku University, Sendai, 980-8578, Japan
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Hayashi H, Sakaguchi Y, Wakasa M. Magnetic Field Effects and Spin Dynamics of Radical Reactions in Solution. BULLETIN OF THE CHEMICAL SOCIETY OF JAPAN 2001. [DOI: 10.1246/bcsj.74.773] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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Woodward JR, Sakaguchi Y. Radical Pair Kinetics in the Hydrogen Abstraction of Benzophenone Derivatives in Micellar Solutions, Studied by Pulsed Microwave Irradiation. J Phys Chem A 2001. [DOI: 10.1021/jp003801x] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Jonathan R. Woodward
- RIKEN (The Institute of Physical and Chemical Research), Wako-shi, Saitama, 351-0198, Japan
| | - Yoshio Sakaguchi
- RIKEN (The Institute of Physical and Chemical Research), Wako-shi, Saitama, 351-0198, Japan
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Araki Y, Maeda K, Murai H. Observation of two-spin controlling of a radical pair by pulsed irradiation of microwave monitored by absorption detected magnetic resonance. Chem Phys Lett 2000. [DOI: 10.1016/s0009-2614(00)01291-4] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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20
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Anishchik S, Borovkov V, Ivannikov V, Shebolaev I, Chernousov Y, Lukzen N, Anisimov O, Molin Y. Microwave field effects on the time dependence of recombination fluorescence from non-polar solutions. Chem Phys 1999. [DOI: 10.1016/s0301-0104(99)00021-x] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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