ANALYSIS OF ANISOTROPIC ELECTRON-SPIN POLARIZATION IN THE PHOTOSYNTHETIC BACTERIUM RHODOSPIRILLUM-RUBRUM - EVIDENCE THAT THE SIGN OF THE EXCHANGE INTERACTION IN THE PRIMARY RADICAL PAIR IS POSITIVE
The transient electron paramagnetic resonance spectrum of pre-reduced, perdeuterated cells of the photosynthetic bacterium Rhodospirillum rubrum is analysed using a quantum mechanical description of the spin dynamics. The spectrum, of the reduced secondary electron acceptor (a ubisemiquinone anion,...
| Main Authors: | , , , , |
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| Format: | Journal article |
| Language: | English |
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1993
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| _version_ | 1826298061880557568 |
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| author | Hore, P Riley, D Semlyen, J Zwanenburg, G Hoff, A |
| author_facet | Hore, P Riley, D Semlyen, J Zwanenburg, G Hoff, A |
| author_sort | Hore, P |
| collection | OXFORD |
| description | The transient electron paramagnetic resonance spectrum of pre-reduced, perdeuterated cells of the photosynthetic bacterium Rhodospirillum rubrum is analysed using a quantum mechanical description of the spin dynamics. The spectrum, of the reduced secondary electron acceptor (a ubisemiquinone anion, Q-), displays anisotropic electron spin polarization, which is seen to arise principally from a combination of three interactions: the dipolar coupling of Q- to the reduced primary electron acceptor (a bacteriopheophytin anion, I-), the g-tensor anisotropy of Q- and the electronic exchange interaction between I- and the oxidised form of the primary electron donor (a bacteriochlorophyll dimer cation, P+). Using parameter values for Rhodobacter sphaeroides, it emerges that the P+I- exchange interaction JPI must be positive to account for the phase of the polarization, that is, the singlet state of the primary radical pair P+I- must lie higher in energy than the triplet. This finding puts restrictions on the permissible values of the energy gap between P* (the excited singlet state of P) and P+BA- (where BA is the accessory chlorophyll) and gives information on the mechanism of primary charge separation, P*I → P+I-. |
| first_indexed | 2024-03-07T04:41:05Z |
| format | Journal article |
| id | oxford-uuid:d1ab5497-d069-4708-916e-d87db7d00f9d |
| institution | University of Oxford |
| language | English |
| last_indexed | 2024-03-07T04:41:05Z |
| publishDate | 1993 |
| record_format | dspace |
| spelling | oxford-uuid:d1ab5497-d069-4708-916e-d87db7d00f9d2022-03-27T07:58:32ZANALYSIS OF ANISOTROPIC ELECTRON-SPIN POLARIZATION IN THE PHOTOSYNTHETIC BACTERIUM RHODOSPIRILLUM-RUBRUM - EVIDENCE THAT THE SIGN OF THE EXCHANGE INTERACTION IN THE PRIMARY RADICAL PAIR IS POSITIVEJournal articlehttp://purl.org/coar/resource_type/c_dcae04bcuuid:d1ab5497-d069-4708-916e-d87db7d00f9dEnglishSymplectic Elements at Oxford1993Hore, PRiley, DSemlyen, JZwanenburg, GHoff, AThe transient electron paramagnetic resonance spectrum of pre-reduced, perdeuterated cells of the photosynthetic bacterium Rhodospirillum rubrum is analysed using a quantum mechanical description of the spin dynamics. The spectrum, of the reduced secondary electron acceptor (a ubisemiquinone anion, Q-), displays anisotropic electron spin polarization, which is seen to arise principally from a combination of three interactions: the dipolar coupling of Q- to the reduced primary electron acceptor (a bacteriopheophytin anion, I-), the g-tensor anisotropy of Q- and the electronic exchange interaction between I- and the oxidised form of the primary electron donor (a bacteriochlorophyll dimer cation, P+). Using parameter values for Rhodobacter sphaeroides, it emerges that the P+I- exchange interaction JPI must be positive to account for the phase of the polarization, that is, the singlet state of the primary radical pair P+I- must lie higher in energy than the triplet. This finding puts restrictions on the permissible values of the energy gap between P* (the excited singlet state of P) and P+BA- (where BA is the accessory chlorophyll) and gives information on the mechanism of primary charge separation, P*I → P+I-. |
| spellingShingle | Hore, P Riley, D Semlyen, J Zwanenburg, G Hoff, A ANALYSIS OF ANISOTROPIC ELECTRON-SPIN POLARIZATION IN THE PHOTOSYNTHETIC BACTERIUM RHODOSPIRILLUM-RUBRUM - EVIDENCE THAT THE SIGN OF THE EXCHANGE INTERACTION IN THE PRIMARY RADICAL PAIR IS POSITIVE |
| title | ANALYSIS OF ANISOTROPIC ELECTRON-SPIN POLARIZATION IN THE PHOTOSYNTHETIC BACTERIUM RHODOSPIRILLUM-RUBRUM - EVIDENCE THAT THE SIGN OF THE EXCHANGE INTERACTION IN THE PRIMARY RADICAL PAIR IS POSITIVE |
| title_full | ANALYSIS OF ANISOTROPIC ELECTRON-SPIN POLARIZATION IN THE PHOTOSYNTHETIC BACTERIUM RHODOSPIRILLUM-RUBRUM - EVIDENCE THAT THE SIGN OF THE EXCHANGE INTERACTION IN THE PRIMARY RADICAL PAIR IS POSITIVE |
| title_fullStr | ANALYSIS OF ANISOTROPIC ELECTRON-SPIN POLARIZATION IN THE PHOTOSYNTHETIC BACTERIUM RHODOSPIRILLUM-RUBRUM - EVIDENCE THAT THE SIGN OF THE EXCHANGE INTERACTION IN THE PRIMARY RADICAL PAIR IS POSITIVE |
| title_full_unstemmed | ANALYSIS OF ANISOTROPIC ELECTRON-SPIN POLARIZATION IN THE PHOTOSYNTHETIC BACTERIUM RHODOSPIRILLUM-RUBRUM - EVIDENCE THAT THE SIGN OF THE EXCHANGE INTERACTION IN THE PRIMARY RADICAL PAIR IS POSITIVE |
| title_short | ANALYSIS OF ANISOTROPIC ELECTRON-SPIN POLARIZATION IN THE PHOTOSYNTHETIC BACTERIUM RHODOSPIRILLUM-RUBRUM - EVIDENCE THAT THE SIGN OF THE EXCHANGE INTERACTION IN THE PRIMARY RADICAL PAIR IS POSITIVE |
| title_sort | analysis of anisotropic electron spin polarization in the photosynthetic bacterium rhodospirillum rubrum evidence that the sign of the exchange interaction in the primary radical pair is positive |
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