Zhang, Jian-Ping and Nagae, Hiroyoshi and Qian, Pu and Limantara, Leenawaty and Fujii, Ritsuko and Watanabe, Yasutaka and Koyama, Yasushi (2001) Localized Excitations on the B850a and B850b Bacteriochlorophylls in the LH2 Antenna Complex from Rhodospirillum molischianum As Probed by the Shifts of the Carotenoid Absorption. Journal of Physical Chemistry, 105 (30). pp. 7312-7322.
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Changes in the carotenoid (Car) 1Bu+ absorption upon excitation (using a photon density of 1015photons cm-2) of bacteriochlorophyll (BChl) in the LH2 complex from Rhodospirillum molischianumwere traced with subpicosecond time resolution. The absorption changes could be empirically fit by two components showing a blue shift and a red shift in a ratio of 1:3.6. The shifts of Car absorption were explained in terms of interaction between change in dipole moment upon the 1Bu+ ← ground transition of Car and that upon the Qy ← ground transition of BChl. Calculations of the shifts for three different types of excitation in the B850 ring of the LH2 complex, i.e., (i) localized excitation on B850a or B850b, (ii) partially delocalized excitation over four B850s, and (iii) completely delocalized excitation over the B850 ring predicted the Car shifts with direction (relative magnitude), (i) a blue shift (1) or a red shift (3.3), (ii) a red shift (0.8), and (iii) a small red shift (0.2), respectively. Thus, the blue shift and the red shift components were attributed to localized excitations on B850a and B850b, respectively. The B850a excitation decayed rapidly (∼ 0.1 ps), whereas the B850b excitation decayed more slowly (∼ 0.4 ps) and then stayed; the former decay was ascribed to singlet−singlet annihilation between B850a and B850b, whereas the latter decay to singlet−singlet annihilation between B850b's. The unique feature of excitation with high photon density, which preferentially generates the localized excitations through multiple excitation, and enhances subsequent singlet−singlet annihilation reactions, is discussed.
| Item Type: | Artikel |
|---|---|
| Subjects: | Q Science > QD Chemistry |
| Divisions: | Fakultas Teknologi dan Desain > Teknik Sipil |
| Depositing User: | Admin Repository |
| Date Deposited: | 15 Apr 2020 10:28 |
| Last Modified: | 03 Jun 2022 02:46 |
| URI: | http://eprints.upj.ac.id/id/eprint/86 |
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