Femtosecond spectral evolution of the excited state of bacterial reaction centers at 10 K.
Femtosecond spectral evolution of the excited state of bacterial reaction centers at 10 K.
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10 K 时细菌反应中心激发态的飞秒光谱演化。
DOI：
10.1073/pnas.89.2.613
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发表时间：
1992
影响因子：
11.1
通讯作者：
Martin,JL
中科院分区：
文献类型：
--
作者：
Vos,MH;Lambry,JC;Robles,SJ;Youvan,DC;Breton,J;Martin,JL
研究了10 K下球形红细菌R-26反应中心的飞秒光谱演化。瞬态光谱在近红外区域，获得45-fs的脉冲（泵浦脉冲中心在870 nm和连续探测脉冲），进行了分析与相关的动力学在特定的波长。t = 0-fs瞬态光谱的结构非常丰富;它包含在807和796 nm处的单独诱导带和760 nm附近的漂白，反映了激发态形成时所有颜料之间相互作用的强烈变化。在800 nm区域的复杂光谱演化，最值得注意的是796 nm波段的漂白，发生在几百飞秒内-即，在时间尺度上比电子从初级供体P转移到细菌脱镁叶绿素受体HL快得多。显着的初始光谱特征和它们的演变可能与HL的存在有关，因为它们在缺乏这种色素的红细菌荚膜的DLL突变体中没有观察到。一个简单的线性反应方案与中间状态不能占我们的数据，初始光谱演化必须反映激发态内的弛豫过程。讨论了反应中心长距离相互作用对初级光化学的重要性。
The femtosecond spectral evolution of reaction centers of Rhodobacter sphaeroides R-26 was studied at 10 K. Transient spectra in the near infrared region, obtained with 45-fs pulses (pump pulses centered at 870 nm and continuum probe pulses), were analyzed with associated kinetics at specific wavelengths. The t = 0-fs transient spectrum is very rich in structure; it contains separate induced bands at 807 and 796 nm and a bleaching near 760 nm, reflecting strong changes in interaction between all pigments upon formation of the excited state. A complex spectral evolution in the 800-nm region, most notably the bleaching of the 796-nm band, takes place within a few hundred femtosecond--i.e., on a time scale much faster than electron transfer from the primary donor P to the bacteriopheophytin acceptor HL. The remarkable initial spectral features and their evolution are presumably related to the presence of HL, as they were not observed in the DLL mutant of Rhodobacter capsulatus, which lacks this pigment. A simple linear reaction scheme with an intermediate state cannot account for our data; the initial spectral evolution must reflect relaxation processes within the excited state. The importance for primary photochemistry of long distance interactions in the reaction center is discussed.