The Stark effect in reaction centers from Rhodobacter sphaeroides R-26 and Rhodopseudomonas viridis.
The Stark effect in reaction centers from Rhodobacter sphaeroides R-26 and Rhodopseudomonas viridis.
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球形红杆菌 R-26 和绿色红假单胞菌反应中心的斯塔克效应。
DOI：
10.1073/pnas.84.21.7537
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发表时间：
1987
影响因子：
11.1
通讯作者：
Okamura,MY
中科院分区：
文献类型：
--
作者：
Lösche,M;Feher,G;Okamura,MY
研究了电场对聚乙烯醇膜中球形红细菌和绿色红细菌反应中心光吸收的影响。在295 K和77 K下考察了红外吸收带。在RP的RC中。在77 K下，与六种色素的Qy跃迁相关的六个峰（在982、849、835、818、803和787 nm处）被分辨;此外，在865 nm处的小宽带被分辨。从Rb到RC。sphaeroides中，只有五个带（在877，817，802，761和754 nm处）被分配给Qy跃迁解析;此外，在697和683 nm处观察到两个小带。额外的带已被暂时分配到振动边带，虽然不能排除来自电荷转移态的贡献。的斯塔克光谱具有类似的吸收光谱的二阶导数的线形，并解释在所施加的电场和偶极矩的基态和激发态之间的相互作用。分析的光谱产生了明显的变化，在偶极矩Δ μ app = f Δ μ（其中的因子f校正的本地字段和应用领域之间的差异）和三角洲，三角洲之间的角度μ-和过渡时刻μ trans. At 77 K的值Δ μ-app和三角洲的峰值在877，802，和761 nm的Rb。球型为6.5德拜，38度; 2.1德拜，23度; 3.5德拜，8度。单位：Rp。在982、835、818和787处的峰值的德拜值为8.2，40度; 1.8，50度; 3.4，14度;和2.7，0度。与细菌叶绿素二聚体的长波长峰相关联的Δ μ app的大值与对初级供体的激发态的显著电荷转移贡献是一致的。
The effect of an electric field on the optical absorption (Stark effect) of reaction centers (RCs) from Rhodobacter sphaeroides and Rhodopseudomonas viridis embedded in films of poly(vinyl alcohol) was measured. The infrared bands were investigated at 295 K and 77 K. In RCs from Rp. viridis at 77 K six peaks (at 982, 849, 835, 818, 803, and 787 nm), associated with the Qy transitions of the six pigments, were resolved; in addition, a small broad band at 865 nm was resolved. In RCs from Rb. sphaeroides only five bands (at 877, 817, 802, 761, and 754 nm) assigned to the Qy transitions were resolved; in addition, two small bands at 697 and 683 nm were observed. The additional bands have been tentatively assigned to vibrational side bands, although the contribution from charge-transfer states cannot be excluded. The Stark spectra had line shapes similar to the second derivative of the absorption spectra and were interpreted in terms of the interaction between the applied electric field and the dipole moments of the ground and excited states. Analyses of the spectra yielded the apparent change in dipole moment delta mu app = f delta mu (where the factor f corrects for the difference between the local field and the applied field) and delta, the angle between delta mu---- and the transition moment mu trans. At 77 K the values of delta mu----app and delta for the peaks at 877, 802, and 761 nm in Rb. sphaeroides were 6.5 debye, 38 degrees; 2.1 debye, 23 degrees; and 3.5 debye, 8 degrees. In Rp. viridis the debye values for the peaks at 982, 835, 818, and 787 were 8.2, 40 degrees; 1.8, 50 degrees; 3.4, 14 degrees; and 2.7, 0 degrees. The large values of delta mu app associated with the long-wavelength peak of the bacteriochlorophyll dimers are consistent with a significant charge-transfer contribution to the excited state of the primary donor.