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Studies on Short-Lived Molecular Species by Raman Spectroscopy

拉曼光谱研究短寿命分子物种

基本信息

批准号：
63045007
负责人：
TASUMI Mitsuo
金额：
$ 3.78万
依托单位：
The University of Tokyo
依托单位国家：
日本
项目类别：
Grant-in-Aid for international Scientific Research
财政年份：
1988
资助国家：
日本
起止时间：
1988 至 1990
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-63045007/
关键词：
Picosecond Spectroscopy Raman Spectroscopy Carotenoid Excited State Relaxation Photosynthetic Bacteria

项目摘要

Two lines of research have been pursued, and the following results have been obtained.(1) Picosecond time-resolved resonance Raman scattering from excited electronic states of carotenoids in vivo and in vitro.The vibrational spectroscopy and population dynamics of excited singlet (2^1Ag), excited triplet (^3Bu), and the ground (^1Ag) electronic states of carotenoids in chromatophores of Chromatium vinosum (mainly spirilloxanthin and rhodopin) and of the same carotenoids in benzene solutions are examined by picosecond time-resolved resonance Raman scattering. Compariosons of the time-dependent intensities of 2^1Ag and ^1Ag resonance Raman bands from both in vitro and in vivo carotenoids suggest that vibrationally-excited livels in ^1Ag are populated directly by the decay of the 2^1Ag state and that these levels relax into a thermalized distribution in <50 ps. The appearance of asymmetrically broadened ground-state resonance Raman bands supports this conclusion. Formation of the ^3Bu sta … More te is observed for carotenoids in chromatophores, but not for in vitro spirilloxanthin indicating that the ^3Bu state is formed by fission processes originating from the spatial organization of pigments within chromatophores.(2) Vibrational Relaxation in Carotenoids in Vivo and in Vitro.The ground-state ^1Ag vibrational relaxation in the population dynamics of carotenoids in pigment-protein complexes of photosynthetic bacteria (in vivo) and of spirilloxanthin in benzene and toluene solutions (in vitro) is quantitatively characterized using picosecond time-resolved anti-Stokes resonance Raman spectroscopy. For in vitro samples, anti-stokes resonance Raman signals reach maxima <approximately equal>10 ps after optical excitation before decaying with a rate of <approximately equal>15 ps to intensities which reflect a thermalized ^1Ag vibrational population. For the in vivo case, the maximum band intensities are found within the cross-correlation time (<approximately equal>8 ps) defined by the 567 nm pump (6 ps FWHM) and 576 nm probe (6 ps FWHM) laser pulses while the decay rate is similar to that of the in vitro samp Less

开展了两方面的研究工作，取得了以下成果：（1）体内外类胡萝卜素激发电子态的皮秒时间分辨共振拉曼散射。Chromatium色素细胞中类胡萝卜素激发单线态（2^1Ag）、激发三线态（^3Bu）和基态（^1Ag）电子态的振动光谱和群体动力学通过皮秒时间分辨共振拉曼散射检测苯溶液中的 vinosum（主要是螺菌黄素和视紫红质）和相同类胡萝卜素的含量。体外和体内类胡萝卜素的 2^1Ag 和 ^1Ag 共振拉曼带的时间依赖性强度的比较表明，^1Ag 中的振动激发肝细胞直接由 2^1Ag 状态的衰变填充，并且这些水平在 <50 ps 内松弛到热化分布。不对称展宽的基态共振拉曼谱带的出现支持了这一结论。在色素细胞中观察到了类胡萝卜素的 ^3Bu sta … More te 的形成，但在体外螺菌黄素中没有观察到，这表明 ^3Bu 状态是由源自色素细胞内色素空间组织的裂变过程形成的。(2) 类胡萝卜素在体内和体外的振动弛豫。群体动力学中的基态 ^1Ag 振动弛豫使用皮秒时间分辨反斯托克斯共振拉曼光谱对光合细菌（体内）和苯和甲苯溶液中的螺黄素（体外）色素-蛋白质复合物中的类胡萝卜素进行定量表征。对于体外样品，反斯托克斯共振拉曼信号在光激发后达到最大值<约等于>10 ps，然后以<约等于>15 ps 的速率衰减到反映热化 ^1Ag 振动群体的强度。对于体内情况，在由 567 nm 泵浦 (6 ps FWHM) 和 576 nm 探针 (6 ps FWHM) 激光脉冲定义的互相关时间（<约等于>8 ps）内找到最大条带强度，而衰减率与体外样品的衰减率相似。