Real-time observation and control of the condensed-phase photochemical dynamics using optimized ultrashort optical pulses

我们研究了凝聚相的光化学动力学，通过使用飞秒电子光谱，皮秒时间分辨振动光谱和泵浦探测光谱，使我们能够观察到核波包运动。主要研究结果如下：1.利用泵浦-探测光谱技术研究了二苯基环丙烯酮分子的超快光解。观察到了S_2态的波包运动，并讨论了它与反应坐标的关系。发展了时间分辨时域拉曼光谱技术。利用飞秒时间分辨光谱研究了7-氮杂吲哚二聚体的光致质子转移和反式偶氮苯的光致异构化反应，并阐明了反应机理。研究了绿色荧光蛋白生色团模型化合物的超快荧光动力学，3.在溶剂化电子的电子跃迁共振条件下，测量了水分子的皮秒时间分辨拉曼光谱，发现溶剂化电子的水分子产生强的共振拉曼散射。转换显微镜。它首次同时实现了飞秒时间分辨率和亚微米空间分辨率的荧光测量。发展了一种新的飞秒荧光成像技术，使我们能够观察荧光强度作为一个时间-波长的二维图像。研制了一种多通道双光子吸收探测装置。测量了视网膜和C_2的精确双光子吸收光谱<60>。

We studied photochemical dynamics in the condensed phase by using femtosecond electronic spectroscopy, picosecond time-resolved vibrational spectroscopy, and pump-probe spectroscopy that enables us to observe nuclear wavepacket motions. Major outcomes are followings.1.Ultrafast photodissociation of diphenylcyclopropenone was studied by pump-probe spectroscopy based on 10-fs pulses. The wavepacket motion of the S_2 state was observed, and its relevance to the reaction coordinate was discussed. Time-resolved time-domain Raman spectroscopy was developed. With this method, we observed Raman-active low-frequency vibrations of trans-stilbene and binapthyl in the excited state in the time domain.2.Photo-induced proton transfer of the 7-azaindole dimer and photoisomerization of trans-azobenzene were studied by femtosecond time-resolved spectroscopy, and their reaction mechanisms were clarified. Ultrafast fluorescence dynamics of a model compound of chromophore of Green Fluorescence Protein was investigated, and its ultrafast radiationless relaxation process was discussed.3.Picosecond time-resolved Raman spectra of water were measured under the resonance condition with the electronic transition of the solvated electron. It was discovered that the water molecules that solvate the electron give rise to strong resonance Raman scattering.4.Fluorescence up-conversion microscope was developed. It simultaneously achieved femtosecond time-resolution and sub-micron space-resolution in fluorescence measurements for the first time. A new femtosecond fluorescence imaging technique was developed, which enabled us to observe fluorescence intensity as a time-wavelength two-dimensional image. An apparatus for multi-channel detection of two-photon absorption was developed. Precise two photon absorption spectra of retinal and C_<60> were measured.