Wang Q, Schoenlein R W, Peteanu L A, Mathies R A, Shank C V
Materials Sciences Division, Lawrence Berkeley Laboratory, University of California, 94720.
Science. 1994 Oct 21;266(5184):422-4. doi: 10.1126/science.7939680.
Femtosecond pump-probe experiments reveal the impulsive production of photoproduct in the primary event in vision. The retinal chromophore of rhodopsin was excited with a 35-femtosecond pulse at 500 nanometers, and transient changes in absorption were measured with 10-femtosecond probe pulses. At probe wavelengths within the photo-product absorption band, oscillatory features with a period of 550 femtoseconds (60 wavenumbers) were observed whose phase and amplitude demonstrate that they are the result of nonstationary vibrational motion in the ground state of the photoproduct. The observation of coherent vibrational motion of the photoproduct supports the idea that the primary step in vision is a vibrationally coherent process and that the high quantum yield of the cis-->trans isomerization in rhodopsin is a consequence of the extreme speed of the excited-state torsional motion.
飞秒泵浦-探测实验揭示了视觉初级事件中光产物的脉冲式产生。用一个500纳米的35飞秒脉冲激发视紫红质的视网膜发色团，并使用10飞秒探测脉冲测量吸收的瞬态变化。在光产物吸收带内的探测波长处，观察到周期为550飞秒（60波数）的振荡特征，其相位和幅度表明它们是光产物基态中非稳态振动运动的结果。对光产物相干振动运动的观察支持了这样一种观点，即视觉的初级步骤是一个振动相干过程，并且视紫红质中顺式到反式异构化的高量子产率是激发态扭转运动极快速度的结果。
