摘要
光致异构化是分子光物理与光化学反应的核心,其量子产率与激发态动力学演化路径相关.改变分子激发态演化路径以实现对光化学反应的精准操控是物理学家、化学家长期以来追求的梦想.本文采用飞秒泵浦-受激亏蚀-探测(pump-dump-probe)光谱技术,研究了受激亏蚀光脉冲对1,1'-二乙基-2,2'-碘化菁(1,1'-diethyl-2,2'-cyanine iodide,1122C)分子光异构化动力学的影响.在泵浦-探测(pump-probe)实验中,1122C分子被泵浦光激发之后,处于激发态的分子以5.6 ps的时间常数沿扭转反应坐标发生结构变化,从反式(trans-)构型转变为顺式(cis-)构型.为了对该反应进行人为调控,本文在传统泵浦-探测光谱的基础上,引入第3束波长为1030 nm的飞秒受激亏蚀光.受激亏蚀光脉冲成功使部分处于激发态的反式构型分子通过受激跃迁直接返回基态,绕过了原本通向顺式产物的异构化通道.通过比较顺式产物吸收信号的变化,计算得出受激亏蚀光作用下顺式构型的产率降低了约12.1%.本文研究实现了利用飞秒激光对超快光化学反应路径的主动干预,展示了飞秒多脉冲光谱技术在调控分子激发态演化路径、优化光异构化反应产率的潜力.该研究为将来对复杂光化学反应精准操控提供了理论和技术支持.
Photoisomerization is a prototypical photophysical and photochemical reaction,and the reaction quantum yield depends on its excited-state dynamic.Changing the evolution path of molecular excited states to achieveprecise control over photochemical reactions has long been a dream pursued by physicists and chemists.To investigate the effect of femtosecond laser pulse on the ultrafast reaction,the ultrafast photoisomerization of 1,1'-diethyl-2,2'-cyanine iodide(1122C)in methanol is studied using pump-dump-probe spectroscopy.A third femtosecond pulse(Dump)at 1030 nm,which is delayed by 1 ps relative to the initial pump pulse,is introduced into the traditional pump-probe experiment.The recovery of ground state bleaching(GSB)and decrease of the cis product are observed in the pump-dump-probe experiment.It indicates that the dump pulse successfully promotes the initial transform:skipping the trans-cis isomerization pathway in the excited state and returning to the ground state directly through stimulated emission.It is found that the cis yield is reduced by approximately 12.1%under irradiation of the dump pulse.Our research shows that the quantum yields of a typic ultrafast photoisomerization reaction is successfully regulated by using femtosecond laser pulse,demonstrating the potential of femtosecond multi-pulse spectroscopy in modifying excited-state evolution pathways and optimizing photochemical reaction yields.This study provides theoretical and technical support for precisely controlling complex photochemical reactions in the future.
作者
徐卉琳
黄程
魏政荣
XU Huilin;HUANG Cheng;WEI Zhengrong(Department of Physics,Hubei University,Wuhan 430062,China;Hubei Optical Fundamental Research Center,Wuhan 430074,China)
出处
《物理学报》
北大核心
2025年第19期164-171,共8页
Acta Physica Sinica
基金
国家自然科学基金(批准号:12074109)
湖北省创新群体项目(批准号:2024AFA038)资助的课题。
