利用超快光谱与可见/红外双激发荧光对长寿命振动热基态的直接观察  

Direct Observation of Long-Lived Vibrational Hot Ground States by Ultrafast Spectroscopy and Visible/Infrared Double Excitation Fluorescence

作　　者：喻琪锐 李鑫茂 沈成桢 于志浩 关键鑫 郑俊荣 Qirui Yu;Xinmao Li;Chengzhen Shen;Zhihao Yu;Jianxin Guan;Junrong Zheng(College of Chemistry and Molecular Engineering,Beijing National Laboratory for Molecular Sciences,Peking University,Beijing 100871,China)

机构地区：[1]北京大学化学与分子工程学院,北京100871

出　　处：《Chinese Journal of Chemical Physics》2024年第2期411-419,I0070-I0087,I0105,共28页化学物理学报（英文）

基　　金：This work is by the National Natural Science Foundation of China(No.22203006,No.21927901,No.92261206,No.21627805,No.12174012,No.21673004,No.21821004,No.21674001,and No.21790363);Ministry of Science and Technology of China(a special talent program)and the Beijing City.

摘　　要：在超快红外光谱测量中观察到的纳秒级弛豫诱导漂白信号被广泛认为是由于红外激发热化产生的局部热效应。本文结合超快红外泵浦/探测、二维红外光谱、可见泵浦/红外探测和超快可见/红外双共振荧光实验,发现甲醇溶液中荧光素二价阴离子的振动热基态寿命出人意料的长,能达到纳秒级.结果表明,在非线性红外实验中观察到的长寿命漂白信号在最初的几纳秒内一定存在这些热基态的重要贡献.类似的机制很可能也适用于其他分子系统,热基态的存在时间能比以往的预期长得多,有可能被应用于调控化学反应.It is widely believed that the relaxation-induced bleaching signals at nanoseconds observed in ultrafast infrared spectroscopic measurements are due to the local heat effect resulting from the thermalization of the infrared excitations.In this work,combining ultrafast IR pump/probe,2D-IR,visible pump/IR probe,and ultrafast visible/IR double resonant fluorescence experiments,the vibrational hot ground states of fluorescein dianion in methanol solutions are found to be unexpectedly long,at the time scale of nanoseconds.This result indicates that the long-standing bleaching signal observed in the nonlinear IR experiments must have significant contributions from these hot ground states for the initial couple of ns.It is likely that a similar mechanism can also hold for other molecular systems.The hot ground states can last much longer than conventionally expected,which can potentially be applied to modify chemical reactions.

关 键 词：超快光谱 荧光 可见红外双激发 长寿命热基态 二维红 外光谱 泵浦-探测 

分 类 号：O657.33[理学—分析化学] TQ427.26[理学—化学]