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Visualizing competing intersystem crossing and internal conversion with a complementary measurement
The Journal of Chemical Physics ( IF 3.1 ) Pub Date : 2016-02-22 15:19:59 , DOI: 10.1063/1.4942124 Yuzhu Liu 1 , Thomas Gerber 2 , Chaochao Qin 3 , Feng Jin 1 , Gregor Knopp 2
The Journal of Chemical Physics ( IF 3.1 ) Pub Date : 2016-02-22 15:19:59 , DOI: 10.1063/1.4942124 Yuzhu Liu 1 , Thomas Gerber 2 , Chaochao Qin 3 , Feng Jin 1 , Gregor Knopp 2
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A complementary measurement method based on a home-built double-sided velocity map imaging setup is introduced. This method can simultaneously obtain time-resolved photoelectron imaging and fragment ion imaging. It has been successfully applied to investigate the ultrafast dynamics of the second singlet electronically excited state (S2) in m-xylene. Time-resolved photoelectron and ion signals derived from the initial populated S2 state are tracked following two-photon absorption of a pump pulse. Time-of-flight mass spectra (TOFMS) show that there are dominant parent ions and one fragment ions with methyl loss during such a process. According to the measured photoelectron images and fragment ions images, transient kinetic energy distributions and angular distributions of the generated photoelectrons and fragments are obtained and analyzed. Compared to stand-alone photoelectron imaging, the obtained fragment ion imaging is powerful for further understanding the mechanisms especially when the dissociation occurs during the pump-probe ionization. Two competing channels intersystem crossing T3←S2 and internal conversion S1←S2 are attributed to the deactivation of the S2 state. A lifetime of ∼50 fs for the initially excited S2 state, of ∼276 fs for the secondary populated S1 state, and of 5.76 ps for the T3 state is inferred.
中文翻译：
可视化竞争性的系统间交叉和内部转换，并进行补充测量
介绍了一种基于自制的双面速度图成像设置的补充测量方法。该方法可以同时获得时间分辨光电子成像和碎片离子成像。它已成功地应用于调查第二单电子激发态的超快动力学（S 2中）米二甲苯。从初始填充的S 2导出的时间分辨光电子和离子信号在泵浦脉冲的两个光子吸收之后跟踪状态。飞行时间质谱（TOFMS）显示，在此过程中存在主要的母体离子和一个碎片离子，且甲基丢失。根据测得的光电子图像和碎片离子图像，获得并分析了产生的光电子和碎片的瞬态动能分布和角分布。与独立的光电子成像相比，获得的碎片离子成像对于进一步了解其机理特别是强大，尤其是在泵浦探针电离过程中发生解离时。两个相互竞争的通道系统间穿越T 3 ←S 2和内部转换S 1 ←S 2归因于S 2状态的去激活。推断出最初激发的S 2状态的寿命约为50 fs，次生S 1状态的寿命约为276 fs，T 3状态的寿命为5.76 ps 。
更新日期：2016-02-23
中文翻译：
可视化竞争性的系统间交叉和内部转换，并进行补充测量
介绍了一种基于自制的双面速度图成像设置的补充测量方法。该方法可以同时获得时间分辨光电子成像和碎片离子成像。它已成功地应用于调查第二单电子激发态的超快动力学（S 2中）米二甲苯。从初始填充的S 2导出的时间分辨光电子和离子信号在泵浦脉冲的两个光子吸收之后跟踪状态。飞行时间质谱（TOFMS）显示，在此过程中存在主要的母体离子和一个碎片离子，且甲基丢失。根据测得的光电子图像和碎片离子图像，获得并分析了产生的光电子和碎片的瞬态动能分布和角分布。与独立的光电子成像相比，获得的碎片离子成像对于进一步了解其机理特别是强大，尤其是在泵浦探针电离过程中发生解离时。两个相互竞争的通道系统间穿越T 3 ←S 2和内部转换S 1 ←S 2归因于S 2状态的去激活。推断出最初激发的S 2状态的寿命约为50 fs，次生S 1状态的寿命约为276 fs，T 3状态的寿命为5.76 ps 。
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