Wang Yanmei, Gu Zhenfei, Deng Xulan, Zhang Bing
State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, Wuhan Institute of Physics and Mathematics, Innovation Academy for Precision Measurement Science and Technology, Chinese Academy of Sciences, Wuhan 430071, People's Republic of China.
J Chem Phys. 2021 Feb 7;154(5):054301. doi: 10.1063/5.0039802.
Structure rearrangement processes, such as isomerization, are attracting extensive interest as a potential carrier in molecular scale electronics design. UV-light-triggered isomerization of Rydberg-excited propanal with two UV photons has been investigated with time-resolved photoelectron spectroscopy. By following the photoionization from 3s Rydberg states in the time domain, the ultrafast structural evolution and the corresponding photoisomerization dynamics are observed and tracked in real-time. The conversion barrier for isomerization from cis-propanal to gauche isomer is estimated to be about 1500 ± 100 cm experimentally. Both the photoisomerization yield and the conversion rate have shown strong dependence on the excitation energy. It is observed that whether vibration modes are selectively excited or not, cis-to-gauche photoisomerization of propanal in 3s Rydberg state occurs once the excitation energy is higher than the conversion barrier without any vibrational excitation specificity. This yields a powerful approach to studying structural evolution dynamics in large molecules, which may have applications in molecular devices.
诸如异构化等结构重排过程，作为分子尺度电子学设计中的潜在载体正吸引着广泛关注。利用时间分辨光电子能谱研究了双光子紫外光激发的里德堡激发丙醛的紫外光触发异构化。通过在时域中跟踪来自3s里德堡态的光电离，实时观测并追踪了超快结构演化及相应的光异构化动力学。实验估计从顺式丙醛异构化为gauche异构体的转化势垒约为1500±100 cm⁻¹。光异构化产率和转化率均表现出对激发能量的强烈依赖性。据观察，无论振动模式是否被选择性激发，一旦激发能量高于转化势垒，3s里德堡态的丙醛从顺式到gauche的光异构化就会发生，且不存在任何振动激发特异性。这产生了一种研究大分子结构演化动力学的有力方法，其可能在分子器件中有应用。
