Key Laboratory of Optoelectronic Devices and Systems of Ministry of Education and Guangdong Province, College of Physics and Optoelectronic Engineering, Shenzhen University, Shenzhen 518060, China.
State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, Wuhan Institute of Physics and Mathematics, Chinese Academy of Sciences, Wuhan 430071, China.
J Chem Phys. 2019 Sep 7;151(9):094302. doi: 10.1063/1.5115307.
The excited-state intramolecular proton transfer (ESIPT) process and subsequent electronic relaxation dynamics in methyl salicylate have been investigated using femtosecond time-resolved ion yield spectroscopy combined with time-resolved photoelectron imaging. Excitation with a tunable pump pulse populates the keto tautomer in the first excited electronic state S(ππ). As a hydrogen atom transfers from the phenolic group to the carbonyl group within 100 fs, the molecular geometry changes gradually, leading to a variation in the electronic photoionization channel. By virtue of the accidental resonance with some intermediate Rydberg states, the time-dependent photoelectron spectra provide a direct mapping of the ESIPT reaction from the initially populated keto tautomer to the proton-transferred enol tautomer. Subsequently, the population around the enol configuration undergoes intramolecular vibrational redistribution on a subpicosecond time scale, followed by internal conversion to the ground state with a wavelength-dependent lifetime in the picosecond range. Furthermore, the excitation energies of several Rydberg states in methyl salicylate are determined experimentally.
利用飞秒时间分辨离子产量光谱结合时间分辨光电子成像技术，研究了水杨酸甲酯中的激发态分子内质子转移（ESIPT）过程及随后的电子弛豫动力学。用可调谐泵浦脉冲激发，将酮式互变异构体激发到第一激发电子态 S(ππ)。在 100 fs 内，氢原子从酚基转移到羰基，分子几何形状逐渐发生变化，导致电子光离通道发生变化。由于与某些中间里德堡态的偶然共振，时间分辨光电子能谱提供了从最初的酮式互变异构体到质子转移的烯醇式互变异构体的 ESIPT 反应的直接映射。随后，在亚皮秒时间尺度上，烯醇构型周围的布居经历分子内振动再分配，随后以与波长相关的皮秒范围内的寿命进行内转换回到基态。此外，实验测定了水杨酸甲酯中几个里德堡态的激发能。
