Issler Kevin, Sturm Floriane, Petersen Jens, Flock Marco, Mitrić Roland, Fischer Ingo, Barreau Lou, Poisson Lionel
Institute of Physical and Theoretical Chemistry, University of Würzburg, Am Hubland, D-97074 Würzburg, Germany.
Institut des Sciences Moléculaires dOrsay (ISMO) UMR 8214, Rue André Rivière, Bâtiment 520, Université Paris-Saclay, F-91405 Orsay Cedex, France.
Phys Chem Chem Phys. 2023 Apr 5;25(14):9837-9845. doi: 10.1039/d3cp00309d.
We investigated the excited-state dynamics of 4-(dimethylamino)benzethyne (4-DMABE) in a combined theoretical and experimental study using surface-hopping simulations and time-resolved ionisation experiments. The simulations predict a decay of the initially excited S state into the S state in only a few femtoseconds, inducing a subsequent partial twist of the dimethylamino group within ∼100 fs. This leads to drastically reduced Franck-Condon factors for the ionisation transition to the cationic ground state, thus inhibiting the effective ionisation of the molecule, which leads to a vanishing photoelectron signal on a similar timescale as observed in our time-resolved photoelectron spectra. From the phototoelectron spectra, an adiabatic ionisation energy of 7.17 ± 0.02 eV was determined. The experimental decays match the theoretical predictions very well and the combination of both reveals the electronic characteristics of the molecule, namely the role of intramolecular charge transfer (ICT) states in the deactivation pathway of electronically excited 4-DMABE.
我们通过表面跳跃模拟和时间分辨电离实验，开展了一项理论与实验相结合的研究，以探究4-（二甲氨基）苯乙炔（4-DMABE）的激发态动力学。模拟结果预测，最初激发的S态在短短几飞秒内就会衰减为S态，在约100飞秒内会引发二甲氨基基团随后的部分扭转。这导致向阳离子基态电离跃迁的弗兰克-康登因子大幅降低，从而抑制了分子的有效电离，进而导致在与我们的时间分辨光电子能谱中观察到的类似时间尺度上光电子信号消失。从光电子能谱中，确定了绝热电离能为7.17±0.02电子伏特。实验衰减与理论预测非常吻合，两者相结合揭示了该分子的电子特性，即分子内电荷转移（ICT）态在电子激发的4-DMABE失活途径中的作用。
