Proton transfer processes form the foundation of many chemical processes. In excited-state intramolecular proton transfer (ESIPT) processes, ultrafast proton transfer is impulsively initiated through light. Here, we explore time-dependent coupled atomic and electronic motions during and following ESIPT through computational time-resolved resonant inelastic X-ray scattering (RIXS). Excited-state ab initio molecular dynamics simulations combined with time-dependent density functional theory calculations were performed for a model ESIPT system, 10-hydroxybenzo[h]quinoline, to obtain transient RIXS signatures. The RIXS spectra at both the nitrogen and oxygen K-edges were computed to resolve the electronic and atomic structural dynamics from both the proton donor and acceptor perspective. The results demonstrate that RIXS provides unprecedented details of the local electronic structure, the coupling between different core and valence excited electronic states, and the reorganization of the electronic structure coupled to the proton transfer process. We also develop a spectroscopic ruler correlating spectral shifts of a RIXS peak to the proton transfer distance during ESIPT. This work highlights the exciting potential of time-resolved RIXS experiments at newly commissioned soft X-ray free electron laser facilities for measuring coupled electronic and structural changes during ultrafast chemical processes.

中文翻译：

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通过计算多边共振非弹性 X 射线散射捕获激发态分子内质子转移过程中的耦合结构和电子运动


质子转移过程构成了许多化学过程的基础。在激发态分子内质子转移 （ESIPT） 过程中，超快质子转移是通过光脉冲启动的。在这里，我们通过计算时间分辨共振非弹性 X 射线散射 （RIXS） 来探索 ESIPT 期间和之后的时间依赖性耦合原子和电子运动。对模型 ESIPT 系统 10-羟基苯并[h]喹啉进行激发态从头分子动力学模拟与时间依赖性密度泛函理论计算相结合，以获得瞬态 RIXS 特征。计算了氮和氧 K 边缘的 RIXS 光谱，以从质子供体和受体的角度解析电子和原子结构动力学。结果表明，RIXS 提供了局部电子结构、不同核心和价激发电子态之间的耦合以及与质子转移过程耦合的电子结构重组的前所未有的细节。我们还开发了一种光谱尺，将 RIXS 峰的光谱偏移与 ESIPT 期间的质子转移距离相关联。这项工作突出了在新调试的软 X 射线自由电子激光器设施中进行时间分辨 RIXS 实验的令人兴奋的潜力，用于测量超快化学过程中的耦合电子和结构变化。