Department of Physics, AlbaNova University Center, Stockholm University, SE-106 91 Stockholm, Sweden.
Institut für Physik und Astronomie, Universität Potsdam, Karl-Liebknecht-Str. 24/25, 14476 Potsdam, Germany.
J Chem Phys. 2019 Sep 21;151(11):114117. doi: 10.1063/1.5109840.
The nitrogen and sulfur K-edge X-ray absorption spectra of aqueous 2-thiopyridone, a model system for excited-state proton transfer in several recent time-resolved measurements, have been simulated from ab initio molecular dynamics. Spectral signatures of the local intra- and inter-molecular structure are identified and rationalized, which facilitates experimental interpretation and optimization. In particular, comparison of aqueous and gas phase spectrum simulations assesses the previously unquantified solvatization effects, where hydrogen bonding is found to yield solvatochromatic shifts up to nearly 1 eV of the main peak positions. Thereby, while each K-edge can still decisively determine the local protonation of its core-excited site, only their combined, complementary fingerprints allow separating all of the three relevant molecular forms, giving a complete picture of the proton transfer.
运用从头算分子动力学，对作为近期几个瞬态测量中激发态质子转移模型体系的 2-巯基吡啶水相的氮和硫 K 边 X 射线吸收光谱进行了模拟。确定并解释了局部分子内和分子间结构的光谱特征，这有助于实验解释和优化。特别是，对水相和气相光谱模拟的比较评估了以前未量化的溶剂化效应，其中氢键导致主峰位置的溶剂化色移高达近 1 eV。因此，虽然每个 K 边仍然可以决定性地确定其核心激发部位的局部质子化，但只有它们的组合、互补指纹才能分离出所有三种相关的分子形式，全面描绘质子转移。
