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H-atom detachment photochemistry of (hetero)aromatic molecules: ab initio quantum dynamics studies

（杂）芳香族分子的氢原子脱离光化学：从头算量子动力学研究

基本信息

批准号：
248983919
负责人：
Professor Dr. Wolfgang Domcke
金额：
--
依托单位：
Lehrstuhl für Theoretische Chemie
依托单位国家：
德国
项目类别：
Research Grants
财政年份：
2014
资助国家：
德国
起止时间：
2013-12-31 至 2017-12-31
项目状态：
已结题

来源：
https://gepris.dfg.de/gepris/projekt/248983919?language=en
关键词：
atom detachment photochemistry hetero aromatic

项目摘要

When aromatic or heteroaromatic molecules with acidic groups (NH, NH2, OH, SH) are excited with ultraviolet (UV) light, the detachment of slow as well as fast hydrogen atoms is observed. These photodissociation processes are currently under extensive experimental scrutiny by means of modern photofragment detection techniques, which provide detailed quantum state-resolved information on this novel nonstatistical unimolecular decay process. In this research project, the electronic and quantum dynamical mechanisms of ultrafast H-atom detachment processes in selected (hetero)aromatic molecules will be explored by means of accurate ab initio electronic-structure and nuclear-dynamics calculations. The three representative molecules to be studied are pyrrole, phenol and thiophenol. Their hallmark is the existence of a conical intersection of the repulsive potential-energy function of a dark electronic state of pisigma* character with the attractive potential-energy function of the electronic ground state in the hydrogen-detachment channel. In phenol and thiophenol, an additional conical intersection between the lowest pipi* state and the pisigma* state is located in the Franck-Condon region. The goal of the project is (a) the construction of accurate ab initio based multi-dimensional diabatic potential-energy surfaces of the coupled electronic states involved in the photodissociation reaction and (b) the elucidation of the photodetachment mechanisms with time-dependent quantum dynamical calculations, in particular the effects of strong nonadiabatic interactions on the absorption spectrum and the final-state distribution of the photofragments. The intention is the rationalization of the rich amount of recent experimental data and the clarification of controversies concerning the assignment of the vibrational structures of the high-resolution H-atom kinetic-energy spectra.

当用紫外光（UV）激发具有酸性基团（NH、NH 2、OH、SH）的芳族或杂芳族分子时，观察到慢氢原子和快氢原子的脱离。这些光解离过程目前正在广泛的实验审查，通过现代的光碎片检测技术，这提供了详细的量子态分辨的信息，这种新的非统计单分子衰变过程。在本研究项目中，将通过精确的从头计算电子结构和核动力学计算，探索选定的（杂）芳族分子中超快H原子脱离过程的电子和量子动力学机制。待研究的三种代表性分子是吡咯、苯酚和苯硫酚。他们的特点是存在一个圆锥形的交叉点的排斥势能函数的暗电子态的pisigma* 字符与吸引力的势能函数的电子基态中的氢分离通道。在苯酚和苯硫酚中，最低pipi* 状态和pisigma* 状态之间的额外圆锥形交叉点位于Franck-Condon区域。该项目的目标是：（a）构建光解离反应中所涉及的耦合电子态的精确的基于从头算的多维非绝热势能面;（B）用随时间变化的量子动力学计算阐明光解离机制，特别是强非绝热相互作用对光碎片的吸收光谱和终态分布的影响。其目的是合理化的丰富数量的最近的实验数据和澄清的争议有关的高分辨率H-原子动能谱的振动结构的分配。