Ab initio quantum dynamics of photoabsorption and dissociation of carbon dioxide in the low lying singlet and triplet states

本项目研究了二氧化碳在200 nm-120 nm(6 eV-10 eV)紫外(UV)波长范围内的吸收光谱和解离动力学。紫外光以单位量子产率破坏二氧化碳，所选择的光谱区域对于大气和行星化学具有相当重要的意义。在第一个资助期进行的对六个单重态的从头算量子动力学研究，允许对主要吸收带进行单义电子指定。第二个资助期的研究集中在六个低位三重态以及它们与单重态耦合的光动力学含义。计划对耦合的全局势能、自旋轨道和跃迁偶极矩表面进行广泛的从头计算，然后是多态量子动力学计算。该项目的目标是从光谱上准确地描述耦合的单重态和三重态流形的吸收性质，并阐明具有空间、时间和能量分辨率的光解离机制。我们设计了从头算/量子动力学相结合的方法来解释大量的实验数据，并研究了非绝热和自旋轨道相互作用对光碎片在自旋允许和自旋禁止解离通道中的吸收光谱和电子、平移、振动和角分布的影响。

This project investigates the absorption spectrum and the dissociation dynamics of carbon dioxide in the ultraviolet (UV) wavelength range of 200 nm - 120 nm (6 eV - 10 eV). UV light destroys CO2 with unit quantum yield, and the chosen spectral region is of considerable importance for the atmospheric and planetary chemistry. The ab initio quantum dynamical studies of the six singlet states, performed in the first funding period, allowed a univocal electronic assignment of the principal absorption bands. Research in the second funding period concentrates on the six low lying triplet states and the photodynamic implications of their coupling with the singlet states. Extensive ab initio calculations of the coupled global potential energy, spin orbit, and the transition dipole moment surfaces are planned, followed by multistate quantum dynamical calculations. The goal of the project is to give a spectroscopically accurate description of the absorption properties of the coupled singlet and triplet manifolds and to elucidate the photodissociation mechanisms with the spatial, temporal, and energyresolution. The combined ab initio/quantum dynamical studies are desinged to rationalize a large body of experimental data and to investigate the impact of non-adiabatic and spin orbit interactions on the absorption spectra and the electronic, translational, vibrational, and angular distributions ofthe photofragments in the spin allowed and the spin forbidden dissociation channels.