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

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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.