State-resolved And State-to-state Photodissociation Study Of Co2 By Two-color Vuv-vuv Laser Pump-probe Method

\chem{CO_2} is known as a strong contributor to the greenhouse effect, and its concentration in the atmosphere increases annually. Photodissociation of \chem{CO_2} is considered an important photochemical sink of \chem{CO_2} molecules which could ultimately limit the increase of \chem{CO_2} concentration in the atmosphere. Since \chem{CO_2} molecules have negligibly small absorption from the visible region down to about 200 nm, photodissociation studies of \chem{CO_2} in the vacuum ultraviolet (VUV) region below 200 nm are of great importance in understanding the photochemical decomposition processes of \chem{CO_2} molecules. State-to-state photodissociation of \chem{CO_2} has been investigated by employing two independent VUV lasers and the time-slice velocity-map-imaging-photoion (VMI-PI) method. The spin-allowed photoproduct channels, CO(X$^{1}$$\Sigma$$^{+}$) + O($^{1}$D), CO(X$^{1}$$\Sigma$$^{+}$) + O($^{1}$S), CO(a$^{3}$$\Pi$) + O($^{3}$P$_{J}$), and C($^{3}$P$_{J}$) + O$_{2}$(X$^{3}$$\Sigma$$_{g}$$^{-}$), and the spin-forbidden photoproduct channel, CO(X$^{1}$$\Sigma$$^{+}$) + O($^{3}$P$_{J}$), were directly observed from the time-slice VMI-PI images. The angular anisotropic parameters were evaluated, allowing us to estimate the lifetimes for the formations of these dissociation channels. To the authors’ knowledge, the current \chem{CO_2} photodissociation studies show for the first time that all of the energetically available photodissociation channels are formed in the \chem{CO_2} photoexcitation energy of interest