State-to-state photodissociation dynamics of CO2 at 157 nm

State-to-state photodissociation of CO2(v(2) = 0 and 1) at 157 nm via the O(D-1) + CO(X-1 sigma(+)) channel was studied by using the sliced velocity map imaging technique. Both the O(D-1) and CO(X-1 sigma(+)) products were detected by (2 + 1) resonance enhanced multiphoton ionization (REMPI). Detection of CO via the B-1 sigma(+) <-<- X-1 sigma(+) transition allowed ro-vibrational state-selective detection, and combined with imaging, the fragment energy and angular distributions have been derived. For CO(v = 0 and 1|j) products from the CO2(v(2) = 0) molecule, the angular distributions of low-j CO display positive anisotropic parameters (about 0.8); with j increasing, the product anisotropic parameters gradually reduce to zero. While for CO(v = 0 and 1|j) products from the vibrational excited CO2(v(2) = 1) molecule, the angular distributions of low-j CO also display positive anisotropic parameters; with j increasing, the product anisotropic parameters first decrease to zero and then become negative (about -0.5). Experimental results show that the observed variation of the product angular distribution with the rotational quantum number of CO is consistent with trends predicted by a classical model for non-axial fragment recoil. The results support advanced theoretical predictions of a predominantly parallel transition to the bent 2(1)A ' excited state of CO2, where bending introduces torque during the direct dissociation process.

Automated summary

This study investigated the state-to-state photodissociation of CO2(v(2) = 0 and 1) at 157 nm via the O(D-1) + CO(X-1 sigma(+)) channel using the sliced velocity map imaging technique. The experimental results showed that the observed variation of the product angular distribution with the rotational quantum number of CO is consistent with theoretical predictions.