Photodissociation of carbon dioxide (CO2) has long been assumed to proceed exclusively to carbon monoxide (CO) and oxygen atom (O) primary products. However, recent theoretical calculations suggested that an exit channel to produce C + O2 should also be energetically accessible. Here we report the direct experimental evidence for the C + O2 channel in CO2 photodissociation near the energetic threshold of the C(3P) + O2(X3Σg–) channel with a yield of 5 ± 2% using vacuum ultraviolet laser pump-probe spectroscopy and velocity-map imaging detection of the C(3PJ) product between 101.5 and 107.2 nanometers. Our results may have implications for nonbiological oxygen production in CO2-heavy atmospheres.

By using a two-color laser excitation-photoionization scheme, we have obtained rovibronically selected and resolved state-to-state pulsed field ionization-photoelectron (PFI-PE) bands for FeC+(X2delta5/2; v+=0-2, J+), allowing unambiguous rotational assignments for the photoionization transitions. The finding of the J+ = 5/2 level as the lowest rotational state confirms that the ground FeC+ ion state is of 2delta5/2 symmetry. The observed changes in total angular momentum upon photoionization of FeC are |deltaJ+| = |J+ - J'|

We have measured the absolute integral cross sections (σ's) for H3O(+) formed by the reaction of rovibrationally selected H2O(+)(X(2)B1; v1 (+)v2 (+)v3 (+) = 000; N(+) K a (+) K c (+) = 000, 111, and 211) ion with H2 at the center-of-mass collision energy (Ecm) range of 0.03-10.00 eV. The σ(000), σ(111), and σ(211) values thus obtained reveal rotational enhancements at low Ecm < 0.50 eV, in agreement with the observation of the previous study of the H2O(+)(X(2)B1) + D2 reaction. This Communication presents important progress concerning the high-level ab initio quantum calculation of the potential energy surface for the H2O(+)(X(2)B1) + H2 (D2) reactions, which has provided valuable insight into the origin of the rotational enhancement effect. Governed by the charge and dipole-induced-multipole interactions, the calculation shows that H2 (D2) approaches the H end of H2O(+)(X(2)B1) in the long range, whereas chemical force in the short range favors the orientation of H2 (D2) toward the O side of H2O(+). The reorientation of H2O(+) reactant ion facilitated by rotational excitation thus promotes the H2O(+) + H2 (D2) reaction along the minimum energy pathway, rendering the observed rotational enhancement effects. The occurrence of this effect at low Ecm indicates that the long range charge and dipole-induced-multipole interactions of the colliding pair play a significant role in the dynamics of the exothermic H2O(+) + H2 (D2) reactions.