Mechanistical studies on the formation and destruction of carbon monoxide (CO), carbon dioxide (CO2), and carbon trioxide (CO3) in interstellar ice analog samples

Abstract

A series of ice mixtures containing carbon monoxide (CO), carbon dioxide (CO(2)), and molecular oxygen (O(2)) with varying carbon-to-oxygen ratios from 1 : 1.5 to 1 : 4 were irradiated at 10 K with energetic electrons to derive formation mechanisms and destruction pathways of carbon monoxide (CO), carbon dioxide (CO(2)), and carbon trioxide (CO(3)) in extraterrestrial, low temperature ices. Reactants and products were analyzed on line and in situ via absorption-reflection-absorption FTIR spectroscopy in the solid state, while the gas phase was sampled by a quadrupole mass spectrometer (QMS). Additionally, isotopically mixed ices consisting of (i) (13)CO ratio C(18)O ratio CO(2), (ii) CO(2)ratio C(18)O(2), and (iii) CO(2)ratio(18)O(2) were irradiated in order to derive mechanistical and kinetic information on the production and destruction pathways of the following species: (i) (13)CO, C(18)O, CO(2), CO, (13)CO(2), (18)OCO, and (13)CO(3) (C(2v)), (ii) CO(2), C(18)O(2), CO, C(18)O, (18)OCO, CO(3) (C(2v)), OC(18)OO (C(2v)), OC(18)O(2) (C(2v)), (18)OCO(2) (C(2v)), (18)OC(18)OO (C(2v)), and C(18)O(3) (C(2v)), and (iii) CO(2), CO, (18)OCO, C(18)O, and C(18)O(2).