SIMBAD references

Investigations with infrared spectroscopy and microgravimetry show that CO₂ forms in small quantities during codeposition of CO and cooled O and O₂ into thin films at 20 K: ∼3x10¹⁴ CO₂/cm2 within a film containing 2.7x10¹⁷ CO/cm2. The reason for the low CO₂ yield is that O atoms react preferentially with O to form O₂, and with O₂ to form ozone, which was not considered in previous studies with atomic beams. Heating a CO + O + O₂ film capped with a ∼2.5 µm thick water ice layer to 80 K increased CO₂ by 30%, showing additional reactions between O and CO diffusing in the ice layer. Although the CO₂:CO = 10^–3 measured in our experiments is at least two orders of magnitude smaller than reported interstellar ratios, sputtering and differential desorption during transient heating events, e.g., by impacts of cosmic rays or stellar winds, can increase the ratio to observed values.