Photodetachment Cross Sections for CO3− and Its First Hydrate

Abstract

The cross sections for the aeronomically important processes ${\mathrm{CO}}_3^{-}\mathrm{+h\nu \to }{\mathrm{CO}}_3{\mathrm{+e}}^{-}$ and ${\mathrm{CO}}_3^{-}·{\mathrm{H}}_2\mathrm{O}\mathrm{+h\nu \to }{\mathrm{CO}}_3·{\mathrm{H}}_2\mathrm{O}{\mathrm{+e}}^{-}$ are measured at a pressure of 2 torr. The ions are detected in a differentially pumped quadrupole mass spectrometer. The photodetachment threshold energy is 1.8 eV for ${\mathrm{CO}}_3^{-}$ and 2.1 eV for ${\mathrm{CO}}_3^{-}·{\mathrm{H}}_2\mathrm{O}$ . Their solar photodetachment rates are, respectively, 1.4 and 1.1 sec⁻¹ relative to the O⁻ rate of 1.44 sec⁻¹.