Formation of Halogen-bearing Species. II. Irradiation of Chloromethane in Carbon Monoxide Ice with VUV Light and Electrons

Abstract

The synthesis of chlorine-bearing species in CO ice was studied by the irradiation of CH3Cl:CO ice at 10 K with vacuum-ultraviolet (VUV) light and energetic electrons. In contrast to the photochemical behavior of CH3F:CO ice, photolysis of CH3Cl:CO ice with Ly alpha or broadband VUV light afforded various products. This discrepancy was attributed to the abundant absorption bands of CH3Cl in the VUV region, particularly in the Ly alpha region. The Cl-bearing species including Cl2O, ClCO, C3Cl2, C3HCl, and HOOCl were characterized by observing their IR features. In contrast, electron bombardment of ice mixtures produced various carbon oxides and primary products, such as CH2Cl and HCO. In addition, the mechanism of energetic processes in electron bombardment was discussed.