Pathways for the release of atomic chlorine from CHClF2 fragmentation by electron impact

Abstract

Chlorine atoms released in the upper atmosphere from CFC and HCFC compounds when impacted by energetic particles are recognized as the main mechanism for the enlargement of the hole in the ozone layer. A recent study showed a strong indication that the chlorine atom could be released from CHClF2 due to the ionization of either chlorine or fluorine present in the molecule. Investigation of the possible pathways for the dissociation of chlorine from CHClF2 by electron impact has been performed by scanning its relative contribution to Cl production along the 2p fluorine threshold and by measuring the energy distributions of the fragments produced by this collision for energies below and above the 2p fluorine threshold using the new delayed extraction time-of-flight technique. The data presented here provide the kinetic energy distribution of the fragments emerging from the collision and show direct experimental evidence that the release of chlorine can be triggered by the removal either of a chlorine electron or of a non-bonding fluorine electron, a result that should also apply to photoionization.