STATIC SIMS STUDIES OF REACTIONS ON MIMICS OF POLAR STRATOSPHERIC CLOUDS II - LOW-TEMPERATURE, LOW-PRESSURE INTERACTIONS OF CL-2 AND CL2O WITH SOLID ICE FILMS

The interactions of molecular chlorine, dichlorine monoxide, and hypoc hlorous acid with solid ice films have been examined. At 90-100 K, chl orine can be made to condense as a molecular solid, forming a discrete layer on top of an existing film of solid H2O. interaction between th e Cl-2 and the water molecules is minimal. At temperatures above appro ximately 130 K, the Cl-2 and water react to produce a mixed film of wa ter, hypochlorous acid, and solvated HCl. As with chlorine, the dichlo rine monoxide did not react with water at 90 K. However, there was evi dence of a hydrogen-bond-like interaction between the Cl2O and H2O mol ecules. Upon warming to 120 K or higher, the two reacted to produce a mixed film of hypochlorous acid and water. The reactions that occurred at the higher temperatures are of interest because of the well-docume nted influence of polar stratospheric clouds, which consist of solid w ater or water/nitric acid particles, on the release of active chlorine species into the stratosphere.