On the Photodecomposition of C10N0

As its major removal process the photodissociat ion of a tmospheric C 1 0 N 0 2 in the ultraviolet is discussed. It has repeatedly been pointed out that significance should be at t r ibuted to the pathways of chlorine nitrate fo rmat ion and its destruction since this compound might be involved in the ozone depletion mechanism through both the C10x and N O x a tmospheric cycles. This communica t ion summarizes our results on the photodecomposi t ion of gaseous chlorine nitrate in the middle ultraviolet using a static experimental set-up. Its publ icat ion is p rompted by a report [1] containing in essence conclusions which are in agreement with an earlier letter by Smith et al. [2] but being at variance with our results [3, 4] and those of others [5]. All experiments were carried out in thermostated all-quartz cells. One set of cells was equipped with an addit ional set of sealed-on Si windows which are transparent in the ir region of interest. I l luminat ion occurred with a Hanovia med ium pressure Hglamp. The Schott filters UV-250 and UV-340 were used either separately or in combinat ion with cutoff filters. The effective wavelength in the experiments was either / = 265 nm with a relative total intensity < 1% for / < 263 nm or / = 313 nm with no measurable contr ibut ions at /, < 300 nm. Irradiations were per formed in the tempera ture range + 2 0 to —30 °C. The C 1 0 N 0 2 pressure was adjusted be-