Direct Observation of CIO from Chlorine Nitrate Photolysis

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Science  20 Nov 1992:
Vol. 258, Issue 5086, pp. 1342-1345
DOI: 10.1126/science.258.5086.1342


Chlorine nitrate photolysis has been investigated with the use of a molecular beam technique. Excitation at both 248 and 193 nanometers led to photodissociation by two pathways, CIONO2 → CIO + NO2 and CIONO2 → Cl + NO3, with comparable yields. This experiment provides a direct measurement of the CIO product channel and consequently raises the possibility of an analogous channel in CIO dimer photolysis. Photodissociation of the CIO dimer is a critical step in the catalytic cycle that is presumed to dominate polar stratospheric ozone destruction. A substantial yield of CIO would reduce the efficiency of this cycle.