Abstract: Separate Xe/03 and Xe/CzH4 mixtures were condensed on a CsI window at 50 K and then warmed to 80-100 K. Strong infrared absorptions due to the secondary ozonide and weaker bands at 409, 647, 727, 846, 927, 983, and 1214 cm-I replaced the ethylene and ozone absorptions. The latter new bands agree with earlier solid film and COz matrix studies and are assigned to the primary ozonide. Isotopic substitution (16* 1803, CHzCD2 ...