35 56 # first data record, number of data records Reference: JPL Publication 97-4 Chemical Kinetics and Photochemical Data for Use in Stratospheric Modeling Evaluation Number 12 January 15, 1997 page 206 ff. CF2Br2 (Halon-1202) + hv -> Products "The preferred absorption cross sections at 298 K, listed in Table 54, are the mean of the values reported by Gillotay and Simon [101] at 2 nm intervals and Burkholder et al. [40] at 1 nm intervals over the wavelength range where the agreement is no more than a factor of two. At wavelengths longer than ca. 250 nm, Burkholder et al. [40] measured cross sections larger than those reported by Gillotay and Simon [101] and Molina et al. [208]. The discrepancy increases with wavelength and is more than a factor of two beyond 280 nm. However, the agreement between all three measurements is acceptable below 250 nm. The values of Molina et al. agree with those of Gillotay and Simon over the entire range of wavelengths. The temperature dependence of the cross sections has been measured by Gillotay and Simon as well as Burkholder et al. [40]. The agreement between these two studies is poor. Orkin and Kasimovskaya [236] measured the cross sections in the wavelength range 190-320 nm at 295 K; their results agree with the recommended values. The quantum yield for the dissociation of CF2Br2 has been measured to be unity at 206, 248 and 308 nm by Molina and Molina [205], independent of pressure, in contrast to an earlier report by Walton [323] that the quantum yield at 265 decreases from unity when the system pressure is raised to 50 torr of CO2." Table 54. Absorption Cross Sections of CF2Br2 -------------------------------------------------------------------------- lambda (nm) 1E20 sigma (cm^2) -------------------------------------------------------------------------- 190 114 192 109 194 100 196 91 198 82 200 75 202 72 204 74 206 81 208 93 210 110 212 136 214 155 216 180 218 203 220 224 222 242 224 251 226 253 228 250 230 241 232 227 234 209 236 189 238 168 240 147 242 126 244 106 246 88 248 73 250 59 252 47 254 37 256 29 258 23 260 18 262 13 264 10 266 7.6 268 5.7 270 4.2 272 3.1 274 2.2 276 1.6 278 1.2 280 0.89 282 0.65 284 0.48 286 0.34 288 0.24 290 0.18 292 0.13 294 0.096 296 0.068 298 0.050 300 0.036