45 57 Reference: JPL Publication 94-26 Chemical Kinetics and Photochemical Data for Use in Stratospheric Modeling Evaluation Number 11 December 15, 1994 page 119 ff. NO2 + hv -> NO + O "Earlier recommendations for the absorption cross sections of nitrogen dioxide were taken from the work of Bass et al. [117]. More recent measurements have been reported by Schneider et al. [1391], at 298K, for the wavelength range from 200 to 700 nm; and by Davidson et al. [411], from 270 to 420 nm, in the 232-397 K temperature range. At room temperature the agreement vetween these three sets of measurements is good; within 5% between 305 and 345 nm, and within 10% at the longer wavelengths. The agreements is poor below room temperate, as well as at the shorter wavelengths. A possible cause for the discrepancies is the presence of N2O4. The corrections needed to account for the presence of this species are largest around 200 nm, where it absorbs strongly. The corrections are also large at the lowest temperatures, because a significant fraction of the NO2 froms N2O4. On the other hand, there is no error apparent in the corrections carried out by Bass et al., so that the reason for the discrepancy is not clear. Measuremets of the absoprtion cross sections in the visible (440 to 460 nm), between 273 and 404 K, have been reported by Amoruso et al. [32]; and Corcoran et al. [361] carried out high resolution measurements at a ferw selected wavelength ranges between 470 and 616 nm, at 295, 573 and 673 K. Table 13 lists the recommended absoprtion cross sections, averaged over the wavelength intervals used for atmospheric photodissociation calculations. For the wavelength range from 200 to 274 nm the values are taken from Schneider et al. [1391]; in this range the temperature effect is negligible. For the 274 to 420 nm region the temperature-dependent values are taken from DAvidson et al. [411]." sigma(T) = sigma(T0) + a* x T with T: temperature in degrees C ----------------------------------------------------------------------------- Table 13. Absorption Cross Sections of NO2 (a* in units of 1E22 cm2 mol-1 deg-1) ----------------------------------------------------------------------------- lambda1 lambda2 sigma @ T0 T0 a* (nm) (nm) (1E-20 cm2 mol-1) (C) (see above) ----------------------------------------------------------------------------- 202.02 204.08 41.45 25 0. 204.08 206.19 44.78 25 0. 206.19 208.33 44.54 25 0. 208.33 210.53 46.41 25 0. 210.53 212.77 48.66 25 0. 212.77 215.09 48.18 25 0. 215.09 217.39 50.22 25 0. 217.39 219.78 44.41 25 0. 219.78 222.22 47.13 25 0. 222.22 224.72 37.72 25 0. 224.72 227.27 39.29 25 0. 227.27 229.89 27.40 25 0. 229.89 232.56 27.78 25 0. 232.56 235.29 16.89 25 0. 235.29 238.09 16.18 25 0. 238.09 240.96 8.812 25 0. 240.96 243.90 7.472 25 0. 243.90 246.91 3.909 25 0. 246.91 250.00 2.753 25 0. 250.00 253.17 2.007 25 0. 253.17 256.41 1.973 25 0. 256.41 259.74 2.111 25 0. 259.74 263.16 2.357 25 0. 263.16 266.67 2.698 25 0. 266.67 270.27 3.247 25 0. 270.27 273.97 3.785 25 0. 273.97 277.78 5.03 0 0.075 277.78 281.69 5.88 0 0.082 281.69 285.71 7.00 0 -0.053 285.71 289.85 8.15 0 -0.043 289.85 294.12 9.72 0 -0.031 294.12 298.51 11.54 0 -0.162 298.51 303.03 13.44 0 -0.284 303.03 307.69 15.89 0 -0.357 307.69 312.50 18.67 0 -0.536 312.50 317.50 21.53 0 -0.686 317.5 322.5 24.77 0 -0.786 322.5 327.5 28.07 0 -1.105 327.5 332.5 31.33 0 -1.355 332.5 337.5 34.25 0 -1.277 337.5 342.5 37.98 0 -1.612 342.5 347.5 40.65 0 -1.890 347.5 352.5 43.13 0 -1.219 352.5 357.5 47.17 0 -1.921 357.5 362.5 48.33 0 -1.095 362.5 367.5 51.66 0 -1.322 367.5 372.5 53.15 0 -1.102 372.5 377.5 55.08 0 -0.806 377.5 382.5 56.44 0 -0.867 382.5 387.5 57.57 0 -0.945 387.5 392.5 59.27 0 -0.923 392.5 397.5 58.45 0 -0.738 397.5 402.5 60.21 0 -0.599 402.5 407.5 57.81 0 -0.545 407.5 412.5 59.99 0 -1.129 412.5 417.5 56.51 0 0.001 417.5 422.5 58.12 0 -1.208