The temperature dependence (203-293 K) of the absorption cross sections ofO-3 in the 230-850 nm region measured by Fourier-transform spectroscopy

Absolute absorption cross sections of O-3 were measured in the 230-850 nm ( 11765-43478 cm(-1)) region at five different temperatures (203-293 K) using a Fourier-transform spectrometer, at a spectral resolution of 5.0 cm(-1) ( corresponding to about 0.027 nm at 230 nm and to about 0.36 nm at 850 nm). The spectral accuracy of the data is better than 0.1 cm(-1) - about 0.5 pm at 230 nm and about 7.2 pm at 850 nm - validated by recording of I-2 absorp tion spectra in the visible using the same experimental set-up. O-3 absorpt ion spectra at different concentrations were recorded at five different sam ple temperatures in the range 203-293 K, and at each temperature at two tot al pressures (100 and 1000 mbar) using O-2/N-2 mixtures as buffer gas. With in the limits of experimental uncertainties, no influence of total pressure on the O-3 spectrum was observed in the entire spectral region, as expecte d from the short lifetimes of the upper electronic states of O-3. The tempe rature dependence of the O-3 absorption cross sections is particularly stro ng in the Huggins bands between 310 and 380 nm, as observed in previous stu dies. An empirical formula is used to model the temperature dependence of t he O-3 absorption cross sections between 236 and 362 nm, a spectral region that is particularly important for atmospheric remote-sensing and for photo chemical modelling. (C) 2001 Elsevier Science B.V. All rights reserved.