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VI/83 O3 and SO2 Absorption Cross Sections (Freeman+ 1984,88,93) ================================================================================ High Resolution Absorption Cross-section Measurements of Ozone at 195 K in the Wavelength Region 240-350 nm Freeman D.E., Yoshino K., Esmond J.R., Parkinson W.H. <Planetary Sp. Sci. 32(2): 239-248, (1984)> Absolute Absorption Cross-section Measurements of Ozone in the Wavelength Region 238-335 nm and the Temperature Dependence Yoshino K., Freeman D.E., Esmond J.R., Parkinson W.H. <Planetary. Sp. Sci., 36(4): 395-398, (1988)> Measurements of Absolute Absorption Cross Sections of Ozone in the 185-to 254-nm Wavelength Region and the Temperature Dependence Yoshino K., Esmond J.R., Freeman D.E., Parkinson W.H. <J. Geophys. Res., March 20, 98(D3): 5205-5211 (1993)> High Resolution Absorption Cross Section Measurements of SO2 at 213 K in the Wavelength Region 172-240 nm Freeman D.E., Yoshino Y., Esmond J.R., Parkinson W.H. <Planetary Sp. Sci. 32, 1125-1134 (1984)> ================================================================================ ADC_Keywords: Atomic physics; Spectroscopy; Cross sections Abstract: Cross sections of the Hartley-Huggins bands of O3 at the temperature 195K were obtained from photoabsorption measurements at column densities in the range 2 x 10^17 - 1 x 10^21 cm-2 throughout the wavelength region 240-350 nm. Measurements of the absolute absorption cross-section of ozone at the temperatures 195, 228 and 295 K were made at several discrete wavelengths in the region 238-335 nm and measurements of the relative absorption cross sections were made temperatures 195, 228 and 295 K throughout the wavelength region 185-254 nm. Laboratory measurements at high resolution of the absorption cross section of SO2 at the temperature 213 K in the wavelength region 172-240 nm are also given. Introduction: O3: Cross sections of the Hartley-Huggins bands of O3 at the temperature 195 K were obtained from photoabsorption measurements at column densities in the range 2 x 10^17 - 1 x 10^21 cm-2 throughout the wavelength region 240-350 nm with a 6.65 m photoelectric scanning spectrometer equipped with a 2400 lines mm-1 grating and operated at an instrumental width (FWHM) of 0.003 nm. These were published in 1984. The cross sections were later put on a different absolute basis reflecting the absolute cross section measurements at discrete points of ozone at three different temperatures, published in 1988 (Planetary Space Science, 36(4): 395-398). The files available here reflect this recalibration. Laboratory measurements of the absolute absorption cross-section of ozone at the temperatures 195, 228 and 295 K were made at several discrete wavelengths in the region 238-335 nm. The results for ozone at 295 K are in excellent agreement with those of Hearn (1961, Proc. phys. Soc. Lond., 78, 932), who used a different technique. Their absolute cross-section measurements of ozone at 195 K have been used by the authors to put their recent relative cross-section measurements at that temperature (Freeman et al., 1984, Planet. Space Sci., 32, 239) on a firm absolute basis throughout the region 240-335 nm; Laboratory measurements of the relative absorption cross sections of ozone at the temperatures 195, 228 and 295 K were made throughout the wavelength region 185-254 nm. The absolute absorption cross sections at the same temperatures were measured at several discrete wavelengths in the region 185-254 nm. The absolute cross sections of ozone were used to put relative cross sections on a firm absolute basis throughout the region 185-255 nm. These recalibrated cross sections below 250 nm are slightly lower than those of Molina and Molina (J. Geophys. Res., 91, 14501 (1986) ), but differences are within a few percent and would not be significant in atmospheric applications. These later measured cross sections supersede the earlier high resolution measurements published (Planet. Space Sci., 32(2): 239-248, (1984); and Planet. Space Sci., 36(4): 395-398, (1988) ) in the region where they overlap. SO2: Laboratory measurements at high resolution of the absorption cross section of SO2 at the temperature 213 K were made in the wavelength region 172-240 nm with a 6.65 m scanning spectrometer/ spectrograph operated at an instrumental width of 0.002 nm. The measured cross sections are presented graphically in representative wavelength regions and are available throughout the region 172-240 nm at wavenumber intervals of 0.4-0.1 cm-1 The measured cross sections, which are relevant to the photochemistry of planetary atmospheres, possess significantly more spectroscopic structure, and are more accurate, than previous measurements made at lower resolution. File information: The file o3k195 contains high resolution cross sections of ozone at 195 K are arranged in files with points in ascending order of wavenumber. This data was originally published in 1984, (Planetary Space Science, 32(2): 239-248) with a discussion of the assumptions on which the relative cross sections were put on an absolute basis. Later, in 1988, absolute cross section measurements were made with which the original data was renormalized (Planetary Space Science, 36(4): 395-398). The cross section files here reflect these most recent absolute measurements. The files sent only go down to 253.75 nm since the cross section measurements of the region with wavenumber lower than that has been superseded by new measurements in the region 185-254 nm published in the Journal of Geophysical Research. This new data is at significantly lower resolution than the earlier data. The 3 files of data containing vuv cross sections of ozone at 195, 228 and 295 K are arranged in files with points in ascending order of wavenumber. The file o3uvr.dat contains the cross sections measured at 295 K, o3uvd.dat at 195 K, and o3uvm.dat at 228 K. This data is published in the March 20, 1993, edition of the Journal of Geophysical Research, 98(D3): 5205-5211. These files supersede the old high resolution measurements in the region where the two sets of data overlap (240-254 nm). The file so2k213.dat contains cross sections of SO2 at 213 K arranged in ascending order of wavenumber. This data is published in 1984, (Planetary Space Science, 32: 1125-1134). The 3 files of data containing vuv cross sections of ozone at 195, 228 and 295 K are arranged in files with points in ascending order of wavenumber. The file o3uvr.dat contains the cross sections measured at 295 K, o3uvd.dat at 195 K, and o3uvm.dat at 228 K. This data is published in the March 20, 1993, edition of the Journal of Geophysical Research, 98(D3): 5205-5211. These files supersede the old high resolution measurements in the region where the two sets of data overlap (240-254 nm). File Summary: ---------------------------------------------------------------------------------- FileName Lrecl Records Explanations -------------------------------------------------------------------------------- ReadMe 80 . This file so2k213.dat 20 152512 sulfur dioxide cross sections o3k195.dat 20 117011 Ozone cross sections at 213K o3uvd.dat 20 5122 Ozone cross sections at 195K o3uvm.dat 20 5122 Ozone cross sections at 228K o3uvr.dat 20 5122 Ozone cross sections at 295K -------------------------------------------------------------------------------- Byte-by-byte Description of file: *.dat -------------------------------------------------------------------------------- Bytes Format Units Label Explanations -------------------------------------------------------------------------------- 1- 9 F9.3 cm-1 nu Wavenumber position, 10- 20 E11.3 --- sigma Cross section/molecule -------------------------------------------------------------------------------- NOTE: The measured data points are not necessarily equally spaced or constant within a file or between files. Acknowledgement: We thank Dr. Yoshino and Jim Esmond for forwarding the files to us. We also thank Mr. Esmond for reviewing our original document, providing corrections and substantial additional information, and replacing a data file which had been received in garbled form. ================================================================================ (End) Nancy G. Roman [ADC/SSDOO] Oct-04-1995