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The GEISA 2011 sub-database on absorption cross-sections


As described in Jacquinet-Husson et al. (1999), besides the line transition parameters data catalog itself, GEISA includes, a second catalog, providing, at various temperatures and pressures, the cross-sections (unit: cm2 molecule-1) of species exhibiting dense spectra , not suitable for a discrete parameterized format.
As in the previous editions of GEISA, the absorption cross-sections are determined through the following expression:


σ (ω)= ( ln [ I0(ω) / I(ω) ] ) / nl

- ω wavenumber (cm-1)
- σ (ω)absorption cross-section (cm2 molecule-1)
- I0(ω) and I(ω) intensities at the wavenumber , of the incident and transmitted radiation, respectively
- n concentration of the absorbing molecules (molecule cm-3)
- l optical path length (cm)


The GEISA 2011 archive has been enriched since the GEISA 2003 issue, as described in Jacquinet-Husson et al. (2008, 2010). Cross-sections are available in two spectral regions, i.e.:


  • In the Infrared :
In the spectral range from 200 cm-1 to 6500 cm-1, 35 molecular species were already archived, i.e.: CFC-13, CFC-113, CFC-114, CFC-115, CFC11, CFC12, CFC14, HCFC22, HCFC123, HCFC124, HFC125, HFC134a, HCFC141b, HCFC142b, HFC152a, HCFC225ca, HCFC225cb, HFC32, HFC143a, HFC134, N2O5, SF6, ClONO2; HFC-143, HCFC-21, CCl4, C2F6, C2H2, C2H4, C2H6, C3H8, C4H8, HNO4, SF5CF3, HCH-365mfc. In the 2011 edition, complementary data have been implemented for SF5CF3, and new molecular species have been archived, too; these are: C6H6, CH3CN, C2H3NO5, (CH3)2CO,


  • In the Ultraviolet/Visible :

The GEISA 2011 database contains UV-visible absorption cross-sections, in the spectral range 7750 cm-1 to 51282 cm-1, for the following molecules and radicals: NO2, CS2, O3, SO2, O2, O2-O2, O2-N2, OClO, H2CO, OBrO, BrO, IO, OIO, and aromatic hydrocarbons; these are C6H6, C7H8 and the three isomers of (C6H4(CH3)2, as well.