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 2003 archive has been significantly enriched since the GEISA-97 issue, and cross-sections are available in two spectral regions, i.e.:
The spectral range has been extended: from 200 cm-1 to 2000 cm-1 (from 556 cm-1 to 1763 cm-1, previously) and the number of molecules has increased, as well, from 23 to 35. The updated already archived species are: CFC11, CFC12, CFC14, HCFC22, HCFC123, HCFC124, HFC125, HFC134a, HCFC141b, HCFC142b, HFC152a, HCFC225ca, HCFC225cb, HFC32, HFC143a, HFC134, N2O5, SF6, ClONO2. No update has occurred for CFC-13, CFC-113, CFC-114, CFC-115. Eleven molecular species are new for GEISA 2003 archive, these are: HFC-143, HCFC-21, C2F6, C2H2, C2H4, C2H6, C3H8, C4H8, HNO4, SF5CF3, HCH-365mfc.
- In the Ultraviolet/Visible :
New cross-sections, in the ultraviolet and visible have been implemented in GEISA. The molecular species involved are: NO2, CS2, O3, SO2, O2, OClO, H2CO, OBrO, in the spectral range: 7,750-43,489 cm-1
General content: