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| Titel |
Temperature dependence of the absorption spectrum of methane by high sensitivity laser spectroscopy between 1.27 and 1.71 micron at 80 K and 300 K. Importance of the CH3D contribution in the 1.58 micron transparency window. |
| VerfasserIn |
Samir Kassi, Le Wang, Alain Campargue |
| Konferenz |
EGU General Assembly 2010
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 12 (2010) |
| Datensatznummer |
250040276
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| Zusammenfassung |
| The high resolution absorption spectrum of methane has been recorded between 1.27 and
1.71 μmby high sensitivity laser absorption spectroscopy at room temperature and at 80 K.
By combining the CW-Cavity Ring Down Spectroscopy technique with a specifically
designed cryogenic cell, a noise equivalent absorption of αmin ~3Ã10-10 cm-1 was
achieved allowing for a the first detailed characterization of the 1.58 μm transparency
window at 80 K. A list of transitions with intensity as weak as 1Ã10-29cm/molecule was
constructed from the recordings at 296 and 80 K. The low energy values of the
transitions observed both at 80 K and at room temperature were derived from the
variation of their line intensities. The quality of the obtained empirical low energy
values is demonstrated by the marked propensity of the empirical low J values of
CH4 to be close to integers. The line lists associated to the low energy values allow
accounting for the temperature dependence of methane absorption between these two
temperatures. A comparison with a spectrum of CH3D recorded separately by Fourier
Transform Spectroscopy shows that the CH3D isotopologue in natural abundance
contributes significantly to the absorbance in the1.58 μm transparency window. |
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