Three-Micrometer CH4 Line Emission from Titan's High-Altitude Atmosphere
✍ Scribed by Sang Joon Kim; T.R. Geballe; Keith S. Noll
- Book ID
- 102569692
- Publisher
- Elsevier Science
- Year
- 2000
- Tongue
- English
- Weight
- 70 KB
- Volume
- 147
- Category
- Article
- ISSN
- 0019-1035
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✦ Synopsis
We have detected 3-µm emission lines of the ν 3 and ν 3 + ν 4 -ν 4 bands of CH 4 from Titan's high-altitude atmosphere using CGS4 on the United Kingdom Infrared Telescope. The intensity of the ν 3 + ν 4 -ν 4 band is comparable to that of the ν 3 fundamental band. Radiative transfer calculations show that the lower absorption coefficients of the ν 3 + ν 4 -ν 4 transitions and the reduced rates of collisional deactivations of the ν 3 + ν 4 level compared with those of the ν 3 → 0 band account for the relatively strong ν 3 + ν 4 -ν 4 band intensity. The CH 4 emissions form mainly in the altitude range 530-630 km, where temperatures are approximately 137-145 K, consistent with the low-temperature mesosphere proposed by R. V.