Physics
Scientific paper
May 1990
adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=1990nascp3077..157h&link_type=abstract
In its First International Conference on Laboratory Research for Planetary Atmospheres p 157-163 (SEE N90-26744 20-91)
Physics
Atmospheric Models, Energy Transfer, Gas Giant Planets, Infrared Spectra, Methane, Molecular Relaxation, Planetary Atmospheres, Radiative Lifetime, Upper Atmosphere, Auroral Zones, Emission Spectra, Infrared Lasers, Infrared Radiation, Low Pressure, Low Temperature, Pulsed Lasers, Stratosphere, Titan
Scientific paper
The 7.8 micrometer emission from the nu4 band of methane (CH4) is a regularly observed feature in the stratosphere of all the giant planets and Titan. On Jupiter, enhancements in this emission are associated with the infrared hot spots in the auroral zone. Attempts to model this phenomenon in particular, and to understand the role of methane in general, have been hampered in part by a lack of adequate laboratory measurements of the collisional relaxation times for the nu3 and nu4 levels over the appropriate temperature range. To provide this needed data, a series of laboratory experiments were initiated. In the experimental arrangement the nu(sub3) band of methane is pumped at 3.3 micrometers using a pulsed infrared source (Nd:YAG/dye laser system equipped with a wave-length extender). The radiative lifetime of the nu3 level (approximately 37 ms) is much shorter than the nu4 lifetime (approximately 390 ms); however, a rapid V-V energy transfer rate ensures that the nu4 level is substantially populated. The photoacoustic technique is used to acquire relaxation rate information. The experiments are performed using a low-temperature, low-pressure cell. Experimental apparatus and technique are described. In addition some of the experimental difficulties associated with making these measurements are discussed and some preliminary results are presented.
Allen John E. Jr.
Burt Jim A.
Caldwell J. Jr. J.
Delaney Paul
Halthore Rangasayi N.
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