we propose to use the sws in the high-resolution f-p mode to search for spectral signatures from diacetylene (c4h2) and benzene (c6h6) on jupiter and saturn. these two undetected compounds are expected to be produced from the photochemistry of methane in the high atmosphere. diacetylene is the first step in the formation of polyacetylenes which may contribute to the stratospheric hazes. benzene is the simplest aromatic molecule and may be a pathway to the formation of more complex aromatics which could contribute to the brownish chromophores and to the formation of a photochemical smog. detecting these two molecules and measuring their concentration profiles would provide a test for some chemical schemes proposed in photochemical models, and help determining some important atmospheric parameters. we will search for thermal emission from the c6h6 band at 14.8 micron and the c4h2 band at 15.9 micron. these are by far the most favorable rovibrational bands in the thermal ir. they occur in a spectral region inaccessible from the ground, and iso offers the only opportunity in the near future to detect for the first time these important compounds. the gain in spectral resolution provided by the f-p mode compared with the grating mode of the sws may be needed to detect unambiguously the expected weak signatures superimposed on the strong h2 continuum. the f-p resolution is also needed to separate the c6h6 emission from a possible emission from hcp near 14.84 micron on saturn. f-p observations will furthermore allow the measurement of the profiles of the q-branches from c6h6 and c4h2, providing valuable information on the vertical profiles of these species. synthetic calculations based on realistic abundances of these two compounds show that these signatures should be easily detectable by sws in the f-p mode.
Instrument
SWS07
Temporal Coverage
1997-12-14T20:53:55Z/1997-12-14T21:53:45Z
Version
1.0
Mission Description
The Infrared Space Observatory (ISO) was the world's first true orbiting infrared observatory. Equipped with four highly-sophisticated and versatile scientific instruments, it was launched by Ariane in November 1995 and provided astronomers world-wide with a facility of unprecedented sensitivity and capabilities for a detailed exploration of the Universe at infrared wavelengths.
