KEEYOON SUNG, GEOFFREY C. TOON, LINDA R. BROWN, Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Dr.,Pasadena, CA 91109; ARLAN W. MANTZ, Dept. of Physics, Connecticut College, New London, CT 06320; MARY ANN H. SMITH, Science Directorate, NASA Langley Research Center, Hampton, VA 23681.
To support atmospheric remote sensing of Titan, the absorption cross sections of N2-broadened C3H8 were obtained at temperatures between 145 and 296 K. For this, 35 spectra of pure- and N2-broadened propane were recorded in the 670 to 1900 cm-1 region using a Fourier transform spectrometer (Bruker IFS-125HR) at the Jet Propulsion Laboratory. A 20.38 cm path temperature-stabilized cryogenic absorption cell was used, which was developed at Connecticut College and described previously . We report the absorption cross sections at the various cold temperatures for nine strong fundamental bands ( 26, 8, 21, 20, 7, 19, 18, 4, 24) as well as for many contributions from hot and combination bands. In addition, we present results from 'pseudo -line generation' (http://mark4sun.jpl.nasa.gov/data/spec/Pseudo/Readme), which includes mean intensities and effective lower state energies on a 0.005 cm-1 frequency grid determined in the 690 - 1536 cm-1 region from all 35 high-resolution laboratory spectra. It was observed that the pseudo lines reproduce all the observed spectral transmittances well within 3% and the C3H8 amounts within 4% on the average. The measured cross sections and synthetic spectra from the pseudoline compilation are compared to earlier work, including the C3H8+N2 spectra recorded at PNNL  and line-by-line predictions available [3, 4].