N2- and (H2+He)-broadened cross sections of benzene (C6H6) in the 7-15 μm region for the Titan and jovian atmospheres

In support of atmospheric remote sensing of Titan and jovian planets, we measured absorption cross sections of benzene (C6H6) in the 7-15 mu m region at temperatures between 235 K and 297 K. For this, high-resolution laboratory spectra of C6H6 were obtained using two cold cells (80 cm and 2.07 cm path length) configured to a high resolution Fourier-transform infrared (FT-IR) spectrometer, Bruker IFS-125HR, at the Jet Propulsion Laboratory (JPL). The spectrum sets include 15 pure and 15 N-2-broadened benzene spectra in the 630-1534 cm(-1) region, along with four additional spectra broadened by an H-2(85%) and He(15%) gas mixture for the 630-740 cm(-1) region. From these spectra, temperature dependent benzene cross sections were obtained for gas phase benzene in the presence of N-2 and (H-2+He) at ambient pressures and temperatures down to 235 K. In addition, we generated two independent sets of pseudolines: one of N2-broadened benzene for Titan and the other of (H-2+He)-broadened benzene for jovian planets. It is shown that the benzene pseudolines can reproduce the observed features to similar to 5% in transmittance, including the continuum-like absorption formed by numerous overlapping weak and hot band transitions. Based on the pseudoline parameters, the integrated band intensities at 296 K for the three strongest bands in the region were measured to be 177.0(73), 14.0(10), 27.2(9)x10(-17) cm(-1) /(molecule.cm(-2)) in the region of nu(4) at 674 cm(-1), nu(14) at 1038.267, and nu(13) at 1483.985 cm(-1), respectively, from the combined set of pure and N-2-broadened benzene spectra. For the (H-2+He) mixture-broadened benzene spectra, the integrated band intensity for nu(4) band in the 630-735 cm(-1) region was measured to be 168.8(17)x 10(-17) cm(-1) Amolecule.cm(-2)) at 296 K, which is in agreement with the intensity derived from the N-2-broadened benzene spectra within the combined measurement uncertainties. The results from this work show an excellent agreement (2%) with one of the latest experimental studies by Rinsland et al. (2008). Furthermore, additional characteristics carried by the pseudolines approach are discussed. Finally, we provide the two sets of pseudo line list (PLL) as electronic supplements. (C) 2016 Elsevier Inc. All rights reserved.