INFRARED CROSS SECTIONS OF HOT HYDROCARBONS CHRISTOPHER A. BEALE, ROBERT J. HARGREAVES, ERIC BUZAN, PETER F. BERNATH Wednesday, June 22nd 2016 ISMS 71st Meeting Urbana-Champaign, Illinois

Cross sections of hot ethane, propane and propene have been obtained in the 3 μm region. These hydrocarbons were studied for their importance in a number of environments. Earth (Doskey & Gaffney, 1992). Outer planets and Titan (Greathouse et al., 2006; Tokunaga et al., 1983; Roe et al., 2003). Brown dwarfs and exoplanets (Venot et al., 2015; Lodders & Fegley, 2002). Industrial applications (Eiji et al., 2003). INTRODUCTION

ASTRONOMICAL HYDROCARBONS Hydrocarbons in the outer planets. Nixon et al., 2013 ASTRONOMICAL HYDROCARBONS Titan limb spectra

Poles of Jupiter – ground based observation (UKIRT) Kim et al., 2009 ASTRONOMICAL HYDROCARBONS Poles of Jupiter – ground based observation (UKIRT)

ASTRONOMICAL HYDROCARBONS Hydrocarbons in exoplanets. ASTRONOMICAL HYDROCARBONS Moses et al., 2011 Photochemical model for HD189733b (hot Jupiter) Lodders & Fegley, 2002 Photochemical and thermodynamical model for GJ436b (hot Neptune)

INDUSTRIAL APPLICATIONS Hydrocarbons in combustion environments. Engine performance depends on fuel composition, fuel density, pressure and temperature. The spectra of a number of hydrocarbons have been recorded in the 3 μm region at low (>1 cm-1) for application to combustion studies. Methane, ethane, ethylene & methanol (Alrefae et al. 2014). Pentane, propene, pentene, toluene, n-heptane, n-dodecane, 2-methyl-butane, 2-methyl-pentane, 2,2,4-trimethyl-pentane, 2-methyl-2-butene, 2,4,4-trimethyl-1-pentene, m-xylene, ethyl-benzene (Klingbeil et al. 2007). However, high resolution cross sections of hot ethane, propane and propene have not been recorded in the 3 μm region. INDUSTRIAL APPLICATIONS

SPECTROSCOPIC DETAILS Propane C2v symmetry (equilibrium) 27 fundamental modes, 21 of which are infrared active. Shimanouchi Vol. 1, 1972 ν1, ν2, ν3, ν15, ν16, ν22, ν23 plus a number of combination bands form the spectrum of propane in the 3 μm region. SPECTROSCOPIC DETAILS

Previously recorded spectra The Pacific Northwest National Laboratory has recorded infrared absorption cross sections for a number of species (http://nwir.pnl.gov). Cross sections have been recorded for ethane, propane and propene at three temperatures, 278, 293 and 323 K. These spectra were used to calibrate our cross sections. Data for ethane and propane are also available from the HITRAN. Ethane: HITRAN – cross sections in 3 μm region from 194-297 K (Harrison et al., 2009). Propane HITRAN – cross sections in 3 μm region from 195-296 K (Harrison & Bernath 2010). Propene Cross sections from 400-6500 cm-1 at 0.08 cm-1 resolution at 298-460 K (Es-sebbar et al. 2014). Previously recorded spectra

CELL DESIGN + EXPERIMENTAL

Zirconia draught spacers Cell design Profile from the side: Quartz sample tube Heating elements Zirconia draught spacers Outer supporting tube Furnace Inner draught tube Quartz halogen Lamp To FTS CELL DESIGN + EXPERIMENTAL 75 cm Spectral range: 2550-3500 cm-1 at 0.005 cm-1 resolution. Temperatures recorded: 296 K, 400 K, 500 K, 600 K, 700 K. Pure propane (no broadener). Sample pressure: 174-430 Pa Sample cell path length: 50 cm.

TRANSMISSION SPECTRA CH4 transmission calculation at 973 K Aabs = Sample + lamp Aem = No sample + lamp Bref = Sample + no lamp Bem = No sample, no lamp τ = (Aabs- Bref)/(Aem- Bem) TRANSMISSION SPECTRA CH4 transmission calculation at 973 K

ETHANE CROSS SECTIONS R.J. Hargreaves et al. Mol. Astrophys. 1 (2015) 20–25

PROPANE CROSS SECTIONS C.A. Beale et al. JQSRT (2016) accepted manuscript

PROPANE CROSS SECTIONS C.A. Beale et al. JQSRT (2016) accepted manuscript

PROPENE CROSS SECTIONS E. M. Buzan et al. Mol. Astrophys. (2016) accepted manuscript

Hydrocarbons have been detected or predicted by models to be in a number of astronomical environments; Exoplanets Brown dwarfs Jupiter Saturn and Titan. Spectra of hot hydrocarbons also aid remote sensing for combustion environments, such as engines. We have obtained spectra of three hydrocarbons at high temperatures in the 3 μm region. SUMMARY