1. 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

2. 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

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

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

5. 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)

6. 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

7. 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

8. Previously recorded spectra
The Pacific Northwest National Laboratory has recorded infrared absorption cross sections for a number of species (
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 K (Harrison et al., 2009).
Propane
HITRAN – cross sections in 3 μm region from K (Harrison & Bernath 2010).
Propene
Cross sections from cm-1 at 0.08 cm-1 resolution at K (Es-sebbar et al. 2014).
Previously recorded spectra

9. CELL DESIGN + EXPERIMENTAL

10. 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: cm-1 at cm-1 resolution.
Temperatures recorded: 296 K, 400 K, 500 K, 600 K, 700 K.
Pure propane (no broadener).
Sample pressure: Pa
Sample cell path length: 50 cm.

11. 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

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

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

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

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

16. 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