H2-induced pressure broadening and pressure shift in the P-branch of the ν3 band of CH4 from 300 to 655 K

Ehsan Gharib-Nezhad, Alan N. Heays, Hans A. Bechtel, James R. Lyons

Research output: Contribution to journalArticlepeer-review

7 Scopus citations


For accurate modelling of observations of exoplanet atmospheres, quantification of the pressure broadening of infrared absorption lines for and by a variety of gases at elevated temperatures is needed. High-resolution high-temperature H2-pressure-broadened spectra are recorded for the CH4 ν3-band P-branch. Measured linewidths for 143 transitions between 2840 and 3000 cm−1 with temperature and pressures ranging between 300 and 655 K, and 10 and 933 Torr, respectively, were used to find rotation- and tetrahedral-symmetry-dependent coefficients for pressure and temperature broadening and pressure-induced lineshifts. The new pressure-broadening data will be useful in radiative-transfer models for retrieving the properties of observed expolanet atmospheres.

Original languageEnglish (US)
Article number106649
JournalJournal of Quantitative Spectroscopy and Radiative Transfer
StatePublished - Dec 2019


  • Exoplanetary atmospheres
  • High-temperature FTIR spectroscopy
  • High-temperature pressure-induced collisional broadening and shift
  • Hydrogen-dominant atmospheres
  • Lorentzian linewidth coefficients
  • Methane (CH)

ASJC Scopus subject areas

  • Radiation
  • Atomic and Molecular Physics, and Optics
  • Spectroscopy


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