Monday, November 28, 2016

Abstract-CH3D photomixing spectroscopy up to 2.5 THz: New set of rotational and dipole parameters, first THz self-broadening measurements

  • a Laboratoire de Physico-Chimie de l’Atmosphère, EA 4493, Université du Littoral – Côte d’Opale, F-59140 Dunkerque, France
  • b Université de Lille, F-59000 Lille, France
  • c Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109-8099, USA

Several previously unmeasured transitions of 12CH3D have been recorded by a terahertz photomixing continuous-wave spectrometer up to QR(10) branch at 2.5 THz. An improved set of rotational constants has been obtained utilizing a THz frequency metrology based on a frequency comb that achieved an averaged frequency position better than 150 kHz on more than fifty ground-state transitions. A detailed analysis of the measured line intensities was undertaken using the multispectrum fitting program and has resulted in a determination of new dipole moment parameters. Measurements at different pressures of the QR(7) transitions provide the first determination of self-broadening coefficients from pure rotational CH3D lines. The THz rotational measurements are consistent with IR rovibrational data but no significant vibrational dependence of self-broadening coefficient may be observed by comparison.

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