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

• Cédric Bray^a, b, , , 
• Arnaud Cuisset^a, b, 
• Francis Hindle^a, b, 
• Robin Bocquet^a, b, 
• Gaël Mouret^a, b, 
• Brian J. Drouin^c

• ^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

http://www.sciencedirect.com/science/article/pii/S0022407316306719

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.