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CH3D photomixing spectroscopy up to 2.5 THz: New set of rotational and dipole...

Bray, C., A. Cuisset, F. Hindle, R. Bocquet, G. Mouret, and B. Drouin (2017), CH3D photomixing spectroscopy up to 2.5 THz: New set of rotational and dipole parameters, first THz self-broadening measurements, J. Quant. Spectrosc. Radiat. Transfer, 189, 198-205, doi:10.1016/j.jqsrt.2016.11.011.

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. Line positions Dipole moment Self-broadening coefficients

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Upper Atmosphere Research Program (UARP)