Experimental studies by complementary terahertz techniques and semi-classical calculations of N2- broadening coefficients of CH335Cl - Archive ouverte HAL
Article Dans Une Revue Journal of Quantitative Spectroscopy and Radiative Transfer Année : 2012

Experimental studies by complementary terahertz techniques and semi-classical calculations of N2- broadening coefficients of CH335Cl

Résumé

Room-temperature N2-broadening coefficients of methyl chloride rotational lines are measured over a large interval of quantum numbers (6≤J≤50, 0≤K≤18) by a submillimeter frequency-multiplication chain (J≤31) and a terahertz photomixing continuous-wave spectrometer (J≥31). In order to check the accuracy of both techniques, the measurements of identical lines are compared for J=31. The pressure broadening coefficients are deduced from line fits using mainly a Voigt profile model. The excellent signal-to-noise ratio of the frequency-multiplication scheme highlights some speed dependence effect on the line shape. Theoretical values of these coefficients are calculated by a semi-classical approach with exact trajectories. An intermolecular potential including atom–atom interactions is used for the first time. It is shown that, contrary to the previous theoretical predictions, the contributions of short-range forces are important for all values of the rotational quantum numbers. Additional testing of modifications required in the semi-classical formalism for a correct application of the cumulant expansion is also performed. It is stated that the use of the cumulant average on the rotational states of the perturbing molecule leads, for high J and small K values, to slightly higher line-broadening coefficients, as expected for the relatively strong interacting CH3Cl–N2 system. The excellent agreement between the theoretical and the experimental results ensures the reliability of these data.

Dates et versions

hal-00749447 , version 1 (07-11-2012)

Identifiants

Citer

M. Guinet, F. Rohart, J. Buldyreva, V. Gupta, S. Eliet, et al.. Experimental studies by complementary terahertz techniques and semi-classical calculations of N2- broadening coefficients of CH335Cl. Journal of Quantitative Spectroscopy and Radiative Transfer, 2012, 113 (11), pp.1113-1126. ⟨10.1016/j.jqsrt.2012.01.022⟩. ⟨hal-00749447⟩
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