Experimental and theoretical studies of room-temperature sub-millimetre CH₃³⁵Cl line shapes broadened by H₂

Analysis of self-broadened pure rotational and rovibrational lines of methyl chloride at room temperature

“…The measurements on the J = 67 rotational line of 12 CH 3 35 Cl at 186 GHz were performed with the PhLAM frequency-modulation spectrometer that has been described in details in previous papers [17,18], so we only recall its principal features. The electromagnetic (e.m.) source consisted of a synthesizer (Agilent E8257D) locked onto a GPS receiver and followed by an active sextupler (Spacek Inc.).…”

“…In this purpose, observed spectra were fitted using an extension of the code used in Ref. [18]. In a first step, the total absorbance A(ν) was computed as the sum of the absorbance contributions a j (ν) corresponding to the different hyperfine j-components, which allowed for a determination of…”

“…In a second step, the signal S(ν) detected with the 2f-frequency modulation technique used was obtained from a generalization of Dore method [18,26]. More precisely, let us define the sample correlation function Θ(τ), that is the time domain response of the sample after a pulse excitation taking place at time τ = 0, which is given by the Fourier transform of T(ν).…”

“…Then, the detected signal S(ν) is proportional to the real part of a Fourier transform written as in Ref. [18]:…”

Line-shapes and broadenings of rotational transitions of CH335Cl in collision with He, Ar and Kr

“…Thus, many laboratory works have been dedicated to this molecule, namely to its rotational [2] and ro-vibrational spectra [3,4]. Many experiments have been also devoted to collisional relaxation, including line-broadening and line-shape studies, in the millimeter-submillimeter [5][6][7][8][9][10][11][12][13] and infrared [4,11,[14][15][16][17][18][19][20][21][22] domains.…”