Self- and N2-collisional broadening coefficients of ethylene in the 1800–2350 cm−1 spectral region

Abstract

Self- and N2-broadening coefficients have been retrieved for 566 lines of C2H4 at room temperature in the 5μm region including the ν7+ν8, ν4+ν8, ν6+ν10, ν6+ν7, ν4+ν6 and ν3+ν10 vibrational bands. Measurements have been performed using Fourier transform infrared spectroscopy. The lines were fitted with a single-spectrum non-linear least squares fitting procedure of Voigt profiles which appeared to properly model the observed molecular line shapes within the noise level. The experimental results are compared with theoretical values calculated using the Robert and Bonamy formalism which reproduces the measured broadening coefficients. For the self- and N2-broadening coefficients, the average discrepancy 〈(γmea−γcal/γmea)×100〉 for 566 lines, is (−1.6±7.8)% and (−2.8±9.9)%, respectively. One standard deviation is given after ±. These coefficients show dependence with both rotational quantum numbers J and Ka. Comparisons with previous measurements taken in the ν7 band of C2H4 show difference range between 7% and 15%. These differences not insignificant can come from inconsistency between experimental measurements.