Measurements and calculations of ethylene line-broadening by argon in the ν7 band at room temperature

Abstract

Argon broadening coefficients are measured for 32 vibrotational lines in the ν7 band of ethylene at room temperature using a tunable diode-laser spectrometer. These lines with 3 ≤ J ≤ 19, 0 ≤ Ka ≤ 4, 2 ≤ Kc ≤ 19 in the P, Q and R branches are located in the spectral range 919–1023 cm−1. The fitting of experimental line shapes with Rautian profile provides collisional widths slightly larger than those derived from the Voigt profile. The independent theoretical estimation of these line widths is performed by the semiclassical approach of Robert-and-Bonamy type with exact isotropic trajectories generalized to asymmetric tops. Even with a rough atom–atom intermolecular potential model the calculated values show good agreement with experimental results.