Low pressure line shape study of nitrogen-perturbed acetylene transitions in the ν1 + ν3 band over a range of temperatures

Abstract

Six nitrogen-perturbed transitions of acetylene within the ν1 + ν3 absorption band have been recorded using a three-channel diode laser spectrometer. The goal being an improved understanding of both broadening and narrowing effects of low-pressure acetylene under the influence of nitrogen gas. To this end we have examined C2H2 spectra using a hard collision Rautian profile over a range of five temperatures (213–333 K) and five pressures (5–40 Torr). From these fits we have obtained the N2-broadening and narrowing coefficients of C2H2 and examined their temperature dependence. The experimentally measured narrowing coefficients have been used to estimate the nitrogen diffusion coefficients (D12) and are presented within. The broadening coefficients and corresponding temperature dependence exponents have also been compared to that of calculations completed using a classical impact approach on an ab initio potential energy surface. We have observed good agreement between our theoretical and experimental results.