Experimental and theoretical study of N₂-broadened acetylene line parameters in the ν₁ + ν₃ band over a range of temperatures

Abstract

N₂-broadened line widths and N₂-pressure induced line shifts have been measured for transitions in the ν₁ + ν₃ band of acetylene at seven temperatures in the range 213–333 K to obtain the temperature dependences of broadening and shift coefficients. For the room-temperature spectra the line mixing effects have been also investigated. The Voigt and hard-collision line profile models were used to retrieve the line parameters. All spectra were recorded using a 3-channel tuneable diode laser spectrometer. The line-broadening and line-shifting coefficients as well as their temperature-dependence parameters have been also evaluated theoretically, in the frame of a semi-classical approach based on an exponential representation of the scattering operator, an intermolecular potential composed of electrostatic quadrupole–quadrupole and pairwise atom–atom interactions as well as on exact trajectories driven by an effective isotropic potential.

Keywords:

• acetylene
• N₂-pressure broadening
• N₂-pressure-induced shifts
• spectral line shape
• infrared spectroscopy
• spectral line parameters
• semi-classical calculations

Acknowledgements

This work was supported by the Natural Sciences and Engineering Research Council of Canada.

Notes

Note

1. For a fixed σ-value, decreasing of the potential depth ε results in an overall downward translation of the theoretical curve for the line widths, so that we have not modified the initial ε-value.