Measurements and Calculations of Room-Temperature Ozone Line-Broadening by N₂ and O₂ in the ν₁ +ν ₃ Band

A high-resolution Fourier transform spectrometer has been used to record a large number of spectra, with ozone and foreign gas pressures ranging from 5 to 50 Torr and 80 to 700 Torr, respectively. The 2100-cm^-1 region corresponding to the ν₁ + ν₃ band of O₃ has been analyzed and the broadening coefficients by N₂ and O₂ at room temperature have been derived for 112 lines with an accuracy better than 3 × 10^-3 cm^-1 atm^-1. This study covers a wide range of rotational quantum numbers (J″ = 0-40, K″_a = 0-11) in an A-type band (ν₁ + ν₃). Calculations of these broadening coefficients have been performed with a theoretical model successfully tested on H₂O linewidths. This model provides a correct modeling of close collisions since the contributions of an atom-atom potential and trajectory modifications at short distance are accounted for. It has been previously applied to O₃ line broadening by N₂ and O₂ but only a dozen of B-type lines were then investigated. In the present study, the atom-atom parameters for the O₃-N₂ and O₃-O₂ interactions have been adjusted to match experiment since no intermolecular anisotropic potential is. to our knowledge, available for O₃. The standard deviations between experimental and theoretical results are about 6%, with absolute maximum deviations of about 14% for O₃-N₂ and O₃-O₂. Furthermore, use of simple empirical polynomial corrections of calculated results versus rotational quantum numbers leads to agreement between observations and calculations better than 2% for the O₂ and N₂ broadenings of most lines.