Broadening parameters of NO2 lines in the 3.4 μm spectral region.

Fourier transform spectra have been recorded to measure self-, N_2-, and O₂-broadening coefficients of NO₂ lines in the υ₁+υ₃ band. For the studied set of transitions, a slight rotational dependence of the broadening coefficients exists versus N″ the rotational quantum number of the lower level of the transition, whereas no significant dependence is observed versus K_a″ An empirical relation, allowing one to calculate approximate values of the air-broadening coefficients γ_air⁰, at 296 K, for lines observable in atmospheric spectra recorded from the ground, is proposed. For typical lines used for atmospheric applications, the single value reported in the HITRAN database for all lines of all bands of NO₂ can differ by more than 20% from the measured ones.