Broadening parameters of NO2 lines in the 3.4 mu m spectral region

Fourier transform spectra have been recorded to measure self-, N-2-, and O-2-broadening coefficients of NO2 lines in the upsilon(1) + upsilon(3) 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 gamma(air)(0), at 296 K, for lines observable in atmospheric spectra recorded from the ground, is proposed: gamma(air)(0) = 84.1 - 0.753 N '' + 0.0059 N ''(2), in 10(-3) cm(-1). atm(-1), with an uncertainty of about +/- 10% when N '' and K-a '' are smaller than about 40 and 10, respectively. 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. (C) 1997 Elsevier Science Ltd.