Abstract High resolution Fourier transform absorption spectra of the 14 N 16 O 2 molecule recorded in the 2630–3510 cm −1 spectral region have been analysed and lines of the ν 1 + ν 3 band of this molecule have been assigned for K a values ranging from 0 to 10 and N values up to 55. The spin–rotation energy levels were very satisfactorily reproduced using a theoretical model which takes explicitly into account both the Coriolis interaction between the spin–rotation levels of the (101) vibrational state and those of (120) and the spin–rotation resonances within (101) and (120). As a consequence, precise vibrational band centers and rotational, spin–rotation, and coupling constants were obtained for the {(120), (101))} interacting states of 14 N 16 O 2 . In addition, using a large set of individual ν 1 + ν 3 experimental line intensities we have determined precisely the ν 1 + ν 3 transition moment constants. Also from ν 1 + ν 2 + ν 3 − ν 2 line intensities measured in this work, the transition moment operator of the ν 1 + ν 2 + ν 3 − ν 2 hot band was found to be in agreement with the transition dipole moment of the corresponding cold band, namely, ν 1 + ν 3 . Finally, a comprehensive list of line positions and intensities of the ν 1 + ν 3 band of 14 N 16 O 2 has been generated at 3.4 μm.