Pressure-broadened linewidths of nitric oxide

N2-broadened linewidths of NO in the 5.4 μ band have been measured. This provides a means of determining the quadrupole moment of NO, which has been poorly measured so far. Using the Anderson–Tsao–Curnutte theory of line broadening, and this new value, 2.4×10−26 esu⋅cm2, for the quadrupole moment of NO, self-broadened and foreign-gas (N2 and O2) -broadened linewidths of NO at 300°K for all important infrared transitions are calculated. In the self-broadening calculations, dipole–dipole, dipole–quadrupole, quadrupole–dipole, quadrupole–quadrupole, induced, and dispersion interactions were taken into account. For the case of foreign-gas broadening, dipole–quadrupole, quadrupole–quadrupole, dipole–hexadecapole, quadrupole–hexadecapole, induced, and dispersion interactions were considered. Air-broadened linewidths of NO have also been computed at 200, 250, and 300°K.