Analysis of the far infrared spectrum of gaseous N₂

Abstract

The far infrared collision-induced spectrum of N 2 gas at 300 and 124 K is analysed using an empirical lineshape function. The theory of the collision-induced spectrum of N 2 is developed and expressions are derived for the first and second spectral moments in the cases of quadrupolar, hexadecapolar, and for L = 1 and L = 3 overlap induction. The spectra are then reconstructed with various combinations of these mechanisms in order to determine the best values and probable ranges of the quadrupole and hexadecapole moments and the strength of the overlap moments. We find an excellent fit for a value of the quadrupole moment that agrees with that found by Buckingham, Q B = −(1.09 ± 0.05)ea 0 2 , with overlap dipole parameters λ 1 = ± 1 × 10 −3 ea 0 , λ 3 = 1 × 10 −3 ea 0 , and an effective hexadecapole moment Φ = −(10.4 ± 1)ea 0 4 .