The far infrared absorption spectrum of N2 in the gas and liquid phases

The collision induced spectrum of N2 has been measured in the gas phase at T=300 °K and T=124 °K and in the liquid phase at T=66 °K. The measurements at room temperature have been extended down to 8 cm−1. It has thus been possible to observe the translational component. From the analysis of the band shape the single rotational profile has been derived. The integrated absorption coefficients in the gas phase and the moment analysis of the spectrum are in agreement with the quadrupolar induction mechanism. The presence of cancellation effects has been deduced from the intensity of the spectrum measured in the liquid phase. The absorption coefficient was also obtained from molecular dynamics calculations and compared with the experimental one. Because of the correspondence of their shape we have concluded that also in liquid phase the spectrum is essentially due to the quadrupolar induction mechanism.