Absolute Far-Infrared Absorption Intensities of α-Nitrogen

The absolute intensities of the translational lattice mode absorptions of α-N2 in the far infrared have been measured. The experimental values are smaller by a factor of 5 than the calculated intensities obtained from a quadrupole-induced mechanism theory. This discrepancy is discussed in terms of the model on which the theory was based. The intensity of the 50-cm−1 line was found to be temperature dependent and decreased gradually between 15°K and 35°K. No discrete absorption was observed for the β phase above 36°K. The 50-cm−1 line has a width smaller than 0.5 cm−1 and the 70-cm−1 line has a width of 6 cm−1. Evidence was found for a decrease of the frequency of the 50-cm−1 line as the phase transition temperature is approached.