The most important differences between the and phases involve the librational motions of the N2 molecules. Motional narrowing of the nuclear quadrupole coupling by three orders of magnitude and disorder detected in the x-ray structure indicated that molecules in the higher temperature phase do not have their orientations fixed with respect to the lattice; they are disordered by precession-like motion about the axis, with the molecular axes making an average angle of 54.7 to the -axis. 
Raman scattering studies have been able to measure the absorption lines corresponding to the high frequency (2200-2500 cm-1) molecular stretch mode and the lower frequency (<150 cm-1) librational and lattice modes at temperatures from 3.6 K to above the transition, under equilibrium vapour pressure.  As temperature is increased within the phase, the mean amplitude of librations away from the preferred orientations grows. This is apparent as a slight broadening of the molecular stretch line with increasing T, which is expected when the molecules are no longer in identical environments, beginning at about T=25 K and continuing into the phase.
The low frequency lines, which are sharp at low temperatures in the phase, gradually become less distinct as the temperature rises to T, and become very broad features above T.This was interpreted as consistent with the build-up of large amplitude, anharmonic librations in the phase and a fully disordered, precessional motion in the phase.
The disorder introduced by librations is of a short-ranged nature, but since these are soft modes, they are excited at relatively low temperatures - they fall among the acoustic phonons in the excitation spectrum of the lattice.