HIGH-PRESSURE RAMAN-SCATTERING OF THE STRETCHING MADE IN NITROGEN ALONG THE 300-K ISOTHERM

We present Raman scattering studies of the vibrational band of nitroge n at room temperature between 1 and 31 GPa allowing a detailed line-sh ape analysis. For the fluid and beta phases the vibrational linewidths compare to dephasing rates T-2(-1) determined by experiments in the t ime domain. The delta-epsilon transition is unmistakably marked by a d rop of the vibrational linewidths around 17 GPa. A further transition into the eta phase around 20 GPa proposed from previous Raman results can be ruled out. Additionally, clear evidence is found for a dynamica l freezing of the N-2 molecules within the delta phase.