Calculation of the inverse relaxation time and the activation energy as a function of temperature for the Raman modes close to the phase transitions in solid nitrogen

Abstract

The inverse relaxation time is calculated as a function of temperature for the transitions of α-β (P = 0) and ε-δloc-δ (at constant pressures) in the solid N2. For this calculation, the observed data from the literature are used for the Raman frequency shifts and linewidths (FWHM) of the librational Eg mode (α-β) and the internal modes of ʋ1 and ʋ2 (ε-δloc-δ) in the nitrogen. From the temperature dependence of the inverse relaxation time, the activation energy is extracted for the Raman modes (Eg, ʋ1 and ʋ2) to explain the order-disorder transitions (α-β and ε-δloc-δ) in this molecular solid. Close to the phase transitions, a power-law formula is suggested for the relaxation time in relation to the frequency shifts and linewidths, which can be applied to the molecular solids.