Vibrational line broadening in the mixed solid N-2-Kr: A high-pressure Raman study of the phase diagram - art. no. 184101

In this paper, the results of an experimental study on the spectral behavio r of the Raman Q branch of nitrogen in the mixed solid N-2-Kr are presented . The experiments have been performed at ambient temperature as a function of pressure up to 15 GPa. On the basis of the results. the p-x cross sectio n of the phase diagram is constructed. In the mixture. the beta region exte nds to very high pressures. The maximum amount of krypton dissolving in bet a -nitrogen is about 85%. As a consequence, the regions where the fcc-Kr la ttice and the delta lattice of nitrogen are stable are relatively small. In all phases, the vibrational frequencies of the nitrogen molecule are shift ed to lower values compared with neat nitrogen. The most interesting aspect is that in the beta solid the linewidth is extremely composition dependent , with maximum values for the mixture with equal mole fractions. It is sugg ested that the increase in the linewidth is mainly due to an increase in th e correlation time rather than an increase of the amplitude of modulation.