OPTICAL AND RAMAN MICROSPECTROSCOPY OF NITROGEN AND HYDROGEN MIXTURES AT HIGH PRESSURES

Abstract

Optical and Raman microspectroscopy measurements performed on N2:H2 mixtures to 83 GPa reveal unusual phase behavior and bonding signatures. To pressures of 30 GPa, large deviations in the internal molecular stretching modes (vibrons) of a 2:1 N2:H2 mixture relative to those of the pure materials are found. An unusual phase separation is observed near 35 GPa, involving the formation of two distinct solid phases, one rich in both nitrogen and hydrogen and the other an amorphous nitrogen phase. Raman bands attributed to N‐N single bonds or polymerized nitrogen were observed at high pressures.