Raman Spectrum of Solid Orthodeuterium to 150 kbar at 5 K

Abstract

We have studied samples of 98.5% $o$-${\mathrm{D}}_2$ in a diamond anvil cell to pressures of 150 kbar at 5 K by means of Raman scattering. At 50-60 kbar the $E_{2\mathrm{g}}$ phonon and roton cross and hybridize. The coupling has been determined. The phase transition from the symmetric ground state at low pressure to an orientationally ordered ground state, predicted to occur between 31 and 73 kbar, does not take place. A predicted hcp-fcc structural phase transition is not observed.