Effect of temperature and hydrostatic pressure on the Raman active internal and external modes of 1,3,5-trinitro-1,3,5-triazocyclohexane

Abstract

The effect of temperature and hydrostatic pressure up to 30 kbars on the Raman active internal and external vibrational modes of solid 1,3,5-trinitro-1,3,5-triazocyclohexane has been measured. Mode Grüneisen parameters have been calculated. The effect of pressure and temperature on the mode frequencies have allowed a separation of the implicit and explicit contributions to the temperature dependence of the vibrational frequencies of the lattice modes. The results indicate an unusually large explicit contribution for a molecular crystal, suggestive of covalent bonding between the molecules of the lattice. The CH2 symmetric stretching vibration of the molecule showed an atypically large pressure dependence for an internal molecular mode, having a slope 30% larger than the most pressure dependent lattice mode.