Vibron dynamics in RDX, β-HMX and Tetryl crystals

Abstract

Abstract The Raman line widths of 16 vibron modes in RDX, β-HMX and Tetryl crystals have been measured at the temperature ranging from 3.6 to 300.0 K. The experimental line shapes were deconvoluted to extract inhomogeneous contribution to the line broadening due to probably crystal defects. The inhomogeneous line width is independent of temperature for most measured modes. The homogeneous line width is interpreted on the basis of elementary relaxation mechanisms. Three-phonon and dephasing processes are dominant relaxation processes for most of the vibrons of RDX, β-HMX and Tetryl. In particular, for Tetryl crystal, the vibrational relaxation is dominated by three-phonon down processes. For RDX and β-HMX crystals, vibrational relaxation is dominated by three-phonon down processes at lower temperature, three-phonon up or dephasing mechanisms generally contribute to the vibron dynamics while above 60 K. The lifetimes of some vibrons in the frequency range of 200–900 cm −1 in RDX, 200–1450 cm −1 in β-HMX and 200–1100 cm −1 in Tetryl crystal were calculated in term of the line widths at low temperature. The lifetimes of the measured vibrons fall in the range of 2.5–11 ps.