Vibrational spectroscopy of shock-compressed nitromethane-d3

Real-time vibrational spectra of shock-compressed nitromethane-d3 (CD3NO2) up to 10 GPa have been measured using a single-pulse laser Raman spectrometer in conjunction with a propellant gun and vibrational mode-dependent behavior has been examined. The NO2 stretching mode shows small frequency shift compared to other stretching modes, which may be attributed to increased intermolecular interaction under pressure. Pressure-induced Raman frequency shift of all the investigated stretching modes shows monotonic increase up to ∼5.0 GPa. Above 5 GPa, however, an abrupt drop in Raman frequency shift is observed for the CN and the CD3 stretching modes. At higher pressures, Raman frequencies of these two modes increase again until all Raman bands disappear at above ∼8.5 GPa, where a strong background emerges over the whole spectral range (500–2600 cm−1). This strong emission appears to indicate an onset of a single shock induced chemical reaction at ∼8.5 GPa.