UV/Visible Absorption Spectra of Shocked Nitromethane and Nitromethane-Amine Mixtures up to a Pressure of 14 GPa

Investigation of Shock-Induced Chemical Decomposition of Sensitized Nitromethane Through Time-Resolved Raman Spectroscopy

“…The background feature around 500-2000 cm-1 that grows in time, and the CN vibrational softening and its disappearance, while the pressure in the material is held constant, indicate that chemical changes are occurring in shocked sensitized nitromethane. These Raman results are consistent with previous conclusions from UV-vis absorption experiments on similarly shocked mixtures [4] where sensitized nitromethane shocked to as low as 10.0 GPa was found to undergo irreversible chemical changes.…”

“…We have utilized time-resolved UV-vis absorption [4] and Raman spectroscopies [5] to probe the electronic and vibrational changes that occur in shocked pure nitromethane and sensitized nitromethane (nitromethane with 0.1 wt% ethylenediamine). In pure nitromethane shocked to 14.0 GPa, a pressure induced red-shift of the n-ir* electronic band edge, and hardening of the CN and N02 and CH 3 stretching modes were observed; however, no time-dependent spectroscopic changes arising from chemical reactions were observed within our experimental time window.…”

Temperature measurements of expansion products from shock compressed materials using high-speed spectroscopy

“…The radiative emissions in turn will be proportional to the temperature and the temperature gradient in the radiating body. Time-resolved spectroscopy has been performed on homogenous transparent liquid explosives while in confinement at high pressures [7,8]. It is quite evident that temperature determination based on thermal radiation emitted by the explosive requires knowledge of the emissivity, and the particle size of the debris products in the debris cloud.…”

“…Previous studies on homogenous explosives [7][8][9], utilized emission spectroscopy to study some of these aspects. However, these studies have been on confined liquid explosives where the explosive phenomenon is observed through a window material and at relatively low shocked pressures (less than 20 GPa).…”

Picosecond time-resolved electronic spectroscopy in plate impact shock experiments: Experimental development

“…Over the past 2 decades, methods have been developed to perform nanosecond time-resolved optical spectroscopies in plate impact shock experiments; these include absorption, 12,[15][16][17][18] reflection, 19 fluorescence, 13 and Raman. [20][21][22][23][24] Measurements with this time resolution are well suited to probe the atomic/molecular changes associated with shock-induced chemical reactions; 50 ns time-resolved absorption and fluorescence measurements were used by Gruzdkov and Gupta 12,13 in their work on sensitized nitromethane.…”