Temperature Response Study Of Raman Spectra Of Nitrobenzene

Reactions happen among molecules in energetic materials under mechanical shock.During the impact of compression, pressure and temperature will change rapidly in thesystem, making it technically difficult to effectively monitor the real-time temperaturein the study of energetic materials impact kinetics. As a result, research on itstemperature response properties becomes very important. Since the energy conversionprocess is ultra-fast from level of picosecond to femtosecond level, most previousstudies were based on theoretical analysis, while experiments and direct observationson energetic material dynamic were rare.In this paper, the typical energetic nitrobenzene’s temperature response propertiesof Raman spectrum were studied by Raman spectroscopy. First, the theories ofnon-coherent and coherent Raman scattering technology are analyzed. Then,continuous and pulse lasers are used respectively in the spontaneous Raman scatteringexperiment of nitrobenzene and the experiment under variable temperatures. Finally,coherent Raman spectroscopy is used in the stimulated Raman and coherent anti-StokesRaman scattering experiment of nitrobenzene and the experiment under variabletemperatures.Under the stimulation of continuous light, multiple Raman modes are detected,indicating the effectiveness of energetic nitrobenzene as the Raman scattering sample.Under the stimulation of nanosecond laser, both Stokes and anti-Stokes Ramanscattering are acquired, with the magnitude of anti-Stokes Raman scattering far smallerthan the anti-Stokes one, based on which temperature variable experiment is conducted.The results shows that as the temperature increases, magnitude of anti-Stokes increases,the one of Stokes decreases. Temperature could be measured by the magnitude ratio ofthe Stokes to the anti-Stokes, verifying its potential as a non-contact method ofmeasuring the temperature of the samples. Under picosecond pulse input laser, noRaman scattering signal of nitrobenzene is detected, implying that it is difficult toobtain scattering signal with pulse lights of several picoseconds as detection lights. Infemtosecond coherent Raman experiment, both stimulated Raman gain spectroscopyand coherent anti-Stokes Raman spectroscopy of nitrobenzene are obtained, based onwhich temperature variable experiment is conducted. The results show that astemperature increases, the magnitude of stimulated Raman gain decreases graduallyand the magnitude of anti-Stokes scattering decreases. The experiment offers a goodtool for observing transient vibration structure of energetic materials under hightemperature, the results of which could be applied to molecule structure analysis of transient process in samples and justify the possibility of femtosecond Ramanthermometry monitoring the ultra-fast decomposition process of energetic materials asfuels and explosives.This paper verifies the potential of direct experimental observation for temperatureresponse properties of nitrobenzene, providing theoretical basis for the study on thetemperature response properties of other energetic materials.