Powell M S, Moore D S, McGrane S D
High Explosives Science and Technology Group, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA.
Shock and Detonation Physics Group, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA.
J Chem Phys. 2021 Feb 7;154(5):054201. doi: 10.1063/5.0032018.
Thin films of trinitrotoluene (TNT) were shock compressed using the ultrafast laser shock apparatus at Los Alamos National Laboratory. Visible (VIS) and mid-infrared (MIR) transient absorption spectroscopies were simultaneously performed to probe for electronic and vibrational changes during shock compression of TNT. Three shock pressures (16 GPa, 33 GPa, and 45 GPa) were selected to observe no reaction, incipient reaction, and strongly developed reactions for TNT within the experimental time scale of <250 ps. Negligible absorption changes in MIR or VIS absorptions were observed at 16 GPa. At 33 GPa, MIR absorptions in the 3000 cm-4000 cm range were observed to increase during the shock and continue to increase during the rarefaction, in contrast to the VIS absorption measurements, which increased during the shock and almost fully recovered during rarefaction. At 45 GPa, both VIS and MIR absorptions were strong and irreversible. The intense and spectrally broad MIR absorptions were attributed to short lived intermediates with strong, spectrally broad absorptions that dominate the spectral response. The MIR and VIS absorption changes observed at 33 GPa and 45 GPa were credited to shock induced chemistry, most likely including the formation of a very broad hydrogenic stretch feature. The results from these experiments are consistent with the chemical mechanisms that include O-H or N-H formation such as CH oxidation or C-N homolysis.
利用洛斯阿拉莫斯国家实验室的超快激光冲击装置对三硝基甲苯（TNT）薄膜进行了冲击压缩。同时进行了可见（VIS）和中红外（MIR）瞬态吸收光谱分析，以探测TNT冲击压缩过程中的电子和振动变化。选择了三种冲击压力（16吉帕、33吉帕和45吉帕），以便在<250皮秒的实验时间尺度内观察TNT的无反应、初始反应和强烈反应。在16吉帕时，MIR或VIS吸收的变化可忽略不计。在33吉帕时，观察到3000厘米-4000厘米范围内的MIR吸收在冲击过程中增加，并在稀疏过程中继续增加，这与VIS吸收测量结果相反，VIS吸收在冲击过程中增加，在稀疏过程中几乎完全恢复。在45吉帕时，VIS和MIR吸收都很强且不可逆。强烈且光谱宽广的MIR吸收归因于具有强烈、光谱宽广吸收的短寿命中间体，这些中间体主导了光谱响应。在33吉帕和45吉帕观察到的MIR和VIS吸收变化归因于冲击诱导的化学反应，很可能包括形成非常宽广的氢伸展特征。这些实验结果与包括O-H或N-H形成（如CH氧化或C-N均裂）的化学机制一致。
