Evolution of molecular structure of TATB under shock loading from transient Raman spectroscopic technique

By combination of the transient Raman spectroscopic measurement and the density functional theoretical calculations, the structural evolution and stability of TATB under shock compression was investigated. Due to the improvement in synchronization control between two-stage light gas gun and the transient Raman spectra acquisition, as well as the sample preparation, the Raman peak of the N–O mode of TATB was firstly observed under shock pressure up to 13.6 GPa, noticeably higher than the upper limit of 8.5 GPa reported in available literatures. By taking into account of the continuous shift of the main peak and other observed Raman peaks, we did not distinguish any structural transition or any new species. Moreover, both the present Raman spectra and the time-resolved radiation of TATB during shock loading showed that TATB exhibits higher chemical stability than previous declaration. To reveal the detailed structural response and evolution of TATB under compression, the density functional theoretical calculations were conducted, and it was found that the pressure make N–O bond lengths shorter, nitro bond angles larger, and intermolecular and intra-molecular hydrogen bond interactions enhanced. The observed red shift of Raman peak was ascribed to the abnormal enhancement of H-bound effect on the scissor vibration mode of the nitro group.