变温红外光谱法研究FOX-7的相变（英）

Abstract

Two kinds of phase transitions (α→β and β→γ) of the insensitive high explosive, 1, 1-diamino-2, 2-dinitroethylene(FOX-7), have been investigated by temperature-dependent Fourier transform infrared(FTIR) spectroscopy, and the effects of intermolecular H-bonding interactions and molecular structure in the phase transitions of FOX-7 were discussed. The frequency of ν11 [NH2 (νas)] and ν10 [NO2 (νs)] shifts about 20 cm-1, together with the loss of ν18 [C—NO2 (ν)] in the range of 55 ℃ to 122 ℃, while ν12 [C—NH2(ν)] disappears and ν20[NO2(ω)] transforms to another broad peaks in the range of 122 ℃ to 190 ℃. The analytical results of the IR spectra indicate that intermolecular hydrogen bonding interactions change in the phase transitions of the FOX-7, which cause the changes of the molecular structure. Moreover, in the process of α→β transition, the changes of H-bonding length with increasing temperature are not consistent with the linear thermal expansion formula, and ν11、ν4[Fermi resonance between the NH2 (νas) and the overtone mode of the NH2 scissor (2ν5)]、ν7 and ν10[NO2(νas)] show special frequencies, which are different from those of α and β-FOX-7. The results confirm the transition state in the α→β transition.