565 / 2019-03-20 17:43:27

Conformer Modifications and Electronic Structural Changes in 3,3′-diamino-4,4′-azoxyfurazan (DAAF) under high pressure

high pessure,,electronic structure,,Conformer Modifications,DAAF

全体主题 > High Pressure Physics and Materials Science

3,3′-diamino-4,4′-azoxyfurazan (DAAF) is one of the high insensitive energetic materials (HIEM) and possess planar molecule structure. The electronic structure changes and molecular conformation evolution of DAAF under high pressure were studied by using Microscopic confocal Raman spectroscopy, FTIR spectrometer, absorbance spectroscopy and fluorescence spectroscopy. A molecular rearrangement and electronic structure changes be obtained via the vibrational spectroscopy, fluorescence spectra and optical-absorption spectra under high pressure. With the increase of pressure, two electronic structure changes are observed at ~3 GPa and ~12 GPa due to the variation of hydrogen-bond network and distortion of the molecule structure. The modes associated to the NH2 presented significant changes, which indicated the increasing intramolecular and intermolecular hydrogen bonding interaction under high pressure. Those interactions resulted in the evident fluorescence intensity enhancement below 3 GPa. Whereas, several new vibration modes appeared and dramatic frequency discontinuities shift of the vibration modes related to lattice modes, like translational and librational modes, with the increasing pressure occurred at 10 GPa, which are responsible for the slipping and rearrangement of
DAAF at a great extent. In addition, the π∙∙∙π intermolecular interaction between layers was increased with the decreasing layer-to-layer distance, as a result, the fluorescence spectra presented red-shift and gradually losing intensity at about 10 GPa. Besides that, the absorbance spectra of DAAF under high pressure presented an electronic structure changes with a subtle sudden shift of the band gap energy towards lower energy at 12 GPa. It can be conclude that a molecular conformation changes accompanied with the changes in electronic structure of DAAF obtained under high pressure.