Infrared study of 1,3,5-triamino-2,4,6-trinitrobenzene under high pressure

We report synchrotron Fourier transform infrared measurements of 1,3,5-triamino-2,4,6-trinitrobenzene in the mid-IR and far-IR spectral regions up to ~100.3em0exGPa, using KBr or petroleum jelly to compress the samples. During the far-IR experiment, we cycled the pressure, measuring IR spectra at various pressures, to determine whether the sample survived. In both experiments, no phase transition was observed. In the high frequency region (~30000.3em0excm^-1), the peak frequencies of the NH₂ symmetric and antisymmetric vibrational modes decrease with increasing pressure, indicating strengthening of intermolecular hydrogen bonding with pressure.