High-pressure behavior of solid nitrobenzene: Combined Raman spectroscopy and DFT-D calculations study

• The vibrational properties of NB were investigated using high-pressure Raman spectroscopy.
• Pressure effects on the structure of solid NB were examined.
• The NB molecule was distorted, and molecular conformation was readjusted under pressure.

Nitrobenzene (NB), a simplest structure of the aromatic nitro compounds, was investigated as a model for understanding structural properties in nitro derivatives of benzene and anilines. Using the Raman spectroscopic technique, the vibrational modes of solid NB were examined under hydrostatic compression up to 10 GPa. The Raman spectra indicated that a subtle phase transition occurred around 5 GPa. Also, the dispersion corrected density functional theory (DFT-D) calculations were performed to provide further insight into pressure effects on the molecular geometry. The calculated data suggested that NB molecules were distorted, and molecular conformation was readjusted when the phase transition with vibrational changes took place under high-pressure.