Pressure-induced phase transitions in stearic acid C form

Pressure-dependent Raman scattering studies have been performed on stearic acid single crystal, C form. The vibrational spectra have been recorded in the 20–1200 cm−1 and in the 2800–3100 cm−1 spectral regions. The behavior of the Raman modes indicates that the crystal undergoes a series of structural modifications. The change observed between 0.8 and 1.27 GPa was associated with a conformational modification or tilting of the dimer. A second modification was observed at ∼2.5 GPa accompanied by jump of lattice mode frequencies, and the appearance and disappearance of bands. Finally, a third set of changes in the Raman band profile was observed between 3.3 and 3.8 GPa and was associated with another structural phase transition.