High-pressure resonance Raman spectroscopic study of ultramarine blue pigment

The resonance Raman spectrum of ultramarine has been studied as a function of pressure up to 5 GPa. The overtone progressions of the nu(1) fundamental and the combination bands of S-3(-) and the nu(1) band of S-2(-) were measured and the pressure dependences were determined. The symmetric stretching mode of S-3(-) is nearly harmonic. No phase transition was observed over the measured pressure range. (C) 2012 Elsevier B.V. All rights reserved.