Absence of phase transformation of dense anthracene from Raman scattering

The high pressure vibrational properties of anthracene are investigated by using Raman scattering techniques in diamond anvil cells up to 7.1?GPa at room temperature. We present a detailed analysis of the normal vibrational modes of anthracene along with assignments of both symmetry and molecular motion. Our results demonstrate that almost all the modes shift toward higher frequencies and some peaks are broadened with increasing pressure. The smooth evolution of peaks corresponding to first and second nearest neighbor shell molecules with pressure rules out the possible existence of phase transformation. The mode Grüneisen parameters are obtained over the wide frequency range and relatively high pressure range.