Raman Spectroscopic study of pure p-terphenyl and tetracene:p-terphenyl doped crystals

The Raman spectra of pure p-terphenyl and tetracene:p-terphenyl doped crystals have been examined for different guest concentrations, above and below the phase transition, at 190 K. As the temperature decreases from the α-phase to the β-phase, similar spectral changes are observed in the corresponding Raman modes of pure p-terphenyl and tetracene:p-terphenyl doped crystals for an equal decrease in temperature. The most evident spectral changes are analysed in terms of changes in the crystalline structure.