Raman Scattering of Light by K2Pb2Si2O7 Pyrosilicate Single Crystals

摘要

Raman spectra of potassium pyrosilicate single crystals K2Pb2Si2O7 are investigated for different polarizations at liquid helium temperature. Two new spectral lines with frequencies 99.5 and 131.1 cm–1, which are assigned to the rotational motion of an anion, are detected. The nature of the high-frequency 687.9 cm–1 line is explained by mixing of the bending valence vibrations with vibrations of the potassium ion. The Raman spectra are interpreted based on the quasi-molecular approach. However, because most of the spectral lines exhibit a complex structure, a conclusion is made about strong mixing of motion of the quasi-molecule with motions of lead and potassium ions.