Raman Spectra of 6LiRbSO4 and 7LiRbSO4

Abstract

The polarized Raman spectra of single-crystal 6LiRbSO4 and 7LiRbSO4 at room temperature are reported. On the basis of these data, symmetry-based band assignments are given for both internal and external optic modes. The translational optic modes of the lithium ion appear in the region between 444 and 364 cm−1. Vibrational coupling interactions are noted between the sulfate ion ν2 and the lithium translational optic modes in the same irreducible representation. Coupling interactions are negligible or small in 7LiRbSO4, while in 6LiRbSO4 the lithium isotope effect shifts the lithium translational modes into more coupling interaction with the sulfate ion ν2 modes.