R. Valiente, I. Hernández, F. Rodríguez, F. Aguado, H. U. Güdel and K. Krämer
High-pressure induced absorption line narrowing in Cs₃Yb₂Cl₉
J. Phys. Conf. Ser. 121, 042002/1-5 (2008)                 

Abstract: In this paper we investigate the pressure dependence of the absorption spectrum of Cs₃Yb₃Cl_9. The polarised absorption spectra enable us to assign the main transitions of Yb³⁺ in C_3v from the complicated phonon-side band structure, and derive the corresponding structure. Special attention is paid on the pressure-induced line narrowing and associated blue shift of the most prominent absorption transition that corresponds to the high energy G₄ G₄ transition at 10668 cm^-1 at ambient conditions. The unusual linewidth reduction with pressure is explained by a Debye-type model considering the different contributions to the linewidth.