1A-4
Anomalous phonons associated with proton transfers in Cs₃H(SeO₄)₂, S. Terao (Tohoku Univ.) et al.

The absorbance spectra in the FIR and MIR ranges were measured at 300~520 K for superprotonic conductor Cs₃H(SeO₄)₂, which possesses strong anharmonicity. The absorbance of SeO₄-tetrahedral deformation accompanied by O-Se-O bending (~500 cm^-1) takes maximum at around 410 K. Furthermore, the SeO₄-tetrahedral deformation accompanied by Se-O stretching (~700 cm^-1) shows that the integrated absorbance anomalously increases approximately above 410 K. Those anomalies may reflect protonic fluctuations irrelevant to conventional hopping, suggesting the formation of a proton polaron.