Jahn-Teller distortion in Cs4C60 studied by vibrational spectroscopy

Abstract

Abstract. We have measured the infrared spectra of Cs 4 C 60 in the temperature range 220 -450 K. Two anomalies in the low-frequency modes at 270 K and 400 K point to changes in molecular or crystal structure. The most probable explanation is a rotator phase above 400 K and a fully ordered phase below 220 K; the intermediate structure is one where molecular Jahn-Teller distortions compete with crystal field effects.