Anomalies in the Pulsed Photoconductivity of Undoped C₆₀ and Their Relationship to Phase Transitions

Abstract

We studied pulsed photoconductivity of face-centered-cubic C₆₀ single crystals in the temperature range 4--300, K and the wave-length one 337--780 nm. Dominant photocarriers turned out to be electrons. We found photoconductivity anomalies at 85, K, 155, K and 260, K where structural phase transitions have been found or are expected to occur in the rotational degree of freedom of C₆₀ clusters. The anomaly at 155, K was found to be quenched by ambient oxygen.