Divalent scandium atoms in the cage of C84

X-ray spectroscopy (XPS) and ultraviolet photoemission spectroscopy (UPS) have been performed on an endohedral fullerene Sc2C84. The Sc 2p XPS core level of Sc2C84 was found to be located just between those of the metal and the oxide (Sc2O3). This suggests that Sc atoms encapsulated in C84 take an intermediate valency between those of the metal (Sc0±) and the oxide (Sc3+). UPS shows that solid Sc2C84 is an insulator with an energy gap of about 1 eV. It was also found that Sc2C84 does not undergo thermal decomposition upon evaporation and is extremely stable even in the air.