Electronic state of an organic molecular magnet: Soft x-ray spectroscopy study of α-TDAE-C₆₀ single crystal

Soft x-ray photoelectron spectroscopy was performed for α-TDAE-C ₆₀ single crystal. A C 1s spectrum with a shakeup satellite of TDAE-C₆₀ is very similar to that of C₆₀ when we shift the energy, indicating a charge transfer to the C₆₀ site. A comparison of a N 1s spectrum with theoretical calculations indicates that TDAE mainly consists of the TDAE⁺ state. The valence-band spectrum near the Fermi edge also suggests a charge transfer from the TDAE to the C₆₀ cage. Based on these results we propose a modified model for the charge transfer: the charge states of C₆₀ ^- and TDAE⁺, and the dimer formation along the c axis between the TDAE⁺ states.