Electronic structure of undoped and potassium-doped coronene investigated by electron energy-loss spectroscopy

We performed electron energy-loss spectroscopy studies in transmission in order to obtain insight into the electronic properties of potassium-intercalated coronene, a recently discovered superconductor with a rather high transition temperature of about 15 K. A comparison of the loss function of undoped and potassium-intercalated coronene shows the appearance of several new peaks in the optical gap upon potassium addition. Furthermore, our core-level excitation data clearly signal filling of the conduction bands with electrons.