Evidence for phase formation in potassium intercalated   1,2;8,9-dibenzopentacene
  We have prepared potassium intercalated 1,2;8,9-dibenzopentacene films under vacuum conditions. The evolution of the electronic excitation spectra upon potassium addition as measured using electron energy-loss spectroscopy clearly indicate the formation of particular doped phases with compositions K$_x$dibenzopentacene ($x$ = 1,2,3). Moreover, the stability of these phases as a function of temperature has been explored. Finally, the electronic excitation spectra also give insight into the electronic ground state of the potassium doped 1,2;8,9-dibenzopentacene films. 
Friedrich Roth, Andreas K\"onig, Benjamin Mahns, Bernd B\"uchner,   Martin Knupfer
cond-mat.supr-con