Mapping spin distributions in electron acceptor molecules adsorbed on nanostructured graphene by the Kondo effect

Electron acceptor molecules adsorbed on nanostructured graphene grown on Ru(0001) were investigated by low temperature scanning tunneling microscopy and spectroscopy (LT-STM/STS). Our experiments reveal a considerable charge transfer from the substrate to the single molecules leading to the partial occupation of the LUMO of the neutral molecules. The nanostructured graphene modulates the hybridization between the transferred unpaired electron and the ruthenium conduction electrons leading to the appearance of a Kondo effect. Spatially resolved LT-STS allows the high resolution mapping of the spin distribution of the charge transferred and a characteristic inelastic Kondo features associated to specific vibrational modes.