Defects in graphenic materials by EPR and DFT methods

Abstract

We have used EPR to characterize a series of defects, which are characterized by tipical g-tensors, linewidths, intensity as function of the temperature. Mostly, signals arises from the presence of conduction electrons, and of so-called "edge states", that are unpaired electrons located at the edges of graphenic flakes; the relative molecular orbitals are not very muche extended as for low-lying orbitals, and are located within few atomic rows from edges with zig-zag topology. All the relative EPR signals are naturally and intrinsically generated by all graphitic materials. We now extend our study to the defects that are formed inside the graphenic structure. There is a full zoo of possible defects that can in principle originate EPR signals, like the presence of ad-atoms, holes, dislocation of atoms.We have started to study and analyze each type of defect from an experimental as well as from a theoretical point of view.