CHARACTERISATION OF AD-ATOMS AND AD-MOLECULES ON GRAPHENE

Achieving n-, p-type stable doping of graphene is being investigated for different metal dopants, particularly for Hg single atoms and the (easily made) stable linear HgO₂ molecule. Several configurations of freestanding Hg and HgO₂ molecules with respect to the graphene surface were analysed with Density Functional Theory (DFT). In parallel Perturbed Angular Correlation experiments were performed with ^199mHg obtaining the experimental hyperfine fields characterising a specific Hg–... HgO₂ ad-atom or ad-molecule configuration on the graphene layer. Among a multitude of possible configurations, the free O-Hg-O dumbbell lying in-plane with the Hg atom above the hollow site (in the centre of the C-hexagon) with oxygen bonds aligned along the C-C bonds, uniquely fit the PAC experimental results.