Probing the zero energy shell wave functions of triangular graphene quantum dots with broken sublattice symmetry using a localized impurity

We present here a method of probing the wave functions of a degenerate shell in a triangular graphene quantum dot, [n]triangulene, using a localized substitutional impurity. We demonstrate its applicability to the example of aza-[n]triangulenes. Using the analytical solution for degenerate states of an all-carbon [n]triangulene as a basis for a [n]triangulene containing a nitrogen impurity, we predict the structure of the zero energy shell in the presence of this impurity. We show that the impurity allows probing of the wave functions of a degenerate shell on a carbon site where it is located. We confirm our predictions by a comparison with the tight-binding and ab-initio calculation as well as with experiment.