Assigning XPS features in B,N-doped graphene: input from ab initio quantum chemical calculations
Ab initio quantum chemical calculations using large enough cluster models have been used to predict the core level binding energies of B(1s) and N(1s), including initial and final state effects, in several possible atomic arrangements in B,N-codoped graphene, such as isolated atoms, different types of B,N pairs and BN domains. To a large extent, the observed trends are dominated by initial state effects that support assigning the experimental features to the neutral samples. For the BN domains the present theoretical results are in full agreement with the experimental assignment thus providing support to the rest of the assignments. In particular, the present results strongly suggest that some of the features observed in the experiments are likely to correspond to isolated B or N atoms in graphene and, others fit well to the prediction corresponding to different types of B,N pairs. The importance of having an unambiguous, rigorous way to assign experimental features is emphasized.