  We report the local atomic and electronic structure of a nitrogen-doped
graphite surface by scanning tunnelling microscopy, scanning tunnelling
spectroscopy, X-ray photoelectron spectroscopy, and first-principles
calculations. The nitrogen-doped graphite was prepared by nitrogen ion
bombardment followed by thermal annealing. Two types of nitrogen species were
identified at the atomic level: pyridinic-N (N bonded to two C nearest
neighbours) and graphitic-N (N bonded to three C nearest neighbours). Distinct
electronic states of localized {\pi} states were found to appear in the
occupied and unoccupied regions near the Fermi level at the carbon atoms around
pyridinic-N and graphitic-N species, respectively. The origin of these states
is discussed based on the experimental results and theoretical simulations.
