Displacement energy threshold forNe+irradiation of graphite

A method for direct determination of the threshold energy (${\mathit{E}}_{\mathit{d}}$) for displacing atoms by low-energy ion irradiation to form residual point defects is described. The method is demonstrated for ${\mathrm{Ne}}^{+}$ irradiation of graphite. The damage induced by low ${\mathrm{Ne}}^{+}$ doses (<2×${10}^{15}$ ions/${\mathrm{cm}}^2$) was quantified by means of a defect-sensitive feature in the Auger electron spectrum. The defect production rates at different ${\mathrm{Ne}}^{+}$ energies yield a displacement energy of ${\mathit{E}}_{\mathit{d}}$=35.3±1 eV. This result provides new insight into the elementary collision processes leading to point defect creation.