DISPLACEMENT ENERGY THRESHOLD FOR NE+ IRRADIATION OF GRAPHITE

A method for direct determination of the threshold energy (E(d)) for displacing atoms by low-energy ion irradiation to form residual point defects is described, The method is demonstrated for Ne+ irradiation of graphite. The damage induced by low Ne+ doses (< 2 x 10(15) ions/cm2) was quantified by means of a defect-sensitive feature in the Auger electron spectrum. The defect production rates at different Ne+ energies yield a displacement energy of E(d) = 35.3 +/- 1 eV. This result provides new insight into the elementary collision processes leading to point defect creation.