Experimental evidence of two-dimensional dislocations in a reconstructed layer

Characterisation of a reconstructed Au(001) surface by scanning tunneling microscopy shows that most of the defects introduced by low dose 600 eV room temperature Ar+ irradiation are individual dislocations or depressions 0.6 Å deep, the latter characterised as two-dimensional dislocation dipoles. We report the observation of a number of motions, reactions and interactions among these two-dimensional dislocations: (i) individual dislocations glide; (ii) dipole climbing; (iii) dipole annealing; (iv) reactions of the type dislocation dipole⇄a pair of individual dislocations; and (v) more complex reactions involving more than one dipole. All are consistent with a picture in which only two-dimensional dislocations are the primary damage after low dose ion bombardment of Au(001) reconstructed surfaces.