Sputtering of silver dimers: a molecular dynamics calculation using a many-body embedded-atom potential

The ejection of neutral Ag atoms and Ag₂ dimers under 1 keV Ar⁺-bombardment of (111)-, (110)- and (100)-silver surfaces was studied by a molecular dynamics simulation using a many-body embedded-atom method (EAM) interaction potential. The absolute dimer yields Y_Ag2 as well as the translational and internal energy distributions were calculated using the EAM potential for the description of both the solid and the isolated dimer. Significant differences were found between Y_Ag2 obtained for different crystal faces which, however, do not agree with the results of previous studies using additive pair potentials. The calculated translational energy distributions of both atoms and dimers, averaged over the three crystal faces, show good agreement with the corresponding experimental data obtained for a polycrystalline silver surface. The internal state distributions calculated for the sputtered Ag₂ molecules can be fitted by thermal populations revealing vibrational and rotational temperatures of 4200-5800 K and 8500-12300 K, respectively, with the (110)-surface always producing the highest and the (111)-surface the lowest temperatures.