Low energy argon differential sputtering yields and thresholds along the ⟨110⟩ and ⟨100⟩ directions from single crystal silver surfaces

The relative differential sputtering yields, dS, in a fixed small solid angle at various directions from a single crystal silver target under normal Ar + ion bombardment (ion energy from threshold to about 100 eV) have been measured. The yields measured in the directions of various sputtering "spots" were: dS 1 in the ⟨110⟩ direction at about 60° from the (110) face;dS 2 , ⟨110⟩ direction, 45° from (100) face;dS 3 , ⟨110⟩ direction, 35° from (111) face;dS 4 , ⟨110⟩ direction, normal to (110) face; and dS 5 , ⟨100⟩ direction, normal to the (100) face. The magnitudes of the yields were: dS 1 ≃ dS 2 > dS 3 . An order of magnitude lower were: dS 4 > dS 5 . For the oblique ⟨110⟩ emissions, the curves of (dS) 1/2 vs. incident ion energy were linear for ion energies of about 20-50 eV; extrapolation of these curves to zero yield gave the following sputtering threshold energies: dS 1 , 14 eV; dS 2 , 18 eV; and dS 3 , 23 eV.