Angular distribution of particles sputtered from metals and alloys

The angular distributions of atoms sputtered from pure Cu and Be as well as Cu98Be2, Cu71Zn29, Co3Au, and WSi/sub 2.3/ were investigated for bombardment with Ar+ ions of 250 eV and 2 keV under normal incidence. Between polar emission angles θ = 00 and 600, for the higher bombarding energy all observed angular distributions look very much alike and follow essentially a cos3 θ law. For the low bombarding energy, however, significant differences between the angular distributions of the alloy constituents are found. The effect, which is most pronounced for CuBe, seems to scale with the atomic mass in the way that the lower mass particles are sputtered preferentially along the surface normal