Angular distributions of atoms sputtered from NiAl{1 1 0} and Ni{1 0 0}

Using the laser post-ionization surface analysis technique, I have for the first time studied angular distributions of Ni and Al atoms sputtered from NiAl{1 1 0}. Emission angular distributions from Ni{1 0 0} have also been measured. I have observed preferential emissions of Ni and Al atoms along h1 1 1i and h1 0 0icrystallographic directions for NiAl{1 1 0} and of Ni atoms along h1 1 0i and h1 0 0i directions for Ni{1 0 0}. The observed preferential ejections can be explained in terms of the theory of focusing-collision sequences. Because of the difference in surface binding energy between Al and Ni atoms, preferential ejection angles of Ni atoms are slightly different from those of Al atoms along the h1 1 1i ejections. For NiAl, the h1 1 1i preferential ejections were less prominent than the h1 0 0i preferential ejections and this can be related to the low efficiency of momentum transfer in Ni–Al collision sequences along h1 1 1i lattice directions. The low efficiency of momentum transfer due to the mass mismatch can also be responsible for the experimental observation that the preferential ejections in the alloy were less prominent than those in the Ni metal.