Ion reflection and the angular sputter yield peak position

Two theories based on reflection of bombarding ions out of (Firsov) and at the surface/vacuum interface (using Lindhard's channeling calculations) of both amorphous and crystalline targets are compared with respect to the calculation of the angular position of the sputter yield peak. Above a few keV the channeling approach yields only very slightly better agreement with experiment than Firsov's theory although the former is more versatile with respect to predicting grain orientation effects. At lower ion energies, Firsov's theory breaks down while the channeling approach produces acceptable results down to at least 0.2 keV.