The sticking probabilities for sputtered atoms of93Nb and103Rh incident on Al2O3surfaces have been measured using the backscattering of MeV heavy ions. In the circumstance where the collecting surface has become thickly covered, the sticking probabilities integrated over the energy distribution of sputtered atoms are 0.97 ± 0.01 and 0.95 ± 0.01 for93Nb and103Rh, respectively. In the limit of negligible areal coverage of the collector. the accuracy is less; in this case the sticking probabilities are 0.97+0.08and 0.95+0.050.08.