Experimental photoemission results on GaN(0 0 0 (1) under bar) and CdTe(1 0 0) surfaces on a function of samarium adsorbate coverage are presented. Energy distribution curves were recorded at photon energies around the Sm 4d --> 4f threshold (135-136 eV) to reveal the Sm contribution to the electronic structure and enhance the sensitivity. The evolution of core-level Ga 3d and Cd 4d spectra was also studied. The interaction of Sm with both GaN and CdTe leads to reactive interface formation. In the case of CdTe, it results in creation of an interfacial Sm-CdTe compound, which inhibits further diffusion of Sm into the bulk. The interaction of Sm with GaN leads to the release of Ga atoms on the surface and segregation of Ga clusters. (C) 2002 Elsevier Science B.V. All rights reserved.