Emission of CsM+ ion clusters (where M represents different elements) was studied experimentally for different elements and matrixes. We analyzed the ionization probability of sputtered Cs particles under different oxygen pressure and found that it varied from 0.05 to 1, and depends on analyzed matrix. Experimental results for CsM+ emission were compared with predictions of an existing model of CsM+ ion formation: some conflict was noticed. We developed another model of CsM+ ion emission based on our results and on data of computer simulations, taken from literature. The model considers recombination of independently sputtered Cs and M atoms on a very short distance from the surface in a field of surface dipoles. Molecule formation process is presumed to be ahead of the molecule ionization process. (C) 2002 Elsevier Science B.V. All rights reserved.