Laser ablation of ZnS or mixtures of elemental zinc and sulfur was used to produce clusters. Mass spectrometric detection was used to identify the products. Regardless of the composition of the ablation sample, mass spectra were dominated by mixed cluster ions. The mass peak corresponding to Zn13S13+ was present in an abundance much greater than its neighbor ions, indicating that the geometry of this particular cluster confers a special stability. The mass spectra of the analogous ZnO clusters did not exhibit magic numbers. Structure calculations were employed to provide a preliminary estimate of the possible geometries of this cluster. (C) 2002 Elsevier Science BN. All rights reserved.