SIZE DISTRIBUTION STUDIES OF SPUTTERED TRANSITION-METAL CLUSTER IONS BY FOURIER-TRANSFORM ION-CYCLOTRON RESONANCE MASS-SPECTROMETRY

Mass spectra of various metal cluster ions, mainly of transition metals are presented. These clusters were sputtered by an external 20 keV Xe+ ion source and detected with a Fourier transform mass spectrometer (FT-MS). Cluster ions could be efficiently trapped in the ion cyclotron resonance cell (ICR-cell). In the case of indium, for instance, clusters containing more than 100 atoms could be observed. The sensitivity of our instrument was sufficient to even detect AU85+ cluster ions with mass 16745 u. "Magic numbers" are observed in the cluster cation distributions of indium and the d10s1 metals copper, silver and gold.