Formation of multiatomic cluster ions of silicon in pulsed-laser stimulated field desorption

Multiatomic cluster ions of 3 to ∼16 atoms/cluster are formed in pulsed-laser stimulated field absorption. Utilizing an isotope mixing which occurs in cluster formation, the most abundant cluster ion species are identified to be Si2+4, Si2+5, and Si2+6. Si4+13 is also found. These magic numbers, 4, 5, 6, and 13, correspond to the highly symmetric, small units of atoms existing in a Si crystal. The critical number of 2+ ions is found to be 3.