Ft-icr Study of Chemical Reaction of Silicon Cluster with Nitric Oxide

Chemical reaction of small silicon cluster ions (Si n: 20 ≤ n ≤ 29) with nitric oxide was studied by using the FT-ICR (Fourier Transform Ion Cyclotron Resonance) mass spectrometer. Silicon clusters were generated by a pulsed laser-vaporization supersonic-expansion cluster beam source directly connected to the FT-ICR mass spectrometer. Injected and size selected clusters were thermalized to the room temperature through collisions with argon, and were exposed to the reactant gas in the ICR cell. As a result, extraction reaction of a silicon atom was observed. When SiO was removed from Si n cluster, resulting Si n-1N clusters occasionally fragmented into smaller pieces. For a comparison, laser induced fragmentation patterns of size-selected clusters were performed. The reaction induced fragmentation was explained that after the Si atom extraction, resulting Si n-1N fragmented in the same manner as pure Si n-1 clusters when the released heat of the initial reaction was not absorbed in the Si n-1N clusters.