Laser annealing of silicon clusters
Anderson, Lila R.
Master of Arts
A miniaturized pulsed laser-vaporization supersonic cluster beam source was developed and mounted on the magnetic axis of a Fourier transform ion cyclotron resonance apparatus (FT-ICR) so that the clusters were directly injected into the ICR ion trap. Mass-selected positive silicon cluster ions were levitated in the FT-ICR, and probed in chemisorption reactions with ethylene and ammonia. Clusters in the 36-51 atom size range were effectively annealed to unique structural forms by excitation with a XeCl excimer laser followed by cooling through infrared radiation and collisions with argon. Reactions on the annealed clusters showed the variation in reactivity with cluster size was enhanced. To our knowledge this is the first reported example of a successful annealing experiment on gas phase clusters of any kind.