Douglas B. Cameron
A pulsed laser vaporization cluster beam apparatus was built to generate and detect clusters of transition metals with time-of-flight mass spectroscopic techniques. The apparatus can be used to observe the optical properties of neutral and charged clusters of either pure or mixed metals. Using this apparatus the characteristics of silver clusters were probed with two optical techniques: photoionization and photodissociation.
Ionization potentials for most clusters in the range
Ag3–Ag100 were determined through photoionization. A theoretical shell model based on ellipsoidal distortions of a ductile volume containing an equivalent number of valence electrons is shown to explain almost all the observed photoionization patterns. A comparison of this model to experimental results suggests the existence of 'shape' isomers in metal cluster structure.
Investigations were also made into silver cluster ion photofragmentation. The fragmentation patterns of a few clusters were observed and found to exhibit features similar to those predicted by the shell model. A detailed RRKM-type model of cluster fragmentation was designed and comparisons to preliminary experimental results were made.
|
|
