Applications of molecular beams: Production of metal oxide thin films and mass spectrometrical study of gas phase clusters
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An intense beam of molecules is accomplished by expanding a high pressure gas of interest into a vacuum chamber. With appropriate design, a molecular beam can be used to generate thin film materials and gas phase clusters. The pulsed arc molecular beam deposition (PAMBD) is a thin film deposition technique that combines the molecular beam and a reliable high energy arc source. By coupling the molecular beam with tandem mass spectrometry, the consequential skimming and ionization of the molecular beam allows for the generation of ionic clusters and as well as the analysis of these clusters. A series of thin film production and three tandem mass spectrometric investigations of gas phase clusters have been performed. The thin film studies focused on the improvement and advantages of molecular beam deposition that the PAMBD system is able to generate various metal oxide thin films and the deposition process can be considered as a low temperature process due to the rapid cooling of expansion. The second and third investigations are the reactions of protonated water clusters with ammonia and methylamine, respectively. For the first time, we were able to investigate the interaction between an ionic cluster and neutral molecules by employing the Compargue type molecular beam source with tandem mass spectrometry. The final study involved a novel aspect of Lewis acid-base interaction accomplished by utilizing the molecular beam to produce benzene-ammonia cluster ions. A three electron interaction between molecules was found to govern within the cluster ions.