Hyperthermal cesium ion initiated reactions on a copper foil surface
Abstract
New instrumentation has been constructed that is capable of hyperthermal bombardment of surfaces by cesium ions. The intent of this research is to explore the chemical interactions of gas phase alkali ions with surface-bound reagent species. It has been proposed that low-volatility unsaturated hydrocarbons may be susceptible to polymerization, and this can occur through activation by cesium ions. This reaction type, termed ‘cationic polymerization’, relies on the presence of a cationic species (in the proposed case, Cs + and derived cations) to initiate the polymerization between two monomers. A principal advantage to carrying out such an experiment is the relatively controlled conditions afforded by a vacuum environment (no potentially interfering solvents or solvated contaminants) and the controlled rate of ion/neutral interaction. The ion optics of the instrument consists of a lens stack, which consists of the following: a cesium ion gun, an einzel lens stack, a decelerating mesh, and a sample-mounting surface. Experiments were performed under vacuum maintained at a pressure of 10-5-10-6 torr. The surface with the desorbed reagent was exposed to a high-current (ca. 1 μA) beam of hyperthermal (<100 >eV) Cs ions and related clusters to induce reactions. Analysis of the samples was achieved via nano-ESI-MS. The placement of neat samples onto a surface demonstrates the ability of the Cs+ ion method to facilitate reactions without the use of other reagents. Tandem mass spectrometry experiments using collision induced dissociation were performed to confirm the presence of the monomer before Cs+ ion bombardment and to determine the product formed by Cs+ ion interaction.
Degree
M.S.
Advisors
Cooks, Purdue University.
Subject Area
Analytical chemistry
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