PART 1: CHARACTERIZATION OF BEAM SYNTHESIZED CATALYTIC MATERIALS. PART 2: FURTHER DEVELOPMENT OF MOLECULAR SIMS (SILVER, DYES, PERRHENATE, IMPLANATION)

STEVEN MICHAEL SCHEIFERS, Purdue University

Abstract

Part 1 of this thesis concerns characterization of catalyst materials prepared by an ion beam implanter and by a multiple expansion cluster source. Ion beam synthesis was carried out on a 250keV ion implanter. After assembling a special reaction chamber, zeolites were implanted with phosphorous and iron. This work contributed to development of a sputter reactor for ion beam synthesis. Silver catalysts were examined in a reactor designed, built and evaluated for catalysts produced by the sputter reactor and by a multiple expansion cluster source. Small surface area silver foil catalysts and silver cluster catalysts showed kinetic activity for epoxidation of ethylene. The turnover numbers and selectivities calculated from these data agree with literature values for unpromoted silver catalysts. Positive results for the small surface area silver cluster catalyst demonstrate the feasibility of studying these catalysts with the special reactor. Part 2 concerns fundamentals and applications of secondary ion mass spectrometry. It also describes a computer interface for a secondary ion mass spectrometer. SIMS was successfully applied to non-volatile, thermally labile organic dyes. Both precharged and neutral dyes showed structurally informative fragmentation and medium to high intensity molecular cations. Desorption of dyes from thin layer and paper chromatographic media was demonstrated. A counterion effect was investigated using perrhenate salts. Neat ammonium perrhenate and lithium perrhenate displayed significant fragmentation by loss of an oxygen atom. Sodium, potassium and rubidium perrhenate salts did not show significant fragmentation. Physical mixtures of neat perrhenate salts with chloride salts of other alkali cations showed complete mixing of the cations on a microscopic level and suppresion of fragmentation by larger cations. A data system was implemented for a secondary ion mass spectrometer which involved design and construction of a computer interface. Software routines for the interface were written in assembly language for increased operation efficiency. Simplicity and ease of operation were stressed in the design. The system provides for data storage and output. The SIMS interface increases thruput by reducing the required acquisition time.

Degree

Ph.D.

Subject Area

Analytical chemistry

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