Yimin Fu

Publication Date

1996

Document Type

Dissertation/Thesis

First Advisor

Carnahan, Jon W.

Degree Name

M.S. (Master of Science)

Legacy Department

Department of Chemistry

LCSH

Plasma (Ionized gases); Charge transfer; Helium

Abstract

The charge transfer (CT) theory examined in this thesis reveals insights of nonmetal emission behavior in the helium microwave-induced plasma. The likelihood of CT occurrence is determined by near resonance energy transfer between ionized helium and an excited state of the nonmetal ion. The magnitude of the energy defect, or departure from resonance, on the likelihood of charge transfer occurrence is considered. From a kinetic point of view, the reaction rate for energy transfer from an ionized plasma species to an energetic state of an excited nonmetal ion is the largest when the energies of the electronic levels are nearly equal, or the energy defect is small. Small energy defects will result in a larger ionization cross sections and, thus, a larger population of the excited nonmetal ions. Prediction of CT is based upon some knowledge of reaction cross sections which are related to the electron state configurations and the energy defects involving the production of those states. In this study, a 24 element CT table is presented to correlate these energy defects and determine which states are CT allowed. The CT tables predict arrangement of nonmetal electrons during the nonmetal ionization reaction and the extent of direct population of given ion electronic states by CT. These tables highlight possible charge transfer with five noble gases. The discussion offers predictions of likely CT reactions. Specific experiments are performed to illustrate plasma chemistry manipulation and test the charge transfer hypothesis. Observed are the intensities of chlorine and bromine emission lines while mixing the helium plasma support gas with argon and neon. Due to the higher ionization potential of helium, doping argon or neon in the plasma results in a reduced population of ground state of helium ions. Since ionized helium directly participates in the CT process, decreases in the intensities of chlorine and bromine ion lines, and increases in the intensities of chlorine and bromine atom lines are observed.

Comments

Includes bibliographical references (pages [53]-55)

Extent

ix, 154 pages

Language

eng

Publisher

Northern Illinois University

Rights Statement

In Copyright

Rights Statement 2

NIU theses are protected by copyright. They may be viewed from Huskie Commons for any purpose, but reproduction or distribution in any format is prohibited without the written permission of the authors.

Media Type

Text

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