Chemistry and Chemical Biology ETDs

Publication Date

7-29-1971

Abstract

The rapid deposition of energy by means of a pulsed ruby laser to degrade organic and inorganic materials is investigated as an analytical tool. Advantages and disadvantages of using a laser are discussed and compared to current conventional pyrolysis methods. The interaction of laser radiation with matter is briefly discussed. A number of different organic compounds including saturated and aromatic hydrocarbons, heterocyclic compounds, and polymers have been studied. The degradation products were separated and identified by use of a gas chromatograph. Degradation studies have also been done on a series of inorganic salts including nitrates, sulfates, thiosulfates, and oxalates. The degradation mechanism is discussed and the degradation product distributions are examined and explained in terms of their origin within the reaction area. Free energy calculations of possible simple degradation products have been made and correlations with the experimental determination of products indicates that the products are formed in the temperature range of 3000 to 4000 K. Larger molecular species observed in the degradation of organic molecules are believed to originate from an area surrounding the crater formed by the interaction of the laser pulse with the material being analyzed. Repetitive runs were made and the repeatability of the degradation process was determined both by graphic calculations of peak areas and by using a digital integrator attached to the gas chromatograph. The repeatability of the degradation process was found to be within the accuracy of the integrator which is ± 0.1% of the peak area. Variations in the product distribution as a function of the energy density of the beam and energy output was also studied. The use of the laser-gas chromatograph degradation system to analyze for absorbed gases in metals is discussed and experimental data presented. Equipment requirements are also discussed. Supplementary information on the design, construction and operation of a beta-induced luminescence detector for chromatographic detection is included in the appendices.

Language

English

Document Type

Dissertation

Degree Name

Chemistry

Level of Degree

Doctoral

Department Name

Department of Chemistry and Chemical Biology

First Committee Member (Chair)

Nicholas Ernest Vanderborgh

Second Committee Member

Milton Kahn

Third Committee Member

Eleftherious Paul Papadopoulos

Fourth Committee Member

Edward A. Walters

Fifth Committee Member

Roy Dudley Caton Jr.

Sixth Committee Member

Bernard T. Kenna

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