Date of Award
1-1-2012
Document Type
Dissertation
Degree Name
Ph.D.
Department
Chemistry and Biochemistry
First Advisor
Keith E. Miller, Ph.D.
Keywords
Direct ablation plasma spectroscopic techniques, Spark-induced breakdown spectroscopy, Laser-induced breakdown spectroscopy
Abstract
The purpose of this research was to apply the use of direct ablation plasma spectroscopic techniques, including spark-induced breakdown spectroscopy (SIBS) and laser-induced breakdown spectroscopy (LIBS), to a variety of environmental matrices. These were applied to two different analytical problems. SIBS instrumentation was adapted in order to develop a fieldable monitor for the measurement of carbon in soil. SIBS spectra in the 200 nm to 400 nm region of several soils were collected, and the neutral carbon line (247.85 nm) was compared to total carbon concentration determined by standard dry combustion analysis. Additionally, Fe and Si were evaluated in a multivariate model in order to determine their impacts on the model's predictive power for total carbon concentrations. The results indicate that SIBS is a viable method to quantify total carbon levels in soils; obtaining a good correlation between measured and predicated carbon in soils. These results indicate that multivariate analysis can be used to construct a calibration model for SIBS soil spectra, and SIBS is a promising method for the determination of total soil carbon.
SIBS was also applied to the study of biological warfare agent simulants. Elemental compositions (determined independently) of bioaerosol samples were compared to the SIBS atomic (Ca, Al, Fe and Si) and molecular (CN, N2 and OH) emission signals. Results indicate a linear relationship between the temporally integrated emission strength and the concentration of the associated element.
Finally, LIBS signals of hematite were analyzed under low pressures of pure CO2 and compared with signals acquired with a mixture of CO2, N2 and Ar, which is representative of the Martian atmosphere. This research was in response to the potential use of LIBS instrumentation on the Martian surface and to the challenges associated with these measurements. Changes in Ca, Fe and Al lineshapes observed in the LIBS spectra at different gas compositions and pressures were studied. It was observed that the size of the plasma formed on the hematite changed in a non-linear way as a function of decreasing pressure in a CO2 atmosphere and a simulated Martian atmosphere.
Publication Statement
Copyright is held by the author. User is responsible for all copyright compliance.
Recommended Citation
Schmidt, Morgan Steele, "Plasma Spectroscopic Techniques Applied to Biological and Environmental Matrices" (2012). Electronic Theses and Dissertations. 921.
https://digitalcommons.du.edu/etd/921
Provenance
Received from ProQuest
Rights holder
Morgan Steele Schmidt
File size
241 p.
Copyright date
2012
File format
application/pdf
Language
en
Discipline
Analytical Chemistry