Keywords

Chemometrics, Discriminant analysis, Explosives -- Detection, Factor analysis, Laser induced breakdown spectroscopy, Organic compounds, Plasma (Ionized gases), Principal components analysis

Abstract

Laser Induced Breakdown Spectroscopy (LIBS) is showing great potential as an atomic analytical technique. With its ability to rapidly analyze all forms of matter, with little-to-no sample preparation, LIBS has many advantages over conventional atomic emission spectroscopy techniques. With the maturation of the technologies that make LIBS possible, there has been a growing movement to implement LIBS in portable analyzers for field applications. In particular, LIBS has long been considered the front-runner in the drive for stand-off detection of trace deposits of explosives. Thus there is a need for a better understanding of the relevant processes that are responsible for the LIBS signature and their relationships to the different system parameters that are helping to improve LIBS as a sensing technology. This study explores the use of LIBS as a method to detect random trace amounts of specific organic materials deposited on organic or non-metallic surfaces. This requirement forces the limitation of single-shot signal analysis. This study is both experimental and theoretical, with a sizeable component addressing data analysis using principal components analysis to reduce the dimensionality of the data, and quadratic discriminant analysis to classify the data. In addition, the alternative approach of ‘target factor analysis’ was employed to improve detection of organic residues on organic substrates. Finally, a new method of characterizing the laser-induced plasma of organics, which should lead to improved data collection and analysis, is introduced. The comparison between modeled and experimental measurements of plasma temperatures and electronic density is discussed in order to improve the present models of low-temperature laser induced plasmas.

Notes

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Graduation Date

2011

Semester

Spring

Advisor

Richardson, Martin

Degree

Doctor of Philosophy (Ph.D.)

College

College of Sciences

Department

Physics

Format

application/pdf

Identifier

CFE0003708

URL

http://purl.fcla.edu/fcla/etd/CFE0003708

Language

English

Release Date

April 2014

Length of Campus-only Access

3 years

Access Status

Doctoral Dissertation (Open Access)

Subjects

Dissertations, Academic -- Sciences, Sciences -- Dissertations, Academic

Restricted to the UCF community until April 2014; it will then be open access.

Included in

Physics Commons

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