A study of the molecular chemistry of glasses by infrared microspectroscopy and its use in forensic glass discrimination and classification
Item
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Title
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A study of the molecular chemistry of glasses by infrared microspectroscopy and its use in forensic glass discrimination and classification
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Identifier
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d_2009_2013:b23544f758cf:11323
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identifier
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11765
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Creator
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Kammrath, Brooke Weinger,
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Contributor
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Thomas A. Kubic
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Date
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2012
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Language
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English
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Publisher
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City University of New York.
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Subject
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Analytical chemistry | Criminology | Attenuated Total Reflection | Criminal Justice | Forensic Science | Glass | Infrared Microspectroscopy | Pure Sciences
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Abstract
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The analysis of the molecular structure of glass is a novel forensic method that provides knowledge about glass chemistry that is not currently employed by forensic scientists as well as improves the discriminatory power within this class of transfer evidence. Infrared (IR) spectra contain extensive information about the molecular structure of the complex silicates in commercial glasses. This research is based on measuring the attenuated total reflection (ATR) mid-IR spectra of soda-lime silicate glasses to detect variations of the molecular structure to assist in the comparison of glass evidence. The use of ATR mid-IR spectra for the discrimination and classification of glasses was investigated. Discrimination error rates of approximately 5% and classification by end-product (window or container) error rates on the order of 2% were achieved with principal component analysis-canonical variate analysis (PCA-CVA) hold-one-out cross validation (HOO-CV) on the first and second derivative spectra of 153 soda-lime silicate glasses.;Silicate glass is a common and valuable class of evidence encountered in criminal and civil litigation. Glass is an excellent source of physical evidence because it is brittle and fractures into fragments that are easily transferred from the source to victim and/or perpetrator. The challenge to the forensic scientist is to reliably associate these fragments with their source with high probative value. The mid-IR microprobe analysis of glass requires only minimal additional sample preparation to that which is already done for refractive index (RI) analysis and uses IR investigated samples that are the same size and smaller than the ablated hole made in laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS). Thus mid-IR microprobe analysis can be used to provide additional discrimination for glass samples that are indistinguishable by RI and too small for elemental analysis. ATR mid-IR spectral analysis provides information about the molecular structure of soda-lime silicate glass to support other traditional analysis and strengthen the association of this evidence.
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Type
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dissertation
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Source
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2009_2013.csv
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degree
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Ph.D.
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Program
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Criminal Justice
