Publication:
High explosives detection in international mail using See-Through Raman Spectroscopy assisted by multivariate analysis

dc.contributor.advisor Hernández Rivera, Samuel P.
dc.contributor.author Muñiz López, Wilmaris
dc.contributor.college College of Arts and Sciences - Sciences en_US
dc.contributor.committee Torres Candelaria, Jessica
dc.contributor.committee Román Velázquez, Félix R.
dc.contributor.department Department of Chemistry en_US
dc.contributor.representative Rodríguez, Domingo
dc.date.accessioned 2021-01-19T12:52:22Z
dc.date.available 2021-01-19T12:52:22Z
dc.date.issued 2020-12-09
dc.description.abstract See-Through Raman Spectroscopy (STRS) was used for the non-invasive, non-destructive sample analysis of high explosives (HEs) in mail envelopes or flats. The method resulted in a safe and rapid analysis of HEs: ammonium nitrate (AN), urea nitrate (UN), and pentaerythritol tetranitrate (PETN). The analysis was carried on under normal conditions without sample preparation to simulate a scenario similar to the ones found at an International Mail Facility (IMF). The ST-RS system operates under high photon scattering conditions enables a deeper penetration by the incident laser beam. It is a portable, rapid, high throughput technology that enables the characterization of chemical and biological threats (CBTs) by exciting their vibrational modes. Multivariate analysis (MVA) was applied due to the vast amount of data generated in the experiments, and the spectral interferences presented by the envelopes (flats). Under these conditions, it was complicated to obtain robust results in a short time. Exploratory Data Analysis (EDA) was applied to separate HEs signals from mail flats spectral data. Principal Component Analysis (PCA) was capable of classifying each variable, explaining most of the experimental variance using the first two principal components: PC-1 and PC-2. The PCA-based models were efficient in classifying HEs' vibrational markers even when contained within several flats layers and classifying HEs into different clusters. PC loadings were used to determine each variable's contribution to the PCA models, which resulted in correlation coefficients (R^2 values) of 0.99 and 0.92 for the first PC for UN and PETN, respectively. en_US
dc.description.abstract La espectroscopía de Raman de “ver a través” (“ST-RS,” por sus siglas en inglés) se utilizó para el análisis no invasivo, no destructivo de muestras de explosivos altos (“HEs”) dentro sobres de correo. El método ofrece un análisis seguro y rápido de los HEs: nitrato de amonio (“AN”), nitrato de urea (“UN”) y tetranitrato de pentaeritritol (“PETN”). El análisis se llevó a cabo bajo condiciones normales sin preparación de muestras para simular un escenario similar al de las Facilidades de Correo Internacional (“IMF”). El Sistema ST-RS que opera bajo el modo de transmisión es una tecnología portátil, rápida y de alto rendimiento que permite la caracterización de estas amenazas por sus modos vibracionales. Se aplicó el análisis multivariado debido a la gran cantidad de datos que se generan habitualmente en las técnicas de espectroscopía vibracionales. Con la gran cantidad de datos es más complicado obtener resultados reales en poco tiempo. Se realiza un análisis de datos exploratorio (“EDA”) para la separación de “HEM” de los datos espectrales del sobre de correo. El análisis de componentes principals (“PCA”) fue capaz de clasificar cada variable explicando la varianza en sus dos primeros componentes, PC-1 y PC-2. El metodo pudo clasificar “HEM” bajo multiples capas de sustrato, además de clasificar “HEM” en sus diferentes grupos en sustratos específicos. Los “loadings” determinaron la contribución de cada variable a los modelos de PCA que demostraron una correlación, R^2, de hasta 0.99 y 0.92 en su primer componente para “UN” y “PETN” respectivamente. en_US
dc.description.graduationSemester Fall en_US
dc.description.graduationYear 2020 en_US
dc.identifier.uri https://hdl.handle.net/20.500.11801/2726
dc.language.iso en en_US
dc.rights.holder (c) 2020 Wilmaris Muñiz López en_US
dc.subject High energetics en_US
dc.subject Chemometrics en_US
dc.subject Mail en_US
dc.subject See Through Raman Spectroscopy en_US
dc.subject.lcsh Raman spectroscopy en_US
dc.subject.lcsh Explosives -- Detection en_US
dc.subject.lcsh Postal service en_US
dc.subject.lcsh Multivariate analysis en_US
dc.title High explosives detection in international mail using See-Through Raman Spectroscopy assisted by multivariate analysis en_US
dc.type Thesis en_US
dspace.entity.type Publication
thesis.degree.discipline Chemistry en_US
thesis.degree.level M.S. en_US
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