Preetom Borah will be defending his thesis on June 9th. Please see the details below:
Time: June 9th at 11AM
Location: HEMI Boardroom, Malone Hall (RM 137)
Thesis Advisor: Tim Weihs
Title: MULTI-SPECTROSCOPIC SYSTEM DEVELOPMENT AND ANALYSIS TO RAPIDLY MEASURE PROMPT DEFEAT OF A CHEMICAL WEAPON AGENT SIMULANT DIISOPROPYLMETHYL PHOSPHONATE IN REACTIVE METAL POWDER ENVIRONMENTS VIA CHEMISTRY AND TEMPERATURE
Abstract: The development of advanced diagnostic systems to evaluate and optimize emerging energetic materials is critical for the neutralization of Chemical Warfare Agents (CWAs). This thesis presents a comprehensive investigation into the prompt defeat of the CWA simulant Diisopropyl Methyl Phosphonate (DIMP) using combusting composite metal powders. We begin by documenting the development and integration of two custom spectroscopic systems: a benchtop Polygonal Rotating
Mirror Infrared Spectrometer (PRiMIRS) for real-time detection of DIMP and its decomposition, and Tunable Diode Laser Absorption Spectroscopy (TDLAS) for simultaneous temperature measurements on reactive materials. Initial experiments confirmed that DIMP remains stable in homogeneous thermal environments below 230 °C, but undergoes rapid decomposition within seconds when exposed to reactive metal particle combustion, evidenced by the appearance of signal indicative of decomposition products such as isopropyl methyl phosphonate (IMP) and isopropyl alcohol (IPA). Using a range of stoichiometrically varied (Al-8Mg):Zr powders and elementally varied aluminum-based thermites—such as 4Al / 3MnO2 and 2Al / Bi2O3, the study quantitatively assessed defeat performance as a function of thermal pulse, chemical composition, and material quantity. A spectral defeat parameter was developed to enable direct comparison between materials. Additional diagnostics including High Speed Videography (HSV), Transmission Electron Microscopy (TEM), Fourier Transform Infrared Spectroscopy (FTIR), and X-ray Photoelectron Spectroscopy (XPS), validated the presence of phosphorous residues and particle dispersion, confirming evidence of chemical interactions between DIMP and combustion products. Notably, markedly different levels of defeat were observed between materials expressing similar thermal behavior, suggesting that alongside thermal mechanisms, chemical reactivity plays a critical role in prompt agent neutralization. This work demonstrates the first repeatable evidence of non-thermal contributions to prompt CWA defeat, establishing a foundation and impetus for future material design strategies to leverage both thermal and chemical pathways to enhance performance.