UC Riverside

Plasma is the state of matter produced when molecules and atoms are energized to a point where their electrons escape and the constituent material becomes ionized. It is described as the fourth state of matter making up the vast majority of the observable universe, and over the past century has been studied and developed into usable human-scale applications. As a category, plasma exists in a thermal spectrum as ionization and unbound electrons are the defining characteristics. Thus, non-thermal plasmas made up of near room temperature ionized gasses formed through strong alternating electromagnetic fields make up one side of the spectrum and thermal plasmas that have heated materials to the point of ionizing constitute the other. This dissertation focuses on the application of non-thermal plasmas for reactive gas generation and nanomaterial synthesis, in addition to more fundamental studies of how the plasma interacts with solid interfaces or forms nanomaterials. The studies that this work is composed of are broken down into sections, the first of which is fundamental investigations of non-thermal plasma properties, such as in-situ monitoring of plasma-induced surface-heating via Raman-thermometry and investigations into nanomaterial growth mechanics when exposed to discontinuous (pulsing) plasma conditions. The second section puts the silicon nanomaterials produced via plasma to use in quantum dots, where the silicon nanocrystal is combined with non-toxic organic molecules to achieve record setting photon upconversion and investigates the fundamental mechanisms impacting this method of light conversion. Next, plasma-grown and commercial silicon nanomaterials are applied as a next generation lithium-ion battery anode material, where unanswered questions about carbon shell structure and solid electrolyte interphase growth are investigated with novel techniques of material production and analysis. Finally, the reactive gas output of a plasma is put to work as a cheap and efficient method of pathogen decontamination for face-piece-respirators, demonstrating the wide breadth of applications for non-thermal plasmas and the materials it can produce.