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Title:Energy and charge dynamics in ion-irradiated surfaces and 2D materials from first principles
Author(s):Kononov, Alina
Director of Research:Schleife, Andre
Doctoral Committee Chair(s):Wagner, Lucas K
Doctoral Committee Member(s):Mason, Nadya; Bellon, Pascal
Department / Program:Physics
Degree Granting Institution:University of Illinois at Urbana-Champaign
2D materials
time-dependent density functional theory
ion radiation
electron density analysis
numerical time-stepping
stopping power
electron emission
charge capture
charge transfer
charge dynamics
emission threshold
ion channel
surface plasmon
Abstract:Materials experience ion radiation in a variety of contexts including cosmic rays in space and focused ion beams in high-resolution imaging and patterning techniques. While most existing knowledge concerning an energetic ion's interaction with solids is limited to bulk materials, many real-life radiation effects inherently involve surface processes such as electron emission. The extreme case of ion-irradiated 2D materials is particularly compelling given their myriad potential applications which rely on precise control of defects. First-principles simulations can characterize the elusive fundamental physics of ion-irradiated surfaces and inform ion beam microscopy and patterning techniques for 2D materials. Accurately modeling the sub-fs excited electron dynamics occurring as an energetic ion impacts a material requires time-dependent density functional theory, and the large simulation cells needed to treat the material-vacuum interface exacerbate the high computational cost of this method. Thus, special efforts were dedicated to improving the numerical algorithms used for evolving the system over time. Then, using this first-principles approach and novel electron density analysis techniques, this thesis investigated surface behavior in proton-irradiated aluminum, including an interesting deviation from bulk electronic stopping power and emitted electron escape depths. This framework was then applied to study ion-irradiated graphene, providing detailed information about sensitivity of energy deposition and electron emission to projectile parameters and offering insights into defect formation mechanisms mediated by electronic excitations. This thesis establishes a predictive approach for theoretical studies of ion-induced charge dynamics in 2D systems with important implications for optimizing focused ion beam techniques in nanotechnological applications.
Issue Date:2020-07-14
Rights Information:Copyright 2020 Alina Kononov
Date Available in IDEALS:2020-10-07
Date Deposited:2020-08

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