MOLECULAR DYNAMICS SIMULATIONS OF CLUSTER BOMBARDMENT
Open Access
- Author:
- Russo Jr., Michael Francis
- Graduate Program:
- Chemistry
- Degree:
- Doctor of Philosophy
- Document Type:
- Dissertation
- Date of Defense:
- October 06, 2008
- Committee Members:
- Barbara Jane Garrison, Dissertation Advisor/Co-Advisor
Nicholas Winograd, Committee Member
Janna Kay Maranas, Committee Member
Mark Maroncelli, Committee Member
Barbara Jane Garrison, Committee Chair/Co-Chair - Keywords:
- SIMS
Cluster Bombardment
C60 - Abstract:
- The overall objective of this thesis is to elucidate the physics that govern the bombardment events of cluster projectiles in SIMS experiments. Specifically, this research utilizes molecular dynamics simulations to study bombardment events. Through this research we aim to provide an atomic scale picture of SIMS events as well as a better understanding of experimental results. To identify the unique properties of bombardment events involving cluster projectiles, an investigation of the dynamics of different cluster projectiles is conducted. Specifically, two predominant experimental sources, Au3 and C60, are used to bombard an amorphous water sample. The physics of these two clusters is examined further via the use of an amorphous water layer of varying thickness on a Ag substrate. The generalized behavior that governs cluster bombardment events is elucidated and examined. This observed behavior has led to the development of an analytical model that can be used to predict the yield dependence on incident energy of the cluster projectile used. The dynamics of multiple bombardment events is also examined through the use of successive bombardment of a silicon sample via a gallium beam by a continuous simulation. The computational techniques that are developed during this study are expanded to allow depth profiling MD simulations to be performed on large samples in a tractable manner. Specifically, C60 projectiles are used to repeatedly bombard a Ag sample at random impact points; many of which overlap. The roughness and topographical effects that arise as well as how these features affect the overall yield from the sample are examined. The results presented in this thesis have expanded the knowledge and understanding of the impact process for those in the SIMS community. The computational techniques that have been adapted and refined throughout the span of this research have opened the door on previously unattainable studies, and have expanded the complexity of systems that can be feasibly performed. Overall, the research presented in this thesis improves the understanding of the cluster SIMS phenomena, and has changed the way the community thinks about many of the dynamics that take place.