Surface Chemistry of Femtosecond Laser Processed Surfaces

Authors

Graham Kaufman, University of Nebraska-LincolnFollow

First Advisor

Craig Zuhlke

Committee Members

Natale Ianno, Jeffrey Shield, Siamak Nejati

Date of this Version

5-2024

Document Type

Dissertation

Citation

A dissertation presented to the faculty of the Graduate College at the University of Nebraska in partial fulfillment of requirements for the degree of Doctor of Philosophy

Major: Electrical Engineering

Under the supervision of Professor Craig Zuhlke

Lincoln, Nebraska, May 2024

Comments

Copyright 2024, Graham Kaufman. Used by permission

Abstract

Micromachining and surface functionalization with femtosecond lasers is a rapidly developing technology in the field of materials and interfacial sciences due to its flexibility towards materials, tunability in surface features, and prospects for scalability. Many interfacial applications have been shown to be enhanced with femtosecond laser-induced surface texturing including two-phase heat transfer, antimicrobial properties, electrochemical systems and more. However, without ideal surface chemistry, the enhancements cannot be optimized for a given application. Surfaces functionalized by femtosecond lasers tend to have transient surface chemistries when exposed to the atmosphere, changing important interfacial properties like the interaction of the solid surfaces and fluids. To completely optimize the surfaces, an understanding of the cause of the transient surface properties is necessary. In this dissertation, reactions between surface metal atoms and the atmosphere that cause the transient surface chemistries of silver and copper processed with femtosecond lasers were studied and correlated to changes in the surface wetting properties. Because the intrinsic surface chemistries of materials functionalized by femtosecond lasers are not always ideal, post-laser-processing techniques to further optimize the surface chemistry of the functionalized surfaces were also explored. Results on enhancements from surfaces functionalized by femtosecond laser with refined surface chemistry are reported for applications in pool boiling heat transfer, catalysis, and repellency to low surface tension fluids.

Advisor: Craig Zuhlke