Understanding and Mitigating Airborne Contamination on Surfaces
| dc.contributor.advisor | Preston, Daniel J. | en_US |
| dc.creator | Liu, Zhen | en_US |
| dc.date.accessioned | 2024-08-30T18:25:13Z | en_US |
| dc.date.created | 2024-08 | en_US |
| dc.date.issued | 2024-07-30 | en_US |
| dc.date.submitted | August 2024 | en_US |
| dc.date.updated | 2024-08-30T18:25:13Z | en_US |
| dc.description | EMBARGO NOTE: This item is embargoed until 2026-08-01 | en_US |
| dc.description.abstract | Contamination from airborne hydrocarbons drastically affects surface chemistry by partially or completely passivating surfaces, in turn hindering nanomanufacturing, limiting characterization techniques, and generating controversies regarding fundamental studies of advanced materials. Consequently, inhibiting contamination is crucial for experiments and applications requiring clean surfaces. However, hydrocarbon contamination is often overlooked and hard to avoid in practice due to the ubiquitous nature of volatile organic compounds in the surrounding environment and the spontaneity of the contamination process; moreover, the evolution of surface contamination under typical storage methods (such as high vacuum) and within small structures or geometries is not well-understood. In the work presented in this thesis, we investigated how—counter to the belief that typical ultra-high vacuum (UHV) environments can reduce exposure to airborne contaminants— contamination occurs and is often even accelerated inside these UHV chambers. We experimentally and theoretically showed that samples with different initial levels of contamination approached the same equilibrium value, demonstrating that both hydrocarbon net adsorption and net desorption are able to occur within UHV. This study highlights a critical consideration for surface scientists, and provides routes to mitigate surface contamination effects. Furthermore, we developed a passive clean storage technology that employs an ultra-clean and high-surface-area medium that can be sacrificed as a getter for containments to maintain cleanliness of materials inside the storage device. The scalability, low cost, reusability, and environmentally friendly fabrication of this approach yield a promising method for storage and transportation of contamination-sensitive materials, which in turn benefits microfluidics and diagnostics, nanofabrication in computer chips, fundamental studies of advanced materials, and more. Finally, beyond inhibiting contamination to pursue clean storage techniques, we studied contamination-induced spatiotemporal variation of surface wettability in structures. We predicted the spatial and temporal distributions of contamination on surfaces in a detailed molecular diffusion–adsorption model and demonstrated the spatiotemporal evolution by characterizing surface wettability in high aspect ratio channels. The resulting understanding of the wettability variation within high aspect ratio surface structures offers guidelines for the design of spatially patterned wettability for tailored fluid manipulation and enhanced boiling and condensation heat transfer utilizing hydrocarbon diffusion and adsorption processes. | en_US |
| dc.embargo.lift | 2026-08-01 | en_US |
| dc.embargo.terms | 2026-08-01 | en_US |
| dc.format.mimetype | application/pdf | en_US |
| dc.identifier.citation | Liu, Zhen. Understanding and Mitigating Airborne Contamination on Surfaces. (2024). PhD diss., Rice University. https://hdl.handle.net/1911/117816 | en_US |
| dc.identifier.uri | https://hdl.handle.net/1911/117816 | en_US |
| dc.language.iso | eng | en_US |
| dc.rights | Copyright is held by the author, unless otherwise indicated. Permission to reuse, publish, or reproduce the work beyond the bounds of fair use or other exemptions to copyright law must be obtained from the copyright holder. | en_US |
| dc.subject | Hydrocarbon contamination | en_US |
| dc.subject | surface wettability | en_US |
| dc.subject | adsorption and desorption | en_US |
| dc.subject | ultra-high vacuum | en_US |
| dc.subject | clean storage | en_US |
| dc.subject | texture-enhanced | en_US |
| dc.subject | spatiotemporal variation | en_US |
| dc.title | Understanding and Mitigating Airborne Contamination on Surfaces | en_US |
| dc.type | Thesis | en_US |
| dc.type.material | Text | en_US |
| thesis.degree.department | Mechanical Engineering | en_US |
| thesis.degree.discipline | Engineering | en_US |
| thesis.degree.grantor | Rice University | en_US |
| thesis.degree.level | Doctoral | en_US |
| thesis.degree.name | Doctor of Philosophy | en_US |