Mid infrared chiroptical spectroscopy in chiral plasmonic metamaterials

Vilaseca, Oriol Roig (2021) Mid infrared chiroptical spectroscopy in chiral plasmonic metamaterials. MSc(R) thesis, University of Glasgow.

Abstract

The present work explores plasmonic phenomena. It does so in the region of the mid infra – red light. We will explore how light interacts with matter, specifically with gold. This metal, due to its unique properties, allows a plasmonic resonance to arise, which can couple afterwards with the characteristic resonances of a biomolecule. In the case exposed here, this biomolecule will be the aminoacid cysteine.

The resonances that arise from the metal structures due to their interaction with light are referred to as being the ‘bright’ and ‘dark’ modes. When these two modes couple, we have an appearing dip, increasing in prominence with shifting angle of light incidence. Afterwards, when placing an adsorbed biomolecule, cysteine in the case exposed here, on top of this gold structure this modes couple with the amide resonance of cysteine, causing a shift in the spectra from the structure, comparable to the spectra of the structure without the aminoacid adsorbed.

After explaining the fundamental theory, we will explain the fabrication and experimental procedures. Regarding the fabrication, we focus on how we fabricated several different structures until we found the one that worked best for our purposes: the 1 μm structure. This size refers to the length arm to-arm of the designed structure, a shuriken-shaped one. We will analyse each step for the fabrication to occur, starting from designing in the computer, to submitting the sample to the e-beam lithograph until having the array fabricated.

In the experimental chapter, which corresponds to a written paper, we examine how we conducted the experiments, both for the case of having the bare substrate or having the substrate with the cysteine adsorbed. We will see how we used the same procedure to take the spectra, the only difference in the experimental process being the previous steps of adsorbing the biomolecule onto the gold substrate.

Finally, the results will prove the possibility to characterize biomolecules, cysteine in our case, by use of plasmonic resonances and nanostructured gold shurikens. We will follow all the analytical process to get these results.

• Item Type: Thesis (MSc(R))
• Qualification Level: Masters
• Subjects: Q Science > QD Chemistry
• Colleges/Schools: College of Science and Engineering > School of Chemistry
• Supervisor's Name: Kadodwala, Professor Malcolm and Lapthorn, Professor Adrian
• Date of Award: 2021
• Depositing User: Theses Team
• Unique ID: glathesis:2021-82508
• Copyright: Copyright of this thesis is held by the author.
• Date Deposited: 15 Oct 2021 13:12
• Last Modified: 26 Oct 2021 14:37
• Thesis DOI: 10.5525/gla.thesis.82508
• URI: https://theses.gla.ac.uk/id/eprint/82508