Probing light-matter interactions with differential polarizations: From chiral nanostructures to molecular sensing
type: CreativeWork
description: Life is chiral and therein lies the true meaning of the universe. Inspired by asymmetry of life, this thesis utilizes plasmonic nanostructures and dark-field scattering to elucidate how differentially polarized light distinguishes between left- and right-handed chiral architectures, and how this discrimination can be utilized for molecular sensing. Leveraging the polarization sensitivity and refractive index sensitivity of localized surface plasmon resonances, this work systematically probes light-matter interactions at the nanoscale. Emphasizing chiral optical phenomena, it demonstrates the fundamental understanding of dichroism at the single‑particle level while unlocking its potential for improved detection of chiral biomolecules. Using DNA-origami templated gold nanorod dimers, we apply single-particle circular differential scattering to probe nanoscale chirality. Supported by electron microscopy and electromagnetic simulations, our study reveals that the presence of a substrate imposes different orientations, each generating unique circular differential scattering line shapes, intensities, and even sign reversals, all from the same enantiomer. These findings highlight how substrate induced orientation profoundly influences single-particle chiroptical measurements and must be considered in both interpretation and design of chiral plasmonic systems. Beyond intrinsic chirality, two-dimensional interfacial dichroism is studied in rotationally symmetric planar chiral pinwheels. Under asymmetric illumination, pinwheels exhibit an orientation-independent linear differential scattering response, forming a linear analogue to optical activity. This work demonstrates that symmetry breaking in the illumination geometry, not the nanostructure itself, can generate chiroptical signals, an approach that broadens chiral sensing modalities. The thesis also presents a biosensing strategy based on plasmon-coupled circular dichroism, utilizing gold nanosphere dimers assembled via c…
abstract: Life is chiral and therein lies the true meaning of the universe. Inspired by asymmetry of life, this thesis utilizes plasmonic nanostructures and dark-field scattering to elucidate how differentially polarized light distinguishes between left- and right-handed chiral architectures, and how this discrimination can be utilized for molecular sensing. Leveraging the polarization sensitivity and refractive index sensitivity of localized surface plasmon resonances, this work systematically probes light-matter interactions at the nanoscale. Emphasizing chiral optical phenomena, it demonstrates the fundamental understanding of dichroism at the single‑particle level while unlocking its potential for improved detection of chiral biomolecules. Using DNA-origami templated gold nanorod dimers, we apply single-particle circular differential scattering to probe nanoscale chirality. Supported by electron microscopy and electromagnetic simulations, our study reveals that the presence of a substrate imposes different orientations, each generating unique circular differential scattering line shapes, intensities, and even sign reversals, all from the same enantiomer. These findings highlight how substrate induced orientation profoundly influences single-particle chiroptical measurements and must be considered in both interpretation and design of chiral plasmonic systems. Beyond intrinsic chirality, two-dimensional interfacial dichroism is studied in rotationally symmetric planar chiral pinwheels. Under asymmetric illumination, pinwheels exhibit an orientation-independent linear differential scattering response, forming a linear analogue to optical activity. This work demonstrates that symmetry breaking in the illumination geometry, not the nanostructure itself, can generate chiroptical signals, an approach that broadens chiral sensing modalities. The thesis also presents a biosensing strategy based on plasmon-coupled circular dichroism, utilizing gold nanosphere dimers assembled via c…
author: Verma, Ojasvi
language: en
keywords: Circular dichroism, chirality, circular differential scattering, dark-field scattering spectroscopy, linear dichroism, linear differential scattering, biosensing, plasmon-coupled circular dichroism, plasmonics, k-space imaging, Fourier transformation, extinction, lattices, surface lattice resonance, extrinsic chirality, refractive index sensitivity
date published: 2025-12
date modified: 2026-07-22T22:25:07Z
provider: University of Illinois - Urbana-Champaign
publisher: Networked Digital Library of Theses and Dissertations
type: WebPage
source organization: University of Illinois Urbana-Champaign

PropertyValue
property ID: Handle
value: https://hdl.handle.net/2142/132622