AbstractsAstronomy & Space Science

Optical Activity of Chiral Nanomaterials: Effects of Short Range and Long Range Electromagnetic Interactions

by Zhiyuan Fan

Institution: Ohio University
Department: Physics and Astronomy (Arts and Sciences)
Degree: PhD
Year: 2014
Keywords: Physics; plasmonic circular dichorism; chiral nanomaterials; chiral nanoparticle assemblies; metamaterials; plasmon-exciton interaction
Record ID: 2025557
Full text PDF: http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1394998277


In this dissertation, chiral nanomaterials with new plasmonic properties have been investigated. Electromagnetic interactions between well-defined building blocks in nanomaterials are modeled using classical and quantum mechanical theories. We predict several new mechanisms of plasmonic circular dichroism (CD) signals in chiral nanomaterials. The predicted CD mechanisms include plasmon-plasmon interactions of nanoparticle assemblies, plasmon-exciton interactions of molecule-nanoparticle conjugates, multipole plasmon mixing in chiral metal nanocrystals and electrodynamic effect of long range plasmon-exciton interactions. It is efficient and accurate to simulate light-matter interactions with analytic solutions. However, only a limited number of geometries can be solved analytically. Many numerical tools based on finite element methods, discrete dipole approximation or finite-difference time-domain methods are available currently. These methods are capable of simulating nanostructures with arbitrary shapes. Numerical simulations using such software have shown agreements with analytical results of our models. Hence, this study may offer a new approach to design of complex nanostructures for sensing of chiral molecules. This dissertation also reviews several experimental papers that have demonstrated successful fabrications of chiral nanostructures and nano-assemblies with new plasmonic CD signals. Our theories strongly motivated the field and have been used in many experimental studies for interpretation and understanding of observations.