Interaction of light with metallic nanoparticles and nanofilms : Extending scattering theory and study of the influence of smooth electron density transitions.

Date: 22 January 2016

Venue: Campus Drie Eiken, S0.01 - Universiteitsplein 1 - 2610 Antwerpen-Wilrijk

Time: 4:00 PM

Organization / co-organization: Department of Physics

PhD candidate: Nick Van den Broeck

Principal investigator: Jacques Tempere & Fons Brosens

Short description: PhD defense Nick Van den Broeck - Department of Physics



Abstract

This theoretical work studies standard scattering theory and expands it to include soft boundaries and a longitudinal response. In the first chapter standard scattering theory applied to a sphere (a.k.a. Mie-theory) is explained. In the second chapter Mie-theory is studied further and expanded to include pressure and temperature. These expansions are then applied to two new nanoparticle applications: nanoparticles as heaters and nanoparticles as pressure gauges. The third chapter presents differential equations, derived from the Maxwell equations, which take into account a different longitudinal and transverse response, and which include smooth electron density distributions as encountered in e.g. electronic spill-out in metals or pn-junctions. The soft transitions are studied in more detail in the final chapter by applying the 3D differential equations from chapter 3 in a layered system of films. A powerful numerical algorithm for stratified nanosystems including several density transitions is developed and applied to the experimental setup used for finding the transition of hydrogen to its metallic phase. The general conclusion is that the profile can have a major effect on the optical response of any system, in some cases leading to a complete suppression of both transition and reflection allowing all the light to be completely absorbed.