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Seminars

09/06/2015

12.00 pm, Seminar Room on the 1st Floor

Open Group Semiar: Linear and ultrafast plasmonics with individual metal and hybrid nanoparticles

Natalia Del Fatti and Fabrice Vallée (Universite Lyon 1 - CNRS, France)

Understanding and modeling the impact of size, shape and environment on the optical properties of nano-objects is an intense field of research with both fundamental and technological motivations. With the advance of single nanoparticle spectroscopy methods, the optical response of a single nano-object can now be addressed, and its morphology independently determined by electron microscopy, opening the way to precise comparison with theoretical models. In this context we will describe investigation of individual nanoparticles deposited on a substrate, and analyze the influence of the latter on their optical absorption. Experiments are performed using the spatial modulation spectroscopy method, which yields access to the absorption cross-section spectra and amplitude of a single nano-object with size down to a few nanometers. In the case of silica-coated nanorods, isolation from the substrate provided by the silica shell largely reduces interaction with the environment, also allowing investigation of quantum size effects. This is no more the case for bare particles such as gold nanorods or bipyramids deposited on transparent or absorbing substrates. In that case, we show that their surface plasmon resonance (SPR) is strongly modified depending on particle-substrate distance and orientation, as determined by 3D electron tomography. Their nonlinear ultrafast response, investigated by time-resolved pump-probe spectroscopy and providing information on acoustic vibrations, will also be discussed.

15/07/2015

12.00 pm, Seminar Room on the 1st Floor

To Be Announced

Prof. Carlito Lebrilla (UC Davis, USA)