Polarimetric Angle Resolved Second Harmonic Scattering

This month we will have the pleasure to host Dr. Arianna Marchioro from the Laboratory of Fundamental Biophotonics with the presentation entitled:

"Surface Characterization of Colloidal Silica Nanoparticles by Polarimetric Angle‑Resolved Second Harmonic Scattering”

For organizational purposes (if you want to eat pizza!), please confirm your participation using this Doodle.

Don’t hesitate to extend the invitation to any postdoc and colleague!

Hope to see you there,
The team of the EPFL Photonics Chapter


Abstract:

Surface properties of colloidal nanoparticles (NPs) are key to a large number of industrial applications, in particular those related to heterogeneous catalysis. However, buried interfaces and surfaces of particles in solution are challenging to probe selectively as the bulk contribution often dominate, and in many cases the surface properties of a colloidal system cannot be inferred from studies of the corresponding planar surface. 

In this talk, I will show that the electrical double layer of silica NPs in solution can be probed with polarimetric angle-resolved second harmonic scattering (AR-SHS). This nonlinear optical technique selectively probes the interfacial region and offers an all-optical alternative to surface‑sensitive techniques that usually require more sophisticated resources, as for example x-ray photoelectron spectroscopy. Furthermore, AR-SHS gives access to quantities such as surface potential and molecular orientation at the interface, two parameters not easily obtained experimentally, without the use of any labeling molecule or a priori models for the structure of the interface. The AR-SHS data can thus be used to monitor surface changes as a function of pH and salt concentration, and provides an accurate description of the interface of colloidal NPs in water.