1 research outputs found
Ellipsometry of Colloidal Solutions: New Experimental Setup and Application to Metallic Colloids
An
ellipsometric cell is developed to simultaneously determine
the shape distribution, the volume fraction, and the complex refractive
index of gold and silver colloids. Simulation reveals that this cell
drastically improves the detection limit of ellipsometry. Indeed,
Ag and Au nanoparticles (NPs) are detected at the ppmv level. We demonstrate
that the NPs shape distribution can be estimated from ellipsometric
measurements by analyzing them with a shape distributed effective
medium theory (SDEMT). The obtained distributions from ellipsometry
are in agreement with those deduced from transmission electron microcopy
(TEM). Contrary to TEM, ellipsometry probes a large number of NPs
estimated at about 10<sup>11</sup> NPs. Finally, we show that the
complex refractive index of colloids as determined from ellipsometry
is sensitive to the optical properties of the solvent and the plasmonic
properties of NPs