Measurement of the Polarizability Tensor of Gold-Nanoparticle-Functionalized Tips

The polarizability tensor of a gold-nanoparticle (GNP) functionalized tip is measured by applying two types of scattering measurements - rotating polarizer analyzer ellipsometry (RPAE) and rotating polarizer ellipsometry (RPE). A suitably small GNP, less than 100 nm in diameter, can be regarded as a good electric dipolar scatterer when the far-field scattered field is considered. In the dipole approximation, we demonstrate how the scattering function of a GNP - the polarizability tensor - is correctly read from each method. The pros and the cons of the two detection schemes are discussed, and their results are compared with experimental measurements