Surface monitoring based on light scattering by metal nanosensors

Light scattering from objects in the proximity of surfaces is of fundamental importance in a variety of surface- and field-enhanced optical sensing, spectroscopy and microscopy applications. Here, we present surface monitoring techniques based on the spectral analysis of the scattered light by metal nanoparticles which act as sensors (nanosensors) of sample substrates interacting with them. We will focus on the detection of surface inhomogeneities by studying the modifications undergone by the local fields produced in the surrounding of the nanosensor, giving rise to spectral changes in its Plasmon Resonances. We will also describe an alternative technique where the sample information is obtained from the changes induced in the linear polarization degree of the far field scattered by the tip and due to the interaction with the sample.