Polarisation study of the light scattered by nanoporous plasmonic microparticles

Nanoporous microparticles exhibit large surface-to-volume ratio and can detect chemicals and biomolecules. Using dark-field microscopy, we observed that, when the nanoporous microparticles are illuminated by circularly polarized laser beams, the scattered light polarization is inverted. The inversion is interesting as the microparticles are (nearly-)spherical, and the nanopores do not exhibit symmetry. We observed that the scattered light polarization is tunable when plasmonic Ag nanoparticles and short molecules are in the pores. We discuss these findings and their exploitation as sensors.