Field enhanced spectroscopy and microscopy
At electromagnetic resonance, metallic nanoparticles show enhanced scattering, enhanced absorption and localization of electromagnetic fields. The enhanced local electric field can be used for the mediation of a better interaction between light and matter in the nanoscale. This field localization and enhancement properties of metallic nanoparticles has been explored in performing spectroscopy of very small amount of molecules. This is called field enhanced spectroscopy. The tunability of the electromagnetic resonance of metallic nanoparticles with size, shape and material composition opens the access to molecular vibrations in a wide spectral range including near ultraviolet, visible and infrared frequencies.
The two popular configurations for performing field enhanced spectroscopy are Surface Enhanced Raman Spectroscopy (SERS) and Surface Enhanced Infrared Absorption Spectroscopy (SEIRA). While SERS explore the enhanced electromagnetic scattering by molecules mediated by the field enhancing capability of metallic nanoparticles, SEIRA relies on the enhanced absorption of electromagnetic radiation by the molecules.
We study theoretically the optical response of metallic nanoparticles for optimizing them to perform field enhanced spectroscopy.