Short-range plasmon guides, resonators and antennas imaged by non-linear photoemission electron microscopy

The exploitation of plasmonic local field enhancements to promote the local interactions between matter and optical fields motivates numerous researches. The objectives are to understand the mechanisms of plasmon-mediated interactions, and to realize molecularly- or atomically-precise nano-structures favouring such phenomena. We have developed a local-probe-free experiment (M-PEEM [1]) to map the electromagnetic field at the nanoscale close to metal structures. The analysis of the optical response of various metal nano-objects shows evidences of the excitation of so-called “short-range” propagative modes, strongly coupled to a metal nano-wire and highly localized around it at subwavelength scales.[2] After a detailed study of the characteristics of these modes, we have been able to design specific metal nano-objects exhibiting diverse functions such as antenna and local field enhancements. These model systems also gave new insights in the enhanced molecule-field interactions observed in the insulating gap of a scanning tunneling microscope [3-7]