8. General Conclusions and Outlook

This thesis proves that the quantum plasmon resonances can be controlled by molecular tunnel junctions through bottom-up self-assembly approach. Controlled immobilization of molecules between two cuboidal metal nanoparticles provides two key advances in this plasmonic studies: (1) The plasmonic resonators (nanoparticles) can be brought into close proximity down to sub-nanometer separation in a controllable fashion, (2) The molecules can act as a frequency controllers in terahertz regime, evolving as a new control parameter in the fabrication of electrical circuits facilitated by quantum plasmon tunneling. On the other hand, in situ liquid-cell electron microscopy allows us to elucidate the reaction mechanism and kinetics during chemical reactions such as galvanic replacement reactions and core-shell nanoparticle formation at the nanoscale. Quantitative picture of the growth process is useful for engineering the composition and morphology of plasmonic resonators that could potentially open up more opportunities for application in plasmonics.