Developing Plasmonics Under the Infrared Microscope: From Ni Nanoparticle Arrays to Infrared Micromesh

Microscopes typically collect light over large ranges of angles dispersing plasmonic resonances. While this is an advantage for recording spectra of microscopic particles, it is a disadvantage for sensing by resonance shifts. Adaptations are described herein which enable one to identify, manipulate, and examine narrow plasmonic resonances under a microscope. Noting more general familiarity with metal nanoparticle arrays, a useful perspective is offered by relating the optical transmission of small Ni nanoparticle arrays to that of Ni metal films with microhole arrays, i.e., infrared-active mesh. This perspective also includes the connection to traditional dispersion studies, a new microscope method to measure the propagation length of surface-plasmon-polariton-mediated resonances, and the shifting of resonance positions by latex microspheres in the holes of mesh. A useful perspective is offered by relating the optical transmission of small Ni nanoparticle arrays to that of Ni metal films with microhole arrays, i.e., infrared-active mesh.