Transition processes emit light when excited electrons return to a relaxed state. Multipolar transitions produce data on the electronic structure of a material through spectroscopy. Quenching (the process of decreasing fluorescence intensity) of organic molecules can be achieved with spin-flip transitions. Broadband light sources, which turn a monochromatic beam of light into a broadband beam, can be built based on multiphoton transitions.
Unfortunately, the three aforementioned transition processes are usually too slow to be observable. The slow emission is attributed to long wavelengths of emitted light being larger than the size of an emitter. Accessing a large set of really slow light emission processes is the major technical challenge that this technology attempts to address through two-dimensional (2D) plasmon fields.