- An unusual observation turned into a scientific breakthrough when researchers investigating the optical properties of nanomaterials discovered a new type of high resolution microscopy for imaging the electric fields of nanostructures.
Optical nanomaterials are mainly based on surface plasmon resonances – the property whereby, in metallic nanostructures, light can collectively excite surface electron waves. With the help of plasmons, light can be captured, modified and even stored in nanostructures. This emerging nanotechnology could find applications in curing cancer, biochemical sensing, solar cells, optical computing, negative refractive index materials, and even invisibility. The imaging of surface plasmons provides a direct way to map and understand the local electric fields that are responsible for the unusual electromagnetic properties of optical nanomaterials; the imaging of surface plasmons, however, is quite challenging. Generally speaking, while there are methods to image plasmons with high resolution, they come at a considerable increase in both cost and complexity.
Now, researchers have demonstrated that upon illuminating nanostructures made of nickel or palladium, the resulting surface plasmon pattern is imprinted on the structures themselves, allowing for subsequent imaging with standard surface probe techniques, such as scanning electron microscopy or atomic force microscopy. The imprinting method is quite unique, combining aspects of both imaging and writing techniques. The combination offers a resolution on plasmons that is, in principle, only limited by that of the atomically-sensitive surface probe techniques.
