“Nanoclusters occupy the intriguing quantum size regime between atoms and nanocrystals, and the synthesis of ultra-small, atomically precise metal nanoclusters is a challenging task,” Thomas said.
Thomas and his team found that nanoclusters developed by adding atoms in a sequential manner could provide interesting optical properties. It turns out that the gold nanoclusters exhibit qualities that may make them suitable for creating surfaces that would diffuse laser beams of high energy. They appear to be much more effective than its big sister, gold nanocrystal which is the (nano)material used by artists to make medieval church window paintings.
Nanoletters - Evolution of Nonlinear Optical Properties: From Gold Atomic Clusters to Plasmonic Nanocrystals
ABSTRACT - Atomic clusters of metals are an emerging class of extremely interesting materials occupying the intermediate size regime between atoms and nanoparticles. Here we report the nonlinear optical (NLO) characteristics of ultrasmall, atomically precise clusters of gold, which are smaller than the critical size for electronic energy quantization (about 2 nm). Our studies reveal remarkable features of the distinct evolution of the optical nonlinearity as the clusters progress in size from the nonplasmonic regime to the plasmonic regime. We ascertain that the smallest atomic clusters do not show saturable absorption at the surface plasmon wavelength of larger gold nanocrystals (over 2 nm). Consequently, the third-order optical nonlinearity in these ultrasmall gold clusters exhibits a significantly lower threshold for optical power limiting. This limiting efficiency, which is superior to that of plasmonic nanocrystals, is highly beneficial for optical limiting applications
So why does it matter?
Think of commercial pilots or fighter pilots. They use sunglasses or helmet shields to protect their eyes from the sun’s light. If the glasses or helmet shield could be coated with nanoclusters tested in Thomas’ lab at UCF, the shield could potentially diffuse high-energy beams of light, such as laser. Highly sensitive instruments needed for navigation and other applications could also be protected in case of an enemy attack using high energy laser beams.
“These results give me great pleasure since the technique we used to study the optical properties of these atomically precise particle is one invented by UCF Professors Eric VanStryland and David Hagan many years ago,” Thomas said. “But the progression we’ve made is very exciting.”
Because nanoclusters appear to have a better ability to diffuse high beams of energy, they are a promising area for future development. There is still plenty of applications to be explored using these very interesting atomically engineered materials. Until now, much research has been focused on the larger nanocrystal.
Thomas is also exploring the use of these particles in the polymer material used for 3D telepresence to make it more sensitive to light. If successful, it can take the current polymers a step closer to developing real time 3D telepresence.
3D-Telepresence provides a holographic illusion to a viewer who is present in another location by giving that person a 360-degree view (in 3D) of everything that’s going on. It’s a step beyond 3-D and is expected to revolutionize the way people see television and in how they participate in activities around the world. For example, by allowing a viewer to “walk around” a remote location as if in a virtual game, a surgeon could help execute a complicated medical procedure from thousands of miles away.
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