UCF researchers collaborate on gold nanoclusters

UCF assistant professor Jayan Thomas, along with Carnegie Mellon University associate professor Rongchao Jin, has created an exciting new material composed of atomically stable gold nanoclusters, a material smaller than nanoparticles. Thomas and his team found that the material, once arranged in a specific order with a certain number of atoms, is capable of being stable and being used for optical limiting applications, which is no small feat. When put into perspective: One nanometer measures roughly one-one hundred thousandth of the thickness of a piece of paper, Thomas said.

“These are very advanced materials. We can tune their optical properties based on the number of atoms in a cluster, so they are very specific. Usually if you put these 25 atoms together they are not that stable, they just disintegrate and that’s it. In our synthesis we have put them together and it becomes a cluster, and the cluster is a stable one,” Thomas said.

Thomas and researchers found that placing atoms sequentially produced the desired effect for the material, creating functional optical properties that can be used in a variety of ways. Contributing researchers included Reji Philip, associate professor at Raman Research Institute at Bangalore and graduate research assistant Panit Chantharasupawong from UCF’s College of Optics and Photonics. Philip and Chantharasupawong measured the optical limiting properties of the atomic samples in the lab.

“We found that the optical limiting efficiency is more for gold clusters compared to that of gold nanoparticles,” Philip wrote in an email. Philip has been performing optical limiting work with gold nanoparticles since 2000.

“It’s interesting to explore how the nanoscale is different from the microscale. Nanoscale materials have properties that are unique and different from microscale with some bulk properties. For example, they might have unique properties from [materials on the nanoscale] that are totally different from the larger scale,” Chantharasupawong said.

On the nanoscale, gold nanoclusters are found at the smaller end, while gold nanocrystals comprise the larger side of the scale and are the same material used to make stained glass church windows. The gold nanocrystals are heated as the sun’s light passes through the window and they resonate as they begin to heat up.

Although this form of nanocrystals has been used aesthetically throughout history, the material is a gain for the military and defense industries. Since the materials are low energy, which allows radiation to pass through them, they can be beneficial.

“Think about a pilot, if a high energy laser beam is used, they are completely blinded,” Thomas said.

A helmet or windshield coated with these nanoclusters would diffuse a beam or the sun’s light, assisting a pilot’s ability to see. Other pertinent tools such as sensitive navigation systems would also benefit from the material, as they would not be threatened by lasers in the event of an attack.

“Military personnel can wear it when they’re in the battlefield, and it can be used as an optical window, as a sensor, to protect the device from enemies,” Chantharasupawong said.

Future possibilities with the material also include applying it to 3D-Telepresence technology. The polymer material will allow researchers to record data and record images as a hologram. The clusters can be used as sensitizers to create an entire 360-degree view of an object. These applications could revolutionize various fields, from gaming to medicine.

“Nanotechnology is one of the latest technological revolutions which has the potential to affect and modify several other existing technologies, ranging from water purification to solar cells. It is currently being explored by a large number of researchers, and new results are being reported regularly,” Philip said. “It has an impact in optics too: For instance, nonlinear optical phenomena can be enhanced by employing noble metal nanoparticles. In [the] course of time, several more applications of nanotechnology will be discovered, and many of these will have industrial implications.”

Thomas acknowledges the benefits this new development will provide, not only to larger industries and futuristic technology, but also to students at UCF. He has seen how his work has inspired his students, which is something he feels is part of the package.

“I like to include these materials so [students] will be interested in the work. It’s a growing field, it’s predicted that lots of manpower will be required in the future. I want to familiarize students in the field. Undergraduate students come to me asking to work with these materials. It’s my job to create passion in [my students] about the science,” Thomas said.