From solar panels to advanced medical devices, many modern technologies depend on special materials that can control light with extreme precision.
These “plasmonic materials” are usually made from expensive metals such as gold and silver, which work well but drive up costs.
Now, researchers have discovered that sodium—a cheap, lightweight, and abundant element—might be able to do the same job, and perhaps even offer new advantages.
The idea of using sodium for light-based technologies is not new.
Scientists have long recognized its potential, but sodium’s biggest weakness has always been its instability.
Exposed to air or moisture, it quickly reacts and breaks down, making it nearly impossible to use in real-world devices.
For decades, this problem kept sodium out of serious consideration for practical applications.
A team of scientists from Yale University, Oakland University, and Cornell University has now taken an important step toward solving this challenge.
By developing a new way to structure sodium into ultra-thin films with carefully patterned surfaces, they managed to stabilize the metal and make it useful for optical technologies.
Their results were recently published in the journal ACS Nano.
The researchers used a process that combines heat and light to shape sodium at the nanoscale, creating patterns that can trap, guide, and amplify light.
This technique, known as thermally-assisted spin coating combined with phase-shift photolithography, allowed them to produce sodium films only a few atoms thick, with precise surface designs.
To see how these films interact with light, the team used ultrafast laser spectroscopy—an advanced method that measures changes occurring in trillionths of a second. What they found surprised them.
Sodium’s electrons responded differently from those in gold and silver, revealing unique behaviors that could open new possibilities in areas such as energy conversion, sensing, and photocatalysis.
The work was led by Yale Ph.D. candidate Conrad A. Kocoj, along with collaborators Shunran Li and Peijun Guo at Yale, Xinran Xie, Honyu Jiang, and Ankun Yang at Oakland University, and Suchismita Sarker at Cornell University.
Their combined expertise in nanofabrication, ultrafast optics, and materials science made it possible to push sodium into territory it had never reached before.
The results suggest that sodium could one day replace gold and silver in many light-based applications, cutting costs and expanding access to technologies ranging from renewable energy devices to next-generation medical tools.
As Kocoj and his team showed, sometimes the most ordinary elements—when reimagined in extraordinary ways—can unlock new paths for science and technology.
