Ultra-thin precisely patterned sodium films manipulate light with extreme precision at lower cost than plasmonic materials made from gold or silver

https://phys.org/news/2025-10-ultra-thin-sodium-alternative-gold.html

"overcomes sodium instability in presence of air/ moisture... combines thermally- assisted spin coating with phase-shift photolithography, using heat/ light to craft nanoscopic surface patterns trapping/ guiding light... sodium's electrons responded in ways that differ from traditional metals, suggesting it could offer new advantages for light-based technologies like photocatalysis, sensing, energy conversion, solar panels, medical devices,"