麻豆淫院

Nanoparticles are everywhere. Nanoparticles find a wide range of applications in biomedical applications, sensing, energy conversion, and industrial processes. But nanoparticles can also have negative implications as environmental pollutants, defects and imperfections in electric and photonic circuits.

There is an urgent need to characterize and understand them. The smallest nanoparticles are especially difficult to detect with conventional light microscopes. They do not fluoresce under UV light and scatter too little light to stand out.

Researchers at the University of Twente have developed a new optical method to make extremely small metallic nanoparticles visible, as tiny as 1.8 nanometers. That's smaller than most viruses and nearly 100,000 times thinner than a human hair. Where normally expensive electron microscopes are required, this new technique works with a relatively simple setup, without complex preparation steps. The study is in Nature Communications.

Golden sandwich amplifies light signal

The researchers developed a technique that lets us "see" the incredibly tiny metallic particles by creating a tiny cavity between a gold film and a gold nanoparticle. Then, they placed the nano-object (the whisper) into this cavity.

"This structure is effectively a nano golden sandwich," says first author and UT-researcher MohammadReza Aghdaee. When light shines into this cavity, it bounces around and interacts with the tiny nano-object specifically. This interaction amplifies the light signal so much that the tiny particle can finally be seen.

This trick works thanks to a physics phenomenon called strong coupling, where light and matter exchange energy so quickly and efficiently that they behave like a single new system. The result? A unique fingerprint in the light signal that reveals the presence of the tiny particle.

Because the method does not rely on fluorescent labels or dyes, it can be applied in many areas, such as early diagnosis of diseases via nanoscale biomarkers or environmental sensors that detect pollutants before they spread. Aghdaee states, "We may also be able to use it to inspect chips and electronics to spot nanoscale defects early."