For over a century, light has been both a friend and a foe in our quest to see the tiny world. Microscopes use light to magnify things like cells and microbes, but light behaves like a wave. Waves can’t fit into spaces smaller than their wavelength, which means looking at individual atoms has been out of reach for traditional microscopes.
Now, a team of researchers has made an exciting breakthrough. They’ve used a regular continuous-wave laser combined with a sharp metal tip to measure down to about 0.1 nanometers. This is nearly equal to the distance between atoms, marking a huge leap in optical microscopy. “This quantum leap lets us see details almost 100,000 times smaller than what regular microscopes can,” says Valentin Bergbauer from the University of Regensburg. This discovery brings us closer to examining matter at the atomic level, something once seen as impossible.
The researchers’ method begins with placing a very sharp metal tip near the surface of a material. By making the gap between them smaller than an atom, they managed to get light to concentrate there. When they shined a mid-infrared laser onto this setup, the light squeezed into this tiny space, achieving a resolution of about 10 nanometers. While this was already an improvement over normal microscopes, it still wasn’t fine enough to see individual atoms.
However, when they brought the tip even closer, they made a surprising discovery. The signal suddenly increased dramatically, revealing changes at sub-nanometer scales despite using a gentle laser instead of powerful pulses. “At small distances, the signal shot up, and we soon realized we detected features down to 0.1 nanometers,” shared Felix Schiegl, the lead researcher and a doctoral candidate at the University of Regensburg.
The reason for this breakthrough lies in quantum physics. Even when the tip and the surface don’t touch, electrons can “tunnel” through the gap. The electric field from the laser vibrates these electrons, similar to charges moving in an antenna, creating a weak electromagnetic signal. This allowed the researchers to see these faint lights through intensity-based measurements, giving insights into atomic-scale tunneling events.
“We’ve moved past limitations of light confinement. Now, we can control and measure quantum electron motion in tiny dimensions,” Bergbauer explains.
This advancement opens the door to exploring the atomic world using optical tools. Since it uses standard lasers, rather than pricey ultrafast systems, more laboratories could adopt this technique. The researchers emphasize, “Our findings pave the way for optical imaging with unprecedented resolution.” This could significantly enhance our understanding of how light interacts with matter at the atomic level, especially in fields like catalysis and quantum materials.
If this method proves successful, scientists may finally be able to visualize and measure the atomic world, making the once-unimaginable a reality. Exciting times lie ahead for both researchers and the advancements in microscopy!
For further details, check out the study published in Nano Letters.
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Optics, Physics, Quantum Physics
