Surface plasmon resonance

Imagine you are at a playground, and you see a swing. When you push the swing, it moves back and forth. Just like the swing, light can also move back and forth, but the way it moves depends on what it hits.

Now, let's look at a metal surface. It's like a big jungle gym for light. When light hits a metal surface, it can't go through it, so it bounces back. But, sometimes, the light can also make the metal surface move - just like when you push a playground swing.

These movements are called surface plasmon oscillations. They're like ripples that travel across the metal surface as the light bounces back and forth - just like when you throw a stone into a pond and see ripples.

Scientists use this to study things like DNA or proteins. By shining light onto a metal surface that's been coated with biological molecules, they can see how the light interacts with those molecules. The metal surface acts like a detector, letting scientists see the movements of the light as the biological molecules bind to it.

This technology is called "surface plasmon resonance," and it's like having a super-sensitive toy microscope that lets us look at things that are too small for our eyes to see.