Fluorescence facts for kids

Look closely! These are endothelial cells seen through a microscope. Different parts of the cells glow with different colors!

Fluorescence is a special kind of glow that happens when certain materials soak up light or other types of energy, like invisible waves. After they absorb this energy, they quickly let out their own light. The cool part is, this glow stops almost immediately when the original light source is taken away. It's a type of luminescence, which just means giving off light.

Usually, the light that comes out (the glow) has a longer wavelength and less energy than the light that was absorbed.

One of the most surprising things about fluorescence is when something absorbs ultraviolet light (which our eyes can't see) but then glows with light that we can see!

Fluorescence is used in many different areas. You can find it in mineralogy (studying minerals), gemology (studying gems), and in special chemical sensors. It's also used in dyes, tools that find biological things, and even in fluorescent lights that brighten our rooms.

In life sciences, fluorescence is a super helpful way to track tiny biological parts. For example, a scientist can attach a glowing dye to a protein. This lets them use a microscope to easily see exactly where that protein is.

How Fluorescence Works

Absorbing and Emitting Light

When a material fluoresces, it first takes in energy from light. Think of it like a sponge soaking up water. This energy makes the tiny parts inside the material, called electrons, jump to a higher energy level.

But these electrons don't stay at that high energy level for long. They quickly fall back down to their normal energy level. As they fall, they release the extra energy as light. This is the glow we see!

Why the Glow Stops Quickly

The glow from fluorescence is very quick. It only lasts for a tiny fraction of a second after the original light source is removed. This is because the electrons drop back down to their normal state almost instantly. If the glow lasted longer, it would be called phosphorescence instead.

Invisible Light to Visible Glow

One of the coolest examples of fluorescence is when something absorbs ultraviolet (UV) light. UV light is invisible to human eyes. But when certain materials absorb it, they can glow with colors we can see, like bright blues, greens, or reds. This is why some things glow under a "black light."

Where We See Fluorescence

Glowing Minerals and Gems

Many minerals and gems can fluoresce. When you shine a UV light on them, they might glow with amazing colors. This helps geologists and jewelers identify different types of rocks and precious stones.

Fluorescent Lights

The long tube lights in many classrooms and offices are fluorescent lights. Inside these tubes, UV light is created. This UV light then hits a special coating on the inside of the tube, which fluoresces and produces visible light. This makes them very energy-efficient.

Security Features

Fluorescence is used to prevent counterfeit money. Many banknotes, like the US dollar, have special security strips or fibers that glow under UV light. This helps people check if the money is real. Passports and other important documents also use fluorescent inks.

Art and Entertainment

You might have seen fluorescent paints or clothes that glow under black lights at parties or in black light theater shows. These materials absorb the invisible UV light and turn it into bright, eye-catching colors, creating cool effects.

Tracking in Science

Scientists use fluorescent dyes to study living things. They can attach these dyes to specific cells, proteins, or even DNA. Then, by shining a light on them, they can see exactly where these parts are and how they move or change. This helps us understand diseases and how our bodies work.

Animals That Glow

Did you know some animals can fluoresce? Certain fish, corals, and even scorpions glow under UV light. Scientists are still learning why these animals have this ability, but it might help them communicate, hide, or find food.

Images for kids

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  Fluorescent minerals emit visible light when exposed to ultraviolet.

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  Fluorescent marine organisms

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  Fluorescent clothes used in black light theater production, Prague

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  Lignum nephriticum cup made from the wood of the narra tree (Pterocarpus indicus), and a flask containing its fluorescent solution

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  Fluorescent security strip in a US twenty dollar bill under UV light

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  Fluorescent coral

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  Fluorescence has multiple origins in the tree of life. This diagram displays the origins within actinopterygians (ray finned fish).

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  Fluorescent marine fish

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  Aequoria victoria, biofluorescent jellyfish known for GFP

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  Fluorescent polka-dot tree frog under UV-light

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  Fluorescing scorpion

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  Fluorescence of aragonite

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  Fluorescent paint and plastic lit by UV-A lamps (blacklight). Paintings by Beo Beyond.

See also

In Spanish: Fluorescencia para niños