What is Fluorescence? Detailed Explanation. Amazing Glowing liquid.

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• published: 02 Apr 2015
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Hello everyone. Today we will conduct experiments with fluorophores, or in other words, fluorescent substances. Fluorescent substances or fluorophores, are those substances which emit light by exposing them to ultraviolet rays. For the fluorophores I will use the following materials: fluorescein, rhodamine 6g and rhodamine b. Concentrated solutions of these substances do not glow in UV light but their diluted solutions emit light in the ultraviolet rays pretty much flawlessly. Let's prepare the diluted solutions of fluorophores. I’ll take the beakers with water and add a drop of each substance to each of them. Now I'll add fluorescein. Its solution has a such bright green color. Another substance will illuminate blue color. This substance is sold in many stores and it’s called tonic water. I bought a usual Schweppes in a store. This drink contains quinine that glows in ultraviolet light. At the moment we’re observing the solutions with fluorophores during normal light. However, let’s turn on the ultraviolet light lamp. In the UV rays the solutions look much more interesting as it can be seen. Schweppes glows blue, rhodamine B glows orange, rhodamine 6g glows yellow. At the end the fluorescein solution glows bright green. However, you can force these solutions to emit light not only by UV light lamps. You can also take a UV laser and shine through all the solutions with it. In this case, you can observe the beautiful light beam which is painted in every beaker in their respective color. Let’s try and mix several different solutions of fluorophores and see what color that solution will obtain throughout. At first I pour rhodamine 6g, which is yellow. Next I pour rhodamine B, the solution turns orange. In the end, I’m topping it up with a solution of fluorescein. As I’ve mentioned earlier, saturated solutions of fluorophores do not glow under the UV light. Immediately upon diluting the concentrate with water the solution begins to glow quite brightly. You can achieve such an interesting effect. As well you can get a white glow if you mix Schweppes and rhodamine 6g, blue and yellow respectively. So why do these solutions glow in UV rays? Now I will try to explain it to you. Let’s take a look at the light spectrum. In the ordinary light we see colors because all the other parts of the light spectrum are absorbed yet one remains. For example, the grass is green because all other colors are absorbed, and the green is reflected and we see the green color. In fluorescence everything is a bit different. In order for fluorophore substances to begin glowing they need high energy. Exactly this energy is being carried by UV radiation. The fluorophore absorbs the UV radiation that is not visible to the human eye and converts it into the one that is visible. For example, into yellow or green. But now you probably have a logical question. Where can you get all these rhodamines and other fluorophores? What else can glow in a UV light? There are a lot of items around us that can glow in UV rays. For example, cash. Banknote of 50 euro under the UV light looks a little bit different. Soap glows under UV light in a blue color, paper glows in white. Fluorescent substances are added into many antifreezes for cars, hence they should also illuminate some light color. Plants contain chlorophyll which glows red. Fluorescence can be seen in normal bananas. If the bananas are stored longer than usual they will acquire such dots. These dots glow in the UV rays in blue color. You can find out about any other material that may glow under UV light on your own. For that you can buy a Wood's lamp or a UV flashlight and do some cool fluorescence study yourself.