Take a phosphor that fits the bill, mix it in with the plastic to be molded into the product, and you have yourself a glow-in-the-dark whatever. Light from the sun or the living room lamp energizes the phosphors in the plastic and excites them, and with the lights off, you can watch as their atoms slowly lose this extra energy in the form of a dim glow. Beyond the usual glow-in-the-dark artifact, there are some special cases where glowing products work a little differently.
Glow sticks work by chemiluminescence — that is, the light is emitted as a product of a chemical reaction. Timepieces like this still use phosphors to create the glow, but also have a little bit of a radioactive element like radium added to the glowing parts, which gives off small amounts of energy — not enough to be dangerous to the user, but, historically, a problem for the people who make the products — that constantly charge the phosphors in the same way a light would and keep the item glowing through the night.
The modern paints are durable and water-resistant, so they can be used for outdoor decorations and fishing lures and not just jewelry and plastic stars. There are two main reasons why glow in the dark stuff mostly glows in green. The first reason is because the human eye is particularly sensitive to green light, so green appears brightest to us. Manufacturers choose phosphors that emit green to get the brightest apparent glow. The other reason green is a common color is because the most common affordable and non-toxic phosphor glows green.
The green phosphor also glows the longest. It's simple safety and economics! To some extent there is a third reason green is the most common color. The green phosphor can absorb a wide range of wavelengths of light to produce a glow, so the material can be charged under sunlight or strong indoor light.
Many other colors of phosphors require specific wavelengths of light to work. Usually, this is ultraviolet light. To get these colors to work e.
In fact, some colors lose their charge when exposed to sunlight or daylight, so they aren't as easy or fun for people to use. Green is easy to charge, long-lasting, and bright.
However, the modern aqua blue color rivals green in all of these aspects. Colors that either require a specific wavelength to charge, don't glow brightly, or need frequent recharging include red, purple, and orange. New phosphors are always being developed, so you can expect constant improvements in products. Thermoluminescence is the release of light from heating. Basically, enough infrared radiation is absorbed to release light in the visible range. One interesting thermoluminescent material is chlorophone, a type of fluorite.
Some chlorophane can glow in the dark simply from exposure to body heat! Some photoluminescent materials glow from triboluminescence. Here, exerting pressure on a material imparts the energy needed to release photons.
The process is believed to be caused by the separation and joining of static electrical charges. Examples of natural triboluminescent materials include sugar , quartz , fluorite, agate, and diamond. You hold them up to a light, and then take them to a dark place.
In the dark they will glow for 10 minutes. Some of the newer glow-in-the-dark stuff will glow for several hours. Usually it is a soft green light, and it is not very bright. You need to be in nearly complete darkness to notice it.
All glow-in-the-dark products contain phosphors. A phosphor is a substance that radiates visible light after being energized. The two places where we most commonly see phosphors are in a TV screen or computer monitor and in fluorescent lights. In a TV screen, an electron beam strikes the phosphor to energize it see How Television Works for details. In a fluorescent light, ultraviolet light energizes the phosphor. In both cases, what we see is visible light. A color TV screen actually contains thousands of tiny phosphor picture elements that emit three different colors red, green and blue.
In the case of a fluorescent light, there is normally a mixture of phosphors that together create light that looks white to us. Chemists have created thousands of chemical substances that behave like a phosphor.
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