Our popular UV Beads, now in a package of 1000 beads!

These beads are sensitive to UV light and change from white to a bright array of colors when they are exposed to sunlight or UV rays. The dye molecules in the beads consist of two large planar conjugated systems that are orthogonal to one another. When high-energy UV light excites the central carbon atom, the two smaller parts form one large conjugated planar molecule. The resulting molecule is large enough to absorb certain wavelengths of visible light, resulting in a color.

The longer the conjugated chain, the longer the wavelength of light that is absorbed by the molecule. Heat from the surroundings provides the activation energy needed to return the planar form of the molecule back to its low energy orthogonal (colorless) structure. You'll want to try then with the UV Flashlight as well. Take them back indoors and they return to a white color. Great addition to your demos on light and color. A lesson suggestion: use the beads to test the ability for UV to pass through certain materials, such as window glass or sun-block. Approximately 1000 beads per pack.