Fifty-two years before GE engineer Nick Holonyak Jr invented LED lamps, a French Engineer named Georges Claude created brilliant signage by combining glass tubes, high-voltage transformers, and noble gasses. But there are probably tiny neon signs in your house…
This one glows when the George Foreman grill on my counter top is heating. Sandwiches will ensue.
Working at a modest 110 volts, these miniature power indicator lamps work the same way as brilliant signs in Vegas. An electric charge raises the energy level of atoms in the glass envelope, bumping their energy to higher levels. And the atoms… don’t like that! They must return to their rest state, so they shed photons; a red-orange glow that makes spectrum bands corresponding to 585 nm and 680 nm.
Power lamps don’t have a high-voltage transformer though; they perform their atomic violence with regular wall current. This is because their little electrodes are only about one millimeter apart. And while they make almost no heat, they also work at temperatures that would fry an LED. You see them in electricians’ tools, appliances of all kinds, and old-timey night lights.
Any gas can be ionized to produce light. Laser cutters use a mixture of carbon dioxide, nitrogen, hydrogen and helium. Oxygen glows green when struck by cosmic rays in the Northern ionosphere. Argon, xenon, and krypton are used alongside neon in “neon signs.”
Some of these are “noble gasses,” refusing to react with such commoners as nitrogen or oxygen. But that is a whole other bunch of stories.