To anyone who lived through the 1980s, the word "neon" may conjure up images of over-the-top fashion. However, to the rest of us, neon—the tenth element on the periodic table—is an amazing substance that is incredibly useful in a wide variety of fields. One of the most commonly recognized uses of neon is, of course, the neon sign. If you were to walk down any large city street at night, you will most likely see a neon advertisement or two glowing in the dark. (More about this later.)
Neon is used extensively in a variety of technical applications such as in lasers for medical operations, plasma screens and television tubes, lightning arresters to protect tall buildings during storms, cryogenic freezing of biological specimens, and much more.
The History of Neon
Neon is one of the elements on the periodic table known as a noble gas (along with helium, argon, krypton and xenon). Neon was discovered by British chemists William Ramsay and Morris Travers in the late 19th century. The name neon is derived from the Greek word neos, meaning “new.” Noble gases like neon are the most stable and least reactive of the elements on the periodic table. Neon can be in liquid or gas form, can conduct electricity, and has the unique feature of glowing orange-red when a current runs through it.
Too bright for indoor lighting, neon signs became popular in the United States in the early 1930s for outdoor signs, and for a time, represented the modernness of American society. Over the years, neon had many applications, including the development of the mass spectrometer and the development of the television tube, among other advancements.
Extracting and producing neon is an involved process that involves separating out neon from other elements using vacuum in what are called cryogenic air-separation plants. In its gas form, neon can be separated from a gas mixture of multiple elements (nitrogen, neon, helium, and hydrogen) using a high-pressure air-separation column (sort of like a distillery). It can then be further purified from helium using activated charcoal. 88,000 pounds of this gas-phase mixture can produce about one pound of pure neon.
Neon, as a liquid or gas, is relatively expensive in small quantities—the price of liquid neon can be more than 55 times that of liquid helium. Historically, more than half of the world's neon has been produced in Russia and Ukraine as a by-product of the steel industry. However, since 2013, as a result of the conflicts in the area, more neon production has moved to China.
Neon is used in vacuum tubes, high-voltage indicators, lightning arresters, wavemeter tubes, television tubes, and helium–neon lasers. Liquefied neon is commercially used as a cryogenic refrigerant in applications not requiring the lower temperature range attainable with more extreme liquid-helium refrigeration.
Nightlights with Neon
Of course, the most fun association we have with neon (besides Madonna's outfits in the 1980s) is the neon sign.
In order to glow, neon must be in a liquid state. However, on Earth neon's natural state is as a gas. This is another place that vacuum comes in. To create a neon sign, a vacuum has to be maintained. Glass blowers create intricate designs out of small glass tubes, sealing off one end. The tube is filled with neon, a vacuum is applied to the tube, and the other end is sealed. As long as the tube remains sealed, a neon sign will glow and glow. But that process still only creates a red-orange sign as we mentioned earlier.
To get the full rainbow of colors, neon is mixed with other gasses like argon, krypton, helium, and mercury. Each of these gasses acts differently in a vacuum, making the pressurizing process to get dazzling lights even more delicate.
For even more complex appearances, the glass tube can be tinted and coated to produce over 50 color variations. While this process takes time and care, the ethereal glow of a true neon sign will never be beaten by LEDs. How’s that for some 80s nostalgia!