Neon Signs On To Light Up Our Lives

[Erik Sine]

Neon signs on to light up our lives

January 8, 2007

How Come

Kathy Wollard

For something so ubiquitous - the fifth most abundant element, by mass, in the universe - neon was actually a Johnny-come-lately to the table of elements. Although hydrogen and oxygen were identified by the 1700s, neon wasn't found until 1898.

Trying to fill in gaps in the periodic table, British chemists William Ramsey and Morris Travers looked for the missing elements in the air of their lab. By cooling air to a very low temperature and compressing it, the chemists were able to liquefy air and isolate three new-to-them elements: krypton, xenon and neon.

Just 12 years later, French inventor George Claude began selling neon signs in Paris. By 1923, a car dealer in Los Angeles had installed neon signs he'd bought on a trip to France. Soon, neon was beckoning customers into restaurants, hotels and barbershops, and advertising everything from chewing gum to coffee.

While there's plenty of neon in the wide universe, there's very little in the air we breathe on Earth. More than 80,000 pounds of liquid air must be distilled to cough out one measly pound of neon. Supercold liquid neon is clear and colorless, but in its gassy form, trapped in an electrified tube, neon naturally glows red-orange.

How it works: Before neon gas is pumped into the glass tube that will make a sign, air is pumped out. When the sign is turned on, an electric current - a stream of electrons - jumps through the gas. The electrons in the current excite the neon atoms, giving their electrons a burst of energy. They also cause some neon atoms to lose an electron, giving the atoms a temporary positive charge.

When an electron in an excited atom relaxes back down into a lower energy level, it sighs out a photon of light. Meanwhile, atoms that lost an electron grab a free one, also releasing a photon in the process. The wavelength of the photons emitted by neon are in the red-orange range, and so we see that familiar orange-y glow.

To make a rainbow of colorful signs, signmakers coat the inside of clear glass tubes with phosphors, which glow in different colors when stimulated by a current. Combining various gases and phosphors and tinting the glass tubes can create hundreds of different colors.

Meanwhile, that familiar light in the sky, our sun, may also contain a surprising amount of neon. Using NASA's X-ray observatory, called Chandra, to look at 21 sunlike stars in X-ray light, scientists at MIT have discovered abundant neon. They believe that our star has plenty of neon, too, and that it plays a pivotal role in the convection zone, which extends down from the sun's surface to a depth of about 125,000 miles. In the turbulent convection zone, neon gas may help move energy produced in the sun's core up to the surface, where it radiates into space.

So besides lighting Las Vegas streets at night, neon may help the sun light streets everywhere in the daytime.

[fishing nut]

nice find,

[B.O.P.]

Somewhat inaccurate, but a good read for the novice to "wet their whistle".