Neon is a chemical element that is commonly used in lighting and signs. When used in these applications, neon emits a distinctive glow that comes in a range of colors. The most common color emitted by neon is red-orange, but neon can also glow blue, green, white, and other hues depending on the gas mixture inside the tube. In this article, we’ll take a closer look at why neon glows the colors it does and the factors that determine its typical reddish-orange glow.
What is Neon?
Neon is a noble gas found in small amounts in the earth’s atmosphere. It has the atomic number 10 and is represented by the symbol Ne on the periodic table. Neon is colorless, odorless, inert, and nontoxic. It has a very low boiling point of -246 degrees Celsius. This low boiling point allows neon to turn to a gas and emit light at normal temperatures.
When an electric current is passed through a sealed tube that contains neon gas, it excites the neon atoms. The neon atoms absorb energy from the electric current, causing their electrons to jump to higher energy levels. When the electrons fall back down to lower energy levels, photons of light are released in the visible spectrum, causing the neon gas to glow.
Why Does Neon Glow?
Neon glows when an electric current excites the electrons in the neon atoms. Here is a brief explanation of how this process works:
1. Electric Current Excites Electrons
The neon atoms normally have electrons in their lowest energy state, called the ground state. When an electric current is applied to the neon gas, it excites the electrons, causing them to move to higher energy states.
2. Electrons Jump to Higher Energy Levels
The excited electrons move farther away from the neon atom’s nucleus and jump to higher energy levels or electron shells. The amount of energy absorbed determines which energy level the electrons reach.
3. Electrons Fall Back Down
The electrons in higher energy states are unstable. They will quickly fall back down to lower energy states, closer to the nucleus again.
4. Energy is Released as Photons
As the electrons fall back down to lower energy levels, energy is released in the form of photons. The photon energy corresponds to distinct colors in the visible light spectrum. This produces the characteristic glow from the neon gas.
5. Neon Color Depends on Gas Composition
The specific color emitted depends on the composition of the neon gas mixture inside the tube. By combining neon with other gases, different neon colors can be produced.
How is the Red-Orange Neon Color Produced?
The most common neon glow is the distinctive red-orange color. This occurs when pure neon gas is used in the tube. The red-orange color results from photons in the longer wavelength range of the visible light spectrum.
Here is a more in-depth look at how pure neon gas produces its signature red-orange emission:
Electron Transitions in Pure Neon
When current passes through pure neon gas, electrons are excited from the ground energy level up to higher levels like Ne 3p and 3s.
When the electrons fall back down, they follow certain transition rules and emit specific wavelengths of photons. The lowest energy transitions that produce visible light are:
– 3p -> 3s = 632.8 nm wavelength (red photon)
– 3s -> 2p = 585 – 588 nm wavelength (yellow photon)
Combination of Wavelengths Produces Red-Orange
The combination of red and yellow wavelengths from these electron transitions result in the overall red-orange glow from pure neon.
The red photons around 632.8 nm dominate, giving neon signs their signature red/orange color. Other transitions produce photons in the ultraviolet and infrared that are invisible to our eyes.
What Other Neon Colors Can Be Produced?
By altering the composition of the neon tube, different neon colors can be generated. Here are some of the other typical neon colors and how they are produced:
Blue Neon
Blue neon is created by adding argon gas to the tube. This changes the gas mixture inside, altering the transitions that electrons make.
Blue neon comes from electrons moving from the Ar 2p1 energy level down to the Ar 1s2 level. This transition produces photons with wavelengths around 467-472 nm, which our eyes see as blue.
White Neon
White neon is produced by coating part of the inside of the glass tube with fluorescent phosphor powder.
When electrons in the neon gas collide with the powder, it releases visible wavelengths across the whole spectrum. This combination is seen as white light.
Green Neon
Green neon comes from mixing neon with a drop of mercury vapor.
Transitions of electrons in the mercury atoms generate photons in the green part of the spectrum around 540 nm, giving the neon a greenish color.
Other Neon Colors
By carefully selecting different additives and tube coatings, neon can also produce purple, yellow, and pinkish-orange hues. Almost any color can be produced by manipulating the composition of the neon tube.
Typical Use Cases of Neon
Some of the most common applications that use neon to produce colored light include:
Neon Signs
Neon lighting is widely recognized for its use in retail signs, theatre marquees, restaurant signs, and advertising displays. The bright, eye-catching glow makes neon ideal for signage and marketing.
Neon Art
Artists often utilize neon tubes to create colorful, luminous neon art installations and sculptures. From neon wall art to large-scale outdoor displays, neon offers vivid effects for artistic expression.
Plasma TVs
Plasma TV display screens contain a mixture of noble gases, including neon and xenon. Ionized neon emits photons to produce the colored pixels.
High Voltage Indicators
The striking glow of neon makes it a useful visual indicator of the presence of high voltages in devices like voltmeters, vacuum tube testers, and taser weapons.
Lighting
Besides signage, neon lighting is also sometimes used decoratively in interiors and exteriors. This includes neon flex tube lighting installed in walls, ceilings, under cabinets, and in display cases.
Neon vs LED Lighting
Both neon and LED lighting systems are ways to produce colorful light for signs, displays, and decorative illumination. Here is a comparison between some of the different characteristics of neon and LED technology:
| Attribute | Neon | LED |
|---|---|---|
| Efficiency | Less efficient – only about 30% of energy is converted to visible light. | More efficient – over 80% of energy is converted to visible light. |
| Lifespan | Around 15,000 hours average lifespan. | Around 50,000 hours average lifespan. |
| Color Range | Produces a smaller range of colors, mostly shades of red, orange, pink, and blue. | Can produce a full spectrum of colors by mixing different LED chips. |
| Color Consistency | Neon color depends on gas fill composition and can vary between signs. | LED color is consistent between signs. |
| Dimming | Cannot be dimmed. | Can be dimmed for variable light levels. |
| Durability | Glass tubes are fragile. | Very durable epoxy resin enclosure. |
| Cost | Higher energy & maintenance costs. | Lower energy costs, inexpensive components. |
As the table shows, LED lighting has advantages when it comes to efficiency, lifespan, color control, durability, and cost. However, neon maintains some popularity due to its distinctive visual appeal and artistic aesthetic for signage applications.
The Future of Neon
The use of neon lighting has declined over the past decades as cheaper and more efficient LED technology has improved. However, neon remains popular for signage and art where the aesthetic appeal of neon is a major factor.
Key future trends for neon include:
– Continued development of creative and artistic neon lighting installations.
– Preservation of historic neon signs as beloved urban relics, especially in areas like Times Square NYC.
– Specialized applications where neon’s visual impact outweighs the efficiency advantages of LEDs.
– Neon flex lighting use in displays, architecture, and interiors when a retro-futuristic aesthetic is desired.
– Potential development of new neon phosphors and gas combinations to produce a broader palette of colors compared to LEDs.
– Niche collectors market for vintage neon signs.
So while more widespread neon use has waned, it will likely remain an integral part of the lighting world thanks to neon’s enduring nostalgic novelty and aesthetic qualities. Neon retains a cool factor and retro charm that continues to inspire signmakers and artists alike.
Conclusion
In summary, the most common neon color is a distinctive red-orange hue produced by pure neon gas. However, neon can glow a variety of colors by altering the gas composition inside the tube. Neon lighting is created by electrically exciting electrons in neon atoms, causing them to release photons in the visible spectrum when they return to lower energy states. While neon lighting has declined relative to more efficient LED technology, it remains popular for specialized applications where neon’s visual flair is desirable, such as signs and art. Neon’s unique aesthetic qualities ensure it will continue to have a place in lighting and design, even as more advanced technologies emerge. Its iconic glow evokes a sense of nostalgia and retro appeal that persists decades after neon’s introduction.
