Neon is a chemical element that is commonly used in signs and other lighting applications. When electricity is applied to neon gas, it emits a bright glow. Neon signs are known for their vibrant colors, especially the iconic red-orange hue. However, neon is actually capable of glowing in a variety of different colors depending on the gas composition and electrical conditions. In this article, we’ll take a closer look at how neon emits light, what factors determine the color, and the different neon colors that are possible.
What is Neon?
Neon is a noble gas found in small amounts in Earth’s atmosphere. Its atomic number is 10 and it has the chemical symbol Ne. Under normal conditions, neon is a colorless, odorless, inert gas. However, when electricity is applied to neon, it emits a bright glow due to a phenomenon called electroluminescence. This occurs when electrons in the neon atoms absorb energy from the electrical current and temporarily jump to higher energy levels. When the electrons fall back down to their normal levels, energy is released in the form of light. The color of this emitted light depends on the spectrum of wavelengths.
How Does Neon Glow?
Neon glows due to electroluminescence, as explained above. More specifically:
1. Electric Current Excites Electrons
An electrical current is applied to neon gas, which contains unbound atoms with electrons in their lowest energy states, called the ground state. The electrical field accelerates electrons, giving them enough energy to move to higher energy levels.
2. Excited Electrons Emit Photons
The excited electrons are unstable in these higher energy levels. As they fall back down to the ground state, the electrons emit energy in the form of photons.
3. Emitted Photons Produce Visible Light
The photons interact with our eyes and we perceive this as colored light. The color depends on the wavelength of the photons. In pure neon gas, this produces an orange-red glow.
What Determines the Color of Neon?
There are a few key factors that determine the color of a neon glow:
Gas Composition
Pure neon gas emits that classic orange-red light. However, other colors can be produced by using different noble gas combinations, such as:
- Neon + Argon = Blue
- Neon + Krypton = Whitish
- Neon + Xenon or Helium = Violet/Lavender
When multiple gases are used, their electrons emit photons at slightly different wavelengths, altering the overall color produced.
Gas Pressure
Higher gas pressure results in more frequent collisions between atoms. This shifts the emitted wavelengths slightly, changing the neon’s color. Lower pressure makes the color shift to blue, while higher pressure shifts it to red.
Electrical Current
The intensity of the electrical current also impacts the photon wavelengths. More current shifts the color toward blue, while less current shifts it toward red.
Tube Size
Small diameter tubes result in more frequent atom collisions, creating a more intense red color. Larger diameter tubes produce orange and yellow hues.
Impurities
Trace contaminants introduce additional electron energy levels, altering the photons emitted. For example, a tiny amount of mercury vapor can shift neon orange to blue.
Different Colors of Neon
By manipulating the gas composition, pressure, current, tube size, and purity, neon tubes can produce a rainbow of different colors. Some examples include:
| Color | Gas Composition |
|---|---|
| Red-orange | Pure neon |
| Blue | Neon + argon |
| Violet | Neon + helium or xenon |
| Yellow | Neon + krypton |
| White | Neon + argon + mercury |
| Green | Neon + argon + helium |
Cooler white shades can also be produced by combining neon with argon, krypton, and xenon. Adjusting the tube size, pressure, and current along with the gas composition enables a vast array of possible neon colors.
Neon Sign Colors
If you’ve ever wandered the streets of a big city at night, you’ve likely seen vibrant neon signs lighting up building facades in an array of colors. While red and blue are the most common, skilled neon artists can create signs in virtually any color by manipulating the neon tube conditions.
Some examples of neon sign colors include:
- Warm red-orange – Pure neon, classic sign color
- Cool blue – Neon with argon
- Soothing purple – Neon with argon and helium
- Neon green – Neon with mercury and argon
- Bright yellow – Neon with krypton
- Shocking pink – Neon with a touch of nitrogen
When driving or walking around cities at night, look closely at the local neon bar and restaurant signs. You’re likely to spot neon illuminated in a rainbow of different hues.
Neon Art
Beyond just signage, neon can also be used as an artistic medium to create vibrant, colorful artworks and installations.
For example, the Neon Museum in Warsaw, Poland features preserved neon signs and objects which showcase Poland’s neon heritage.
Many neon artists bend and shape tubes into abstract sculptures and pictures. Since any color can be produced, this allows for neon art in shades ranging from bright turquoise to deep magenta.
Can Neon Be Other Colors?
In summary, while pure neon produces that iconic warm red-orange glow, neon tubes can actually emit light in a vast array of colors by modifying:
- Gas composition – Adding other noble gases like argon, krypton, etc.
- Gas pressure – Higher pressure reddens, lower pressure blues the color
- Electrical current – More current blues, less currents reddens
- Tube size – Smaller tubes intensify redness
- Impurities – Contaminants introduce additional electron energies
So yes, neon can glow in virtually any color, ranging from red to violet to white to green. Next time you see a neon sign, take a closer look at its colorful glow.
Conclusion
While most people associate neon’s bright glow with red-orange, neon tubes can actually produce a spectrum of different colors by modifying the gas composition, pressure, current, tube size, and purity. From neon blue to neon pink, a vast array of vibrant hues can be achieved. Neon’s color capabilities allow it to be used not just for signs, but also for illuminating artwork and installations. So the next time you see neon lighting up a shop window, look closely and you might just witness neon glowing in a surprising new shade.
