Neon is a chemical element that is commonly associated with the color orange. This is because neon gas emits an orange-red glow when electrically charged. However, neon is not limited to the color orange. In fact, neon can glow in a variety of colors depending on factors like the gas pressure, voltage, and tube diameter. So while orange may be the most familiar neon color, it is not the only one that neon can produce. In this article, we’ll take a closer look at the science behind neon’s colorful glows and discuss the different neon colors that are possible beyond orange.
What is Neon?
Neon is a noble gas element on the periodic table with the symbol Ne and atomic number 10. Under standard conditions, neon is a colorless, odorless, inert monatomic gas. Like other noble gases, neon has a full valence shell, so it rarely forms molecules or chemical compounds.
In its natural form, neon does not have any visible color. However, when neon gas is electrically charged and excited, it emits a distinctive glow. This occurs because the electrical stimulation causes electrons in the neon atoms to temporarily jump to higher energy levels. When the electrons fall back down to lower energy levels, photons are released in the form of visible light.
The most common neon glow is the distinctive reddish-orange color. But by adjusting certain variables, neon can also glow blue, purple, green, and even white.
How Neon Glows Different Colors
There are a few key factors that determine what color neon will glow:
Gas Pressure
Higher gas pressure increases the density of neon atoms. This allows more neon atoms to get excited and release photons. At low pressures, neon glows red-orange. As the pressure increases, neon begins to glow orange, yellow, green, blue, violet, and eventually white.
Voltage
Higher voltage means more energy is put into the neon gas. This energy excites electrons to jump to higher energy levels before falling back down and releasing photons. Low voltage produces lower energy red/orange photons. But with more voltage, higher energy photons in the blue, violet and ultraviolet range are emitted, causing neon to glow blue/white.
Tube Diameter
Wide tube diameters spread out the neon gas atoms, lowering density. Narrow tubes concentrate the atoms together. Wider tubes reduce collisions, causing neon to glow red/orange. Narrow tubes increase collisions and excite more electrons, producing more blue/white light.
Impurities
Introducing trace amounts of other gases can impart colors like green or purple. The impurity atoms absorb certain energies and alter the photons released. For example, a little argon makes neon glow blue, while mercury makes it glow green/aqua.
By tuning these variables of gas pressure, voltage, tube size, and impurities, neon tubes can glow in a rainbow of colors beyond orange.
Neon Color Possibilities
Here is a breakdown of the different colors that neon can generate by manipulating the key factors:
Red-Orange
The iconic neon orange glow. Produced with low pressure gas and low voltages. The lowest energy neon emission in the red 600-610 nm range.
Yellow
As voltage/pressure increases, higher energy yellow 580-590 nm photons are emitted, shifting the color toward yellow.
Green
Medium pressures and voltages begin to access the green 520-560 nm range. Adding traces of mercury gas also shifts neon green.
Blue
At higher pressures and voltages, neon’s dominant wavelengths enter the blue 430-500 nm band, generating a blue glow. Adding argon can also produce blue.
Violet/Purple
With enough energy input, neon emits higher energy photons in the violet/ultraviolet 400-420 nm wavelengths, giving a violet/purple glow.
White
Extremely high density and energy excites electrons to emit a full spectrum of visible wavelengths, yielding white light.
Pink
Combining higher red-orange emissions and lower blue emissions creates a pinkish tone. Different gas fill ratios fine-tune the hue.
So while orange is the default, adjusting these parameters allows neon to generate a palette of colorful glows.
Neon Color Trends
Different neon colors have come in and out of popularity over time as the technology has evolved:
1910s-1920s
Early neon was mostly red-orange due to low vacuum and voltage limits.
1930s-1940s
Improved technology allowed brighter oranges, as well as some blues.
1950s
Higher intensities made neon light up in vivid blues, greens, and whites.
1960s-1970s
The psychedelic era saw neon embrace unconventional hues like hot pinks and purples.
1980s-1990s
Neon became associated with bright pop art colors like shocking pink and acid green.
2000s-today
Modern neon features multi-colored displays glowing together in artful compositions.
So while orange has historically been the representative color, improved neon tech continues to push the boundaries of possible colors today.
Uses of Colored Neon
Beyond lighting and signage, colored neon finds many applications thanks to its striking visual impact:
- Decorative lighting – Accent lighting, art installations, wall decor
- Illumination – Lighting in theaters, concerts, clubs
- Signage – Business logos, open/closed signs, advertising
- Safety – Emergency vehicle lighting, runway markers
- Science – Spectroscopy, lasers, plasma devices
- Art – Sculptures, photography, graphic design
- Entertainment – Props, special effects
Neon’s versatility to glow in attention-grabbing colors makes it useful across many settings.
Noteworthy Examples of Colored Neon
Here are some interesting examples of neon being used in different colors:
Las Vegas Strip – Iconic for extravagant multi-colored neon signs and marquees glowing against the night sky.
Neon Museum – Collection of preserved neon signs from old Las Vegas casinos and businesses.
Times Square – Famous intersection renowned for its dense cluster of brightly colored neon billboards and signage.
Neon Lighting in K-Pop – Korean pop music performances feature elaborate multi-hued neon light displays.
Sculptures by Bruce Nauman – American artist famous for creative neon sculptures that glow in rainbow hues.
Claude Monet’s Water Lilies – Monet captured the magic of colored neon lighting in his impressionist paintings of water lilies.
Neon Signs in Tokyo, Japan – Japanese streets are adorned with masterful neon signs glowing in pinks, blues, greens and more.
These examples highlight neon’s capacity as an art form to generate colorful lighting effects beyond standard orange.
How Neon Lighting Is Made
Producing colored neon lighting requires a glass tube, neon/other gases, electrodes, and a high-voltage electrical supply:
Glass Tube – Tinted glass can filter colors, while shape/diameter affect density.
Gas Medium – 99.9% neon is typical, with trace “dopant” gases added to shift colors.
Electrodes – Metal electrodes at each end of the tube apply voltage to ionize and excite the gas.
Power Supply – High voltage (5-15 kV) alternating current supply energizes the gas.
Gas Ionization – Voltage strips electrons from the neon atoms, creating charged plasma.
Electron Transitions – Electrons shift between quantized energy levels, emitting photons.
Visible Light Emission – Photons in the visible wavelength range exit the tube as colored light.
With the right tube, gases, power supply and other factors, many vivid neon colors can be produced.
The Science of Neon’s Glow
The science behind neon’s glow lies in atomic physics and electromagnetism:
– Neon atoms have 10 electrons, with 2 electrons in the outermost shell.
– When voltage is applied, the electrons absorb energy and jump to higher quantized energy levels.
– When the electrons fall back down, energy is emitted in the form of photons.
– Visible photons produce light colors, while UV photons are invisible.
– Red-orange indicates lower energy transitions in the outer shell.
– Higher energy transitions yield blue/violet, even into UV range.
– Density of gas affects how many atoms absorb and emit photons.
– Impurity atoms introduce alternate electron energies that alter emitted photons.
So the color comes down to the quantized energies of the electrons in the neon atoms, as well as interactions between the gas particles. Adjusting the parameters tunes the emitted photon energies and mix of wavelengths.
Health and Safety
Neon is generally safe with responsible handling:
- Neon is non-toxic and inert. It does not react or combine with other elements.
- However, inhaling neon can cause asphyxiation by displacing oxygen needed for breathing.
- Neon is compressed to high pressures for glow discharge applications. Mishandling tanks can lead to explosion hazard.
- UV photons from neon can damage skin and eyes. Do not directly view neon tubes without UV filtering.
- High voltage electricity for neon signs poses a shock risk. Systems should only be serviced by qualified personnel.
- Neon installations should be properly grounded to prevent electric shock from casings.
With common sense precautions for the high pressure gas and high voltage electricity, neon lights are generally safe to handle and install. Proper ventilation and UV safety factors should always be considered as well.
Conclusion
In summary, neon’s glowing colors are not restricted only to the common orange-red hue. By adjusting the gas pressure, voltage, tube size, and gas composition, neon can produce a spectrum of vibrant colors, including red, orange, yellow, green, blue, violet, purple, pink, and white. Early neon was limited to red-oranges, but modern neon technology allows far more colorful applications for signs, art, displays, lighting, and more. So next time you see the familiar neon orange, remember that with the right conditions, neon’s illumination can span the entire rainbow.
