Neon lamps consist of a small glass housing filled with a noble gas (usually neon, sometimes argon). They have two electrodes between which a voltage is applied. With sufficient voltage, the gas ionizes and produces a faint shine (glow) around the negatively charged electrode (cathode).

Glow lamps are often used as inexpensive indicators, for example in power strips.

• Red
• Green
• Blue

Red Neon Lamp

Neon

As a rule, red glow lamps only use neon to generate the emitted light. The spectrum therefore contains many typical emission lines between 585 nm and 703 nm.

Green Neon Lamp

Neon/Xenon with Phosphor

In addition to neon, this type of neon lamp also contains xenon. The latter has emission peaks in the ultraviolet, which are then converted into green light via a phosphor. However, xenon also has additional emission peaks at higher wavelengths, which can also be used to calibrate spectrometers.

Blue Neon Lamp

Xenon/Krypton with phosphor

The color of this glow lamp is also produced by a corresponding phosphor. There are also emission lines of xenon and krypton in the spectrum.

¹ The spectra were recorded with the Czerny-Turner spectrometers from our optoelectronic consctruction kit.

The data of the superimposed emission lines are from the Atomic Spectra Database | NIST.

Kramida, A., Ralchenko, Yu., Reader, J., and NIST ASD Team (2023). NIST Atomic Spectra Database (ver. 5.11), [Online]. Available: https://physics.nist.gov/asd [2024, June 23]. National Institute of Standards and Technology, Gaithersburg, MD. DOI: https://doi.org/10.18434/T4W30F