These sources are based on electrical discharges in gases, whereby atoms and molecules are excited and emit characteristic emission lines. This type of light source is particularly suitable for the fields of physics, electrical engineering, chemistry and materials science.

We have created separate pages for the various light sources in our example spectra.

Neon Lamps

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. [More …]

Cold Cathode Lamps

Cold cathode fluorescent lamps (CCFLs) are a type of fluorescent lamp known for their use in the backlighting of LCD screens, for example. They can be manufactured in thin, compact form factors, making them ideal for use in slim display designs. CCFLs use cold cathode electrodes which, unlike hot cathodes, do not need to be preheated. These electrodes are robust and can generate a discharge directly as soon as a high voltage is applied. [More …]

Plasma Globes

Plasma globes, also known as plasma lamps or Tesla globes, are decorative objects that produce fascinating light patterns.

A plasma globe consists of a transparent glass sphere filled with a noble gas or gas mixture (such as neon, argon or xenon) at low pressure. In the center of the sphere is an electrode, which often has a spherical or columnar structure and is connected to a high-voltage alternating current generator. A transformer or oscillator generates a high voltage, typically in the range of several kilovolts, which is applied to the central electrode to ionize the gas molecules in the sphere. This produces positively charged gas molecules and free electrons, which together form a plasma. [More …]

Pen-Ray Light Sources

Pen-Ray light sources are compact, durable and reliable light sources in the form of a pen, which are often used in spectroscopy. They are low-pressure gas discharge lamps in a quartz tube. They are available in different fillings, including UV, visible and infrared light. This enables their use in a variety of spectroscopic applications, such as UV-Vis spectroscopy, fluorescence spectroscopy and absorption spectroscopy. [More …]