A glow discharge is a plasma formed by the passage of electric current through a gas. It is often created by applying a voltage between two electrodes in a glass tube containing a low-pressure gas. When the voltage exceeds a value called the striking voltage, the gas ionization becomes self-sustaining, and the tube glows with a colored light. The color depends on the gas used.
DC powered neon lamp, showing glow discharge surrounding only the cathode
A 5651 voltage-regulator tube in operation
Image: Glow discharge regions
Atomic absorption spectroscopy (AAS) and atomic emission spectroscopy (AES) is a spectroanalytical procedure for the quantitative determination of chemical elements by free atoms in the gaseous state. Atomic absorption spectroscopy is based on absorption of light by free metallic ions.
Flame atomic absorption spectroscopy instrument
A scientist preparing solutions for atomic absorption spectroscopy, reflected in the glass window of the AAS's flame atomizer cover door
Atomic absorption spectrometer block diagram
A laboratory flame photometer that uses a propane operated flame atomizer