Neon Lamps are evacuated and neon gas filled gas discharge tubes. Gas discharge stimulates a plasma inside these tubes. Neon Plasma is characterized by a very brilliant yellow radation. The frequency of the plasma radiation ist determined by energy gap between the energy level of valence electrons and the first level of stimulation. As neon and other inert gases are elementary gases the visible radiation of a plasma is monochromatic and very bright. Therefore inert gases are prefered gases used for gas discharge lamps.
Neon lamps are characterized by an intensive orange illumination.