The light color depends on the emission spectra of the atoms in the gas, ... Low pressure: includes the neon lamp, fluorescent lamps and low pressure sodium lamps. High pressure: ...

WAWRZYNIAK, J., SUJAK, B. Photo-stimulated Emission of Exo-electrons from the Surface Layer of Amphoteric Metals reacting with Concentrated Sodium Hydroxide or Potassium Hydroxide. Nature 186 ...