1. to ionize (an atom or molecule) by the action of light or photons
Usage: technical; physics and chemistry

Examples

• Ultraviolet light can photoionize oxygen molecules in the upper atmosphere.
• The laser was used to photoionize the gas sample in the experiment.
• When high-energy photons photoionize an atom, they eject electrons from its outer shells.
• Researchers photoionized the noble gas to study its ionization properties.
• The photoionization process is essential in understanding stellar atmospheres.