Penning ionization
![The process of ionization interaction between excited molecule and target molecule.](/Images/godic/202502/01/Penning_ionization4816.jpg")
Penning ionization is a form of chemi-ionization, an ionization process involving reactions between neutral atoms or molecules. The Penning effect is put to practical use in applications such as gas-discharge neon lamps and fluorescent lamps, where the lamp is filled with a Penning mixture to improve the electrical characteristics of the lamps.