Articles by others on the same topic
An **F-center** (or Farbzentrum, German for "color center") is a type of defect in a crystalline solid, particularly in ionic crystals. It arises when an anion is removed from its lattice site, leaving behind a vacant site (also called a vacancy). Electrons can occupy this vacancy, which can lead to the absorption of specific wavelengths of light, giving the crystal a characteristic color.