photoinduced

Photoinduced refers to processes that are initiated or driven by exposure to light. It covers physical or chemical changes triggered by photon absorption, including electronic excitation, bond rearrangements, and energy transfer. The term is used across chemistry, physics, materials science, and biology and encompasses both photophysical phenomena, where light affects energy states without permanent chemical change, and photochemical phenomena, where light causes chemical transformation.

When light is absorbed, a molecule or material can reach excited electronic states. Relaxation can occur via fluorescence or phosphorescence, internal conversion, or intersystem crossing. If the excited state engages in chemical reactions, the process is photochemical, such as photoisomerization, photodissociation, or photoinduced electron or energy transfer. In condensed matter, light can drive phase transitions, structural rearrangements, or changes in electronic order (for example, photodoping or photoinduced metallic states in certain materials and devices).

Techniques used to study photoinduced processes include pump–probe experiments, transient absorption spectroscopy, time‑resolved luminescence, and, in solids, structural probes. Key metrics include quantum yield, excited‑state lifetimes, and rate constants for competing pathways. Applications span solar energy conversion, photocatalysis, optical switching, data storage, and, in medicine, photodynamic therapy, among others. The term remains broad and context dependent, reflecting the diversity of systems and pathways by which light can influence matter.