elektroninsiirron

Elektroninsiirron (Finnish for "electron transfer") refers to the movement of one or more electrons from a donor to an acceptor species. It is a fundamental process in chemistry, physics and biology, underlying redox reactions, electrochemistry, photosynthesis, respiration and many catalytic and electronic technologies. Electron transfer can occur between atoms, molecules, ions, solids or across interfaces.

Mechanisms are commonly classified as inner-sphere, where a chemical bridge or shared ligand facilitates transfer, and outer-sphere, where the donor and acceptor remain chemically intact and transfer proceeds through space or tunneling. In condensed phases and biological systems, electrons often move by tunneling or hopping over short distances; rates depend strongly on donor–acceptor distance, driving force, electronic coupling and reorganization energy. Marcus theory provides a quantitative framework linking these factors to transfer rates and earned the Nobel Prize in Chemistry for explaining electron-transfer kinetics.

Electron transfer is central to energy conversion: in photosynthesis light-induced transfers drive chemical synthesis, while in cellular respiration chains of transfers generate a proton gradient for ATP synthesis. In technology, controlled electron transfer is exploited in batteries, fuel cells, sensors, organic electronics and catalysis. Experimental approaches to study electron transfer include electrochemical methods (cyclic voltammetry), time-resolved spectroscopy, electron paramagnetic resonance and single-molecule techniques. Understanding and tuning elektroninsiirron remain active research areas for improving energy storage, molecular electronics and catalytic efficiency.