Fotofysik

Fotofysik, or photophysics, is the branch of science that studies the physical processes governing the interaction of light with matter. It focuses on how photons are absorbed and how excited electronic states are formed, how energy is released as light or heat, and how energy is transferred within molecules, across interfaces, or through materials. The field seeks to understand the mechanisms of absorption, emission (fluorescence and phosphorescence), nonradiative decay, energy transfer, and charge separation and recombination.

Key concepts include quantum yield, fluorescence lifetime, radiative versus nonradiative decay, intersystem crossing, Förster and Dexter energy transfer, internal conversion, and vibrational relaxation. Photophysics emphasizes physical mechanisms and excited-state dynamics, while often intersecting with photochemistry where chemical changes accompany light interactions.

Experimental methods commonly used in photophysics include UV-Vis and photoluminescence spectroscopy, time-resolved techniques such as pump-probe and transient absorption, and ultrafast laser spectroscopy. These approaches reveal lifetimes, quantum efficiencies, and the pathways by which excited states relax or drive reactions.

Materials and systems studied span organic dyes and polymers, inorganic crystals, semiconductor nanocrystals (quantum dots), and emerging materials like perovskites and two-dimensional systems. Photophysics also overlaps with biology and chemistry in studying natural light-harvesting complexes and photoinduced processes in cells.

Applications extend to solar cells, light-emitting devices (OLEDs), photodetectors, photocatalysis, bioimaging, and fluorescence-based sensing, among other photonic technologies. The field has a long history—from Planck’s and Einstein’s foundational work on energy quanta and the photoelectric effect to the modern development of quantum-mechanical descriptions of light–matter interactions.