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Dexter (also known as Dexter exchange or collisional energy transfer, colloquially known as Dexter Energy Transfer) is another dynamic quenching mechanism. [12] Dexter electron transfer is a short-range phenomenon that falls off exponentially with distance (proportional to e −kR where k is a constant that is the inverse of the sum of both van der Waals radius of the atom over 2 [13]) and ...
For diffusion-limited quenching (i.e., quenching in which the time for quencher particles to diffuse toward and collide with excited particles is the limiting factor, and almost all such collisions are effective), the quenching rate coefficient is given by = /, where is the ideal gas constant, is temperature in kelvins and is the viscosity of ...
Photochemistry is the branch of chemistry concerned with the chemical effects of light. Generally, this term is used to describe a chemical reaction caused by absorption of ultraviolet ( wavelength from 100 to 400 nm ), visible (400–750 nm), or infrared radiation (750–2500 nm).
Jablonski diagram including vibrational levels for absorbance, non-radiative decay, and fluorescence.. When a molecule absorbs a photon, the photon energy is converted and increases the molecule's internal energy level.
Here, I and I 0 denote the emission intensity with and without quenching agent present, k q the rate constant of the quenching process, τ 0 the excited-state lifetime in the absence of quenching agent and [Q] the concentration of quenching agent. Thus, if the excited-state lifetime of the photoredox catalyst is known from other experiments ...
To use measurements of chlorophyll fluorescence to analyse photosynthesis, researchers must distinguish between photochemical quenching and non-photochemical quenching (heat dissipation). This is achieved by stopping photochemistry, which allows researchers to measure fluorescence in the presence of non-photochemical quenching alone.
A classic example of this process is the quinine sulfate fluorescence, which can be quenched by the use of various halide salts. [citation needed] The excited molecule can de-excite by increasing the thermal energy of the surrounding solvated ions.
One of the roles of carotenoids in photosynthetic systems is to prevent damage caused by produced singlet oxygen by either removing excess light energy from chlorophyll molecules or quenching the singlet oxygen molecules directly.