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Photochemical immersion well reactor (50 mL) with a mercury-vapor lamp.. 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).
Photochemical action plots are a scientific tool used to understand the effects of different wavelengths of light on photochemical reactions.The methodology involves exposing a reaction solution to the same number of photons at varying monochromatic wavelengths, monitoring the conversion or reaction yield of starting materials and/or reaction products.
where E is the energy of the quantum , f is the frequency of the light wave, h is the Planck constant, λ is the wavelength and c is the speed of light. The relationships between the energies of the various quantum states are treated by atomic orbital , molecular orbital , Ligand Field Theory and Crystal Field Theory .
The center wavelength for most actinic light products is 420 nanometers, with longer wavelengths regarded as "royal blue" (450nm) to sky blue (470nm) and cyan (490nm) and shorter wavelengths regarded as "violet" (400nm) and blacklight (365nm). Actinic light centered at 420nm may appear to the naked eye as a color between deep blue and violet.
It shows which wavelength of light is most effectively used in a specific chemical reaction. Some reactants are able to use specific wavelengths of light more effectively to complete their reactions. For example, chlorophyll is much more efficient at using the red and blue regions than the green region of the light spectrum to carry out ...
A white light source—emitting light of multiple wavelengths—is focused on a sample (the pairs of complementary colors are indicated by the yellow dotted lines). Upon striking the sample, photons that match the energy gap of the molecules present (green light in this example) are absorbed, exciting the molecules. Other photons are scattered ...
In chemistry, many reactions depend on the absorption of photons to provide the energy needed to overcome the activation energy barrier and hence can be labelled light-dependent. Such reactions range from the silver halide reactions used in photographic film to the creation and destruction of ozone in the upper atmosphere. This article ...
Unlike most chemical reactions, the product C converts to a further product, which is produced in an electronically excited state often indicated with an asterisk: A + B → C C → D* D* then emits a photon (hν), to give the ground state of D: [1] I D* → D + hν. In theory, one photon of light should be given off for each molecule of reactant.