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Photochemistry Wiki

Foreword

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A
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Actinometry

Actinometry is the use of an actinometer, that is a chemical system or a physical device (e.g. a bolometer or photo cell) to determine the number of photons in a light beam per time interval (photon flux) or integrally (photon fluence).

Advanced Oxidation Process

Advanced Oxidation Processes are distinct processing methods that make use of the formation of hydroxyl radicals OH.

B
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BARTON reaction

The Barton reaction, also known as the Barton Nitrite Ester Reaction, is a photochemical reaction that involves the photolysis of an alkyl nitrite to form a δ-nitroso alcohol.

Beer-Lambert Law

The Beer–Lambert law relates the attenuation of light to the properties of the material through which the light is traveling.

C
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Charge-Transfer Transitions

The large energy of photons can induce different electronic excitations in metal complexes. The
decreasing transmission at a certain wavelength can be observed as the color of the complexes.

Chemical Structure Electron Spectra Relations

Absorption of light, or more general electromagnetic irradiation, strongly depends on the chemical composition of the molecule.

Cycloadditions

A cycloaddition is a pericyclic chemical reaction, in which two or more unsaturated molecules (or parts of the same molecule) combine with the formation of a cyclic adduct in which there is a net reduction of the bond multiplicity.

D
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Decarbonyliation

Decarbonylation is a chemical reaction that destroys a ketone.

E
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Electromagnetic radiation

Electromagnetic radiation (EM radiation or EMR) is a form of radiant energy released by certain electromagnetic processes.

Energy of Photons

The energy of photons can cause electronic transitions between the different orbitals of chemical sunstances.

Excited states

In quantum mechanics an excited state of a system (such as an atom, molecule or nucleus) is any quantum state of the system that has a higher energy than the ground state (that is, more energy than the absolute minimum).

F
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Franck-Condon principle

The Franck–Condon principle is a rule in spectroscopy and quantum chemistry that explains the intensity of vibronic transitions

I
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Industrial Preparative Photochemical Processes

Industrial photochemical applications can be classified into three parts: i) waste water treatment and disinfection, ii) surface treatment and iii) preparative photochemistry.

J
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JABLONSKI diagram

A Jablonski diagram is a diagram that illustrates the electronic states of a molecule and the transitions between them

L
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Ligand Field Theory

The ligand field theory (LFT) describes the interaction of the ligand’s electron pairs with the
d-orbitals of the central transition metal.

Light sources

The choice of the light source is probably the most important decision when photoreactions shall be conducted.

M
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Molecular Orbital Therory

A fundamental knowledge of the electronic states in molecules or complexes is the foundation of a thorough understanding of photochemical processes that these substances can undergo. The molecular orbital theory provides such an understanding.

N
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NORRISH type I/II reactions

Norrish reaction in organic chemistry describes the photochemical reactions taking place with ketones and aldehydes.

O
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Optical Filter

The optical filter between the light source and the reaction zone has to be transparent for light with wavelengths required to drive the desired reaction.

P
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Photocatalytic water splitting

Photocatalytic water splitting is a photocatalytic process for the dissoziation of water into hydrogen (H
2
) and oxygen (O
2
) in a photoelectrochemical cell.

Photochemical Reactions of Metal Complexes

The absorption of light by a metal complex causes a change of the coordination sphere. Consequently,
this physical process can lead to photochemical reactions as well

Photodesulfonation

The term photodesulfonation describes the elimination of a sulfonyloxy group ( –SO3X– ) by
photochemical methods.

Photohalogenation

Photohalogenation is a chemical reaction of alkanes with halogenes induced by photons.

Photohydrodimerization

Some carbonylated compounds (ketones, aldehydes) can be excited by irradiation due to a chromophore and subsequently be reduced by adding a hydrogen atom from an appropriate hydrogen donor (an alcohol, hydrocarbon or amine). In a second step, two intermediate ketyl radicals can combine and form a 1,2-ethanediol. This photoinduced two-reaction-process including reduction and dimerization is called photohydrodimerization.

Photoinduced Cationic Polymerization

Photoinduced cationic polymerization is a polymerization by a SN-1 reaction of a cation with the help of photoinitiator at the chain start reaction.

Photoinduced Polyaddition for the Synthesis of PUR

The formations of a link in PUR (Polyurethane polymers) by polyaddition induced by photoinitiators.

Photoinduced Radical Polymerization

Photoinduced radical polymerization is a method to form a polymer by successively adding monomers that have formed radicals with the help of photoinitiator at the chain start reaction.

Photoinduced Ring Opening Metathesis of Cyclic Olefines

Photoinduced ring opening metathesis is a photo-catalyzed metathesis reaction of cyclic olefines and used in most cases for chain growth polymerization.

Photolysis of azido compounds

Photolysis of azido compounds is a chemical reaction in which a azido compound is broken down by photons

Photonitrolisation

Photonitrosylation build up nitroso functionalities in organic compounds.

Photooxygenations

A photooxygenation is a light-induced oxidation reaction in which molecular oxygen is incorporated into the product(s).

Photoreactions in the Laboratory Course of Technical Chemistry

The laboratory course of Technical Chemistry is an obligatory part of the chemistry studies in the 5th semester as a part of the Bachelor grade. It consists of six different experiments to get basic knowledge on mechanical and thermal unit operations as well as reaction engineering.

Photosulfochlorination

Introducing sulfon groups into alkanes or alkyl aromates.

Photosynthesis

Photosynthesis is a chemical process that uses sunlight to turn carbon dioxide into sugars.

Phototransduction

Phototransduction describes the process of converting light to electrical signals in a photoreceptor cell in the eyes of vertebrates.

R
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Radiometry

Radiometry is a set of techniques for characterizing the distribution of the radiation's power in space,

Reaction Engineering

Controlling photochemical reactions with the objective of high yields and high process efficiency
is more challenging as the same task for thermally initiated reactions.

Reactor Types and Concepts

To a large extent the design of a photoreactor is determined by the geometric characteristics of the light source.

S
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Scale-Up Aspects of Photoreactors

Scale-up is the migration of a process from the lab-scale to the pilot plant-scale or commercial scale. Scale-up of photoreactors requires the consideration of several crucial aspects.

Schenck-En-reactions

The Schenck ene reaction is an example of a Type II photooxygenation

Spin states

Spin states when describing transition metal coordination complexes refers to the potential spin configurations of the metal center's d electrons.

W
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Waste water processing

The process to treat water that have been contaminated in some way prior to its release into the environment or its re-use.

Wave-particle dualism

Wave–particle duality is the concept that every elementary particle or quantic entity exhibits the properties of not only particles, but also waves

WOODWARD-HOffMANN rules

The Woodward–Hoffmann rules, devised by Robert Burns Woodward and Roald Hoffmann, are a set of rules in organic chemistry predicting the barrier heights of pericyclic reactions based upon conservation of orbital symmetry.

 Download the complete photochemistry script here.


Found an error or want to submit a new article? Please send your correction or article in by mail in word or pdf to photo-wiki@itc.uni-stuttgart.de.