Chemical actinometry involves measuring radiant flux via the yield from a chemical reaction. It requires a chemical with a known quantum yield and easily analyzed reaction products.
What is photochemistry Actinometry?
actinometer, in chemistry, a substance or a mixture of substances that reacts through the action of light and that, because of the easily determined quantitative relationship between the extent of the reaction and the energy of the absorbed light, is used as a standard for measurement of light energies involved in …
What is meant by actinometer?
actinometer. / (ˌæktɪˈnɒmɪtə) / noun. an instrument for measuring the intensity of radiation, esp of the sun’s rays.
How does an Actinometer work?
The actinometer was invented by John Herschel in 1825. It works based on the principle that the rate of photolytic conversion of molecules within an actinometer cell is equal to the rate of absorption of photons in the actinometer.
What is called photochemical decomposition?
Photochemical decomposition: When Photon or light energy is used for decomposition or breaking of complex substances into simpler substances, then this reaction is called a photochemical decomposition reaction.
What is direct solar radiation?
The solar radiation that reaches the Earth’s surface without being diffused is called direct beam solar radiation. The sum of the diffuse and direct solar radiation is called global solar radiation. Atmospheric conditions can reduce direct beam radiation by 10% on clear, dry days and by 100% during thick, cloudy days.
What is photochemical yield?
The quantum yield (ϕ) of a product of a photochemical reaction is defined as the number of moles of product formed per Einstein (N quanta) of light absorbed by the photosensitive agent.
What is ferferrioxalate actinometry?
Ferrioxalate actinometry has been a standard tool of photochemical investigations for more than half a century now and is also recommended by IUPAC [1], [2], [3], [4], [5].
What is decomposition of ferrioxalate?
Decomposition of ferrioxalate is also accompanied by reproducible spectral changes, which are measured if the above mentioned techniques are used. This renders complexation and spectrophotometric Fe (II) concentration determination unnecessary.
Can potassium ferrioxalate be used as a substitute for uranyl oxalate?
At some wavelengths independent values of quantum efficiency have been obtained by comparison with uranyl oxalate and by direct comparison with a calibrated thermopile. The results indicate that potassium ferrioxalate provides a very valuable new chemical actinometer, and its use is recommended in place of uranyl oxalate for many purposes.
What is the wavelength range of actinometric Fe(II) formation?
Standard values for the quantum yield of Fe (II) formation, and their wavelength dependence are known lending the method high adaptability. The useful wavelength range of the actinometric application (usually between 200 and 450 nm) is limited by the absorption characteristics of the complex.
