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Units for photochemical and photobiological quantitites
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Summary
Actinic action spectrum
Measurement of photochemical or photobiological quantities and their corresponding units

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SI brochure, Appendix 3

Optical radiation is able to cause chemical changes in certain living or non-living materials: this property is called actinism, and radiation capable of causing such changes is referred to as actinic radiation. Actinic radiation has the fundamental characteristic that, at the molecular level, one photon interacts with one molecule to alter or break the molecule into new molecular species. It is therefore possible to define specific photochemical or photobiological quantities in terms of the result of optical radiation on the associated chemical or biological receptors.

In the field of metrology, the only photobiological quantity which has been formally defined for measurement in the SI is for the interaction of light with the human eye in vision. An SI base unit, the candela, has been defined for this important photobiological quantity. Several other photometric quantities with units derived from the candela have also been defined (such as the lumen and the lux, see Table 3 in Chapter 2).

 
     
Summary


Actinic action spectrum
Measurement of photochemical or photobiological quantities and their corresponding units

     

Note: For the official text, please refer to the PDF files available at:
  • http://www.bipm.org/utils/common/pdf/si_brochure_8_en.pdf (in English) and
  • http://www.bipm.org/utils/common/pdf/si_brochure_8_fr.pdf (in French).
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