radiant intensity, \(I\)

Also contains definition of: intensity
@R05046-1@, \(P\), at all wavelengths per solid @A00346@, \(\varOmega\). The @R05046-2@ emitted in a given direction by a source or an element of the source in a small cone containing the given direction divided by the solid @A00346@ of the cone. SI unit is \(\text{W sr}^{-1}\).
  1. Mathematical definition: \(I = \text{d}P/\text{d}\varOmega\). If the @R05046-2@ is constant over the solid @A00346@ considered, \(I = P/\varOmega\).
  2. Equivalent to \(I = \int_{\lambda}I_{\lambda}\, \text{d}\lambda\), where \(I_{\lambda}\) is the @S05827@ at @W06659@ \(\lambda\).
  3. It is not recommended to abbreviate this term to just intensity because it is confusing.
PAC, 2007, 79, 293. (Glossary of terms used in photochemistry, 3rd edition (IUPAC Recommendations 2006)) on page 410 [Terms] [Paper]