fluence rate, \(E_{\unicode{x26ac}}\)

Also contains definitions of: radiant energy fluence rate, spherical irradiance
Total @[email protected], \(P\), incident from all directions onto a small sphere divided by the cross-sectional area of that sphere. SI unit is \(\text{W m}^{-2}\).
  1. Mathematical definition: \(E_{\text{o}} = \frac{\text{d}P}{\text{d}S} = \frac{\text{d}H_{\text{o}}}{\text{d}t}\). If the @[email protected] is constant over the area \(S\), \(E_{\text{o}} = \frac{P}{S}\). Equivalent definition: \(E_{\text{o}} = \int_{4\pi}L\text{d}\varOmega\), with \(\varOmega\) the solid @[email protected] of each beam passing through the given point on the surface and \(L\) the @[email protected] of the beam at that point.
  2. Fluence rate is identical to spherical irradiance and reduces to @[email protected], \(E\), for a parallel and perpendicularly incident beam not scattered or reflected by the target or its surroundings.
PAC, 2007, 79, 293. (Glossary of terms used in photochemistry, 3rd edition (IUPAC Recommendations 2006)) on page 340 [Terms] [Paper]