Preferred Label : photon irradiance;
Detailed label : photon irradiance, Ep;
IUPAC acronym : SI;
IUPAC definition : Number of photons (quanta of radiation, Np) per time interval (photon flux), qp,
u incident /u from all u upward /u directions on a small u element of surface
/u containing the point under consideration divided by the area of the element. SI
unit is m-2 s-1. Equivalent definition: Integral, taken over the hemisphere visible
from the given point, of the expression Lp.cos θ.dΩ the photon radiance at the given
point in the various directions of the incident beam of solid angle Ω and θ the angle
between any of these beams and the normal to the surface at the given point.;
Scope note : this quantity can be used on a chemical amount basis by dividing ep by the avogadro
constant, the symbol then being en,p, the name photon irradiance, amount basis, si
unit is mol m-2 s-1;common unit is einstein m-2 s-1.; this term refers to a beam not scattered or reflected by the target or its surroundings.
for a beam incident from all directions photon fluence rate (ep,o) is an equivalent
term.; mathematical definition: ep s qp . if the photon flux is constant
over the surface considered, ep qp s . equivalent definition: ep
2p ¿ lp ¿ .;
Origin ID : P04637;
Automatic exact mappings (from CISMeF team)
- See also
Number of photons (quanta of radiation, Np) per time interval (photon flux), qp,
u incident /u from all u upward /u directions on a small u element of surface
/u containing the point under consideration divided by the area of the element. SI
unit is m-2 s-1. Equivalent definition: Integral, taken over the hemisphere visible
from the given point, of the expression Lp.cos θ.dΩ the photon radiance at the given
point in the various directions of the incident beam of solid angle Ω and θ the angle
between any of these beams and the normal to the surface at the given point.
