The measurement of quantities associated with
radiant energy. The quantities may also describe the variation of the energy with respect to other
variables such as
wavelength, time, position, direction (solid
angle), area normal to the light or projected area of emitting or receiving surfaces. If
the light is monochromatic, it is sometimes convenient to replace the
radiant energy by the corresponding number of photons (or quanta) which is obtained by dividing
the energy by
where
is the
Planck constant,
the velocity of light and
the
wavelength of the light.
Source:
PAC, 1990, 62, 2167
(Glossary of atmospheric chemistry terms (Recommendations 1990))
on page 2209
Cite as:
IUPAC. Compendium of Chemical Terminology, 2nd ed. (the "Gold Book"). Compiled by
A. D. McNaught and A. Wilkinson. Blackwell Scientific Publications, Oxford (1997).
XML on-line corrected version: http://goldbook.iupac.org (2006-) created by M. Nic,
J. Jirat, B. Kosata; updates compiled by A. Jenkins. ISBN 0-9678550-9-8.
https://doi.org/10.1351/goldbook.
