Actinism

n. element in radiant energy which produces photochemical activity

Actinism is a property of radiation (particularly solar radiation) that leads to the production of photochemical effects. Actinism is derived from Greek with the meaning a radiant force. The word actinism seems to be used particularly in terms of imaging technology especially photography although it is used in medical literature for photo-biochemical effects such as a sunburn or radiation exposure from ultraviolet rays and in chemistry for containers that protect from photo-degradation. Chemical photography and X-ray imaging are two applications of actinism.
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Noun
1. the property of radiation that enables it to produce photochemical effects
(hypernym) property

(n.)
The property of radiant energy (found chiefly in solar or electric light) by which chemical changes are produced, as in photography.
  

property of radiant energy that produces chemical changes, particularly in the visible and ultraviolet spectrum.