photochemistry

n. branch of chemistry that studies chemical reactions resulting from the influence of light or radiation

Photochemistry, a sub-discipline of chemistry, is the study of the interactions between atoms, small molecules, and light (or electromagnetic radiation).Like most scientific disciplines, photochemistry utilizes the SI or metric measurement system. Important units and constants that show up regularly include the meter (and variants such as centimeter, millimeter, micrometer, nanometer, etc.), seconds, hertz, joules, moles, the gas constant R, and the Boltzmann constant. These units and constants are also integral to the field of physical chemistry.
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Photochemistry /pho·to·chem·is·try/ the branch of chemistry dealing with the chemical properties or effects of light rays or other radiation. [more]Photochemistry - Community and Resources

Noun
1. branch of chemistry that deals with the chemical action of light
(hypernym) chemistry, chemical science

(n.)
The branch of chemistry which relates to the effect of light in producing chemical changes, as in photography.