Photochemical Processing
Chemical reactions triggered by light energy, commonly used in photography and materials science to create images or alter substances.
A chemical reaction initiated or accelerated by exposure to light (visible, ultraviolet, or infrared radiation). Photochemical processing underlies photography, where light-sensitive compounds in film or sensors change state to record images, and occurs in many industrial and natural processes including water purification, atmospheric chemistry, and material synthesis.
What this means in real life
When you take a photo with a film camera, light hits silver halide crystals on the film, triggering a chemical change that captures the image—that light-driven reaction is photochemical processing.
What it isn’t
It is not simply light exposure or illumination alone. Photochemical processing requires a chemical transformation caused by light energy; merely shining light on an object without triggering a chemical change is not photochemical processing.
Commonly misused online
People often use 'photochemical' to mean any process involving light and chemistry separately, rather than a reaction where light energy directly drives the chemical change—conflating correlation with causation.