It is usually synonymous with chromotropism, the (reversible) change in color of a substance due to the physical and chemical properties of its ambient surrounding medium, such as temperature and pressure, light, solvent, and presence of ions and electrons.
These can be categorized under the following five headings: Those phenomena which involve the change in color of a chemical compound under an external stimulus fall under the generic term of chromisms.
Examples include: Color changes are also observed on the interaction of metallic nanoparticles and their attached ligands with another stimulus.
Organic dyes are used mainly to color textile fibers, paper, hair, leather, while pigments are used largely in inks, paints, plastic and cosmetics.
Cathodoluminescence is used in cathode-ray tubes, photoluminescence in fluorescent lighting and plasma display panels, phosphorescence in safety signs and low energy lighting, fluorescence in pigments, inks, optical brighteners, safety clothing, and biological and medicinal analysis and diagnostics, chemoluminescence and bioluminescence in analysis, diagnostics and sensors, and electroluminescence in the burgeoning areas of light-emitting diodes (LEDs/OLEDs), displays and panel lighting.
These laser addressable colorants, also called near-infrared absorbers, are used in thermal energy conversion, photosensitisation of chemical reactions and the selective absorption of light.
A developing area is the conversion of light into kinetic energy, often described under the generic term of lightdriven molecular machines.
For instance, a change of orientation of molecules to produce a visual effect as in liquid crystal displays.