Term: heliochromism
https://doi.org/10.1351/goldbook.HT07392

Definition:
Applied to photochromic compounds possessing a high efficiency for colouring with near-ultraviolet radiation and a low efficiency for bleaching with visible radiation, but a moderate efficiency for thermal fading at ambient temperature. These compounds are activated by unfiltered sunlight and deactivated under diffuse daylight conditions, therefore being suitable for sun-lens applications.

Related Terms:
1) photochromic (http://doi.org/10.1351/goldbook.P04589).
2) bleaching (<em>in photochemistry</em>) (http://doi.org/10.1351/goldbook.B00681).
3) ultraviolet (http://doi.org/10.1351/goldbook.UT07492).
4) visible (<em>in photochemistry</em>) (http://doi.org/10.1351/goldbook.VT07496).

Source: PAC, 2007, 79, 293. 'Glossary of terms used in photochemistry, 3rd edition (IUPAC Recommendations 2006)' on page 350 (https://doi.org/10.1351/pac200779030293)

Citation: 'heliochromism' in IUPAC Compendium of Chemical Terminology, 5th ed. International Union of Pure and Applied Chemistry; 2025. Online version 5.0.0, 2025. https://doi.org/10.1351/goldbook.HT07392

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