What is photochromism?

Photochromism (or reaction to light) is a reversible color change, which is often used to describe the color change process in the presence of ultraviolet (UV), visible and infrared (IR) This phenomenon is most common in transition lenses, such as lenses that darken in the outdoor sun and clear in the indoor light The photochromic material shows color change when there is a specific light, such as the ultraviolet light activating the transition lens This phenomenon is related to the absorption characteristics of the molecular materials responding to the wavelength radiation Different materials have the corresponding transmission spectrum characteristics, which will change when the luminosity changes The precise understanding of this phenomenon was first discovered by the German organic chemist Dr Willi marckwald Although photochromism was observed by others as early as 1867, Dr Willie determined its presence when he studied the behavior of benzo-1-naphthoic acid and tetrachloro-1,2-one-naphthone under light In short, photochromism refers to the conversion of one compound to another when exposed to light When there is no light, it changes back to the original compound This condition is also known as pre and post reaction Both organic and man-made compounds can change color, and it also happens in nature Although the permanent change of color caused by the exposure of materials to ultraviolet radiation will make the photochromism irreversible, the reversibility is the key criterion to evaluate this process Many photochromic molecules are classified into many categories, including spiropyran, diarylethene and photochromic quinone Inorganic photochromic materials include silver, silver chloride and zinc halide Silver chloride is a compound often used in the production of color changing lenses There are other photochromic applications in the field of supramolecular chemistry, such as observing photochromic conversion to show molecular conversion Three dimensional optical data storage also uses photochromism to produce memory disk capabilities that maintain terabyte data In addition, many products use this change to create attractive toys, textiles and cosmetics Observing the photochromic band of a specific part of the spectrum can monitor the process and conversion related to light For example, nanotechnology relies on photochromism in the production of thin films This effect can be used in any number of light or material film applications For example, applications including semiconductors, filters, and other surface treatment technologies Generally, the photochromic system is based on the single molecule reaction in the state of obviously different absorption spectrum This process is usually the reversible change of visible light and thermal radiation In the application of photochromism in consumer goods and industrial technology, it is necessary to turn these natural molecules into ideal light transmission and absorb a large number of ideal effects The band function of products and technologies is greatly enhanced by color sensing modification among light, materials and elements.