Preferred Label : photochromism;
IUPAC definition : Reversible transformation of a molecular entity between two forms, A and B, having
different absorption spectra, induced in one or both directions by absorption of electromagnetic
radiation. The spectral change produced is typically, but not necessarily, of visible
colour and is accompanied by differences in other physical properties. The thermodynamically
stable form A is transformed by irradiation into form B. The back reaction can occur
thermally (photochromism of type T) or photochemically (photochromism of type P).
The terms 'switch-on' and 'switch-of' are sometimes used to denote the two directions
of the photochromic reaction.;
Scope note : an important parameter is the number of cycles that a photochromic system can undergo
under well-defined conditions (solution, matrix, concentration, temperature).;
Origin ID : P04589;
See also
Reversible transformation of a molecular entity between two forms, A and B, having
different absorption spectra, induced in one or both directions by absorption of electromagnetic
radiation. The spectral change produced is typically, but not necessarily, of visible
colour and is accompanied by differences in other physical properties. The thermodynamically
stable form A is transformed by irradiation into form B. The back reaction can occur
thermally (photochromism of type T) or photochemically (photochromism of type P).
The terms 'switch-on' and 'switch-of' are sometimes used to denote the two directions
of the photochromic reaction.
