Disperse Orange 1 is a dye

Dye

A dye is a colored substance that has an affinity to the substrate to which it is being applied. The dye is generally applied in an aqueous solution, and requires a mordant to improve the fastness of the dye on the fiber....

 of the azobenzene

Azobenzene

Azobenzene is a chemical compound composed of two phenyl rings linked by a N=N double bond. It is the best known example of an azo compound. The term 'azobenzene' or simply 'azo' is often used to refer to a wide class of molecules that share the core azobenzene structure, with different chemical...

 class. Disperse Orange 1 contains approximately 25% dye by weight, with the remaining mass consisting of NaCl

Sodium chloride

Sodium chloride, also known as salt, common salt, table salt or halite, is an inorganic compound with the formula NaCl. Sodium chloride is the salt most responsible for the salinity of the ocean and of the extracellular fluid of many multicellular organisms...

 and other salts. This dye is useful in conducting experiments with flash photolysis

Flash photolysis

Flash photolysis is a pump-probe laboratory technique, in which a sample is firstly excited by a strong pulse of light from a laser of nanosecond, picosecond, or femtosecond pulse width or by a short-pulse light source such as a flash lamp...

 due to the isomerization effect between the trans-4A4N and cis-4A4N states that occurs during photo relaxation.