G PHYSICS
G01 MEASURING; TESTING
G01N INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
21/00 Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
G01N21/75 Systems in which material is subjected to a chemical reaction, the progress or the result of the reaction being investigated