Ultraviolet light refers to invisible light with a wavelength range of 100-400 nm. Different wavelengths of ultraviolet light have different functions.
Ultraviolet light is divided into four parts according to wavelength:
A-band, called black spot effect ultraviolet (400-320nm), has attached pigment and photochemical effect, also known as chemical line;
B-band, called erythema effect ultraviolet (320-275nm), can promote the production of vitamin D, which is called health line;
C-band, called sterilization ultraviolet (275-200nm), has sterilization effect;
D-band, called vacuum ultraviolet (200-100nm), can effectively produce ozone.
Ultraviolet disinfection is a physical disinfection method, which does not kill microorganisms (bacteria, viruses, spores and other pathogens), but makes them lose their reproductive ability and inactivate them.
The principle of ultraviolet disinfection is usually considered to use ultraviolet C-band (UV-C) to change and destroy the genetic material nucleic acid (DNA or RNA) of microorganisms, so that organisms lose the ability of protein synthesis, replication and reproduction.
Ultraviolet disinfection mainly adopts C-band, as shown in the figure below. The absorption spectrum of DNA is 240-280nm, and the absorption peak is about 260nm.
