The key principle of ultraviolet fluorescent ink is to add visible fluorescent (complex) compound with ultraviolet excitation to the ink. Through the absorbed light energy, the energy level transition of the atom is generated, and the absorbed additional energy is released. The anti-counterfeiting feature is to emit visible light of red, yellow, green and blue (400nm-800nm) under ultraviolet light (200nm-400nm).
This ink is divided into colored and colorless, there are two kinds of long wave (365nm) and short wave (254nm). The fluorescent pigment is an organic complex, which is finely ground and has high luminous efficiency. It is usually colorless or light white. (200nm ~ 400nm) irradiation, the square presents various colors of visible light (400nm ~ 800nm). According to the wavelength of the excitation light source, it can be divided into short-wave ultraviolet-excited fluorescent pigments (excitation wavelength of 254nm) and long-wave ultraviolet-excited pigments (excitation wavelength of 365nm).
The highlighter has a fluorescent agent, which produces a fluorescent effect when it encounters ultraviolet rays (sunlight, fluorescent lamps, mercury lamps are more), and emits white light, which makes the color look dazzling and fluorescent.
Nowadays, there are also colorless highlighters that can be hidden. There is no color after writing, and the content of the writing can be displayed when the purple light behind the pen is illuminated.