Phosphorescent sheet glows after lighting only by blue and UV light
name: Phosphorescence is initiated by light of specific spectrum
Phosphorescent glow-in-the-dark vinyl sheets contain ZnS doped Cu. For phosphorescence to arise, electrons of ZnS doped copper must be excited by sufficient energy. Photons of red (630 nm), orange (605 nm), yellow (592 nm) and green (525 nm) do not have sufficient energy to excite the electrons. But blue (470 nm), violet (405 nm) and UV (>400 nm) light photons can excite electrons. The greater the energy, the more intense is the glow. The maximum of absorption of light is 365 nm.
During phosphorescence conversion of the excited singlet state to a lower energy excited triplet state occurs. Then all excited electrons return to initial ground state and emit the light with a wavelength of 520 nm.