Modification of photoluminescence spectrum of artificial opal under external effects

The effects of washing and heat treatment on photoluminescence (PL) behavior from artificial opals are studied. The PL spectra excited by N2-laser radiation (337 nm) display a broad maximum at around 435 nm and range from ∼340 to ∼700 nm. It is found that washing of the opal in different solvents and liquids leads to suppression of the long wavelength PL band at ∼500 nm, whereas heat treatment in air and vacuum results in a decrease in intensity of both of the PL bands. The obtained results indicate that the emission centers located on the surface of SiO2 spheres constructing artificial opal may be responsible for the PL band around ∼500 nm.