The surface luminescence of silica nanospheres depending on different excitation wavelengths and accompanied photochemical reactions

We report a novel scheme for investigating the emission on the surface of silica depending on different excitation wavelengths and accompanied photochemical reactions. Silica nanospheres with a typical feature of quality fractal are fabricated by drying out the hydrolysates of tetraethylorthosilicate in alcohol-absent aqueous solution. The residual organic groups sustain a comparatively stable surface system, kinetically hindering the relaxation of the defect structures. This surface state provides stable and intermediate energy states to accommodate the excitation electrons. Multiphoton processes accelerate the dissociation energy of the Si–O bond and therefore, greatly decrease the photoreaction threshold of photochemical reactions. Thus, different radiation energy stimulates different photochemical processes and thereby creates different luminescence centers on the surface of silica. It becomes possible to tune the position of the emission band by adjust the excitation conditions. The study is significant not only in control and adjusts the surface defects, but also in color-tunable optoelectronic nanodevice.