EFFECT OF POROSITY ON INFRARED-ABSORPTION SPECTRA OF SILICON DIOXIDE

The infrared-absorption spectra of silicon dioxide have been studied for many years and most of the peaks have been identified. During the investigation of silicon dioxide deposited by the liquid-phase-deposition technique, an interesting phenomenon was observed. It was found that the intensity ratio between the side lobe (1200 cm-1) and main peak (1090 cm -1) varies and depends on both the concentration of boric acid and the dilution ratio of the growth solution. Measurement of the refractive index shows that the material with larger absorption at 1200 cm-1 has a smaller index and thus more porous structure; therefore, the peak at 1200 cm-1 is suggested to arise from porous oxide, i.e., Si - O - Si, in a large void. © 1995 American Institute of Physics.