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1.3 PHYSICAL SCIENCES, Optics
We report the redistribution of colloidal zeolite Beta nanoparticles during holographic recording in acrylamide-based photopolymers. Using the techniques of confocal Raman spectroscopy and scanning electron microscopy coupled with energy dispersive x-ray analysis (SEM–EDX), we have observed a periodic pattern, whose spacing agrees with the fringe spacing of the recorded holographic diffraction grating. It was estimated that the fraction of nanoparticles redistributed as a result of the holographic recording is 40%. The effect of the nanoparticles on the average refractive index of the nanocomposite layers was studied by UV–visible spectroscopy. It was observed that the addition of zeolite nanoparticles leads to an increase of the photopolymer layer’s thickness, and this is ascribed to the interaction between molecules of monomer and the zeolite nanoparticles, further supported by Raman spectroscopic studies, indicating that these nanoparticles are not an entirely inert additive. The holographic recording properties of the new nanocomposite were characterized and no significant improvement of the net refractive index modulation was observed. This result is explained after taking into account two main factors influencing the final refractive index modulation—the redistribution of the nanoparticles and the change in the monomer’s volume concentration due to change in the thickness of the solid layers. The results presented here contribute to insights about the role of nanoparticles in the mechanism of holographic recording in acrylamide-based photopolymeric systems. The zeolite nanoparticle redistribution achieved in this new nanocomposite could be useful for the fabrication of holographic sensors, as demonstrated by initial studies with toluene.
Leite, E. et al. (2009) Investigation of the light induced redistribution of zeolite beta nanoparticles in an acrylamide-based photopolymer. Journal of Optics A: Pure and Applied Optics, vol. 11, no. 2. doi:10.1088/1464-4258/11/2/024016