%0 Generic
%9 Master's Thesis
%A Deering, Thomas
%D 2020
%F pittir:38634
%K sol-gel, inverse opal, photonic crystal, Bragg diffraction
%T Inward-Growing Self-Assembly of Inverse Opal Deep UV Wavelength-Selecting Device
%U http://d-scholarship-dev.library.pitt.edu/38634/
%X Photonic crystals (PhCs) are materials which use spatial modulations in their refractive   index to affect the propagation of light. PhCs possess photonic stopbands, at which significant   amounts of light of particular wavelengths are Bragg diffracted. The diffraction properties of PhCs   have previously been utilized for wavelength-selecting devices (WSDs) for spectrometers.   Previous PhC-based WSDs consisted of particles suspended in water, and therefore were not   mechanically robust, while solid WSDs diffusely scattered most of the incident light. Therefore,   we developed the inward-growing co-assembly method to fabricate solid deep UV-diffracting   PhCs with low diffuse scattering.      We self-assembled polystyrene nanoparticles (PSNPs) on a horizontal substrate while sol  gel reactions of a silicate precursor formed an ordered network of silica around the PSNPs.   Removing the PSNPs by dissolution in tetrahydrofuran (THF) and piranha solution yielded an   inverse opal (IO) consisting of an ordered array of air voids surrounded by the silica network. This   IO diffracts deep UV light with much less diffuse scattering than previously-published deep UV  diffracting IOs. Scanning electron microscopy (SEM) shows that removing the PSNPs using THF   and piranha solution does not deform the silica network to the same extent as other methods like   calcination. The diffraction band of these IOs is narrower and more intense than our group’s   previously-published deep UV-diffracting IO, and the diffuse scattering is much lower. Further   optimization of this method could produce WSDs that are sufficiently selective for use in deep UV   spectrometers.