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Inward-Growing Self-Assembly of Inverse Opal Deep UV Wavelength-Selecting Device

Deering, Thomas (2020) Inward-Growing Self-Assembly of Inverse Opal Deep UV Wavelength-Selecting Device. Master's Thesis, University of Pittsburgh. (Unpublished)

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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


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Item Type: University of Pittsburgh ETD
Status: Unpublished
CreatorsEmailPitt UsernameORCID
Deering, Thomastjd67@pitt.edutjd67
ETD Committee:
TitleMemberEmail AddressPitt UsernameORCID
Committee ChairAsher, Sanfordasher@pitt.eduasher
Committee MemberWaldeck, Daviddave@pitt.edudave
Committee MemberLiu, Haitaohliu@pitt.eduhliu
Date: 8 June 2020
Date Type: Publication
Defense Date: 27 March 2020
Approval Date: 8 June 2020
Submission Date: 8 April 2020
Access Restriction: No restriction; Release the ETD for access worldwide immediately.
Number of Pages: 61
Institution: University of Pittsburgh
Schools and Programs: Dietrich School of Arts and Sciences > Chemistry
Degree: MS - Master of Science
Thesis Type: Master's Thesis
Refereed: Yes
Uncontrolled Keywords: sol-gel, inverse opal, photonic crystal, Bragg diffraction
Date Deposited: 08 Jun 2020 15:06
Last Modified: 08 Jun 2020 15:06


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