• Login
    View Item 
    •   Home
    • UA Graduate and Undergraduate Research
    • UA Theses and Dissertations
    • Dissertations
    • View Item
    •   Home
    • UA Graduate and Undergraduate Research
    • UA Theses and Dissertations
    • Dissertations
    • View Item
    JavaScript is disabled for your browser. Some features of this site may not work without it.

    Browse

    All of UA Campus RepositoryCommunitiesTitleAuthorsIssue DateSubmit DateSubjectsPublisherJournalThis CollectionTitleAuthorsIssue DateSubmit DateSubjectsPublisherJournal

    My Account

    LoginRegister

    About

    AboutUA Faculty PublicationsUA DissertationsUA Master's ThesesUA Honors ThesesUA PressUA YearbooksUA CatalogsUA Libraries

    Statistics

    Most Popular ItemsStatistics by CountryMost Popular Authors

    Characterization of the Photosensitive Response in Polysilane-based Organic/Inorganic Hybrid Materials

    • CSV
    • RefMan
    • EndNote
    • BibTex
    • RefWorks
    Thumbnail
    Name:
    azu_etd_2499_sip1_m.pdf
    Size:
    1.341Mb
    Format:
    PDF
    Description:
    azu_etd_2499_sip1_m.pdf
    Download
    Author
    Chandra, Haripin
    Issue Date
    2007
    Keywords
    Polysilane
    photosensitive
    polysilylene
    photoinduced
    photopatterning
    Advisor
    Potter, Barrett G.
    Potter, Kelly S.
    Committee Chair
    Potter, Barrett G.
    
    Metadata
    Show full item record
    Publisher
    The University of Arizona.
    Rights
    Copyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.
    Abstract
    The motivation for the current work stems from a unique application, i.e. the photopatterning of optical functionality in a photosensitive material immediately prior to use. In this case, optical devices such as diffraction gratings and optical interconnects are produced in thin films using integrated photonic sources under relatively uncontrolled environmental conditions. The compatibility of the material photoexcitation mechanism with wavelength and fluence levels available from compact solid-state optical sources and the need to understand the impact of local atmospheric composition and temperature on the photosensitive material response are therefore of primary concern. The primary goal of the current study was to investigate photoexcitation mechanisms and photoinduced optical and structural changes in promising candidate material systems for this application: polysilane and polygermane-based molecular hybrid polymers. The work pursued the development of a fundamental understanding of the key photophysical and photostructural responses of thin films composed of both pure, linear-chain polysilanes and of a Ge-Si copolymer. The effects of molecular modifications to the polymers, including polymer backbone catenate structure and side-group identity, on the optical and photosensitive behavior observed in these systems are examined. Through such effort, an understanding of how such structural characteristics influence key photosensitive properties, i.e. the excitation wavelength and the resulting photoinduced optical property changes, was attained. A related objective in the present work was to characterize the thermal stability of these hybrid polymers, specifically in terms of the effect of thermal treatment on as-deposited and photomodified materials. In this case, an evaluation of the similarities and differences in structural modification in response to both thermal and optical fields was pursued. The primary mechanism associated with the photoinduced phenomena observed in both polysilane and polygermane involves backbone chain scissioning and the formation of silane-radicals upon absorption of near-UV (λ ≈ 300 to 400 nm) photons, resonant with the lowest energy, σ - σ* (HOMO-LUMO) transition of the Group IVA backbone. The final photoproducts obtained result from a mixture of different competing processes which occur subsequent to this initial photoscissioning. In aerobic atmospheric environments, the radicals formed capture oxygen and form oxide linkages forming the dominant photoproducts. On the other hand, under anaerobic conditions, photooxidation is suppressed while hydride passivation of the radical dominates the response. The oxidized product, resulting from irradiation under the aerobic environment, exhibited higher refractive index changes than irradiation under anaerobic conditions. Photoexcitation using higher energy photons (typically λ ≈ 230 to 300 nm) are resonant with side-group transitions associated with π-conjugated states of the cyclic moieties. Under these conditions, the excitation accesses both these organic side-groups as well as the Group IVA backbone structure. Such excitation conditions resulted in a larger photoinduced structural modification in the irradiated polymer, as observed both in terms of its electronic structure as well as the resulting refractive index change. Thermally induced structural modification to the backbone and side-group moieties were found to be qualitatively similar those produced under optical irradiation. For example, the primary structural changes were again associated with backbone chain scissioning. Photoinduced structural modifications through resonant optical excitation of the material, however, tended to be more focused on the specific structural moieties accessed.
    Type
    text
    Electronic Dissertation
    Degree Name
    PhD
    Degree Level
    doctoral
    Degree Program
    Materials Science & Engineering
    Graduate College
    Degree Grantor
    University of Arizona
    Collections
    Dissertations

    entitlement

     
    The University of Arizona Libraries | 1510 E. University Blvd. | Tucson, AZ 85721-0055
    Tel 520-621-6442 | repository@u.library.arizona.edu
    DSpace software copyright © 2002-2017  DuraSpace
    Quick Guide | Contact Us | Send Feedback
    Open Repository is a service operated by 
    Atmire NV
     

    Export search results

    The export option will allow you to export the current search results of the entered query to a file. Different formats are available for download. To export the items, click on the button corresponding with the preferred download format.

    By default, clicking on the export buttons will result in a download of the allowed maximum amount of items.

    To select a subset of the search results, click "Selective Export" button and make a selection of the items you want to export. The amount of items that can be exported at once is similarly restricted as the full export.

    After making a selection, click one of the export format buttons. The amount of items that will be exported is indicated in the bubble next to export format.