Optically Active Chiral Mediums Fabricated with Glancing Angle Deposition

dc.contributor.authorYang, Jianen
dc.contributor.departmentPhysics, Engineering Physics and Astronomyen
dc.contributor.supervisorRobbie, Kevinen
dc.date2012-07-06 09:59:20.751
dc.degree.grantorQueen's University at Kingstonen
dc.descriptionThesis (Ph.D, Physics, Engineering Physics and Astronomy) -- Queen's University, 2012-07-06 09:59:20.751en
dc.description.abstractOptically active helical microparticles are studied in the forms of thin films, suspensions and powders. From fabricated helical porous thin films, microparticle suspensions are obtained by removing the microparticles (film columns) from their substrates and dispersing them into water. For removing microparticles, four methods are explored and compared: sacrificial NaCl layer, gold (Au) layer, buffered oxide etching, and direct ultrasonic agitation. The primary film material studied in this work is amorphous silicon (Si). Physical morphology of the microparticles is examined with scanning electron microscopy (SEM). Methods employed to characterize optical activity of the microparticles include: polarimetry, spectrophotometry, and spectroscopic ellipsometry (SE). The produced chiral microparticles exhibit optical activity: optical rotation (OR) and circular dichroism (CD - in the form of differential circular transmission (DCT)). Significant findings include: (a) we observe the largest optical rotatory power ever reported in scientific literature, 11◦/μm at 610 nm wavelength for a Si film; (b) for the helical thin films, there is one dominant DCT band in the measured wavelength range; however for microparticle suspensions and powders, there exist two DCT bands: one broad band at long wavelengths, and one narrow band in the short wavelength range; compared to their thin film forms, microparticle suspensions and powders have inverted sign for the broad DCT band. A discrete dipole approximation (DDA) model is employed to calculate optical response (e.g. extinction, scattering, and absorption cross-sections) of the microparticles, so as to enable us to understand the effects of different structural parameters of the microparticles on their optical response. Calculation confirms that optical activity of chiral microparticles is due to coherent light scatterings with the chiral structures of the particles. The inversion in sign of the broad DCT bands of microparticle suspensions and powders is likely due to the averaging effect from random orientation of the helical microparticles, as is indicated both from experimental results and from calculation.en
dc.relation.ispartofseriesCanadian thesesen
dc.rightsThis publication is made available by the authority of the copyright owner solely for the purpose of private study and research and may not be copied or reproduced except as permitted by the copyright laws without written authority from the copyright owner.en
dc.subjectGlancing Angle Depositionen
dc.subjectBi-Isotropic Mediumsen
dc.subjectDiscrete Dipole Approximationen
dc.subjectIsotropic Chiral Mediumsen
dc.subjectMueller Matrixen
dc.subjectOptical Activityen
dc.subjectCircular Dichroismen
dc.subjectChiral Microparticlesen
dc.subjectOptical Rotation Dispersionen
dc.subjectTThin Filmsen
dc.titleOptically Active Chiral Mediums Fabricated with Glancing Angle Depositionen
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