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Raman characterization of iodine nanostructures formed in channels of an A1PO[subscript 4]-11 single crystal

Authors Peng, Wei Wei
Issue Date 2009
Summary Various iodine nanostructures have been synthesized by introducing iodine molecules into the channels of AlPO4-11 single crystals by physical diffusion method. Since the pure AlPO4-11 single crystals are optically transparent from ultraviolet to near infrared, the optical properties of these nanostructures may have a great potential in application. The main task of this thesis is to confirm the geometrical structures and also their optical properties by optical characterization. Polarized Raman spectra have been investigated to give the geometrical information of these structures. Due to size confinement of AlPO4-11 channels, iodine molecules are confined in a plane. The structures can be validated by comparing the Raman signals of these structures and that of known structures. The detailed information, that the molecules can only orient along or perpendicular the channel direction, are given by the polarized Raman spectra using three different measurement methods. The structures existing in the channels can be altered by changing the iodine loading density. Vapor like molecules, one dimensional iodine chains and iodine sheets which is crystal like are found to exist in the channels. The electronic band structures of iodine nanostructures can be revealed by Resonant Raman spectroscopy and polarized absorption spectroscopy. The density increases from vapor like molecules to iodine chains, then to iodine sheets. The band gap decreases with increase density of the structure. This result is consistent with theoretical assumption.
Note Thesis (M.Phil.)--Hong Kong University of Science and Technology, 2009
Language English
Format Thesis
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