Browsing by Subject "Carbon Nanotubes"

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Open Access
Excitonics of semiconductor quantum dots and wires for lighting and displays
(Wiley-VCH Verlag, 2013) Guzelturk, B.; Martinez, P. L. H.; Zhang, Q.; Xiong, Q.; Sun, H.; Sun, X. W.; Govorov, A. O.; Demir, Hilmi Volkan
In the past two decades, semiconductor quantum dots and wires have developed into new, promising classes of materials for next-generation lighting and display systems due to their superior optical properties. In particular, exciton-exciton interactions through nonradiative energy transfer in hybrid systems of these quantum-confined structures have enabled exciting possibilities in light generation. This review focuses on the excitonics of such quantum dot and wire emitters, particularly transfer of the excitons in the complex media of the quantum dots and wires. Mastering excitonic interactions in low-dimensional systems is essential for the development of better light sources, e.g., high-efficiency, high-quality white-light generation; wide-range color tuning; and high-purity color generation. In addition, introducing plasmon coupling provides the ability to amplify emission in specially designed exciton-plasmon nanostructures and also to exceed the Forster limit in excitonic interactions. In this respect, new routes to control excitonic pathways are reviewed in this paper. The review further discusses research opportunities and challenges in the quantum dot and wire excitonics with a future outlook.
Open Access
Persistent currents in carbon nanotubes
(2003) Çetiner, Sinem Binicioğlu
Carbon nanotubes are one of the most important findings of physics in the recent years. They are of great interest because of their various electrical, and mechanical features. All the properties of the nanotubes are being investigated thoroughly. In my thesis, two dimensional helical potential is introduced. The problem takes the type of Kronig-Penney model when Hamiltonian is separated into two parts. I will investigate the persistent currents in helical nanotubes. Persistent currents are due to the external vector potential. Vector potential was first introduced as a mathematical tool, later Aharonov and Bohm showed that vector potential has effect on charged particles even there is no magnetic field (i.e. field is confined into a solenoid).
Open Access
Tailoring insoluble nanobelts into soluble anti-UV nanopotpourris
(Royal Society of Chemistry, 2011) Wang, J.; Sun, X. W.; Jiao, Z.; Khoo, E.; Lee, P. S.; Ma, J.; Demir, Hilmi Volkan
Soluble, transparent and anti-UV nanopotpourris have been prepared by tailoring long nanobelts. The strains and layered structures facilitate the breaking of the as-synthesized nanobelts under an applied mechanical action. The developed tailoring process of nanobelts is a general top-down secondary processing of layered nanostructures at the nanoscale level, which can be expended to the modifications of layered nanowires, nanotubes and hierarchical nanostructures. By tailoring, the size, morphology and solubility are modified, which may open up an area of advanced processing of nanomaterials and hint at some potential applications. Because of the excellent solubility of the tailored nanopotpourris, they are easily dispersed in cosmetics or polymer films, which are quite useful for some anti-UV protection applications, such as anti-UV sunscreen creams and anti-UV window films for vehicles and buildings.