Browsing by Subject "Absorbance"
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Item Open Access Chemical modulation of singlet oxygen generation rates in thermal endoperoxide decomposition & novel fluorescent sensors for hyperphosporylated tau proteins(Bilkent University, 2016-05) Kaya, CansuChemical control over singlet oxygen generation is an open to improvement because of the importance of this reactive species in biological systems. In the first project, we aimed to synthesize a silylated 1,4-dimethylnaphthalene endoperoxide derivative which is expected to release singlet oxygen on thermolysis at a relatively slow rate at room temperature. Upon the deprotection of the silyl units with fluorine ions, it is expected it to release singlet oxygen at a much higher rate, giving rise to a control over the release of the product. The absorption and the fluorescence measurement with a trap molecule which consumes the generated singlet oxygen reveals promising results for the future work for the control of singlet oxygen generation rates. In the second part of this thesis, we focused on the synthesis of a novel fluorescent sensor of a BODIPY derivative which is capable of sensing Zinc cations. The zinc complex is also expected to have a further usage for the sensing of hyperphosphorylated tau proteins, which are commonly produced in the brains of people with Alzheimer’s disease. With this, it has a potential usage in the field of early detection of Alzheimer’s disease.Item Open Access Synthesis of nanoparticles by laser ablation in liquid method and optical applications(Bilkent University, 2023-08) Taylan, UmutPulsed laser ablation in liquids (PLAL) method is a fast, green, and straightforward method that can be used to synthesize pure nanoparticles free of ligands, capping agents, and waste products. Several types of nanoparticles such as metals, oxides, alloys, semiconductors, composite and compound nanoparticles with spherical or complex morphologies can be synthesized with PLAL method. In this thesis, AuCu nanoparticles for photovoltaic application, AgCu nanoparticles for tunable optical properties, CuS/Cu1.8S nanoparticles for photothermal and photoacoustic application, and (Y0.83Yb0.16Er0.01)2O3 nanoparticles for upconversion photoluminescence application are synthesized. The synthesized AuCu nanoparticles are used in organic solar cells and enhanced the photocurrent production, proven by the 21.4% increase in the power conversion efficiency. AgCu nanoparticles show composition and laser fragmentation dependent tunable surface plasmon resonance between 420 nm – 580 nm, giving 160 nm tunability. These nanoparticles also show complex morphologies with Janus nanoparticle and core-shell type configurations. Copper sulphide nanoparticles show a broad absorbance in the NIR region with absorbance peak at 1183 nm. Nanoparticles with 1 mg/mL concentration show a 52.2 °C temperature increase in 3 minutes of 3.23 W/cm2 1080 nm CW laser irradiation. Photoacoustic imaging experiments where copper sulphide nanoparticles are utilized show a significant contrast enhancement compared to ultrasonic imaging at 1 cm depth. The upconversion nanoparticles show an intense red emission at 651 nm from 980 nm laser irradiation and lowered green emission compared to the target material which shows nanoparticles produce more heat compared to the target which can be useful for photoluminescence – photothermal applications.