Master Degree / Yüksek Lisans Tezleri
Permanent URI for this collectionhttps://hdl.handle.net/11147/3008
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Master Thesis Investigating the Effect of Metallic Nanoparticles Presence on Signal Intensity for Dried-Droplet Analysis by Laser-Induced Plasma Spectroscopy(01. Izmir Institute of Technology, 2021) Tetik Karabıyık, Özge; Yalçın, Şerife HanımWhile solid sample analysis by LIBS is more easy and straightforward, liquid analysis is more troubling. One of the studies aimed at removing the problems in liquid analysis is the Nanoparticle Enhanced LIBS technique. This study aims to investigate the effect of the presence of Ag nanoparticles of different shape and absorption wavelengths on the signal strength of heavy metals Pb and Cr. For that purpose, spherical, prism, and disc-shaped silver nanoparticles with an absorption wavelength in the range of 394-761 nm were used. Among all types of NPs with different sizes and shapes, silver nanoparticles with an absorption maximum at 535 nm were found to enhance LIBS signal intensity of Pb element at 405.8 nm 5-6 times, and that of Cr at 428.9 nm 3-3.5 times. Under optimized conditions, a LOD value of 1,16 and 0.69 ppb were obtained for Pb and Cr, respectively. The applicability of the system for the determination of Pb and Cr in aqueous environments has also been tested on reference water samples. The silver nanoparticle with an maximum absorbance wavelength of 535 nm shows the most improvement in signal. The wavelength of the laser used is very close to the absorbance wavelength of the silver nanoparticle, effectively overlapping it. Thanks to the transmitted laser light, plasmons are formed on the nanoparticle surface. These formed surface plasmons interact with the laser electromagnetic field, resulting in an increase in the signal.Master Thesis Characterization of Ion Implanted Surfaces by Laser Induced Breakdown Spectroscopy, Libs(01. Izmir Institute of Technology, 2008) Örer, Sabiha; Yalçın, ŞerifeLaser Induced Breakdown Spectroscopy, LIBS, is a versatile atomic emission spectrometric technique for the determination of the elemental composition of solids, liquids, gases and aerosols with the need for little or no sample preparation.In this study, an optical LIBS system from its conventional parts was designed, constructed and optimized for spectrochemical analysis of solid materials. Specifically, the 2-D elemental distribution of Ge ions on silicon oxide surfaces, prepared by the method of ion implantation, with differing atomic concentrations between 1016 - 1017 ions/cm2 have been investigated by LIBS. For this purpose a Nd: YAG laser operating at the second harmonic wavelength, 532 nm, was used to create a plasma on the material surfaces. Spatially and temporally resolved atomic emission from the luminous plasma was detected by an Echelle spectroctrograph and Intensified Charged Coupled Device (ICCD) detector combination. Spectral emission intensity from the LIBS measurements has been optimized with respect to time, crater size, ablation depth and laser energy. Atomic Force Microscopy (AFM) and Scanning Electron Microscopy (SEM) coupled with Energy Dispersive X-Ray Spectroscopy (EDX) have been utilized to obtain crater depth, morphology and elemental composition of the sample material, respectively. LIBS spectral data revealed the possibility of performing 2-D distribution analysis of Ge ions over the silicon oxide substrate at Ge ion concentrations lower than 0.5% (atomic). LIBS as a fast semi-quantitative analysis method with 50.m lateral and 800 nm depth resolutions has been evaluated. In this wok, elemental analysis of some metal surfaces, such as Al and Cu, was also performed by LIBS.Keywords: LIBS, surface analysis, Ge ion implantation, lateral resolution,Master Thesis Identification and Detection of Phosphorylated Proteins by Laser Induced Breakdown Spectroscopy(Izmir Institute of Technology, 2011) Aras, Nadir; Yalçın, ŞerifeLaser-Induced Breakdown Spectroscopy (LIBS) is an optical atomic emission spectroscopic technique that uses an energetic laser source to generate a luminous plasma. Spectrochemical analysis of the light emitted from the plasma reveals information about the elemental composition of the sample. Phosphorylation is an important regulatory mechanism that activates or deactivates many proteins and enzymes in a wide range of cellular process. Identification and detection of phosphoproteins have a crucial importance in phosphopeptide mapping. This study is based on the assessment of the capabilities and limitations of LIBS as a quick and simple method for in-gel identification and determination of phosphorylated proteins, specifically casein and ovalbumin before mass spectrometric analysis for the elucidation of phosporylation sites. For this purpose, an optical LIBS set-up was constructed from its commercially available parts and the system was optimized for LIBS analysis of polyacrylamide gels. Nd:YAG laser operating at 532 nm wavelength and at 10 Hz frequency was used to create plasma on dry gel surfaces. Emitted light from a luminous plasma was analyzed and detected by an Echelle type spectrograph containing Intensified CCD, detector. With this study, LIBS detection of phosphorous proteins after electrophoretic separation of phosphorylated proteins has been shown, for the first time. After SDS-PAGE gel separation process, phosphoproteins were recognized from prominent P(I) lines (at 253.5 nm and 255.3 nm) in a plasma formed by the focused laser pulses on the gel, just in the center or in the vicinity of the electrophoretic spot. Spectral emission intensity of P(I) lines from LIBS data has been optimized with respect to laser energy and detector timing parameters by using standard Na2HPO4. It has been shown that phosphorylated proteins (casein and ovalbumin in mixture) can be identified by LIBS after both coomassie brilliant blue and silver staining procedures. Technique shows a great promise in microlocal spotting of phosphorylated proteins in gel before MS analysis for the determination of the phosphorylation sites.Master Thesis Laser Induced Breakdown Spectroscopic Analysis of Metal Aerosols Generated by Pneumatic Nebuliztion of Aqueous Solutions(Izmir Institute of Technology, 2010) Ateş Arıca, Dilek; Yalçın, ŞerifeLaser Induced Breakdown Spectroscopy, LIBS, is an analytical technique used to determine the elemental composition of samples in all forms. In this study, an experimental LIBS system has been designed and constructed for the analysis of metal aerosol particles that are generated by a pneumatic nebulizer. This research provides a basis and preliminary data for the construction of a portable LIBS system to analyze metals in aqueous environments.The aerosol particles generated from the pneumatic nebulizer travel through a sample introduction unit to reach the sample cell in which they interact with the laser beam. The source of light is a Nd:YAG laser at 532 nm, 10 Hz. When the laser beam is focused inside the sample cell, plasma is generated, and the emission containing the spectral information about the sample being analyzed is focused onto the spectrograph and detected by a gated detector. The optimum optical and experimental parameters were systematically investigated.The aqueous analyte solutions were prepared from their salts before introduced into the system. In this work, laser-induced breakdown spectroscopic emissions of Na, Ca, Mg and K aerosols were studied. In single shot mode, the minimum detectable aqueous concentrations were found as 250 ppb, 500 ppb, 400 ppb and 10 mg/L respectively. For 10 shot accumulated analyses in repetitive mode, based on 3. criterion, the detection limit (LOD) was determined as 1 mg/L, 0.6 mg/L, 1.5 mg/L and 16.3 mg/L respectively. The efficiency of the drying unit has been evaluated by particle size measurements. It has been shown that the Na aerosols with particle size of 4.3 .m decreases to 0.5 .m after passing through the membrane dryer unit.