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; Yalçın, Şerife Hanım; 04.01. Department of Chemistry; 04. Faculty of Science; 01. Izmir Institute of TechnologyWhile 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, Şerife; Yalçın, Şerife; 04.01. Department of Chemistry; 04. Faculty of Science; 01. Izmir Institute of TechnologyLaser 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,