Date of Award

12-2019

Degree Name

Master of Arts

Department

Physics

First Advisor

Dr. Asghar N. Kayani

Second Advisor

Dr. Paul Pancella

Third Advisor

Dr. Ramakrishna Guda

Keywords

Gold nanoparticles, ion implantation, fluence, Rutherford Backscattering Spectrometry, UV/Vis Spectroscopy

Access Setting

Masters Thesis-Open Access

Abstract

Gold negative ions of 70 keV energy were implanted within the quartz substrates at room temperature at seven different fluences starting from 2 x 1016 particles/cm2 to 8 x 1016 particles/cm2 with the increment of 1 x 1016. Prior to the implantation, Stopping and Range of Ions in Matter (SRIM) calculations were carried to obtain the Bragg peak below the surface of quartz. Rutherford Backscattering Spectrometry (RBS) was carried out using 2.0 MeV He++ ions to measure depth and implanted fluence of gold, and learn how they varied with fluence. Backscattered He particles were recorded by a surface barrier silicon detector at 150o scattering angle. Exit angle for the RBS measurements was 30o. UV/Vis measurements were carried out to detect and obtain the Localized Surface Plasmon Resonance (LSPR) of Au nanoparticles with in the quartz substrate.

From RBS data, the Au concentration below the surface of the substrate was observed to increase with the fluence. Increase in fluence creates a higher density of Au atoms in the implant layer, thereby increasing the number of Au nanoparticles developed in quartz. However, saturation in the implanted Au fluence was found to occur at 5 x 1016 particles/cm2. Moreover, as the implanted fluence was increased, Au nanoparticles nucleated closer to the surface of the substrate.

UV/Vis data on the implanted substrates gave the characteristic LSPR peak indicating the formation of Au nanoparticles. Moreover, UV/Vis measurement showed an increase in the optical absorption of the Au nanoparticles with the increase in Au implanted fluence, indicating an increased formation of the Au nanoparticles within the substrate. Also, with the increase in fluence the LSPR peak was redshifted, which could be attributed to either the increase in size of nanoparticles or the formation of hotspots or both.

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