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Optical characterisation of growth dynamics for colloidal gold nanoparticles in citrate environment

This study emphasises on detection and characterisation of gold nanoparticles based on its optical response. Water dispersed gold nanoparticles are synthesised from citrate reduction with dilute gold chloride under external energy sources. Three methods (i.e. heat-reflux, UV photoreaction, and UV ph...

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Main Author: Chong, Jia Cherng
Format: Thesis
Language:English
Published: 2020
Subjects:
QC Physics
Online Access:http://eprints.utm.my/id/eprint/102681/1/ChongJiaCherngPFS2020.pdf.pdf
http://eprints.utm.my/id/eprint/102681/
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spelling my.utm.1026812023-09-13T02:34:41Z http://eprints.utm.my/id/eprint/102681/ Optical characterisation of growth dynamics for colloidal gold nanoparticles in citrate environment Chong, Jia Cherng QC Physics This study emphasises on detection and characterisation of gold nanoparticles based on its optical response. Water dispersed gold nanoparticles are synthesised from citrate reduction with dilute gold chloride under external energy sources. Three methods (i.e. heat-reflux, UV photoreaction, and UV photoinitiation) were used as reaction energy source to produce the nanoparticles. Firstly, exact solution of Mie equations was vigorously tested by varying particle diameter for monodisperse and polydisperse size distributions to investigate its limitations and effects on extinction cross-sections respectively. Changes in peak extinction cross-sections due to effect of temperature are negligible even at 100 °C. Simulated fragmentation mechanism in the particle size distribution produced calculated extinction cross-section that are comparable to time-resolved experiments with λpk blue-shifted from approximately 610 nm to 520 nm. Secondly, verification of size distribution derived from photon correlation spectroscopy and small angle X-ray scattering was carried out with extinction profile used as comparison; the results shows general agreement between these instruments with mode particle size ranged from 20 nm to 80 nm. However, size distribution derived from small angle X-ray scattering produced expected extinction lower than measured values for λ > 600 nm. Thus, the following characteristics of the colloid are as follows: in general, heat-refluxed nanoparticles are smaller compared to UV synthesised particles. Weaker incident photon energy produced consistently larger particles with broader size distribution and emerged later when compared reactants exposed to high energy UV. The isoelectric point for our colloidal system was measured at pI = 2.31 ± 0.56. Lastly, time-resolved scattering measurements were carried out in three separate experiments involving photon correlation spectroscopy and home-built configurations. They collectively indicate the likelihood of fragmentation mechanism in particle size distribution during the time as the colloidal colour turn from transparent to blue. 2020 Thesis NonPeerReviewed application/pdf en http://eprints.utm.my/id/eprint/102681/1/ChongJiaCherngPFS2020.pdf.pdf Chong, Jia Cherng (2020) Optical characterisation of growth dynamics for colloidal gold nanoparticles in citrate environment. PhD thesis, Universiti Teknologi Malaysia. http://dms.library.utm.my:8080/vital/access/manager/Repository/vital:145882
institution Universiti Teknologi Malaysia
building UTM Library
collection Institutional Repository
continent Asia
country Malaysia
content_provider Universiti Teknologi Malaysia
content_source UTM Institutional Repository
url_provider http://eprints.utm.my/
language English
topic QC Physics
spellingShingle QC Physics
Chong, Jia Cherng
Optical characterisation of growth dynamics for colloidal gold nanoparticles in citrate environment
description This study emphasises on detection and characterisation of gold nanoparticles based on its optical response. Water dispersed gold nanoparticles are synthesised from citrate reduction with dilute gold chloride under external energy sources. Three methods (i.e. heat-reflux, UV photoreaction, and UV photoinitiation) were used as reaction energy source to produce the nanoparticles. Firstly, exact solution of Mie equations was vigorously tested by varying particle diameter for monodisperse and polydisperse size distributions to investigate its limitations and effects on extinction cross-sections respectively. Changes in peak extinction cross-sections due to effect of temperature are negligible even at 100 °C. Simulated fragmentation mechanism in the particle size distribution produced calculated extinction cross-section that are comparable to time-resolved experiments with λpk blue-shifted from approximately 610 nm to 520 nm. Secondly, verification of size distribution derived from photon correlation spectroscopy and small angle X-ray scattering was carried out with extinction profile used as comparison; the results shows general agreement between these instruments with mode particle size ranged from 20 nm to 80 nm. However, size distribution derived from small angle X-ray scattering produced expected extinction lower than measured values for λ > 600 nm. Thus, the following characteristics of the colloid are as follows: in general, heat-refluxed nanoparticles are smaller compared to UV synthesised particles. Weaker incident photon energy produced consistently larger particles with broader size distribution and emerged later when compared reactants exposed to high energy UV. The isoelectric point for our colloidal system was measured at pI = 2.31 ± 0.56. Lastly, time-resolved scattering measurements were carried out in three separate experiments involving photon correlation spectroscopy and home-built configurations. They collectively indicate the likelihood of fragmentation mechanism in particle size distribution during the time as the colloidal colour turn from transparent to blue.
format Thesis
author Chong, Jia Cherng
author_facet Chong, Jia Cherng
author_sort Chong, Jia Cherng
title Optical characterisation of growth dynamics for colloidal gold nanoparticles in citrate environment
title_short Optical characterisation of growth dynamics for colloidal gold nanoparticles in citrate environment
title_full Optical characterisation of growth dynamics for colloidal gold nanoparticles in citrate environment
title_fullStr Optical characterisation of growth dynamics for colloidal gold nanoparticles in citrate environment
title_full_unstemmed Optical characterisation of growth dynamics for colloidal gold nanoparticles in citrate environment
title_sort optical characterisation of growth dynamics for colloidal gold nanoparticles in citrate environment
publishDate 2020
url http://eprints.utm.my/id/eprint/102681/1/ChongJiaCherngPFS2020.pdf.pdf
http://eprints.utm.my/id/eprint/102681/
http://dms.library.utm.my:8080/vital/access/manager/Repository/vital:145882
_version_ 1778160766042505216
score 13.211869

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