One important driving force in nanotechnology today is the change which can be made in the properties of a material when the dimensions of its individual building blocks are decreased below approximately 100 nm. Such small building blocks, typically nanoparticles, may induce new and unique properties compared to those of the corresponding bulk material. The challenge in nanotechnology is to make nanoparticles with a discrete particle size within the range 1-10 nm. It is also important to develop appropriate assembly methodologies in order to construct devices composed of such small building blocks.This thesis reports iron nanoparticle synthesis using laser-assisted photolysis of ferrocene. The particles were protected against oxidation by a carbon shell formed in situ during their growth. By varying the experimental conditions such as fluence, repetition rate and laser beam area, particles could be synthesized in the size range 1 to 100 nm. Their size was measured using a differential mobility analyser (DMA), transmission electron microscopy (TEM) and X-ray diffraction (XRD). DMA was also used successfully to size-select particles to facilitate the deposition of monodisperse nanoparticle films.A theoretical “residence time approach (RTA)” model was developed to relate particle volume to the laser parameters used. The growth of these particles was studied in situ using optical emission spectroscopy; the results were compared with those from quantum mechanical calculations. The particles were characterised ex situ by TEM, convergent beam electron diffraction…
Contents
1 Nanoparticles
2 Synthesis of nanoparticles
3 Growth of nanoparticles
3.1 Optical emission spectroscopy
3.1.1 Determination of nanoparticle temperature
3.2 Theoretical calculations
3.2.1 Density functional theory
3.2.2 Molecular dynamics
4 Size determination of nanoparticles
4.1 Differential mobility particle sizer
5 Synthesis of carbon-covered iron nanoparticles
5.1 Experimental set-up
5.2 Experimental parameters
5.3 Ferrocene as LCVD precursor
5.4 Particle characterisations
6 Growth of carbon-covered iron nanoparticles
7 Size control and size selection of carbon-covered iron nanoparticles
8 Concluding remark
Acknowledgements
References
Author: Elihn, Karine
Source: Uppsala University Library
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