In this research, we aim to achieve sub-mK effective electron measurements to better analyze effects that occur at these very low temperatures. We do this by using a Faraday cage, through which we...Show moreIn this research, we aim to achieve sub-mK effective electron measurements to better analyze effects that occur at these very low temperatures. We do this by using a Faraday cage, through which we send a signal using sets of inductors. In order to test this, we define an effective frequency range for our signal by analyzing the theoretical electrical side effects that occur in our system. We perform multiple room temperature tests on our system within the defined frequency range, and work towards testing the effectiveness of our system at millikelvin temperatures as well.Show less
In this study we investigate if we can change the interfacial conductivity in LaAlO3/SrTiO3 heterostructures by adding some oxygen to the argon sputter gas. We vary the deposition parameters to...Show moreIn this study we investigate if we can change the interfacial conductivity in LaAlO3/SrTiO3 heterostructures by adding some oxygen to the argon sputter gas. We vary the deposition parameters to minimise the effect of the oxygen. We find that an increase in oxygen partial pressure increases the surface roughness. We also find that an increase in argon flow increases surface roughness. The optimised parameters, which minimise surface roughness, are in agreement with previous results of growing a conducting interface in LaAlO3/SrTiO3 by sputtering. However all our samples grown with oxygen are found to be insulating. A possible explanation for the effect of oxygen in the sputter gas is that the species oxidise before reaching the sample. We conclude that even a very small amount of oxygen in the sputter gas gives an insulating interface and that we can not make a conducting interface with oxygen in the sputter gas with the experimental set-up used.Show less
Using the notched wire mechanically controllable break junction technique charge transport of a single-molecule junction, containing the OPE3 molecule, is studied at room temperature. By deposition...Show moreUsing the notched wire mechanically controllable break junction technique charge transport of a single-molecule junction, containing the OPE3 molecule, is studied at room temperature. By deposition of molecules from solution between two gold leads we were able to determine the conductance of the OPE3 at (1.6±0.3)·10−4G0. The measurement speed of the LabVIEW control program for this experiment was improved by more than a factor of 7 compared to the previous version.Show less
This work examines the network structure of illicit marketplaces that operate on the darknet. These on-line marketplaces are crawled to obtain data of inter-user communications and this data is...Show moreThis work examines the network structure of illicit marketplaces that operate on the darknet. These on-line marketplaces are crawled to obtain data of inter-user communications and this data is parsed in a network structure and its physical properties are analysed. The Configuration Model is used as a null model to investigate the patterns in these networks to reveal information about their topology. This information is applied to interpret the behaviour of users within these illegal marketplaces.Show less
Colloidal particles at a liquid-liquid interface can order into interesting structures. In this work poly(methyl methacrylate) colloids with a core-shell structure have been synthesized and studied...Show moreColloidal particles at a liquid-liquid interface can order into interesting structures. In this work poly(methyl methacrylate) colloids with a core-shell structure have been synthesized and studied. They have been clustered to create anisotropic particles with regular shapes. Their structure is optimal for studies at water-oil interface with both bright field and confocal microscopy. The stability of the colloids has been tested in aqueous and organic media with single and clustered particles. Both single spherical particles and clusters have been observed at an water-oil interface. A computational project related to self-assembly problem in virus-like protein capsid is presented inShow less
To sense the movement or piling up of single charges, a system interacting strongly with these charges is required. An available system, having these properties, is a single electron transistor ...Show moreTo sense the movement or piling up of single charges, a system interacting strongly with these charges is required. An available system, having these properties, is a single electron transistor (SET). The electric fi eld caused by the charge, strongly changes the resistance of the SET. Yet experiments opt for a less invasive charge sensor. Such a proposed charge sensor is a single fluorescent dye molecule. The distinguishable zero phonon lines (ZPL's) of the fluorescence of the molecules shifts strongly by the Stark e ffect. The lineshift of each molecule can be tracked with an excitation laser, allowing to observe the change in charging. Tracking the ZPL's of multiple molecules allows the observation of slow charge movement. The optical charge sensing method needs to be tested on devices fabricated on a glass substrate. In particular devices, which exhibit single electron charging. These devices have been constructed with electron beam lithography (EBL). Nanoparticles, representing an island to hold the charge, have been trapped between nano-electrodes using dielectrophoresis. The nanogaps have been created by electromigration or by EBL. Eventually, nano-electrodes were also fabricated on glass by coating the glass with a 1,5 nm Cr layer. This coating was removed afterwards with plasma etching. The project focused on the fabrication of the devices. The deposition of fluorescent dye molecules and tracking the lineshifts was left for subsequent experiments. A fluorescence microscope, also necessary for the lineshift measurements, was used to observe quantum dots. Proposed experiments with quantum dots are the tracking of the movement of quantum dots in a strong alternating electric fi eld or the eff ect of a high electric field on the fluorescence of a quantum dot in a nano-electrode junction.Show less
