So far, most well-known helioscopes have to be aligned manually with the ever-changing position of the sun in the sky. In this project, it was assessed whether a gas- or liquid-filled transparent...Show moreSo far, most well-known helioscopes have to be aligned manually with the ever-changing position of the sun in the sky. In this project, it was assessed whether a gas- or liquid-filled transparent sphere has adequate potential to function as a helioscope. If this would be possible, this helioscope would allow for omnidirectional imaging, solving the problem of constant manual adjustment. The numerical assessment of this gas- or liquid-filled ball lens was done with the help of a ray-tracing simulation, which was tested and confirmed by comparison with analytical as well as experimental results. Then, the suitability of available materials for the experimental assessment was evaluated. The final experimental assessment of the ball lens functioning as a helioscope was done with the help of a miniature version of the envisioned helioscope. It was found that the resolution limit of the ball lens used for the experiments should be sufficient to image a sunspot of average diameter.Show less
Gold nanorods (GNRs) are plasmonic nanoparticles of which the plasmon resonance wavelength is influenced by the near-field surroundings. Even binding of single proteins with GNRs can cause a shift...Show moreGold nanorods (GNRs) are plasmonic nanoparticles of which the plasmon resonance wavelength is influenced by the near-field surroundings. Even binding of single proteins with GNRs can cause a shift in their resonance wavelength. Previous studies have used this resonance shift to detect single binding events of proteins with GNRs. However, those results are limited in their throughput and sensitivity. Here we use a multifocal two-photon microscopy technique to measure hundreds of single GNRs simultaneously with high spectral sensitivity and signal-to-noise ratio. Using numerical simulations we determined how we can optimise the homogeneity of the illumination pattern over an area of 200 × 200 µm2 and minimise the melting of GNRs during measurements. Finally, we measured GNRs in various concentrations of fibronectin proteins and found an increase in power spectral density of the two-photon luminescence signal for fibronectin concentrations of 1.25 µg/mL to 2.5 µg/mL. Through a better understanding of the setup, we can now perform reliable spectral measurements of hundreds of individual GNRs. This should make two-photon microscopy techniques more competitive with bio-sensing experiments based on scattering of GNRs.Show less
With the help of single-molecule fluorescence detection methods, optical studies have made many breakthroughs in the field of physics. Single-molecule fluorescence resonance energy transfer (FRET)...Show moreWith the help of single-molecule fluorescence detection methods, optical studies have made many breakthroughs in the field of physics. Single-molecule fluorescence resonance energy transfer (FRET) is one of the most generally applied techniques. In this thesis are the details of a setup described, which controls the potential electrochemically. Over 50 single blue copper azurin (CuAz) labeled with ATTO655 (position K122) were analyzed. Its properties, such as the midpoint potential (E0), the distribution of on- and off-times, and the autocorrelation are discussed.Show less
This thesis consists of two parts, one part describes the heating of a gold nanosphere and the forming of a vapor bubble as a result of this. The first part consist mainly of theory and there are...Show moreThis thesis consists of two parts, one part describes the heating of a gold nanosphere and the forming of a vapor bubble as a result of this. The first part consist mainly of theory and there are no measurement results to support the theory, the second part describes a Matlab simulation of a random walk of a ATTO 647N molecule close to a gold nanorod that is being placed in an electromagnetic field. The simulation uses the MNPBEM toolbox to calculate the electric field generated by the gold nanorod and a random walk for the movement of the molecule.Show 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
