Well width study of InGaN multiple quantum wells for blue–green emitter

InGaN/GaN multiple quantum well structures emitting in the blue/green wavelength region were grown by metal organic vapor phase epitaxy. By reducing the quantum well growth time the influence of the quantum well thicknesses between 3.8 and 1.1 nm on the indium incorporation and the distribution of indium in the quantum wells in growth direction were investigated. X-ray diffraction measurements show that the average indium mole fraction in the quantum wells decreases with reducing quantum well width due to a delay in the indium incorporation at the barrier/well interface. Quantitative analysis reveals a segregation length of about 2 nm as a measure of the graded region in growth direction. Cathodoluminescence imaging reveals that the spatial variation of the wavelength is reduced with decreasing quantum well thickness down to 1.7 nm. Reducing the width of the quantum well further results in an increase of the spatial wavelength variation.     

Ultrafast fluorescence spectroscopy for axial resolution of flurorophore distributions

A new method for determining the fluorophore distribution along the propagation axis of an ultrashort optical pulse is presented. The axial resolution is obtained by temporal gating of the backward emitted fluorescence via optical parametric amplification, and we demonstrated a resolution in the order of a few 100 μm. With this approach, sampling of the fluorophore concentration of thin layers without using optics with a large numerical aperture will be possible, such as investigating the human retina via time-resolved fluorescence measurements. Additionally, we verified the gain is orders of magnitude higher for coherent seeding, making optical parametric gating very interesting for discriminating between coherently and incoherently scattered light for other multimodal imaging applications.     

Papierchromatographische Trennung des Dibenzpyrrols von Anthracen und Phenanthren bei der Analyse von Steinkohlenteerprodukten

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Analysis of transverse momentum and event shape invN scattering

The transverse momentum distributions of hadrons produced in neutrino-nucleon charged current interactions and their dependence onW are analysed in detail. It is found that the components of the transverse momentum in the event plane and normal to it increase withW at about the same rate throughout the availableW range. A comparison withe ⁺ e ^? data is made. Studies of the energy flow and angular distributions in the events classified as planar do not show clear evidence for high energy, wide angle gluon radiation, in contrast to the conclusion of a previous analysis of similar neutrino data.     

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Critical capture radius in single wire HGMS

The observation of a large number of particle trajectories in a transversi single wire HGMS has made possible the experimental determination of the critical capture radius. Both the trajectories and the capture radius were found to be in good agreement with calculated values obtained by numerical means using a laminar flow model.