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No description available.

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No description available.

The thesis aims to study the motion of individual fluorescent molecules in the gel environments, and applies to the sensitive electrophoretic and dielectrophoretic studies. Firstly, dye molecules (Rhodamine B and DiI) are dispersed, and investigate the individual fluorescent spots. Later on, we study the motion of individual B-phycoerythrin molecules under external electrical field driving. Due to the porosity, agarose gel is used to contain the liquid, and the dye molecules can freely move within the pores. Thus, one can easily observe the motion of individual dye molecules under high numerical aperture objectives. B-phycoerythrin is chosen for the high extinction coefficient, native charge, and good fluorescent properties. Our results indicate most dye molecules are attached in the rigid structure of the gel. Only very limited molecular motions are observed. Moreover, we study the dielectrophoretic interaction of the dye molecules. Nano-electrodes are fabricated by electrolysis to have sub-micron aperture silver tips. Due to the high gradient of the electric field, it is used to have strong enough attractive forces around the apex of the tip, to overcome the thermal fluctuations. It allows us further trapping and manipulating small non-charged objects, up to single dye molecules.

Abstract In this study, ZrN films were deposited on silicon wafer¡Bcopper and aluminum sheets by reactive sputtering of Zr target at room temperature in a mixed N2-Ar atmosphere with N2 gas flow rates of 5 and 6 sccm. Films of ZrN about 1£gm thick were annealed at various temperatures in order to study the grain growth and the inter-diffusion of atoms. Electron probe X-ray microanalyzer¡]EPMA¡^ showed that the as-deposited ZrN films were stoichiometric. The ring patterns of electron diffraction in transmission electron microscope (TEM) indicated that only ZrN was present without any Zr metal. The grain size of ZrN showed no apparent change after annealing at 900¢J and 1000¢J, but showed that¡]200¡^ orientation is preferred to ¡]111¡^orientation. No Zr-Si compound were found at the ZrN/Si interface after annealing. It was revealed that the ZrN grain size in the ZrN/Si interface was about 5¡ã15 nm, then broadened to columnar structure of 20¡ã50nm in diameter away from the interface. The grain size of ZrN on Cu substrate was 3¡ã15 nm at the ZrN/Cu interface and leave away from the interface was 10¡ã80 nm. No Cu-Zr compound was found at the interface after annealing at 650¢J for 1 hour.

In the scope of this master thesis, a home-made brass scanning tunneling microscope (STM) was machined, assembled and tested for its functionality. For this microscope, a new approach-technique was used which follows the design suggested by Pan. The difference to Pan's design is the use of piezoplates, instead of piezostacks. Hence, the approach is still based on the stick and slip motion, but it allows the microscope to be more compact. A new and simple electronic circuit, in order to control the approach, is presented and was put together. This circuit is based on mechanical relays, which provide a sufficient long time gap between the single moving steps, due to their mechanical functional principle. Subsequently the approach-technique and the scanning was successfully tested. Finally, first images of HOPG were taken under ambient conditions. / text

From many perspectives copper is a very important metal for the modern society. It can be found in everything from jewellery to electronics. For this reason it is very important for geologists to be able to develop efficient methods for identification, characterisation, extraction and processing of copper. One method for the identification of copper bearing minerals is ore microscopy which has been used in this paper along with a general introduction. Samples from the study collection of the Department of Earth Sciences and the area of Långban and Månhöjden have been examined, documented and described in detail. The thesis begins with an introduction to the history and geochemistry of copper along with some ore forming processes.

Thesis--Copenhagen. / "Summary": p. 261-265. Bibliography: p. [266]-272.

Th. doct.-ing.--Toulouse 3, 1978. N°: 612.