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1	Laboratorní výzkum nabíjení prachových zrn / Laboratory Investigation of Dust Grain Charging Beránek, Martin January 2015 (has links) The present thesis is focused on study of dust grain charging. The experimental part covers interaction between dust grains and high-energy electrons and self-discharging of grains by both field electron emission and field ionization. The second part of the thesis describes construction and evaluation of a linear electrodynamic trap of the novel design. We have observed charging of small dust grains towards high positive electric potentials when bombarded by the high-energy electron beam. We have described an increase of the secondary electron- electron emission yield from negatively charged grains due to the surface field. Further, self-discharging characteristics for both positively and negatively charged grains were measured. The relationship between discharging rate and the rate of the flow of atoms leaving the grain surface due to diffusion was observed for positively charged grains. This suggests significantly lower surface field necessary for ionizing such atoms compared to the ionization of atoms of surrounding gas and compared to the typically published field ionization thresholds. Based on the design published in the master thesis, a linear quadrupole trap of novel design was constructed. Testing measurements confirmed functionality and expected characteristics of the trap. In addition, effects of...
2	Präzisionsmassebestimmung einzelner Partikel im Femtogrammbereich und Anwendungen in der Oberflächenphysik Illemann, Jens 03 August 2000 (has links) (PDF) In this work, a new method for mass determination of single low-charged particles in the sub-picogram regime is developed. It opens applications to chemical physics and surface science via determination of growth rates. The method combines the well-known electrodynamic quadrupole ion trap in a UHV-chamber and fourier transformation of scattered light. The achieved mass resolution of down to $10^{-4}$ at 100 fg mass on a time scale of ten seconds allows a resolution of a few percent of the mass of an adsorbed monolayer and to determine growth rates down to one molecule per second on a time scale of one day. The observation of temperature dependent sticking coefficients results in the measures of the energy of an adsorption barrier. Observation of discrete steps in the rate gives information about the density of molecules in an ordered layer. Temperature dependent desorption data gives the binding energy. The dependence of these observables on the controllable curvature and charge of the substrate's surface is measurable. The first part of this dissertation consists of a description of the common theory of the quadrupole ion trap with the completion of not widely known, newly introduced, contributions to the trapping potential. These contributions lead to systematic shifts in the mass determination. In particular the influence of the inhomogenity of the electrical field, that is used for compensating the gravitational force, is investigated analytically and corroborated experimentally. It is assumed, that the particle's finite size effects in a further shift. In the experimental part initial demonstrative measurements are presented: the time-resolved adsorption of fullerene, anthracene and NO on silica spheres with 500nm diameter has been measured at room temperature. In addition the secondary electron yield of in-situ prepared particles during irradiation with monoenergetic electrons has been determined by analyzing the distribution of change of the number of elementary charges by single events of charging. high precision mass determination weighing picogram femtogram quadrupole trap electrodynamic trap octopole term multipole extension anharmonicity adsorption desorption monolayer scattered light aerosol particle dust fullerene anthracene nitrogenmonoxyd silicondioxyd secondary electron emission yield ddc:530 ddc:620 Adsorptionskinetik Quadrupolmassenspektrometrie ICR-Spektroskopie Sekundärelektronenemission Nanopartikel
3	Präzisionsmassebestimmung einzelner Partikel im Femtogrammbereich und Anwendungen in der Oberflächenphysik Illemann, Jens 26 July 2000 (has links) In this work, a new method for mass determination of single low-charged particles in the sub-picogram regime is developed. It opens applications to chemical physics and surface science via determination of growth rates. The method combines the well-known electrodynamic quadrupole ion trap in a UHV-chamber and fourier transformation of scattered light. The achieved mass resolution of down to $10^{-4}$ at 100 fg mass on a time scale of ten seconds allows a resolution of a few percent of the mass of an adsorbed monolayer and to determine growth rates down to one molecule per second on a time scale of one day. The observation of temperature dependent sticking coefficients results in the measures of the energy of an adsorption barrier. Observation of discrete steps in the rate gives information about the density of molecules in an ordered layer. Temperature dependent desorption data gives the binding energy. The dependence of these observables on the controllable curvature and charge of the substrate's surface is measurable. The first part of this dissertation consists of a description of the common theory of the quadrupole ion trap with the completion of not widely known, newly introduced, contributions to the trapping potential. These contributions lead to systematic shifts in the mass determination. In particular the influence of the inhomogenity of the electrical field, that is used for compensating the gravitational force, is investigated analytically and corroborated experimentally. It is assumed, that the particle's finite size effects in a further shift. In the experimental part initial demonstrative measurements are presented: the time-resolved adsorption of fullerene, anthracene and NO on silica spheres with 500nm diameter has been measured at room temperature. In addition the secondary electron yield of in-situ prepared particles during irradiation with monoenergetic electrons has been determined by analyzing the distribution of change of the number of elementary charges by single events of charging. info:eu-repo/classification/ddc/530 ddc:530 info:eu-repo/classification/ddc/620 ddc:620 Adsorptionskinetik Quadrupolmassenspektrometrie ICR-Spektroskopie Sekundärelektronenemission Nanopartikel high precision mass determination weighing picogram femtogram quadrupole trap electrodynamic trap octopole term multipole extension anharmonicity adsorption desorption monolayer scattered light aerosol particle dust fullerene anthracene nitrogenmonoxyd silicondioxyd secondary electron emission yield

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