Jens Illemann

Präzisionsmassebestimmung einzelner Partikel im Femtogrammbereich und Anwendungen in der Oberflächenphysik

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Kurzfassung in Englisch

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.

weitere Metadaten

Schlagwörter
high precision mass determination
Schlagwörter
weighing
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picogram
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femtogram
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quadrupole trap
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electrodynamic trap
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octopole term
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multipole extension
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anharmonicity
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adsorption
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desorption
Schlagwörter
monolayer
Schlagwörter
scattered light
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aerosol
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particle
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dust
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fullerene
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anthracene
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nitrogenmonoxyd
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silicondioxyd
Schlagwörter
secondary electron emission yield
SWD SchlagworteAdsorptionskinetik
SWD SchlagworteQuadrupolmassenspektrometrie
SWD SchlagworteICR-Spektroskopie
SWD SchlagworteSekundärelektronenemission
SWD SchlagworteNanopartikel
DDC Klassifikation530
DDC Klassifikation620
Institution(en) 
HochschuleTU Chemnitz
FakultätFakultät für Naturwissenschaften
DokumententypDissertation
SpracheDeutsch
Tag d. Einreichung (bei der Fakultät)03.08.2000
Tag d. Verteidigung / Kolloquiums / Prüfung26.07.2000
Veröffentlichungsdatum (online)03.08.2000
persistente URNurn:nbn:de:bsz:ch1-200000677

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