Untersuchungen zur Adsorptionsdynamik von Tetrahydrofuran, Trimethylamin und Cyclooctin auf Silizium-(001)
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Philipps-Universität Marburg
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Abstract
The adsorption dynamics of tetrahydrofuran, trimethylamine and cyclooctyne on the
Si(001)-surface was studied by means of molecular beam techniques. It was shown
that all three molecules follow a fundamentally different adsorption pathway and
therefore feature a different potential energy surface. To characterize the adsorption
dynamics, sticking coeffcients where measured using the King-and-Wells method,
optical second harmonic generation (SHG) and Auger electron spectroscopy (AES).
By using a molecular beam, adsorption experiments where performed at a well defined
kinetic beam energy Ekin of the impinging molecules. The King-and-Wells-method as
well as the measurement of the SHG-Signal during molecular beam exposure allowed
the in-situ evaluation of the sticking coefficient s or the reactivity of adsorbates on
the sample surface. By combining the measurements of the initial sticking coefficient
s0 at different kinetic beam energies Ekin and at different sample temperatures Ts a
clear picture of the potential energy surfaces, the corresponding adsorption dynamics,
and the energy dissipation of the systems could be drawn.
Tetrahydrofuran is a cyclic ether, which is often used as a solvent because of
its inert behavior towards other organic molecules. In contrast, the molecular beam
experiments performed in this work show that tetrahydrofuran reacts with a high
initial sticking propability of s0 ' 0:9 on the Si(001)-surface when adsorbed at low
kinetic beam energies Ekin and surface temperatures Ts. The initial sticking coefficient
remains at this level up to surface temperatures of Ts 350 K, at higher surface
temperatures, the initial sticking coefficient drops and reaches s0 = 0:2 at Ts
700 K. This temperature dependence was qualitatively and quantitatively described
by taking into account an intermediate state in the adsorption pathway. The difference
of the energy barriers for conversion from the intermediate state into the final state
and desorption back into the gas phase where determined to be "d
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Dates
Created: 2015Issued: 2015-02-26Updated: 2020-01-23
Faculty
Fachbereich Physik
Publisher
Philipps-Universität Marburg
Language
ger
Data types
DoctoralThesis
Keywords
AdsorptionSiliciumDynamicOrganic
DFG-subjects
SiliziumOrganikDynamikAdsorption
DDC-Numbers
530
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Lipponer, Marcus Americanus: Untersuchungen zur Adsorptionsdynamik von Tetrahydrofuran, Trimethylamin und Cyclooctin auf Silizium-(001). : Philipps-Universität Marburg 2015-02-26. DOI: https://doi.org/10.17192/z2015.0078.
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This item has been published with the following license: In Copyright