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@PHDTHESIS{Mller:230028,
author = {Müller, Mirko},
othercontributors = {Tautz, Stefan},
title = {{S}trukturelle und chemische {C}harakterisierung von
selbst-assemblierten {M}onolagen organischer {M}oleküle auf
{O}berflächen},
volume = {66},
address = {Jülich},
publisher = {Forschungszentrum Jülich, Zentralbibliothek},
reportid = {RWTH-CONV-144811},
series = {Schriften des Forschungszentrums Jülich : Reihe
Schlüsseltechnologien},
pages = {168 S. : Ill., graph. Darst.},
year = {2013},
note = {Zugl.: Aachen, Techn. Hochsch., Diss., 2013},
abstract = {In this thesis self-assembled monolayers (SAM) of
4(4´methylbiphenyl4yl)butane 1thiol (BP4) on a gold(111)
surface were fabricated. The deposited amount of molecules
could be adjusted very precisely, using an upstream vessel.
Two coverage depending phases could be observed: the
alpha-Phase and the delta-phase. The letter has a lower
areal density. BP4 adsorbs on a gold(111) surface in an
Au-S-C-angle of 104° due to the sp3 hybridization of
sulfur. Starting from a coverage of 0.07 island formation of
the delta-phase occurs. The unit cell can be described with
an unit cell. the film thickness is 6.4 Å. Two
perpendicular glide planes parallel to the unit cell axes
give rise to systematically vanishing LEED-Spots. At a
coverage of 0.16 a homogenous film of the delta-phase
exists. Adsorbing additional molecules leads to a disordered
phase. At a coverage of 0.33 a chemisorbed monolayer is
achieved. Only few weakly physisorbed molecules can be
additionally deposited. Short time heating at 330 K leads to
desorption of these molecules. The chemisorbed molecules
desorb at temperatures between 340 and 380 K (DeltaH: AuS ~
184 kJ/mol). Higher temperatures lead to dissociation of the
BP4 molecules (DeltaH: CS = 289 kJ/mol). Heating between 340
and 380 K also leads to a deformation of the Au-S-C-angle
from 104° to 144°. Therefore the molecules can arrange in
the alpha-Phase. The more upright standing molecules give
rise to a stronger intermolecular interaction. A homogenous
chemisorbed monolayer of the alpha-phase exist at a coverage
of 0.33. It can be described with an unit cell consisting of
16 molecules. The film thickness is 13.4 Å and thereby
twice as much as in the delta-phase. At coverages between
0.19 and 0.22 both Phases can coexist. The transition from
the alpha-Phase to the delta-Phase is thermic irreversible.
Both phases can be distinct by their S2p binding energy. Due
to the deformation of the Au-S-C-angle the electron density
at the sulfur is higher in the alpha-phase. Therefore the
S2p binding energy is higher in the alpha-phase. Further
phases of BP4 on gold(111) could not be observed. Hence it
is assumed that the previously observed beta- and
gamma-phases are contaminated. The volume density of both
observed phases is nearly the same: rho(alpha) = 1,46 g/cm3
vs. rho(delta) = 1,50 g/cm3. The molecules in the
alpha-phase are standing more upright. Therefore it is
assumed, that there is a better intermolecular interaction
in the alpha-phase. For this reason it can be assumed, that
the electronic properties are different in both phases.},
keywords = {CVD-Verfahren (SWD) / Röntgen-Photoelektronenspektroskopie
(SWD) / LEED (SWD) / Monoschicht (SWD)},
cin = {130000 / 134110},
ddc = {530},
cid = {$I:(DE-82)130000_20140620$ / $I:(DE-82)134110_20140620$},
typ = {PUB:(DE-HGF)11 / PUB:(DE-HGF)3},
urn = {urn:nbn:de:hbz:82-opus-46947},
url = {https://publications.rwth-aachen.de/record/230028},
}
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