38518
2015
2015
eng
10117
10124
8
19
87
article
American Chemical Society
Washington
1
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--
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Quantification of Silane Molecules on Oxidized Silicon: Are there Options for a Traceable and Absolute Determination?
Organosilanes are used routinely to functionalize various support materials for further modifications. Nevertheless, reliable quantitative information about surface functional group densities after layer formation is rarely available. Here, we present the analysis of thin organic nanolayers made from nitrogen containing silane molecules on naturally oxidized silicon wafers with reference-free total reflection X-ray fluorescence (TXR.F) and X-ray photoelectron spectroscopy (XPS). An areic density of 2-4 silane molecules per nm(2) was calculated from the layer's nitrogen mass deposition per area unit obtained by reference-free TXRF. Complementary energy and angle-resolved XPS (ER/AR-XPS) in the Si 2p core-level region was used to analyze the outermost surface region of the organic (silane layer)-inorganic (silicon wafer) interface. Different coexisting silicon species as silicon, native silicon oxide, and silane were identified and quantified. As a result of the presented proof-of-concept, absolute and traceable values for the areic density of silanes containing nitrogen as intrinsic marker are obtained by calibration of the XPS methods with reference-free TXRF. Furthermore, ER/AR-XPS is shown to facilitate the determination of areic densities in (mono)layers made from silanes having no heteroatomic marker other than silicon. After calibration with reference-free TXRF, these areic densities of silane molecules can be determined when using the XPS component intensity of the silane's silicon atom.
Analytical chemistry
10.1021/acs.analchem.5b02846
26334589
0003-2700
1520-6882
wos:2015
WOS:000362628600085
Dietrich, PM (reprint author), Bundesanstalt Matforsch & Prufung BAM, Unter Eichen 87, D-12205 Berlin, Germany., paul.dietrich@bam.de
European Union through the European Metrology Research Program (EMRP);
EMRP within EURAMET; European Union
Paul M. Dietrich
Cornelia Streeck
Stephan Glamsch
Christopher Ehlert
Andreas Lippitz
Andreas Nutsch
Nora Kulak
Burkhard Beckhoff
W. E. S. Unger
Institut für Chemie
Referiert
45610
2016
2016
eng
406
411
6
363
article
Elsevier
Amsterdam
1
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Synchrotron-radiation XPS analysis of ultra-thin silane films: Specifying the organic silicon
The analysis of chemical and elemental in-depth variations in ultra-thin organic layers with thicknesses below 5 nm is very challenging. Energy- and angle-resolved XPS (ER/AR-XPS) opens up the possibility for non-destructive chemical ultra-shallow depth profiling of the outermost surface layer of ultra-thin organic films due to its exceptional surface sensitivity. For common organic materials a reliable chemical in-depth analysis with a lower limit of the XPS information depth z(95) of about 1 nm can be performed. As a proof-of-principle example with relevance for industrial applications the ER/AR-XPS analysis of different organic monolayers made of amino- or benzamidosilane molecules on silicon oxide surfaces is presented. It is demonstrated how to use the Si 2p core-level region to non-destructively depth-profile the organic (silane monolayer) - inorganic (SiO2/Si) interface and how to quantify Si species, ranging from elemental silicon over native silicon oxide to the silane itself. The main advantage of the applied ER/AR-XPS method is the improved specification of organic from inorganic silicon components in Si 2p core-level spectra with exceptional low uncertainties compared to conventional laboratory XPS. (C) 2015 Elsevier B.V. All rights reserved.
Applied surface science : a journal devoted to applied physics and chemistry of surfaces and interfaces
10.1016/j.apsusc.2015.12.052
0169-4332
1873-5584
wos2016:2019
WOS:000370572400052
Dietrich, PM (reprint author), Bundesanstalt Mat Forsch & Prufung BAM, Unter Eichen 87, D-12205 Berlin, Germany., paul.dietrich@yahoo.de
European Union through the European Metrology Research Program (EMRP); EMRP participating countries within EURAMET; European Union
importub
2020-03-22T19:58:01+00:00
filename=package.tar
87d93672388badba15a6d30dbd0384a3
Paul M. Dietrich
Stephan Glamsch
Christopher Ehlert
Andreas Lippitz
Nora Kulak
Wolfgang E. S. Unger
eng
uncontrolled
Synchrotron radiation XPS
eng
uncontrolled
Depth profiling
eng
uncontrolled
Silanes
eng
uncontrolled
Monolayer
eng
uncontrolled
Amines
eng
uncontrolled
Amides
Institut für Chemie
Referiert
Import
45500
2016
2016
eng
8654
8661
8
18
article
Royal Society of Chemistry
Cambridge
1
--
--
--
A detailed assignment of NEXAFS resonances of imidazolium based ionic liquids
In Near Edge X-Ray Absorption Fine Structure (NEXAFS) spectroscopy X-Ray photons are used to excite tightly bound core electrons to low-lying unoccupied orbitals of the system. This technique offers insight into the electronic structure of the system as well as useful structural information. In this work, we apply NEXAFS to two kinds of imidazolium based ionic liquids ([C(n)C(1)im](+)[NTf2](-) and [C(4)C(1)im](+)[I](-)). A combination of measurements and quantum chemical calculations of C K and N K NEXAFS resonances is presented. The simulations, based on the transition potential density functional theory method (TP-DFT), reproduce all characteristic features observed by the experiment. Furthermore, a detailed assignment of resonance features to excitation centers (carbon or nitrogen atoms) leads to a consistent interpretation of the spectra.
Physical chemistry, chemical physics : a journal of European Chemical Societies
10.1039/c5cp07434g
26948544
1463-9076
1463-9084
wos2016:2019
WOS:000372249100036
Saalfrank, P (reprint author), Univ Potsdam, Inst Chem, Karl Liebknecht Str 24-25, D-14476 Potsdam, Germany., peter.saalfrank@uni-potsdam.de
BAM as part of the BAM MIS Program [Ideen_2012_59]; Austrian Science Found (FWF) through the Erwin-Schrodinger fellowship program [J 3471-N28]
importub
2020-03-22T19:03:01+00:00
filename=package.tar
6fc5074a9ae2206e9db08f4cc1e21426
Christopher Ehlert
Markus Holzweber
Andreas Lippitz
Wolfgang E. S. Unger
Peter Saalfrank
Institut für Chemie
Referiert
Import
39441
2016
2016
eng
8654
8661
8
postprint
1
--
2016-02-05
--
A detailed assignment of NEXAFS resonances of imidazolium based ionic liquids
In Near Edge X-Ray Absorption Fine Structure (NEXAFS) spectroscopy X-Ray photons are used to excite tightly bound core electrons to low-lying unoccupied orbitals of the system. This technique offers insight into the electronic structure of the system as well as useful structural information. In this work, we apply NEXAFS to two kinds of imidazolium based ionic liquids ([CnC1im]+[NTf2]- and [C4C1im]+[I]-). A combination of measurements and quantum chemical calculations of C K and N K NEXAFS resonances is presented. The simulations, based on the transition potential density functional theory method (TP-DFT), reproduce all characteristic features observed by the experiment. Furthermore, a detailed assignment of resonance features to excitation centers (carbon or nitrogen atoms) leads to a consistent interpretation of the spectra.
urn:nbn:de:kobv:517-opus4-394417
online registration
Au-032781
Phys. Chem. Chem. Phys. (2016) Nr. 18, S. 8654-8661. - DOI: 10.1039/C5CP07434G
Christopher Ehlert
Markus Holzweber
Andreas Lippitz
Wolfgang E. S. Unger
Peter Saalfrank
Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe
315
eng
uncontrolled
ray absorption-spectroscopy
eng
uncontrolled
fine-structure
eng
uncontrolled
spectra
eng
uncontrolled
simulations
eng
uncontrolled
molecules
eng
uncontrolled
dynamics
eng
uncontrolled
graphene
eng
uncontrolled
surface
eng
uncontrolled
salts
Chemie und zugeordnete Wissenschaften
open_access
Institut für Chemie
Referiert
RSC
Universität Potsdam
https://publishup.uni-potsdam.de/files/39441/pmnr315_online.pdf