% Encoding: UTF-8 @COMMENT{BibTeX export based on data in FAU CRIS: https://cris.fau.de/} @COMMENT{For any questions please write to cris-support@fau.de} @article{faucris.113096104, abstract = {Carbon dioxide (CO2) absorption by the amine-functionalized ionic liquid (IL) dihydroxyethyl dimethylammonium taurinate at 310 K was studied using surface- and bulk-sensitive experimental techniques. From near-ambient pressure X-ray photoelectron spectroscopy at 0.9 mbar CO2, the amount of captured CO2 per mole of IL in the near-surface region is quantified to similar to 0.58 mol, with similar to 0.15 mol in form of carbamate dianions and similar to 0.43 mol in form of carbamic acid. From isothermal uptake experiments combined with infrared spectroscopy, CO2 is found to be bound in the bulk as carbamate (with nominally 0.5 mol of CO2 bound per 1 mol of IL) up to similar to 2.5 bar CO2, and as carbamic acid (with nominally 1 mol CO2 bound per 1 mol IL) at higher pressures. We attribute the fact that at low pressures carbamic acid is the dominating species in the near-surface region, while only carbamate is formed in the bulk, to differences in solvation in the outermost IL layers as compared to the bulk situation.}, author = {Niedermaier, Inga and Bahlmann, Matthias and Papp, Christian and Kolbeck, Claudia and Wei, Wei and Krick Calderon, Sandra and Grabau, Mathias and Schulz, Peter and Wasserscheid, Peter and Steinrück, Hans-Peter and Maier, Florian}, doi = {10.1021/ja410745a}, faupublication = {yes}, journal = {Journal of the American Chemical Society}, month = {Jan}, pages = {436-441}, peerreviewed = {Yes}, title = {{Carbon} {Dioxide} {Capture} by an {Amine} {Functionalized} {Ionic} {Liquid}: {Fundamental} {Differences} of {Surface} and {Bulk} {Behavior}}, volume = {136}, year = {2014} } @article{faucris.107825124, abstract = {Radiography of a structure skeleton: Cyclic thiouronium ionic liquids have been synthesized and characterized in such a way that the straightforward introduction of three different alkyl substituents at the cation has been realized. X-ray induced photoelectron spectroscopy studies indicated a significant electronic contribution of the free electrons at the sulfur to stabilize the cationic charge, leading to structures with peculiar physicochemical properties (see figure). Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.}, author = {Taccardi, Nicola and Niedermaier, Inga and Maier, Florian and Steinrück, Hans-Peter and Wasserscheid, Peter}, doi = {10.1002/chem.201200971}, faupublication = {yes}, journal = {Chemistry - A European Journal}, pages = {8288-8291}, peerreviewed = {Yes}, title = {{Cyclic} thiouronium ionic liquids: {Physicochemical} properties and their electronic structure probed by {X}-ray induced photoelectron spectroscopy}, volume = {18}, year = {2012} } @article{faucris.110162624, abstract = {The investigation of liquid surfaces and interfaces with the powerful toolbox of ultra-high vacuum (UHV)-based surface science techniques generally has to overcome the issue of liquid evaporation within the vacuum system. In the last decade, however, new classes of liquids with negligible vapor pressure at room temperature-in particular, ionic liquids (ILs)-have emerged for surface science studies. It has been demonstrated that particularly angle-resolved X-ray Photoelectron Spectroscopy (ARXPS) allows for investigating phenomena that occur at gas-liquid and liquid-solid interfaces on the molecular level. The results are not only relevant for IL systems but also for liquids in general. In all of these previous ARXPS studies, the sample holder had to be tilted in order to change the polar detection angle of emitted photoelectrons, which restricted the liquid systems to very thin viscous IL films coating a flat solid support. We now report on the concept and realization of a new and unique laboratory "Dual Analyzer System for Surface Analysis (DASSA)" which enables fast ARXPS, UV photoelectron spectroscopy, imaging XPS, and low-energy ion scattering at the horizontal surface plane of macroscopically thick non-volatile liquid samples. It comprises a UHV chamber equipped with two electron analyzers mounted for simultaneous measurements in 0 degrees and 80 degrees emission relative to the surface normal. The performance of DASSA on a first macroscopic liquid system will be demonstrated. (C) 2016 AIP Publishing LLC.}, author = {Niedermaier, Inga and Kolbeck, Claudia and Steinrück, Hans-Peter and Maier, Florian}, doi = {10.1063/1.4942943}, faupublication = {yes}, journal = {Review of Scientific Instruments}, peerreviewed = {Yes}, title = {{Dual} analyzer system for surface analysis dedicated for angle-resolved photoelectron spectroscopy at liquid surfaces and interfaces}, volume = {87}, year = {2016} } @article{faucris.272838749, author = {Niedermaier, Inga and Kolbeck, Claudia and Steinrück, Hans-Peter and Maier, Florian}, doi = {10.1063/1.4983571}, faupublication = {yes}, journal = {Review of Scientific Instruments}, note = {CRIS-Team Scopus Importer:2022-04-14}, pages = {059902-}, peerreviewed = {unknown}, title = {{Erratum}: "{Dual} analyzer system for surface analysis dedicated for angle-resolved photoelectron spectroscopy at liquid surfaces and interfaces" [{Rev}. {Sci}. {Instrum}. 87, 045105 (2016)}, volume = {88}, year = {2017} } @article{faucris.109607344, abstract = {We have performed a systematic study addressing the surface behavior of a variety of functionalized and non-functionalized ionic liquids (ILs). From angle-resolved X-ray photoelectron spectroscopy, detailed conclusions on the surface enrichment of the functional groups and the molecular orientation of the cations and anions is derived. The systems include imidazolium-based ILs methylated at the C2 position, a phenyl-functionalized IL, an alkoxysilane-functionalized IL, halo-functionalized ILs, thioether- functionalized ILs, and amine-functionalized ILs. The results are compared with the results for corresponding non-functionalized ILs where available. Generally, enrichment of the functional group at the surface is only observed for systems that have very weak interaction between the functional group and the ionic head groups. Scratching the surface: The surface behavior of various functionalized ionic liquids (ILs) is studied by angle-resolved X-ray photoelectron spectroscopy and conclusions on surface-enrichment effects and molecular orientation of cations and anions are derived (see figure; Im=imidazolium, Tf=trifluoromethanesulfonyl). Overall, surface enrichment is only observed for functional groups that interact weakly with the ionic head groups. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.}, author = {Kolbeck, Claudia and Niedermaier, Inga and Deyko, Alexey and Lovelock, Kevin and Taccardi, Nicola and Wei, Wei and Wasserscheid, Peter and Maier, Florian and Steinrück, Hans-Peter}, doi = {10.1002/chem.201304549}, faupublication = {yes}, journal = {Chemistry - A European Journal}, pages = {3954-3965}, peerreviewed = {Yes}, title = {{Influence} of substituents and functional groups on the surface composition of ionic liquids}, volume = {20}, year = {2014} } @article{faucris.119122784, abstract = {There are strings attached: After linking the reacting groups to head groups of ionic liquids to drastically lower the vapour pressures of the reactants, ordinary liquid-phase organic reactions can be monitored by in situ X-ray photoelectron spectroscopy. This approach is demonstrated for the nucleophilic substitution of an alkyl amine and an alkyl chloride moiety, which are attached to the cation and anion of ionic liquids, respectively. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.}, author = {Kolbeck, Claudia and Niedermaier, Inga and Taccardi, Nicola and Schulz, Peter and Maier, Florian and Wasserscheid, Peter and Steinrück, Hans-Peter}, doi = {10.1002/anie.201107402}, faupublication = {yes}, journal = {Angewandte Chemie International Edition}, pages = {2610-2613}, peerreviewed = {Yes}, title = {{Monitoring} of liquid-phase organic reactions by photoelectron spectroscopy}, volume = {51}, year = {2012} } @article{faucris.121304524, abstract = {We demonstrate the application of in situ X-ray photoelectron spectroscopy (XPS) to monitor organic, liquid-phase reactions. By covalently attaching ionic head groups to the reacting organic molecules, their volatility can be reduced such that they withstand ultra high vacuum conditions. The applied method, which is new for the investigation of organic reactions, allows for following the fate of all elements present in the reaction mixtureexcept for hydrogenin a quantitative and oxidation-state-sensitive manner in one experiment. This concept is demonstrated for the alkylation of a tertiary amine attached to an imidazolium or phosphonium moiety by the anion 4-chlorobutylsulfonate ([ClC H SO ] ). In the course of the reaction, the covalently bound chlorine is converted to chloride and the amine to ammonium as reflected by the distinct shifts in the N 1s and Cl 2p binding energies. © 2012 Wiley-VCH Verlag GmbH& Co. KGaA, Weinheim.}, author = {Niedermaier, Inga and Kolbeck, Claudia and Taccardi, Nicola and Schulz, Peter and Li, Jing and Drewello, Thomas and Wasserscheid, Peter and Steinrück, Hans-Peter and Maier, Florian}, doi = {10.1002/cphc.201100965}, faupublication = {yes}, journal = {ChemPhysChem}, pages = {1725-1735}, peerreviewed = {Yes}, title = {{Organic} reactions in ionic liquids studied by in situ {XPS}}, volume = {13}, year = {2012} } @article{faucris.110438064, abstract = {This perspective analyzes the potential of X-ray photoelectron spectroscopy under ultrahigh vacuum (UHV) conditions to follow chemical reactions in ionic liquids in situ. Traditionally, only reactions occurring on solid surfaces were investigated by X-ray photoelectron spectroscopy (XPS) in situ. This was due to the high vapor pressures of common liquids or solvents, which are not compatible with the required UHV conditions. It was only recently realized that the situation is very different when studying reactions in Ionic Liquids (ILs), which have an inherently low vapor pressure, and first studies have been performed within the last years. Compared to classical spectroscopy techniques used to monitor chemical reactions, the advantage of XPS is that through the analysis of their core levels all relevant elements can be quantified and their chemical state can be analyzed under well-defined (ultraclean) conditions. In this perspective, we cover six very different reactions which occur in the IL, with the IL, or at an IL/support interface, demonstrating the outstanding potential of in situ XPS to gain insights into liquid phase reactions in the near-surface region. (C) 2017 Author(s).}, author = {Maier, Florian and Niedermaier, Inga and Steinrück, Hans-Peter}, doi = {10.1063/1.4982355}, faupublication = {yes}, journal = {Journal of Chemical Physics}, peerreviewed = {Yes}, title = {{Perspective}: {Chemical} reactions in ionic liquids monitored through the gas (vacuum)/liquid interface}, volume = {146}, year = {2017} } @article{faucris.121282964, abstract = {A mechanistic study: In a Brønsted acid/base reaction, gaseous triflic acid (OTfH) transfers its proton to the basic Cl anion of the ionic liquid [CCIm]Cl forming volatile HCl and the IL [CCIm][TfO]. This anion exchange reaction is monitored in the near-surface region quantitatively by X-ray photoelectron spectroscopy as a function of time (see picture; BE=binding energy). Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.}, author = {Niedermaier, Inga and Taccardi, Nicola and Wasserscheid, Peter and Maier, Florian and Steinrück, Hans-Peter}, doi = {10.1002/anie.201304115}, faupublication = {yes}, journal = {Angewandte Chemie International Edition}, pages = {8904-8907}, peerreviewed = {Yes}, title = {{Probing} a gas/liquid acid-base reaction by {X}-ray photoelectron spectroscopy}, volume = {52}, year = {2013} } @article{faucris.201791821, abstract = {
For equimolar mixtures of ionic liquids with imidazolium-based cations of very different electronic structure, we observe very pronounced surface enrichment effects by angle-resolved X-ray photoelectron spectroscopy (XPS). For a mixture with the same anion, that is, 1-methyl-3-octylimidazolium hexafluorophos phate+1,3-di(methoxy)imidazolium hexafluorophosphate ([C8C1Im][PF6]+[(MeO)2Im][PF6]), we find a strong enrichment of the octyl chain-containing [C8C1Im]+ cation and a correspond ing depletion of the [(MeO)2Im]+ cation in the topmost layer. For a mixture with different cations and anions, that is, [C8C1Im] [Tf2N]+[(MeO)2Im][PF6], we find both surface enrichment of the
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