Berit Hinnemann - Academia.edu (original) (raw)
Papers by Berit Hinnemann
Adsorption of Al, O, Hf, Y, Pt, and S atoms on α-Al2O3(0001)
Journal of Physical Chemistry C, 2007
Magnetic edge states in MoS2 characterized using density-functional theory
Physical Review B Condensed Matter and Materials Physics, 2009
It is known that the edges of a two-dimensional slab of insulating MoS2 exhibit one-dimensional m... more It is known that the edges of a two-dimensional slab of insulating MoS2 exhibit one-dimensional metallic edge states, the so-called “brim states.” Here, we find from density-functional theory calculations that several edge structures, which are relevant for the hydrodesulfurization process, are magnetic. The magnetism is an edge phenomenon associated with certain metallic edge states. Interestingly, we find that among the two low-index edges, only the S edge displays magnetism under hydrodesulfurization conditions. In addition, the implications of this on the catalytic activity are investigated. Despite large changes in the magnetic moments, a small influence on the adsorption energies is observed. This has implications on the suitability of magnetic measurements for monitoring the catalytic properties.
Chracterization of MoS2 Magnetic States Using Density-Functional Theory
Physical Review B, 2009
Structure of and ion segregation to an alumina grain boundary: Implications for growth and creep
Journal of Materials Research, May 1, 2008
... Ivan Milas, Berit Hinnemann,a) and Emily A. Carterb) Department of Mechanical and Aerospace E... more ... Ivan Milas, Berit Hinnemann,a) and Emily A. Carterb) Department of Mechanical and Aerospace Engineering, Princeton University, Princeton, New ... latter observations may still be consistent with higher overall rates, when one considers the experiments of Monty and coworkers,5 ...
Trends in Hydrodesulfurization Catalysis Based on Realistic Surface Models
Catalysis Letters, 2014
ABSTRACT Abstract Trends in hydrodesulfurization (HDS) activity are investigated on the basis of ... more ABSTRACT Abstract Trends in hydrodesulfurization (HDS) activity are investigated on the basis of surface properties calculated by density functional theory for a series of HDS catalysts. It is shown that approximately linear correlations exist between HS group binding energies and activation barriers of key elementary reactions in HDS of thiophene. These linear correlations are used to develop a simple kinetic model, which qualitatively describes experimental trends in activity. The kinetic model identifies the HS-binding energy as a descriptor of HDS activity. This insight contributes to understanding the effect of promotion and structure–activity relationships. Graphical Abstract
Surface Science, 2011
We investigate the structure and surface composition of the -Ni 3 Al(111) and -NiAl(110) alloy su... more We investigate the structure and surface composition of the -Ni 3 Al(111) and -NiAl(110) alloy surfaces at conditions relevant for metal dusting corrosion related to catalytic steam reforming of natural gas. In regular service as protective coatings, nickel-aluminum alloys are protected by an oxide scale, but in case of oxide scale spallation, the alloy surface may be directly exposed to the reactive gas environment and vulnerable to metal dusting. By means of density functional theory and thermochemical calculations for both the Ni 3 Al and NiAl surfaces, the conditions under which C O and O H adsorption is to be expected and under which it is inhibited, are mapped out. Because C O and O H are regarded as precursors for nucleating graphite or oxide on the surfaces, phase diagrams for the surfaces provide a simple description of their stability. Specifically, this study shows how the C O and O H coverages depend on the steam to carbon ratio (S/C) in the gas and thereby provide a ranking of the carbon limits on the different surface phases.
Catalysis by Enzymes: The Biological Ammonia Synthesis
Topics in Catalysis, 2006
Enzymes are nature’s own catalysts and fundamental for life, as they catalyze essentially all bio... more Enzymes are nature’s own catalysts and fundamental for life, as they catalyze essentially all biological processes. Compared to inorganic catalysts, however, their structure and function is immensely more complicated. Computational modeling has played an increasing role in elucidating enzyme mechanisms, as it can provide information complementary to experimental techniques. Elucidating enzyme structure and mechanism is not only important to understand
On the Role of Metal Step-Edges in Graphene Growth
The Journal of Physical Chemistry C, 2010
ABSTRACT Graphene growth on transition metal surfaces is studied by means of density functional t... more ABSTRACT Graphene growth on transition metal surfaces is studied by means of density functional theory calculations. The results show that graphene grows preferentially out from surface step edges onto lower facets on fcc and hcp metal surfaces. The results also reveal that an epitaxial lattice match between graphene and the metal step-edge stabilizes graphene and lowers the corresponding critical graphene nucleus size. In the case of a graphene−metal lattice mismatch, a destabilization of the critical graphene nucleus size may be compensated by tuning the carbon chemical potential. The concepts of metal−graphene lattice and carbon chemical potential are included in a simple growth model that describes experimental trends in graphene formation at different metal surfaces under varying growth conditions.
Adsorption of Al, O, Hf, Y, Pt, and S Atoms on α-Al2O3(0001)
Journal of Physical Chemistry C, 2007
Surface Science, 2009
Catalytic carbon deposition on Ni nanoparticles and surfaces is the first step towards coking of ... more Catalytic carbon deposition on Ni nanoparticles and surfaces is the first step towards coking of steam reforming Ni catalysts and carbon-induced corrosion, i.e., metal dusting corrosion, on Ni-based alloy surfaces . The fundamental processes at the atomic scale are essentially the same. Therefore an atomistic understanding of how the gas-phase components influence carbon deposition and nucleation is very valuable for the understanding of metal dusting and avoid this degradation. The growth of graphene on the Ni surface is a necessary step in both processes. Recent ETEM [3] and DFT [4] studies have shown that steps on the metal surface act as growth centers for graphene.
Physical Review Letters, 2009
Through the interplay of noncontact atomic force microscopy studies and density functional theory... more Through the interplay of noncontact atomic force microscopy studies and density functional theory calculations, an atomistic model for the Al 2 O 3 ð0001Þ-ffiffiffiffiffi ffi 31 p  ffiffiffiffiffi ffi 31 p R9 surface reconstruction is revealed. The surface is found to consist of an Al adlayer on the Al 2 O 3 substrate, and the driving force for the formation of the reconstruction is related to a detailed balance between strain in the adlayer and the preference for Al atoms to be located on distinct substrate sites.
Magnetic edge states in MoS2 characterized using density-functional theory
Physical Review B, 2009
... REVIEW B 80, 125416 [?]2009[?] Magnetic edge states in MoS2 characterized using density-funct... more ... REVIEW B 80, 125416 [?]2009[?] Magnetic edge states in MoS2 characterized using density-functional theory Aleksandra Vojvodic,1 ... Given are the relaxed MoS2 structures, the nomenclature [?]Nom.[?], the non-spinpolarized S vacancy formation energies [?]ES[?] the ...
Structure of the FeFe-cofactor of the iron-only nitrogenase and possible mechanism for dinitrogen reductionElectronic supplementary information (ESI) available. Optimized atomic coordinates for the FeFeco and FeMoco structures. See http://www.rsc.org/suppdata/cp/b3/b310850c/
Physical Chemistry Chemical Physics, 2004
Oxidation of Metals, 2011
Metal dusting is a catastrophic form of carburization attack that takes place in carbon-supersatu... more Metal dusting is a catastrophic form of carburization attack that takes place in carbon-supersaturated gaseous atmospheres, and is most commonly encountered in steam reforming processes such as the production of hydrogen or syngas for ammonia, Fischer-Tropsch and methanol applications. The consequence of metal dusting can be a severe loss of metal from the process units, leading to high-cost maintenance and serious safety issues. The present literature review discusses the latest developments within metal dusting protection of alloys with special emphasis on protective coatings. In the first part of the paper, an overview of the main theories for metal dusting of alloys as well as fundamental studies is provided. In the second part, the paper focuses on the different methods to prevent metal dusting, including surface poisoning, alloying, chemical, mechanical and laser treatments as well as coatings. Particular focus is given to coatings and their composition, and fabrication methods, and a critical analysis of the different materials' behaviours and the suitability perspectives of deposition techniques are provided.
Nanotechnology, 2010
We demonstrate that the characteristic √ 31 × √ 31 R9 • reconstructed surface of α-alumina (Al 2 ... more We demonstrate that the characteristic √ 31 × √ 31 R9 • reconstructed surface of α-alumina (Al 2 O 3 ) acts as a nanotemplate for the growth of well-ordered monodisperse arrays of Ni nanoclusters. Due to the insulating nature of the substrate we use dynamic scanning force microscopy operated in the non-contact mode (NC-AFM) to characterize the nanotemplate, to examine the size and distribution of metallic clusters on the surface and to investigate their position with respect to the surface atomic structure. The present NC-AFM results for the interaction of Ni with α-Al 2 O 3 are supported by density functional theory (DFT) calculations. The ability of α-Al 2 O 3 (0001) to act as a nanotemplate is attributed to a spatially modulated affinity towards the accommodation of Ni into the top layer by substituting the surface Al atoms at certain sites on the √ 31 × √ 31 R9 • reconstructed surface formed by high-temperature annealing. The insulating template, demonstrated for Al 2 O 3 , may be a generally attractive system for the study of nanostructures which need to be isolated from a conducting bulk.
Structure of and ion segregation to an alumina grain boundary: Implications for growth and creep
Journal of Materials Research, 2008
... Ivan Milas, Berit Hinnemann,a) and Emily A. Carterb) Department of Mechanical and Aerospace E... more ... Ivan Milas, Berit Hinnemann,a) and Emily A. Carterb) Department of Mechanical and Aerospace Engineering, Princeton University, Princeton, New ... latter observations may still be consistent with higher overall rates, when one considers the experiments of Monty and coworkers,5 ...
Diffusion of Al, O, Pt, Hf, and Y atoms on α-Al2O3(0001): implications for the role of alloying elements in thermal barrier coatings
Journal of Materials Chemistry, 2011
Journal of Catalysis, 2012
Catalysts based on copper, such as the Cu/ZnO/Al 2 O 3 system are widely used for industrial scal... more Catalysts based on copper, such as the Cu/ZnO/Al 2 O 3 system are widely used for industrial scale methanol synthesis and the low temperature water gas shift reaction. A common characteristic of these catalysts is that they deactivate quite rapidly during operation and therefore understanding their deactivation by sintering is highly relevant. In this work, we study the nature of the species that are responsible for transport of the Cu metal in this catalyst type using density functional theory calculations within a chemical potential formalism. The stability and mobility of Cu-X (Cu, OH, CO, CH 3 O, HCOO) species are investigated in relevant synthesis gas compositions. The CuCO and Cu 2 HCOO species are identified to be predominant for metal transport on Cu particles, which may contribute to sintering of Cu by particle migration and coalescence. Furthermore, transport of Cu on ZnO is found mostly to occur through CuCO species, which indicates that CuCO is an important species for Ostwald ripening in a Cu/ZnO catalyst. These results provide atomistic perspective on the diffusion of the species that may contribute to catalyst sintering, therefore lending a valuable foundation for future investigations of the stability of Cu catalysts.
Characterization and Identification of the most Refractory Nitrogen Compounds in Hydroprocessed Vacuum Gas Oil
Industrial & Engineering Chemistry Research, 2010
ABSTRACT There is currently a growing need to hydroprocess heavier and tougher crude oils with in... more ABSTRACT There is currently a growing need to hydroprocess heavier and tougher crude oils with increased nitrogen content. Therefore, hydrodenitrogenation (HDN) has become a critical hydroprocessing reaction, making it essential to gain insight into which nitrogen-containing compounds are the most difficult to treat. In the present article, we describe the identification of nitrogen compounds in severely pretreated feed for hydrocracking (HC). The nitrogen compounds in the N-slip to the hydrocracker are isolated and concentrated on solid-phase extraction (SPE) columns and identified by gas chromatography mass spectrometry (GC-MS), gas chromatography with atomic emission detection (GC-AED), and nuclear magnetic resonance (NMR) spectroscopy. Density functional theory (DFT) calculations support the structural identification and are further used to investigate the reactivity. We find that the most refractory organic nitrogen compounds in the N-slip belong to the family of 4,8,9,10-tetrahydrocyclohepta[def]carbazoles. These molecules are slightly more basic than other carbazoles and thus are likely to have an impact on the performance of the downstream catalysts; however, their very low reactivities make them extremely difficult to remove under normal hydrotreating conditions.
Noncontact atomic force microscopy imaging of ferroelectric domains with functionalized tips
Applied Physics Letters, 2011
ABSTRACT We report on an imaging method for ferroelectric domains by noncontact atomic force micr... more ABSTRACT We report on an imaging method for ferroelectric domains by noncontact atomic force microscopy with dipole-molecule decorated tips. The Coulombic tip-sample interaction is revealing the domains monitored as an additional topography contribution. As proof of concept, we present agreement between numerical simulations and experiments on antiparallel out-of-plane domains on LiNbO3. This contact-free imaging technique promises substantially increased lifetime of read-heads for high-density ferroelectric data storages, and high resolution and improved image quality in scanning probe microscopy on systems with surface charge density variations.
Adsorption of Al, O, Hf, Y, Pt, and S atoms on α-Al2O3(0001)
Journal of Physical Chemistry C, 2007
Magnetic edge states in MoS2 characterized using density-functional theory
Physical Review B Condensed Matter and Materials Physics, 2009
It is known that the edges of a two-dimensional slab of insulating MoS2 exhibit one-dimensional m... more It is known that the edges of a two-dimensional slab of insulating MoS2 exhibit one-dimensional metallic edge states, the so-called “brim states.” Here, we find from density-functional theory calculations that several edge structures, which are relevant for the hydrodesulfurization process, are magnetic. The magnetism is an edge phenomenon associated with certain metallic edge states. Interestingly, we find that among the two low-index edges, only the S edge displays magnetism under hydrodesulfurization conditions. In addition, the implications of this on the catalytic activity are investigated. Despite large changes in the magnetic moments, a small influence on the adsorption energies is observed. This has implications on the suitability of magnetic measurements for monitoring the catalytic properties.
Chracterization of MoS2 Magnetic States Using Density-Functional Theory
Physical Review B, 2009
Structure of and ion segregation to an alumina grain boundary: Implications for growth and creep
Journal of Materials Research, May 1, 2008
... Ivan Milas, Berit Hinnemann,a) and Emily A. Carterb) Department of Mechanical and Aerospace E... more ... Ivan Milas, Berit Hinnemann,a) and Emily A. Carterb) Department of Mechanical and Aerospace Engineering, Princeton University, Princeton, New ... latter observations may still be consistent with higher overall rates, when one considers the experiments of Monty and coworkers,5 ...
Trends in Hydrodesulfurization Catalysis Based on Realistic Surface Models
Catalysis Letters, 2014
ABSTRACT Abstract Trends in hydrodesulfurization (HDS) activity are investigated on the basis of ... more ABSTRACT Abstract Trends in hydrodesulfurization (HDS) activity are investigated on the basis of surface properties calculated by density functional theory for a series of HDS catalysts. It is shown that approximately linear correlations exist between HS group binding energies and activation barriers of key elementary reactions in HDS of thiophene. These linear correlations are used to develop a simple kinetic model, which qualitatively describes experimental trends in activity. The kinetic model identifies the HS-binding energy as a descriptor of HDS activity. This insight contributes to understanding the effect of promotion and structure–activity relationships. Graphical Abstract
Surface Science, 2011
We investigate the structure and surface composition of the -Ni 3 Al(111) and -NiAl(110) alloy su... more We investigate the structure and surface composition of the -Ni 3 Al(111) and -NiAl(110) alloy surfaces at conditions relevant for metal dusting corrosion related to catalytic steam reforming of natural gas. In regular service as protective coatings, nickel-aluminum alloys are protected by an oxide scale, but in case of oxide scale spallation, the alloy surface may be directly exposed to the reactive gas environment and vulnerable to metal dusting. By means of density functional theory and thermochemical calculations for both the Ni 3 Al and NiAl surfaces, the conditions under which C O and O H adsorption is to be expected and under which it is inhibited, are mapped out. Because C O and O H are regarded as precursors for nucleating graphite or oxide on the surfaces, phase diagrams for the surfaces provide a simple description of their stability. Specifically, this study shows how the C O and O H coverages depend on the steam to carbon ratio (S/C) in the gas and thereby provide a ranking of the carbon limits on the different surface phases.
Catalysis by Enzymes: The Biological Ammonia Synthesis
Topics in Catalysis, 2006
Enzymes are nature’s own catalysts and fundamental for life, as they catalyze essentially all bio... more Enzymes are nature’s own catalysts and fundamental for life, as they catalyze essentially all biological processes. Compared to inorganic catalysts, however, their structure and function is immensely more complicated. Computational modeling has played an increasing role in elucidating enzyme mechanisms, as it can provide information complementary to experimental techniques. Elucidating enzyme structure and mechanism is not only important to understand
On the Role of Metal Step-Edges in Graphene Growth
The Journal of Physical Chemistry C, 2010
ABSTRACT Graphene growth on transition metal surfaces is studied by means of density functional t... more ABSTRACT Graphene growth on transition metal surfaces is studied by means of density functional theory calculations. The results show that graphene grows preferentially out from surface step edges onto lower facets on fcc and hcp metal surfaces. The results also reveal that an epitaxial lattice match between graphene and the metal step-edge stabilizes graphene and lowers the corresponding critical graphene nucleus size. In the case of a graphene−metal lattice mismatch, a destabilization of the critical graphene nucleus size may be compensated by tuning the carbon chemical potential. The concepts of metal−graphene lattice and carbon chemical potential are included in a simple growth model that describes experimental trends in graphene formation at different metal surfaces under varying growth conditions.
Adsorption of Al, O, Hf, Y, Pt, and S Atoms on α-Al2O3(0001)
Journal of Physical Chemistry C, 2007
Surface Science, 2009
Catalytic carbon deposition on Ni nanoparticles and surfaces is the first step towards coking of ... more Catalytic carbon deposition on Ni nanoparticles and surfaces is the first step towards coking of steam reforming Ni catalysts and carbon-induced corrosion, i.e., metal dusting corrosion, on Ni-based alloy surfaces . The fundamental processes at the atomic scale are essentially the same. Therefore an atomistic understanding of how the gas-phase components influence carbon deposition and nucleation is very valuable for the understanding of metal dusting and avoid this degradation. The growth of graphene on the Ni surface is a necessary step in both processes. Recent ETEM [3] and DFT [4] studies have shown that steps on the metal surface act as growth centers for graphene.
Physical Review Letters, 2009
Through the interplay of noncontact atomic force microscopy studies and density functional theory... more Through the interplay of noncontact atomic force microscopy studies and density functional theory calculations, an atomistic model for the Al 2 O 3 ð0001Þ-ffiffiffiffiffi ffi 31 p  ffiffiffiffiffi ffi 31 p R9 surface reconstruction is revealed. The surface is found to consist of an Al adlayer on the Al 2 O 3 substrate, and the driving force for the formation of the reconstruction is related to a detailed balance between strain in the adlayer and the preference for Al atoms to be located on distinct substrate sites.
Magnetic edge states in MoS2 characterized using density-functional theory
Physical Review B, 2009
... REVIEW B 80, 125416 [?]2009[?] Magnetic edge states in MoS2 characterized using density-funct... more ... REVIEW B 80, 125416 [?]2009[?] Magnetic edge states in MoS2 characterized using density-functional theory Aleksandra Vojvodic,1 ... Given are the relaxed MoS2 structures, the nomenclature [?]Nom.[?], the non-spinpolarized S vacancy formation energies [?]ES[?] the ...
Structure of the FeFe-cofactor of the iron-only nitrogenase and possible mechanism for dinitrogen reductionElectronic supplementary information (ESI) available. Optimized atomic coordinates for the FeFeco and FeMoco structures. See http://www.rsc.org/suppdata/cp/b3/b310850c/
Physical Chemistry Chemical Physics, 2004
Oxidation of Metals, 2011
Metal dusting is a catastrophic form of carburization attack that takes place in carbon-supersatu... more Metal dusting is a catastrophic form of carburization attack that takes place in carbon-supersaturated gaseous atmospheres, and is most commonly encountered in steam reforming processes such as the production of hydrogen or syngas for ammonia, Fischer-Tropsch and methanol applications. The consequence of metal dusting can be a severe loss of metal from the process units, leading to high-cost maintenance and serious safety issues. The present literature review discusses the latest developments within metal dusting protection of alloys with special emphasis on protective coatings. In the first part of the paper, an overview of the main theories for metal dusting of alloys as well as fundamental studies is provided. In the second part, the paper focuses on the different methods to prevent metal dusting, including surface poisoning, alloying, chemical, mechanical and laser treatments as well as coatings. Particular focus is given to coatings and their composition, and fabrication methods, and a critical analysis of the different materials' behaviours and the suitability perspectives of deposition techniques are provided.
Nanotechnology, 2010
We demonstrate that the characteristic √ 31 × √ 31 R9 • reconstructed surface of α-alumina (Al 2 ... more We demonstrate that the characteristic √ 31 × √ 31 R9 • reconstructed surface of α-alumina (Al 2 O 3 ) acts as a nanotemplate for the growth of well-ordered monodisperse arrays of Ni nanoclusters. Due to the insulating nature of the substrate we use dynamic scanning force microscopy operated in the non-contact mode (NC-AFM) to characterize the nanotemplate, to examine the size and distribution of metallic clusters on the surface and to investigate their position with respect to the surface atomic structure. The present NC-AFM results for the interaction of Ni with α-Al 2 O 3 are supported by density functional theory (DFT) calculations. The ability of α-Al 2 O 3 (0001) to act as a nanotemplate is attributed to a spatially modulated affinity towards the accommodation of Ni into the top layer by substituting the surface Al atoms at certain sites on the √ 31 × √ 31 R9 • reconstructed surface formed by high-temperature annealing. The insulating template, demonstrated for Al 2 O 3 , may be a generally attractive system for the study of nanostructures which need to be isolated from a conducting bulk.
Structure of and ion segregation to an alumina grain boundary: Implications for growth and creep
Journal of Materials Research, 2008
... Ivan Milas, Berit Hinnemann,a) and Emily A. Carterb) Department of Mechanical and Aerospace E... more ... Ivan Milas, Berit Hinnemann,a) and Emily A. Carterb) Department of Mechanical and Aerospace Engineering, Princeton University, Princeton, New ... latter observations may still be consistent with higher overall rates, when one considers the experiments of Monty and coworkers,5 ...
Diffusion of Al, O, Pt, Hf, and Y atoms on α-Al2O3(0001): implications for the role of alloying elements in thermal barrier coatings
Journal of Materials Chemistry, 2011
Journal of Catalysis, 2012
Catalysts based on copper, such as the Cu/ZnO/Al 2 O 3 system are widely used for industrial scal... more Catalysts based on copper, such as the Cu/ZnO/Al 2 O 3 system are widely used for industrial scale methanol synthesis and the low temperature water gas shift reaction. A common characteristic of these catalysts is that they deactivate quite rapidly during operation and therefore understanding their deactivation by sintering is highly relevant. In this work, we study the nature of the species that are responsible for transport of the Cu metal in this catalyst type using density functional theory calculations within a chemical potential formalism. The stability and mobility of Cu-X (Cu, OH, CO, CH 3 O, HCOO) species are investigated in relevant synthesis gas compositions. The CuCO and Cu 2 HCOO species are identified to be predominant for metal transport on Cu particles, which may contribute to sintering of Cu by particle migration and coalescence. Furthermore, transport of Cu on ZnO is found mostly to occur through CuCO species, which indicates that CuCO is an important species for Ostwald ripening in a Cu/ZnO catalyst. These results provide atomistic perspective on the diffusion of the species that may contribute to catalyst sintering, therefore lending a valuable foundation for future investigations of the stability of Cu catalysts.
Characterization and Identification of the most Refractory Nitrogen Compounds in Hydroprocessed Vacuum Gas Oil
Industrial & Engineering Chemistry Research, 2010
ABSTRACT There is currently a growing need to hydroprocess heavier and tougher crude oils with in... more ABSTRACT There is currently a growing need to hydroprocess heavier and tougher crude oils with increased nitrogen content. Therefore, hydrodenitrogenation (HDN) has become a critical hydroprocessing reaction, making it essential to gain insight into which nitrogen-containing compounds are the most difficult to treat. In the present article, we describe the identification of nitrogen compounds in severely pretreated feed for hydrocracking (HC). The nitrogen compounds in the N-slip to the hydrocracker are isolated and concentrated on solid-phase extraction (SPE) columns and identified by gas chromatography mass spectrometry (GC-MS), gas chromatography with atomic emission detection (GC-AED), and nuclear magnetic resonance (NMR) spectroscopy. Density functional theory (DFT) calculations support the structural identification and are further used to investigate the reactivity. We find that the most refractory organic nitrogen compounds in the N-slip belong to the family of 4,8,9,10-tetrahydrocyclohepta[def]carbazoles. These molecules are slightly more basic than other carbazoles and thus are likely to have an impact on the performance of the downstream catalysts; however, their very low reactivities make them extremely difficult to remove under normal hydrotreating conditions.
Noncontact atomic force microscopy imaging of ferroelectric domains with functionalized tips
Applied Physics Letters, 2011
ABSTRACT We report on an imaging method for ferroelectric domains by noncontact atomic force micr... more ABSTRACT We report on an imaging method for ferroelectric domains by noncontact atomic force microscopy with dipole-molecule decorated tips. The Coulombic tip-sample interaction is revealing the domains monitored as an additional topography contribution. As proof of concept, we present agreement between numerical simulations and experiments on antiparallel out-of-plane domains on LiNbO3. This contact-free imaging technique promises substantially increased lifetime of read-heads for high-density ferroelectric data storages, and high resolution and improved image quality in scanning probe microscopy on systems with surface charge density variations.