(-) Remove <label class='research-domain' title='Cultures and Cultural Production'>SH5 (111)</label> filter SH5 (111)
Project acronym 2D–SYNETRA
Project Two-dimensional colloidal nanostructures - Synthesis and electrical transport
Researcher (PI) Christian Klinke
Host Institution (HI) UNIVERSITAET HAMBURG
Summary We propose to develop truly two-dimensional continuous materials and two-dimensional monolayer films composed of individual nanocrystals by the comparatively fast, inexpensive, and scalable colloidal synthesis method. The materials' properties will be studied in detail, especially regarding their (photo-) electrical transport. This will allow developing new types of device structures, such as Coulomb blockade and field enhancement based transistors. Recently, we demonstrated the possibility to synthesize in a controlled manner truly two-dimensional colloidal nanostructures. We will investigate their formation mechanism, synthesize further materials as "nanosheets", develop methodologies to tune their geometrical properties, and study their (photo-) electrical properties. Furthermore, we will use the Langmuir-Blodgett method to deposit highly ordered monolayers of monodisperse nanoparticles. Such structures show interesting transport properties governed by Coulomb blockade effects known from individual nanoparticles. This leads to semiconductor-like behavior in metal nanoparticle films. The understanding of the electric transport in such "multi-tunnel devices" is still very limited. Thus, we will investigate this concept in detail and take it to its limits. Beside improvement of quality and exchange of material we will tune the nanoparticles' size and shape in order to gain a deeper understanding of the electrical properties of supercrystallographic assemblies. Furthermore, we will develop device concepts for diode and transistor structures which take into account the novel properties of the low-dimensional assemblies. Nanosheets and monolayers of nanoparticles truly follow the principle of building devices by the bottom-up approach and allow electric transport measurements in a 2D regime. Highly ordered nanomaterial systems possess easy and reliably to manipulate electronic properties what make them interesting for future (inexpensive) electronic devices.
We propose to develop truly two-dimensional continuous materials and two-dimensional monolayer films composed of individual nanocrystals by the comparatively fast, inexpensive, and scalable colloidal synthesis method. The materials' properties will be studied in detail, especially regarding their (photo-) electrical transport. This will allow developing new types of device structures, such as Coulomb blockade and field enhancement based transistors. Recently, we demonstrated the possibility to synthesize in a controlled manner truly two-dimensional colloidal nanostructures. We will investigate their formation mechanism, synthesize further materials as "nanosheets", develop methodologies to tune their geometrical properties, and study their (photo-) electrical properties. Furthermore, we will use the Langmuir-Blodgett method to deposit highly ordered monolayers of monodisperse nanoparticles. Such structures show interesting transport properties governed by Coulomb blockade effects known from individual nanoparticles. This leads to semiconductor-like behavior in metal nanoparticle films. The understanding of the electric transport in such "multi-tunnel devices" is still very limited. Thus, we will investigate this concept in detail and take it to its limits. Beside improvement of quality and exchange of material we will tune the nanoparticles' size and shape in order to gain a deeper understanding of the electrical properties of supercrystallographic assemblies. Furthermore, we will develop device concepts for diode and transistor structures which take into account the novel properties of the low-dimensional assemblies. Nanosheets and monolayers of nanoparticles truly follow the principle of building devices by the bottom-up approach and allow electric transport measurements in a 2D regime. Highly ordered nanomaterial systems possess easy and reliably to manipulate electronic properties what make them interesting for future (inexpensive) electronic devices.
Project acronym 2F4BIODYN
Project Two-Field Nuclear Magnetic Resonance Spectroscopy for the Exploration of Biomolecular Dynamics
Researcher (PI) Fabien Ferrage
Host Institution (HI) CENTRE NATIONAL DE LA RECHERCHE SCIENTIFIQUE CNRS
Summary The paradigm of the structure-function relationship in proteins is outdated. Biological macromolecules and supramolecular assemblies are highly dynamic objects. Evidence that their motions are of utmost importance to their functions is regularly identified. The understanding of the physical chemistry of biological processes at an atomic level has to rely not only on the description of structure but also on the characterization of molecular motions. The investigation of protein motions will be undertaken with a very innovative methodological approach in nuclear magnetic resonance relaxation. In order to widen the ranges of frequencies at which local motions in proteins are probed, we will first use and develop new techniques for a prototype shuttle system for the measurement of relaxation at low fields on a high-field NMR spectrometer. Second, we will develop a novel system: a set of low-field NMR spectrometers designed as accessories for high-field spectrometers. Used in conjunction with the shuttle, this system will offer (i) the sensitivity and resolution (i.e. atomic level information) of a high-field spectrometer (ii) the access to low fields of a relaxometer and (iii) the ability to measure a wide variety of relaxation rates with high accuracy. This system will benefit from the latest technology in homogeneous permanent magnet development to allow a control of spin systems identical to that of a high-resolution probe. This new apparatus will open the way to the use of NMR relaxation at low fields for the refinement of protein motions at an atomic scale. Applications of this novel approach will focus on the bright side of protein dynamics: (i) the largely unexplored dynamics of intrinsically disordered proteins, and (ii) domain motions in large proteins. In both cases, we will investigate a series of diverse protein systems with implications in development, cancer and immunity.
The paradigm of the structure-function relationship in proteins is outdated. Biological macromolecules and supramolecular assemblies are highly dynamic objects. Evidence that their motions are of utmost importance to their functions is regularly identified. The understanding of the physical chemistry of biological processes at an atomic level has to rely not only on the description of structure but also on the characterization of molecular motions. The investigation of protein motions will be undertaken with a very innovative methodological approach in nuclear magnetic resonance relaxation. In order to widen the ranges of frequencies at which local motions in proteins are probed, we will first use and develop new techniques for a prototype shuttle system for the measurement of relaxation at low fields on a high-field NMR spectrometer. Second, we will develop a novel system: a set of low-field NMR spectrometers designed as accessories for high-field spectrometers. Used in conjunction with the shuttle, this system will offer (i) the sensitivity and resolution (i.e. atomic level information) of a high-field spectrometer (ii) the access to low fields of a relaxometer and (iii) the ability to measure a wide variety of relaxation rates with high accuracy. This system will benefit from the latest technology in homogeneous permanent magnet development to allow a control of spin systems identical to that of a high-resolution probe. This new apparatus will open the way to the use of NMR relaxation at low fields for the refinement of protein motions at an atomic scale. Applications of this novel approach will focus on the bright side of protein dynamics: (i) the largely unexplored dynamics of intrinsically disordered proteins, and (ii) domain motions in large proteins. In both cases, we will investigate a series of diverse protein systems with implications in development, cancer and immunity.
Project acronym a SMILE
Project analyse Soluble + Membrane complexes with Improved LILBID Experiments
Researcher (PI) Nina Morgner
Host Institution (HI) JOHANN WOLFGANG GOETHE-UNIVERSITATFRANKFURT AM MAIN
Summary Crucial processes within cells depend on specific non-covalent interactions which mediate the assembly of proteins and other biomolecules. Deriving structural information to understand the function of these complex systems is the primary goal of Structural Biology. In this application, the recently developed LILBID method (Laser Induced Liquid Bead Ion Desorption) will be optimized for investigation of macromolecular complexes with a mass accuracy two orders of magnitude better than in 1st generation spectrometers. Controlled disassembly of the multiprotein complexes in the mass spectrometric analysis while keeping the 3D structure intact, will allow for the determination of complex stoichiometry and connectivity of the constituting proteins. Methods for such controlled disassembly will be developed in two separate units of the proposed LILBID spectrometer, in a collision chamber and in a laser dissociation chamber, enabling gas phase dissociation of protein complexes and removal of excess water/buffer molecules. As a third unit, a chamber allowing determination of ion mobility (IM) will be integrated to determine collisional cross sections (CCS). From CCS, unique information regarding the spatial arrangement of proteins in complexes or subcomplexes will then be obtainable from LILBID. The proposed design of the new spectrometer will offer fundamentally new possibilities for the investigation of non-covalent RNA, soluble and membrane protein complexes, as well as broadening the applicability of non-covalent MS towards supercomplexes.
Crucial processes within cells depend on specific non-covalent interactions which mediate the assembly of proteins and other biomolecules. Deriving structural information to understand the function of these complex systems is the primary goal of Structural Biology. In this application, the recently developed LILBID method (Laser Induced Liquid Bead Ion Desorption) will be optimized for investigation of macromolecular complexes with a mass accuracy two orders of magnitude better than in 1st generation spectrometers. Controlled disassembly of the multiprotein complexes in the mass spectrometric analysis while keeping the 3D structure intact, will allow for the determination of complex stoichiometry and connectivity of the constituting proteins. Methods for such controlled disassembly will be developed in two separate units of the proposed LILBID spectrometer, in a collision chamber and in a laser dissociation chamber, enabling gas phase dissociation of protein complexes and removal of excess water/buffer molecules. As a third unit, a chamber allowing determination of ion mobility (IM) will be integrated to determine collisional cross sections (CCS). From CCS, unique information regarding the spatial arrangement of proteins in complexes or subcomplexes will then be obtainable from LILBID. The proposed design of the new spectrometer will offer fundamentally new possibilities for the investigation of non-covalent RNA, soluble and membrane protein complexes, as well as broadening the applicability of non-covalent MS towards supercomplexes.
Project acronym A-LIFE
Project The asymmetry of life: towards a unified view of the emergence of biological homochirality
Researcher (PI) Cornelia MEINERT
Summary What is responsible for the emergence of homochirality, the almost exclusive use of one enantiomer over its mirror image? And what led to the evolution of life's homochiral biopolymers, DNA/RNA, proteins and lipids, where all the constituent monomers exhibit the same handedness? Based on in-situ observations and laboratory studies, we propose that this handedness occurs when chiral biomolecules are synthesized asymmetrically through interaction with circularly polarized photons in interstellar space. The ultimate goal of this project will be to demonstrate how the diverse set of heterogeneous enantioenriched molecules, available from meteoritic impact, assembles into homochiral pre-biopolymers, by simulating the evolutionary stages on early Earth. My recent research has shown that the central chiral unit of RNA, ribose, forms readily under simulated comet conditions and this has provided valuable new insights into the accessibility of precursors of genetic material in interstellar environments. The significance of this project arises due to the current lack of experimental demonstration that amino acids, sugars and lipids can simultaneously and asymmetrically be synthesized by a universal physical selection process. A synergistic methodology will be developed to build a unified theory for the origin of all chiral biological building blocks and their assembly into homochiral supramolecular entities. For the first time, advanced analyses of astrophysical-relevant samples, asymmetric photochemistry triggered by circularly polarized synchrotron and laser sources, and chiral amplification due to polymerization processes will be combined. Intermediates and autocatalytic reaction kinetics will be monitored and supported by quantum calculations to understand the underlying processes. A unified theory on the asymmetric formation and self-assembly of life's biopolymers is groundbreaking and will impact the whole conceptual foundation of the origin of life.
What is responsible for the emergence of homochirality, the almost exclusive use of one enantiomer over its mirror image? And what led to the evolution of life's homochiral biopolymers, DNA/RNA, proteins and lipids, where all the constituent monomers exhibit the same handedness? Based on in-situ observations and laboratory studies, we propose that this handedness occurs when chiral biomolecules are synthesized asymmetrically through interaction with circularly polarized photons in interstellar space. The ultimate goal of this project will be to demonstrate how the diverse set of heterogeneous enantioenriched molecules, available from meteoritic impact, assembles into homochiral pre-biopolymers, by simulating the evolutionary stages on early Earth. My recent research has shown that the central chiral unit of RNA, ribose, forms readily under simulated comet conditions and this has provided valuable new insights into the accessibility of precursors of genetic material in interstellar environments. The significance of this project arises due to the current lack of experimental demonstration that amino acids, sugars and lipids can simultaneously and asymmetrically be synthesized by a universal physical selection process. A synergistic methodology will be developed to build a unified theory for the origin of all chiral biological building blocks and their assembly into homochiral supramolecular entities. For the first time, advanced analyses of astrophysical-relevant samples, asymmetric photochemistry triggered by circularly polarized synchrotron and laser sources, and chiral amplification due to polymerization processes will be combined. Intermediates and autocatalytic reaction kinetics will be monitored and supported by quantum calculations to understand the underlying processes. A unified theory on the asymmetric formation and self-assembly of life's biopolymers is groundbreaking and will impact the whole conceptual foundation of the origin of life.
Project acronym ABIOS
Project ABIOtic Synthesis of RNA: an investigation on how life started before biology existed
Researcher (PI) Guillaume STIRNEMANN
Summary The emergence of life is one of the most fascinating and yet largely unsolved questions in the natural sciences, and thus a significant challenge for scientists from many disciplines. There is growing evidence that ribonucleic acid (RNA) polymers, which are capable of genetic information storage and self-catalysis, were involved in the early forms of life. But despite recent progress, RNA synthesis without biological machineries is very challenging. The current project aims at understanding how to synthesize RNA in abiotic conditions. I will solve problems associated with three critical aspects of RNA formation that I will rationalize at a molecular level: (i) accumulation of precursors, (ii) formation of a chemical bond between RNA monomers, and (iii) tolerance for alternative backbone sugars or linkages. Because I will study problems ranging from the formation of chemical bonds up to the stability of large biopolymers, I propose an original computational multi-scale approach combining techniques that range from quantum calculations to large-scale all-atom simulations, employed together with efficient enhanced-sampling algorithms, forcefield improvement, cutting-edge analysis methods and model development. My objectives are the following: 1 • To explain why the poorly-understood thermally-driven process of thermophoresis can contribute to the accumulation of dilute precursors. 2 • To understand why linking RNA monomers with phosphoester bonds is so difficult, to understand the molecular mechanism of possible catalysts and to suggest key improvements. 3 • To rationalize the molecular basis for RNA tolerance for alternative backbone sugars or linkages that have probably been incorporated in abiotic conditions. This unique in-silico laboratory setup should significantly impact our comprehension of life's origin by overcoming major obstacles to RNA abiotic formation, and in addition will reveal significant orthogonal outcomes for (bio)technological applications.
The emergence of life is one of the most fascinating and yet largely unsolved questions in the natural sciences, and thus a significant challenge for scientists from many disciplines. There is growing evidence that ribonucleic acid (RNA) polymers, which are capable of genetic information storage and self-catalysis, were involved in the early forms of life. But despite recent progress, RNA synthesis without biological machineries is very challenging. The current project aims at understanding how to synthesize RNA in abiotic conditions. I will solve problems associated with three critical aspects of RNA formation that I will rationalize at a molecular level: (i) accumulation of precursors, (ii) formation of a chemical bond between RNA monomers, and (iii) tolerance for alternative backbone sugars or linkages. Because I will study problems ranging from the formation of chemical bonds up to the stability of large biopolymers, I propose an original computational multi-scale approach combining techniques that range from quantum calculations to large-scale all-atom simulations, employed together with efficient enhanced-sampling algorithms, forcefield improvement, cutting-edge analysis methods and model development. My objectives are the following: 1 • To explain why the poorly-understood thermally-driven process of thermophoresis can contribute to the accumulation of dilute precursors. 2 • To understand why linking RNA monomers with phosphoester bonds is so difficult, to understand the molecular mechanism of possible catalysts and to suggest key improvements. 3 • To rationalize the molecular basis for RNA tolerance for alternative backbone sugars or linkages that have probably been incorporated in abiotic conditions. This unique in-silico laboratory setup should significantly impact our comprehension of life's origin by overcoming major obstacles to RNA abiotic formation, and in addition will reveal significant orthogonal outcomes for (bio)technological applications.
Project acronym ACO
Project The Proceedings of the Ecumenical Councils from Oral Utterance to Manuscript Edition as Evidence for Late Antique Persuasion and Self-Representation Techniques
Researcher (PI) Peter Alfred Riedlberger
Host Institution (HI) OTTO-FRIEDRICH-UNIVERSITAET BAMBERG
Summary The Acts of the Ecumenical Councils of Late Antiquity include (purportedly) verbatim minutes of the proceedings, a formal framework and copies of relevant documents which were either (allegedly) read out during the proceedings or which were later attached to the Acts proper. Despite this unusual wealth of documentary evidence, the daunting nature of the Acts demanding multidisciplinary competency, their complex structure with a matryoshka-like nesting of proceedings from different dates, and the stereotype that their contents bear only on Christological niceties have deterred generations of historians from studying them. Only in recent years have their fortunes begun to improve, but this recent research has not always been based on sound principles: the recorded proceedings of the sessions are still often accepted as verbatim minutes. Yet even a superficial reading quickly reveals widespread editorial interference. We must accept that in many cases the Acts will teach us less about the actual debates than about the editors who shaped their presentation. This does not depreciate the Acts' evidence: on the contrary, they are first-rate material for the rhetoric of persuasion and self-representation. It is possible, in fact, to take the investigation to a deeper level and examine in what manner the oral proceedings were put into writing: several passages in the Acts comment upon the process of note-taking and the work of the shorthand writers. Thus, the main objective of the proposed research project could be described as an attempt to trace the destinies of the Acts' texts, from the oral utterance to the manuscript texts we have today. This will include the fullest study on ancient transcript techniques to date; a structural analysis of the Acts' texts with the aim of highlighting edited passages; and a careful comparison of the various editions of the Acts, which survive in Greek, Latin, Syriac and Coptic, in order to detect traces of editorial interference.
The Acts of the Ecumenical Councils of Late Antiquity include (purportedly) verbatim minutes of the proceedings, a formal framework and copies of relevant documents which were either (allegedly) read out during the proceedings or which were later attached to the Acts proper. Despite this unusual wealth of documentary evidence, the daunting nature of the Acts demanding multidisciplinary competency, their complex structure with a matryoshka-like nesting of proceedings from different dates, and the stereotype that their contents bear only on Christological niceties have deterred generations of historians from studying them. Only in recent years have their fortunes begun to improve, but this recent research has not always been based on sound principles: the recorded proceedings of the sessions are still often accepted as verbatim minutes. Yet even a superficial reading quickly reveals widespread editorial interference. We must accept that in many cases the Acts will teach us less about the actual debates than about the editors who shaped their presentation. This does not depreciate the Acts' evidence: on the contrary, they are first-rate material for the rhetoric of persuasion and self-representation. It is possible, in fact, to take the investigation to a deeper level and examine in what manner the oral proceedings were put into writing: several passages in the Acts comment upon the process of note-taking and the work of the shorthand writers. Thus, the main objective of the proposed research project could be described as an attempt to trace the destinies of the Acts' texts, from the oral utterance to the manuscript texts we have today. This will include the fullest study on ancient transcript techniques to date; a structural analysis of the Acts' texts with the aim of highlighting edited passages; and a careful comparison of the various editions of the Acts, which survive in Greek, Latin, Syriac and Coptic, in order to detect traces of editorial interference.
Project acronym AncNar
Project Experience and Teleology in Ancient Narrative
Researcher (PI) Jonas Grethlein
Host Institution (HI) RUPRECHT-KARLS-UNIVERSITAET HEIDELBERG
Call Details Starting Grant (StG), SH5, ERC-2012-StG_20111124
Summary The last two decades have seen fascinating attempts to establish new narratologies, basing narratology on cognitive science or coupling it with other approaches such as postcolonial studies. While appreciating that these attempts have raised questions beyond the limits of structuralist narratology, critics have noted that by doing so they tend to abandon narratology's strength, that is its analytical tools. In many cases, narratology has become a label that is as empty as it is fashionable. The project as outlined here, on the other hand, develops a new approach that combines the analytical arsenal of structuralist narratology with a phenomenological take on time in order to provide new answers as to the question of narrative's function. By exploring the tension between experience and teleology in ancient literature, it sets out to demonstrate how narrative serves as a mode of coming to grips with time. Besides offering a new narratology that cross-fertilizes the strengths of different disciplines and pioneering a new approach to ancient literature, the project will steer the current debate on experience and presence into a new direction across disciplines in the humanities.
The last two decades have seen fascinating attempts to establish new narratologies, basing narratology on cognitive science or coupling it with other approaches such as postcolonial studies. While appreciating that these attempts have raised questions beyond the limits of structuralist narratology, critics have noted that by doing so they tend to abandon narratology's strength, that is its analytical tools. In many cases, narratology has become a label that is as empty as it is fashionable. The project as outlined here, on the other hand, develops a new approach that combines the analytical arsenal of structuralist narratology with a phenomenological take on time in order to provide new answers as to the question of narrative's function. By exploring the tension between experience and teleology in ancient literature, it sets out to demonstrate how narrative serves as a mode of coming to grips with time. Besides offering a new narratology that cross-fertilizes the strengths of different disciplines and pioneering a new approach to ancient literature, the project will steer the current debate on experience and presence into a new direction across disciplines in the humanities.
Project acronym ANGLE
Project Accelerated design and discovery of novel molecular materials via global lattice energy minimisation
Researcher (PI) Graeme Matthew Day
Host Institution (HI) UNIVERSITY OF SOUTHAMPTON
Summary The goal of crystal engineering is the design of functional crystalline materials in which the arrangement of basic structural building blocks imparts desired properties. The engineering of organic molecular crystals has, to date, relied largely on empirical rules governing the intermolecular association of functional groups in the solid state. However, many materials properties depend intricately on the complete crystal structure, i.e. the unit cell, space group and atomic positions, which cannot be predicted solely using such rules. Therefore, the development of computational methods for crystal structure prediction (CSP) from first principles has been a goal of computational chemistry that could significantly accelerate the design of new materials. It is only recently that the necessary advances in the modelling of intermolecular interactions and developments in algorithms for identifying all relevant crystal structures have come together to provide predictive methods that are becoming reliable and affordable on a timescale that could usefully complement an experimental research programme. The principle aim of the proposed work is to establish the use of state-of-the-art crystal structure prediction methods as a means of guiding the discovery and design of novel molecular materials. This research proposal both continues the development of the computational methods for CSP and, by developing a computational framework for screening of potential molecules, develops the application of these methods for materials design. The areas on which we will focus are organic molecular semiconductors with high charge carrier mobilities and, building on our recently published results in Nature [1], the development of porous organic molecular materials. The project will both deliver novel materials, as well as improvements in the reliability of computational methods that will find widespread applications in materials chemistry. [1] Nature 2011, 474, 367-371.
The goal of crystal engineering is the design of functional crystalline materials in which the arrangement of basic structural building blocks imparts desired properties. The engineering of organic molecular crystals has, to date, relied largely on empirical rules governing the intermolecular association of functional groups in the solid state. However, many materials properties depend intricately on the complete crystal structure, i.e. the unit cell, space group and atomic positions, which cannot be predicted solely using such rules. Therefore, the development of computational methods for crystal structure prediction (CSP) from first principles has been a goal of computational chemistry that could significantly accelerate the design of new materials. It is only recently that the necessary advances in the modelling of intermolecular interactions and developments in algorithms for identifying all relevant crystal structures have come together to provide predictive methods that are becoming reliable and affordable on a timescale that could usefully complement an experimental research programme. The principle aim of the proposed work is to establish the use of state-of-the-art crystal structure prediction methods as a means of guiding the discovery and design of novel molecular materials. This research proposal both continues the development of the computational methods for CSP and, by developing a computational framework for screening of potential molecules, develops the application of these methods for materials design. The areas on which we will focus are organic molecular semiconductors with high charge carrier mobilities and, building on our recently published results in Nature [1], the development of porous organic molecular materials. The project will both deliver novel materials, as well as improvements in the reliability of computational methods that will find widespread applications in materials chemistry. [1] Nature 2011, 474, 367-371.
Project acronym APES
Project Accuracy and precision for molecular solids
Researcher (PI) Jiri KLIMES
Summary The description of high pressure phases or polymorphism of molecular solids represents a significant scientific challenge both for experiment and theory. Theoretical methods that are currently used struggle to describe the tiny energy differences between different phases. It is the aim of this project to develop a scheme that would allow accurate and reliable predictions of the binding energies of molecular solids and of the energy differences between different phases. To reach the required accuracy, we will combine the coupled cluster approach, widely used for reference quality calculations for molecules, with the random phase approximation (RPA) within periodic boundary conditions. As I have recently shown, RPA-based approaches are already some of the most accurate and practically usable methods for the description of extended systems. However, reliability is not only a question of accuracy. Reliable data need to be precise, that is, converged with the numerical parameters so that they are reproducible by other researchers. Reproducibility is already a growing concern in the field. It is likely to become a considerable issue for highly accurate methods as the calculated energies have a stronger dependence on the simulation parameters such as the basis set size. Two main approaches will be explored to assure precision. First, we will develop the so-called asymptotic correction scheme to speed-up the convergence of the correlation energies with the basis set size. Second, we will directly compare the lattice energies from periodic and finite cluster based calculations. Both should yield identical answers, but if and how the agreement can be reached for general system is currently far from being understood for methods such as coupled cluster. Reliable data will allow us to answer some of the open questions regarding the stability of polymorphs and high pressure phases, such as the possibility of existence of high pressure ionic phases of water and ammonia.
The description of high pressure phases or polymorphism of molecular solids represents a significant scientific challenge both for experiment and theory. Theoretical methods that are currently used struggle to describe the tiny energy differences between different phases. It is the aim of this project to develop a scheme that would allow accurate and reliable predictions of the binding energies of molecular solids and of the energy differences between different phases. To reach the required accuracy, we will combine the coupled cluster approach, widely used for reference quality calculations for molecules, with the random phase approximation (RPA) within periodic boundary conditions. As I have recently shown, RPA-based approaches are already some of the most accurate and practically usable methods for the description of extended systems. However, reliability is not only a question of accuracy. Reliable data need to be precise, that is, converged with the numerical parameters so that they are reproducible by other researchers. Reproducibility is already a growing concern in the field. It is likely to become a considerable issue for highly accurate methods as the calculated energies have a stronger dependence on the simulation parameters such as the basis set size. Two main approaches will be explored to assure precision. First, we will develop the so-called asymptotic correction scheme to speed-up the convergence of the correlation energies with the basis set size. Second, we will directly compare the lattice energies from periodic and finite cluster based calculations. Both should yield identical answers, but if and how the agreement can be reached for general system is currently far from being understood for methods such as coupled cluster. Reliable data will allow us to answer some of the open questions regarding the stability of polymorphs and high pressure phases, such as the possibility of existence of high pressure ionic phases of water and ammonia.
Project acronym AQUARAMAN
Project Pipet Based Scanning Probe Microscopy Tip-Enhanced Raman Spectroscopy: A Novel Approach for TERS in Liquids
Researcher (PI) Aleix Garcia Guell
Host Institution (HI) ECOLE POLYTECHNIQUE
Summary Tip-enhanced Raman spectroscopy (TERS) is often described as the most powerful tool for optical characterization of surfaces and their proximities. It combines the intrinsic spatial resolution of scanning probe techniques (AFM or STM) with the chemical information content of vibrational Raman spectroscopy. Capable to reveal surface heterogeneity at the nanoscale, TERS is currently playing a fundamental role in the understanding of interfacial physicochemical processes in key areas of science and technology such as chemistry, biology and material science. Unfortunately, the undeniable potential of TERS as a label-free tool for nanoscale chemical and structural characterization is, nowadays, limited to air and vacuum environments, with it failing to operate in a reliable and systematic manner in liquid. The reasons are more technical than fundamental, as what is hindering the application of TERS in water is, among other issues, the low stability of the probes and their consistency. Fields of science and technology where the presence of water/electrolyte is unavoidable, such as biology and electrochemistry, remain unexplored with this powerful technique. We propose a revolutionary approach for TERS in liquids founded on the employment of pipet-based scanning probe microscopy techniques (pb-SPM) as an alternative to AFM and STM. The use of recent but well established pb-SPM brings the opportunity to develop unprecedented pipet-based TERS probes (beyond the classic and limited metallized solid probes from AFM and STM), together with the implementation of ingenious and innovative measures to enhance tip stability, sensitivity and reliability, unattainable with the current techniques. We will be in possession of a unique nano-spectroscopy platform capable of experiments in liquids, to follow dynamic processes in-situ, addressing fundamental questions and bringing insight into interfacial phenomena spanning from materials science, physics, chemistry and biology.
Tip-enhanced Raman spectroscopy (TERS) is often described as the most powerful tool for optical characterization of surfaces and their proximities. It combines the intrinsic spatial resolution of scanning probe techniques (AFM or STM) with the chemical information content of vibrational Raman spectroscopy. Capable to reveal surface heterogeneity at the nanoscale, TERS is currently playing a fundamental role in the understanding of interfacial physicochemical processes in key areas of science and technology such as chemistry, biology and material science. Unfortunately, the undeniable potential of TERS as a label-free tool for nanoscale chemical and structural characterization is, nowadays, limited to air and vacuum environments, with it failing to operate in a reliable and systematic manner in liquid. The reasons are more technical than fundamental, as what is hindering the application of TERS in water is, among other issues, the low stability of the probes and their consistency. Fields of science and technology where the presence of water/electrolyte is unavoidable, such as biology and electrochemistry, remain unexplored with this powerful technique. We propose a revolutionary approach for TERS in liquids founded on the employment of pipet-based scanning probe microscopy techniques (pb-SPM) as an alternative to AFM and STM. The use of recent but well established pb-SPM brings the opportunity to develop unprecedented pipet-based TERS probes (beyond the classic and limited metallized solid probes from AFM and STM), together with the implementation of ingenious and innovative measures to enhance tip stability, sensitivity and reliability, unattainable with the current techniques. We will be in possession of a unique nano-spectroscopy platform capable of experiments in liquids, to follow dynamic processes in-situ, addressing fundamental questions and bringing insight into interfacial phenomena spanning from materials science, physics, chemistry and biology.