This research was funded by the International Research Training Group (IRTG) &#8220;Diffusion in porous Materials&#8221;. We acknowledge the technical support from Gert Klotzsche and stimulating discussions with Steven Reichhardt, Thomas Meissner, Damian Rybicki, Tobias Herzig, Natalya Georgieva, Jonas Kohlrautz, and Michael Jurkutat.

1. Montage und Ausrichtung der 6H-SiC großen Kegel Böhler-Typ Ambosse <ol><li> Befestigen Sie den Kolben und xy Platte in der Montagewerkzeuge und legen Sie die Böhler-Typ Ambosse in der Sitzecke. </li><li> Stellen Sie sicher, jeder Amboß sitzt fest in der Trägerplatten. </li><li> Mit Epoxidharz, (zB Stycast 1266), kleben Sie beide Ambosse auf ihre Plätze. Heilmittel für 12 h bei RT oder 65 ° C in einem Ofen für 2 Stunden. </li><li> Für eine ausreichende Amboß-Ausrichtungs, verwenden Sie die M1 Stellschrauben, um die Trägerplatten ausrichten und überwachen die Parallelität der beiden Ambosse. Wenn die Ambosse wurden nicht parallel zu sein, entfernen Sie das Epoxidharz und starten Sie bei Punkt 1.2. </li></ol> 2. Dichtung Vorbereitung <ol><li> Bohrer 1 mm Löcher in einen Chip von geglüht Cu-Be-(Cu 98% w, Be 2 Gew%, Dicke von 0,5 mm) für die Führungsstifte aus Messing. </li><li> Legen Sie drei 5 mm lange Stücke von 1 mm Durchmesser nicht isolierten Kupferdraht in die Löcher, die sich entlang der Amboss verteilt sind, dienen als GUIDe Pins für die Cu-Be-Dichtung. </li><li> Überprüfen Sie die korrekte Erdung zwischen den Führungsstiften und der Zellkörper. Typischerweise wird ein Gleichstromwiderstand von etwa 0,1 Ω Wunsch. Verbesserung mit einer Anwendung einer geringen Menge von leitfähigen Silber. </li><li> Legen Sie die Cu-Be-Chip auf der moissanite Amboss und schließen Sie die Zelle. </li><li> Verwendung einer hydraulischen Presse, die Dichtung unter Druck zu setzen, um zu 1/8 der culet Durchmesser für maximale Betriebsstabilität. Überwachung der tatsächlichen Dicke der Vertiefung unter Verwendung eines Mikrometermessschieber. </li><li> Bohren Sie ein Loch von dem entsprechenden Durchmesser (½ der culet Durchmesser) in der Mitte der Vertiefung. </li><li> Schnitzen zwei Kanäle in die Pre-rückt Dichtung. Die Kanäle sollten tief genug, um die 18 um Kupferdraht der Mikrospule aufzunehmen. </li><li> Härten die hergestellte Dichtung bei 617 K für 2 bis 3 h in einem Ofen. </li></ol> 3. Vorbereitung und Beladung der Mikrospule <ol><li> Verwenden Sie ein Stück von 1 mm Kupferdraht eind wird durch das Durchgangsgewinde des Kolbens. Befestigen Sie den Kupferdraht mit Epoxid-Harz und heilen nach Schritt 1.3. </li><li> Wählen Sie eine Ahle (siehe Liste der Materialien), die den gewünschten Durchmesser der Mikrospule und befestigen Sie es zwischen einem Paar von drehbaren Spannfutter-Backen. </li><li> Kleber (mit zB Lack von SCB, siehe Liste der Materialien) ein Ende des 18 um Kupferdraht auf die Spannbacken, während das andere Ende hält und drehen Sie die Spannbacken, so dass der Draht auf die Ahle aufgerollt. </li><li> Wenn der Mikrospule aus der gewünschten Geometrie, Das andere Ende des Drahtes auf den Leim auch. </li><li> Mit verdünntem Lack, um die Spule, indem eine kleine Menge auf der Wicklungen zu beheben. </li><li> Entfernen Sie die Spule vorsichtig von der Ahle mit Teflonband. </li><li> Platzieren Sie einige Epoxidharz (siehe Punkt 1.3), ohne jegliche Zusätze, die in den Kanälen der Dichtung. </li><li> Legen Sie die Mikrospule innerhalb der Probenkammer und befestigen Sie die Kabel in die Kanäle. </li><li> Heilung der EPoXy Harz gemäß Schritt 1.3. </li><li> Löt einem Vorsprung des Mikrospule mit dem heißen Draht und die andere mit einem Führungszapfen. </li><li> Fügen Sie etwas Silber leitende Paste auf der jeweils Kreuzung. Die Aushärtung dauert in der Regel einige Minuten. </li><li> Abzudichten beide Übergänge mit einer geringen Menge von Epoxidharz. </li><li> Heilung der Epoxy gemäß Schritt 1.3. </li><li> Nun überprüfen Sie die Gleichstromwiderstand der Spule nach jedem Schritt. </li><li> Legen Sie die Probe in der Mikro-Spule. Seien Sie sich bewusst, dass jede unnötige Körperkontakt kann die Spule zu zerstören. </li><li> Fügen Sie fein gemahlene Pulver Rubin zur Probe für die Druckkalibrierung. </li><li> Schließlich überschwemmen die Probenkammer mit einem geeigneten Druckmedium. Verwenden Paraffinöl auf fast-hydrostatischen Bedingungen bis zu 9 GPa gewährleisten. </li><li> Küvette sorgfältig. </li></ol> 4. Anwendung und Überwachung von Druck <ol><li> Auf den ersten, leicht die M3 Allen versenkten Schrauben festziehen. </li><li> Für Druck fixieren die Zelle in einen Schraubstock einspannen. Nun ziehenzwei gegenüberliegende Schrauben paarweise. </li><li> Platzieren Sie den Druck Zelle in einem geeigneten Zellenhalter. </li><li> Einstellen der Position der Zelle, so daß der Laserstrahl in die Probenkammer gelangt. </li><li> Verwenden Sie die Feineinstellung Tabelle, um die Ruby-Pulver in den Laserstrahl konzentrieren. </li><li> Überwachen Sie die Rubin Photolumineszenzspektrum mit der entsprechenden Software-Spektrometer. </li><li> Entpacken Sie die aktuellen Druck in der Probenraum von der beobachteten spektralen Verschiebung der Rubin R1 und R2 Linien. </li><li> Äquilibrieren das Druckzelle für mindestens 12 h vor der NMR-Messungen gestartet. </li></ol> 5. Darstellende NMR-Experimente <ol><li> Montieren Sie die Druckzelle auf einem typischen NMR-Sonde. Herstellung geeignete Zellhalter in einer mechanischen Werkstatt. </li><li> Löten Sie den heißen Draht zu der Sonde. Überprüfen Sie den elektrischen Kontakt zwischen der Zelle und der Sonde. </li><li> Jetzt, führen Standard-NMR-Experimente. Die Aufmerksamkeit auf die Tatsache, dass die Mikrospule ist very empfindlich auf die angelegte Hochfrequenzleistung. </li></ol>

<ol>
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The authors have nothing to disclose.

Eine neue und vielversprechende Methode, um NMR bei Giga-Pascal Druck durchzuführen wurde beschrieben. Diese Methode öffnet die Tür zu einer Vielzahl von NMR-Experimente durch seine hervorragende Empfindlichkeit und Auflösung. Dennoch sind mehrere in der Protokoll Abschnitt beschriebenen Schritte für den Ausgang des Experiments. Insbesondere ist die Herstellung der Mikrospule und deren Fixierung in der Cu-Be-Dichtung sehr schwierig und erfordert einige Erfahrung. Im Folgenden sind einige wichtige Tipps gegeben, was...

Da Percy Bridgman Markenzeichen Experimente der kondensierten Materie unter hohen hydrostatischen Drücke am Anfang des letzten Jahrhunderts hat sich das Feld der Hochdruckphysik schnell 1 entwickelt. Eine große Anzahl von interessanten Phänomene sind bekannt, unter Drücken von einigen GPa 2 auftreten. Darüber hinaus hat die Reaktion der Systeme kondensierter Materie mit Hochdruck uns viel über ihre elektronischen Grundzustand und angeregten Zuständen 3,4 unterrichtet. Leider sind Techniken für die Untersuchung der elektronischen Eigenschaften von kondensierter Materie bei Giga-Pascal Druck selten, mit x-ray-oder DC-Widerstandsmessungen den Weg 5. Insbesondere wird die Erfassung der elektronischen oder magnetischen Kernmomente mit Elektronenspin (ESR) oder Kernspinresonanz (NMR)-Experimente, gebunden zu sein, fast unmöglich, in einem typischen Hochdruck-Amboss-Zellen, wo man das Signal abrufen muss umsetzen ein kleines volume durch Ambosse und einer Dichtung verankert. Mehrere Gruppen haben versucht, dieses Problem durch die Verwendung komplexer Arrangements, lösen zB zwei Split-Pair-Radiofrequenz (RF)-Spulen entlang der Flanken der Ambosse 6 aufgewickelt, ein Einzel-oder Doppelschleife Haarnadel-Resonator 7,8; . oder sogar eine Spaltung Rhenium Dichtung als HF-Pick-up-Spule 9, siehe Abbildung 1 Leider sind diese Ansätze noch von einem niedrigen Signal-zu-Rausch-Verhältnis (SNR) gelitten, die Begrenzung der experimentelle Anwendungen zu großen - γ Kerne wie 1 H 10. 15 - Der interessierte Leser kann auf andere Hochdruck-Schwingkreis 11 Experimente bezeichnet werden. Pravica und Silvera 16 Bericht der höchste Druck in einer Druckzelle für die NMR mit 12,8 GPa, der die ortho-para-Umwandlung von Wasserstoff untersucht erreicht. Mit großem Interesse bei der Anwendung NMR, um die Eigenschaften der Quantenfestkörper zu untersuchen, war unsere Gruppe interessiert, NMR erhältlich bei hohen Drücken, wie gut. Schließlich im Jahr 2009 konnte gezeigt werden, dass mit hoher Empfindlichkeit Tempelzelle NMR ist in der Tat möglich, wenn eine Resonanz Radiofrequenz (RF)-Mikrospule direkt in der Hochdruckkammer 17 umschließt die Probe gestellt. Bei einem solchen Ansatz wird die NMR-Empfindlichkeit um mehrere Größenordnungen (hauptsächlich wegen der dramatischen Zunahme Füllfaktor der HF-Spule), die noch schwieriger NMR-Experimente möglich, zB an Pulverproben eine verbesserte, 17 O-NMR Hochtemperatur-Supraleiter mit bis zu 7 GPa 18. Supraleitung in diesen Materialien kann durch die Anwendung von Druck verstärkt werden, und es ist nun möglich, diesen Prozess mit einer lokalen elektronischen Sonde, die grundlegenden Einblick in die Steuerungsprozesse verspricht folgen. Ein weiteres Beispiel für die Macht der NMR unter hohem Druck entstanden, was waren Believed Routine Referenzierung Experimente: Um die eingeführte neue Tempelzelle NMR zu testen, eine der besten bekannten Materialien wurde gemessen - einfache Aluminium-Metall. Als der Druck erhöht wurde, war eine unerwartete Abweichung der NMR-Verschiebung von dem, was man für einen Freie-Elektronen-System erwarten gefunden. Unter erhöhtem Druck wiederholte Versuche, auch zeigte, dass die neuen Ergebnisse waren in der Tat zuverlässig. Schließlich mit Bandstruktur Berechnungen wurde dann festgestellt, dass die Ergebnisse der Manifestation einer topologischen Übergang des Fermi-Oberfläche von Aluminium, die vor Jahren nicht durch Berechnungen nachgewiesen werden, wenn die Rechenleistung niedrig war. Extrapolation der Ergebnisse an die Umgebungsbedingungen zeigten, dass die Eigenschaften dieses Metalls, die fast überall verwendet wird, werden von dieser speziellen elektronischen Zustand beeinflusst. Um eine Reihe von verschiedenen Anwendungen zu verfolgen hatte speziell Tempelzellen (Zellen, die aus dem vorherigen Cavend importiertish Labor und für die NMR nachgerüstet) entwickelt worden. Derzeit sind die verwendeten selbst gebaute Chassis der Lage zu erreichen Drücke bis 25 GPa mit einem Paar 800 um culet 6H-SiC Ambosse. NMR-Experimente wurden erfolgreich auf 10,1 GPa, so weit durchgeführt. Die NMR-Leistung dieses neuen Zellen wurde gezeigt, gut 19 ​​sein. Die Hauptkomponente ist Titan-Aluminium-(6) -Vanadium (4) mit einem extra niedrigen interstitiellen Stufe (Klasse 23), wodurch eine Streckgrenze von 800 MPa über 20. Aufgrund seiner nicht-magnetischen Eigenschaften (die magnetische Suszeptibilität χ etwa 5 ppm) es eine ausreichende Material für die Druckzelle Chassis ist. Die Abmessungen der eingesetzten Zellen (siehe Abbildung 2 für einen Überblick über alle selbst gebaute Tempelzelle Designs) sind klein genug, um in reguläre Standardbohrung NMR Magneten passen. Die kleinste Design, die LAC-TM1, die nur 20 mm in der Höhe und 17 mm im Durchmesser ist, passt typischen kleinen Kalt Bohrung Magneten (30 mm Bohrungsdurchmesser). Die LAC-TM2, die neuesten Chassis die Autoren konzipiert ist, arbeitet mit vier M4 Allen Senker Schrauben als Druckantriebsmechanismus (aus der gleichen Legierung wie die Zelle Chassis gemacht), so dass für eine reibungslose Steuerung der Innendruck (Blaupausen in der beigefügten Zusatz Abschnitt). Typischerweise werden Diamant Ambosse verwendet, um höchsten Drücke von über 100 GPa zu erzeugen. Xu und Mao 21. - 23. haben gezeigt, dass moissanite Ambosse eine kostengünstige Alternative in Hochdruck-Forschung, bis zu Drücken von etwa 60 GPa. Daher wurden für die Ambosse moissanite eingeführt GPa NMR-Ansatz verwendet. Die besten Ergebnisse wurden mit maßgeschneiderten großen Kegel 6H-SiC Ambosse vom Amboss-Abteilung von Charles &amp; Colvard erreicht. Mit diesen Zellen, für Drücke bis 10,1 GPa, die Verwendung von 800 um culet Ambossen wurde gefunden, in sehr guten NMR Empfindlichkeit führen. Zum Vergleich, Lee et al. Berichten über einen SNR von 1 1 H NMR Leitungswasser, während das SNR des eingeführten Mikrospule Ansatz zeigte einen Wert von 25 für 1/7 ihres Volumens, selbst bei einer etwas niedrigeren Magnetfeld. Mit diesem neuen Ansatz zur hochempfindlichen Tempelzelle NMR kann man viele Anwendungen, die spannende neue Einblicke in die Physik und Chemie der modernen Materialien versprechen zu verfolgen. Aber wie immer, Empfindlichkeit und Auflösung letztlich begrenzen die Anwendung der NMR, insbesondere dann, wenn man sich für viel höhere Drücke, die kleiner culet Größen fordern ist. Dann hat man nicht nur die Zellenkonstruktion mit noch kleineren HF-Spulen zu optimieren, sondern auch darüber nachdenken, Verfahren zur Erhöhung der Kernpolarisation.

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high-sensitivity nuclear magnetic resonance at giga-pascal pressures: a new tool for probing electronic and chemical properties of condensed matter under extreme conditions

Nuclear Magnetic Resonance (NMR) is one of the most important techniques for the study of condensed matter systems, their chemical structure, and their electronic properties. The application of high pressure enables one to synthesize new materials, but the response of known materials to high pressure is a very useful tool for studying their electronic structure and developing theories. For example, high-pressure synthesis might be at the origin of life; and understanding the behavior of small molecules under extreme pressure will tell us more about fundamental processes in our universe. It is no wonder that there has always been great interest in having NMR available at high pressures. Unfortunately, the desired pressures are often well into the Giga-Pascal (GPa) range and require special anvil cell devices where only very small, secluded volumes are available. This has restricted the use of NMR almost entirely in the past, and only recently, a new approach to high-sensitivity GPa NMR, which has a resonating micro-coil inside the sample chamber, was put forward. This approach enables us to achieve high sensitivity with experiments that bring the power of NMR to Giga-Pascal pressure condensed matter research. First applications, the detection of a topological electronic transition in ordinary aluminum metal and the closing of the pseudo-gap in high-temperature superconductivity, show the power of such an approach. Meanwhile, the range of achievable pressures was increased tremendously with a new generation of anvil cells (up to 10.1 GPa), that fit standard-bore NMR magnets. This approach might become a new, important tool for the investigation of many condensed matter systems, in chemistry, geochemistry, and in physics, since we can now watch structural changes with the eyes of a very versatile probe.

Figur 3 zeigt, wie die komplett montierte Druckzelle, die Verdrahtung und die Montage auf einem typischen NMR-Sonde aussehen. Im Folgenden werden verschiedene Experimente überprüft werden, welche der Leser sollte einen breiten Überblick über die Vorteile und Grenzen der Technik eingeführt sammeln. <img alt="Figur 1" src="/files/ftp_upload/52243/52243fig1highres.jpg" /> Abbildung 1. Verschiedene Ansätze für Hochdruck-N...

Watch this Scientific Journal Video about High-Sensitivity Nuclear Magnetic Resonance at Giga-Pascal Pressures: A New Tool for Probing Electronic and Chemical Properties of Condensed Matter under Extr

High-Sensitivity Nuclear Magnetic Resonance at Giga-Pascal Pressures: A New Tool for Probing Electronic and Chemical Properties of Condensed Matter under Extreme Conditions

Nuclear magnetic resonance is one of the most important spectroscopic tools. Here, the development of a new approach under high pressure, currently up to 10.1 GPa, is presented. This opens a new window into condensed matter physics and chemistry, where high-pressure research is of great importance.

High-Sensitivity Nuclear Magnetic Resonance bei Giga-Pascal Drücke: ein neues Instrument zur Sondierung elektronischen und chemischen Eigenschaften von kondensierter Materie unter extremen Bedingungen

Nuclear Magnetic Resonance (NMR) is one of the most important techniques for the study of condensed matter systems, their chemical structure, and their ...

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Principles of Nuclear Magnetic Resonance

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11.5K Aufrufe.  University of Leipzig. Nuclear magnetic resonance is one of the most important spectroscopic tools. Here, the development of a new approach under high pressure, currently up to 10.1 GPa, is presented. This opens a new window into condensed matter physics and chemistry, where high-pressure research is of great importance.

Serie: High-Sensitivity Nuclear Magnetic Resonance at Giga-Pascal Pressures: A New Tool for Probing Electronic and Chemical Properties of Condensed Matter under Extreme Conditions

Synthesis and Microdiffraction at Extreme Pressures and Temperatures

High pressure compounds and polymorphs are investigated for a broad range of purposes such as determine structures and processes of deep planetary interiors, design materials with novel properties, understand the mechanical behavior of materials exposed to very high stresses as in explosions or impacts. Synthesis and structural analysis of materials at extreme conditions of pressure and temperature entails remarkable technical challenges. In the laser heated diamond anvil cell (LH-DAC), very high pressure is generated between the tips of two opposing diamond anvils forced against each other; focused infrared laser beams, shined through the diamonds, allow to reach very high temperatures on samples absorbing the laser radiation. When the LH-DAC is installed in a synchrotron beamline that provides extremely brilliant x-ray radiation, the structure of materials under extreme conditions can be probed in situ. LH-DAC samples, although very small, can show highly variable grain size, phase and chemical composition. In order to obtain the high resolution structural analysis and the most comprehensive characterization of a sample, we collect diffraction data in 2D grids and combine powder, single crystal and multigrain diffraction techniques. Representative results obtained in the synthesis of a new iron oxide, Fe4O5 1 will be shown.

The laser heated diamond anvil cell combined with synchrotron micro-diffraction techniques allows researchers to explore the nature and properties of new phases of matter at extreme pressure and temperature (PT) conditions. Heterogeneous samples can be characterized in situ under high pressure by 2D mapping and combined powder, single-crystal and multigrain diffraction approaches.

Synthese und Mikrodiffraktion bei extremen Drücken und Temperaturen

High pressure compounds and polymorphs are investigated for a broad range of purposes such as determine structures and processes of deep planetary ...

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Flame Experiments at the Advanced Light Source: New Insights into Soot Formation Processes

The following experimental protocols and the accompanying video are concerned with the flame experiments that are performed at the Chemical Dynamics Beamline of the Advanced Light Source (ALS) of the Lawrence Berkeley National Laboratory1-4. This video demonstrates how the complex chemical structures of laboratory-based model flames are analyzed using flame-sampling mass spectrometry with tunable synchrotron-generated vacuum-ultraviolet (VUV) radiation. This experimental approach combines isomer-resolving capabilities with high sensitivity and a large dynamic range5,6. The first part of the video describes experiments involving burner-stabilized, reduced-pressure (20-80 mbar) laminar premixed flames. A small hydrocarbon fuel was used for the selected flame to demonstrate the general experimental approach. It is shown how species&#8217; profiles are acquired as a function of distance from the burner surface and how the tunability of the VUV photon energy is used advantageously to identify many combustion intermediates based on their ionization energies. For example, this technique has been used to study gas-phase aspects of the soot-formation processes, and the video shows how the resonance-stabilized radicals, such as C3H3, C3H5, and i-C4H5, are identified as important intermediates7. The work has been focused on soot formation processes, and, from the chemical point of view, this process is very intriguing because chemical structures containing millions of carbon atoms are assembled from a fuel molecule possessing only a few carbon atoms in just milliseconds. The second part of the video highlights a new experiment, in which an opposed-flow diffusion flame and synchrotron-based aerosol mass spectrometry are used to study the chemical composition of the combustion-generated soot particles4. The experimental results indicate that the widely accepted H-abstraction-C2H2-addition (HACA) mechanism is not the sole molecular growth process responsible for the formation of the observed large polycyclic aromatic hydrocarbons (PAHs).

Gas sampling from laboratory-scale flames with online analysis of all species by mass spectrometry is a powerful method to investigate the complex mixture of chemical compounds occurring during combustion processes. Coupled with tunable soft ionization via synchrotron-generated vacuum-ultraviolet radiation, this technique provides isomer-resolved information and potentially fragment-free mass spectra.

Flammen-Experimente an der Advanced Light Source: Neue Einblicke in Rußbildung Prozesse

The following experimental protocols and the accompanying video are concerned with the flame experiments that are performed at the Chemical Dynamics ...

In Situ Neutron Powder Diffraction Using Custom-made Lithium-ion Batteries

Li-ion batteries are widely used in portable electronic devices and are considered as promising candidates for higher-energy applications such as electric vehicles.1,2 However, many challenges, such as energy density and battery lifetimes, need to be overcome before this particular battery technology can be widely implemented in such applications.3 This research is challenging, and we outline a method to address these challenges using in situ NPD to probe the crystal structure of electrodes undergoing electrochemical cycling (charge/discharge) in a battery. NPD data help determine the underlying structural mechanism responsible for a range of electrode properties, and this information can direct the development of better electrodes and batteries.
We briefly review six types of battery designs custom-made for NPD experiments and detail the method to construct the &#8216;roll-over&#8217; cell that we have successfully used on the high-intensity NPD instrument, WOMBAT, at the Australian Nuclear Science and Technology Organisation (ANSTO). The design considerations and materials used for cell construction are discussed in conjunction with aspects of the actual in situ NPD experiment and initial directions are presented on how to analyze such complex in situ data.

In Situ Neutron Powder Diffraction Using Custom-made Lithium-ion Batteries

We describe the design and construction of an electrochemical cell for the examination of electrode materials using in situ neutron powder diffraction (NPD). We briefly comment on alternate in situ NPD cell designs and discuss methods for the analysis of the corresponding in situ NPD data produced using this cell.

In Situ Neutronenpulver Mit Maßgeschneiderte Lithium-Ionen-Batterien

Li-ion batteries are widely used in portable electronic devices and are considered as promising candidates for higher-energy applications such as electric ...

Resonance Raman Spectroscopy of Extreme Nanowires and Other 1D Systems

This paper briefly describes how nanowires with diameters corresponding to 1 to 5 atoms can be produced by melting a range of inorganic solids in the presence of carbon nanotubes. These nanowires are extreme in the sense that they are the limit of miniaturization of nanowires and their behavior is not always a simple extrapolation of the behavior of larger nanowires as their diameter decreases. The paper then describes the methods required to obtain Raman spectra from extreme nanowires and the fact that due to the van Hove singularities that 1D systems exhibit in their optical density of states, that determining the correct choice of photon excitation energy is critical. It describes the techniques required to determine the photon energy dependence of the resonances observed in Raman spectroscopy of 1D systems and in particular how to obtain measurements of Raman cross-sections with better than 8% noise and measure the variation in the resonance as a function of sample temperature. The paper describes the importance of ensuring that the Raman scattering is linearly proportional to the intensity of the laser excitation intensity. It also describes how to use the polarization dependence of the Raman scattering to separate Raman scattering of the encapsulated 1D systems from those of other extraneous components in any sample.

The paper describes a method for producing extreme nanowires by melt infiltration into carbon nanotubes and how 1D systems may be characterized and investigated using Resonance Raman Spectroscopy to determine vibrational and optical excitation energies.

Resonanz-Raman-Spektroskopie von Extreme Nanodrähte und andere 1D-Systeme

This paper briefly describes how nanowires with diameters corresponding to 1 to 5 atoms can be produced by melting a range of inorganic solids in the ...

Use of a Multi-compartment Dynamic Single Enzyme Phantom for Studies of Hyperpolarized Magnetic Resonance Agents

Imaging of hyperpolarized substrates by magnetic resonance shows great clinical promise for assessment of critical biochemical processes in real time. Due to fundamental constraints imposed by the hyperpolarized state, exotic imaging and reconstruction techniques are commonly used. A practical system for characterization of dynamic, multi-spectral imaging methods is critically needed. Such a system must reproducibly recapitulate the relevant chemical dynamics of normal and pathological tissues. The most widely utilized substrate to date is hyperpolarized [1-13C]-pyruvate for assessment of cancer metabolism. We describe an enzyme-based phantom system that mediates the conversion of pyruvate to lactate. The reaction is initiated by injection of the hyperpolarized agent into multiple chambers within the phantom, each of which contains varying concentrations of reagents that control the reaction rate. Multiple compartments are necessary to ensure that imaging sequences faithfully capture the spatial and metabolic heterogeneity of tissue. This system will aid the development and validation of advanced imaging strategies by providing chemical dynamics that are not available from conventional phantoms, as well as control and reproducibility that is not possible in vivo.

A multi-compartment dynamic phantom is used to simulate some biology of interest for metabolic studies using hyperpolarized magnet resonance agents.

Die Verwendung eines Mehrfach Dynamische einzelner Enzym-Phantom für Studien von hyperpolarisiertem Magnetic Resonance Agents

Imaging of hyperpolarized substrates by magnetic resonance shows great clinical promise for assessment of critical biochemical processes in real time. Due ...

In Situ Visualization of the Phase Behavior of Oil Samples Under Refinery Process Conditions

To help address production issues in refineries caused by the fouling of process units and lines, we have developed a setup as well as a method to visualize the behavior of petroleum samples under process conditions. The experimental setup relies on a custom-built micro-reactor fitted with a sapphire window at the bottom, which is placed over the objective of an inverted microscope equipped with a cross-polarizer module. Using reflection microscopy enables the visualization of opaque samples, such as petroleum vacuum residues, or asphaltenes. The combination of the sapphire window from the micro-reactor with the cross-polarizer module of the microscope on the light path allows high-contrast imaging of isotropic and anisotropic media. While observations are carried out, the micro-reactor can be heated to the temperature range of cracking reactions (up to 450 &#176;C), can be subjected to H2 pressure relevant to hydroconversion reactions (up to 16 MPa), and can stir the sample by magnetic coupling. 
Observations are typically carried out by taking snapshots of the sample under cross-polarized light at regular time intervals. Image analyses may not only provide information on the temperature, pressure, and reactive conditions yielding phase separation, but may also give an estimate of the evolution of the chemical (absorption/reflection spectra) and physical (refractive index) properties of the sample before the onset of phase separation.

In Situ Visualization of the Phase Behavior of Oil Samples Under Refinery Process Conditions

This article describes a setup and method for the in situ visualization of oil samples under a variety of temperature and pressure conditions that aim to emulate refining and upgrading processes. It is primarily used for studying isotropic and anisotropic media involved in the fouling behavior of petroleum feeds.

In Situ Visualisierung der Phasenverhalten von Ölproben Unter Raffinerie Prozessbedingungen

To help address production issues in refineries caused by the fouling of process units and lines, we have developed a setup as well as a method to ...

A Novel Biaxial Testing Apparatus for the Determination of Forming Limit under Hot Stamping Conditions

The hot stamping and cold die quenching process is increasingly used to form complex shaped structural components of sheet metals. Conventional experimental approaches, such as out-of-plane and in-plane tests, are not applicable to the determination of forming limits when heating and rapid cooling processes are introduced prior to forming for tests conducted under hot stamping conditions. A novel in-plane biaxial testing system was designed and used for the determination of forming limits of sheet metals at various strain paths, temperatures, and strain rates after heating and cooling processes in a resistance heating uniaxial testing machine. The core part of the biaxial testing system is a biaxial apparatus, which transfers a uniaxial force provided by the uniaxial testing machine to a biaxial force. One type of cruciform specimen was designed and verified for the formability test of aluminum alloy 6082 using the proposed biaxial testing system. The digital image correlation (DIC) system with a high-speed camera was used for taking strain measurements of a specimen during a deformation. The aim of proposing this biaxial testing system is to enable the forming limits of an alloy to be determined at various temperatures and strain rates under hot stamping conditions.

This protocol proposes a novel biaxial testing system used on a resistance heating uniaxial tensile test machine in order to determine the forming limit diagram (FLD) of sheet metals under hot stamping conditions.

A Novel Biaxial Testvorrichtung für die Bestimmung der Grenzformänderung unter Hot Stamping Bedingungen

The hot stamping and cold die quenching process is increasingly used to form complex shaped structural components of sheet metals. Conventional ...

Orientational Transition in a Liquid Crystal Triggered by the Thermodynamic Growth of Interfacial Wetting Sheets

In liquid crystal (LC) physical chemistry, molecules near the surface play a great role in controlling bulk orientation. Thus far, mainly to achieve desired molecular orientation states in LC displays, the "static" surface property of LCs, so-called surface anchoring, has been intensively studied. As a rule of thumb, once the initial orientation of LCs is "locked" by specific surface treatments, such as rubbing or treatment with a specific alignment layer, it hardly changes with temperature. Here, we present a system exhibiting an orientational transition upon temperature variation, which conflicts with the consensus. Right on the transition, the bulk LC molecules experience the orientational rotation, with 90&#176; between the planar (P) orientation at high temperatures and the vertical (V) orientation at low temperatures in the first-order transitional manner. We have tracked thermodynamic surface anchoring behavior by means of polarizing optical microscopy (POM), dielectric spectroscopy (DS), high-resolution differential scanning calorimetry (HR-DSC), and grazing incidence X-ray diffraction (GI-XRD) and reached a plausible physical explanation: that the transition is triggered by a growth of surface wetting sheets, which impose the V orientation locally against the P orientation in the bulk. This landscape would provide a general link explaining how the equilibrium bulk orientation is affected by surface-localized orientation in many LC systems. In our characterization, POM and DS are advantageous by offering information on the spatial distribution of the orientation of LC molecules. HR-DSC gives information about the precise thermodynamic information on transitions, which cannot be addressed by conventional DSC instruments due to limited resolution. GI-XRD provides information on surface-specific molecular orientation and short-range orderings. The goal of this paper is to present a protocol for preparing a sample that exhibits the transition and to demonstrate how the thermodynamic structural variation, both in the bulk and on surfaces, can be analyzed through the abovementioned methods.

Here, we present a protocol to trigger an orientational transition of a liquid crystal in response to temperature. Methodologies are described for preparing a sample in order to observe the transition and the detailed transitional evolution.

Orientationaler Übergang in einem Flüssigkristall, der durch das thermodynamische Wachstum von Grenzflächenbetonplatten ausgelöst wird

In liquid crystal (LC) physical chemistry, molecules near the surface play a great role in controlling bulk orientation. Thus far, mainly to achieve ...

All-electronic Nanosecond-resolved Scanning Tunneling Microscopy: Facilitating the Investigation of Single Dopant Charge Dynamics

The miniaturization of semiconductor devices to scales where small numbers of dopants can control device properties requires the development of new techniques capable of characterizing their dynamics. Investigating single dopants requires sub-nanometer spatial resolution, which motivates the use of scanning tunneling microscopy (STM). However, conventional STM is limited to millisecond temporal resolution. Several methods have been developed to overcome this shortcoming, including all-electronic time-resolved STM, which is used in this study to examine dopant dynamics in silicon with nanosecond resolution. The methods presented here are widely accessible and allow for local measurement of a wide variety of dynamics at the atomic scale. A novel time-resolved scanning tunneling spectroscopy technique is presented and used to efficiently search for dynamics.

We demonstrate an all-electronic method to observe nanosecond-resolved charge dynamics of dopant atoms in silicon with a scanning tunneling microscope.

Vollelektronische Nanosekunde gelöst Scanning Tunneling Microscopy: Erleichterung der Untersuchung der einzelnen Dotierstoff kostenlos Dynamik

The miniaturization of semiconductor devices to scales where small numbers of dopants can control device properties requires the development of new ...

Electric-field Control of Electronic States in WS2 Nanodevices by Electrolyte Gating

A method of carrier number control by electrolyte gating is demonstrated. We have obtained WS2 thin flakes with atomically flat surface via scotch tape method or individual WS2 nanotubes by dispersing the suspension of WS2 nanotubes. The selected samples have been fabricated into devices by the use of the electron beam lithography and electrolyte is put on the devices. We have characterized the electronic properties of the devices under applying the gate voltage. In the small gate voltage region, ions in the electrolyte are accumulated on the surface of the samples which leads to the large electric potential drop and resultant electrostatic carrier doping at the interface. Ambipolar transfer curve has been observed in this electrostatic doping region. When the gate voltage is further increased, we met another drastic increase of source-drain current which implies that ions are intercalated into layers of WS2 and electrochemical carrier doping is realized. In such electrochemical doping region, superconductivity has been observed. The focused technique provides a powerful strategy for achieving the electric-filed-induced quantum phase transition.

Electric-field Control of Electronic States in WS2 Nanodevices by Electrolyte Gating

Here, we present a protocol to control the carrier number in solids by using the electrolyte.

Elektrisches Feld Kontrolle der elektronischen Zustände in WS2 Nanosysteme durch Elektrolyt Anspritzung

A method of carrier number control by electrolyte gating is demonstrated. We have obtained WS2 thin flakes with atomically flat surface via scotch tape ...