Videos
Surprising Consequences of High Electron Spin Polarization
During the 59th session of the Global NMR Discussion Meetings held on January 10th, 2023 via Zoom, Dr. Quentin Chappuis Stern gave a talk on the topic "The surprising consequences of near unity electron spin polarization". The recording serves as a tutorial.
Abstract:
The inherent low sensitivity of NMR can be overcome by hyperpolarization techniques, which increase the polarization of nuclear spins far beyond the Boltzmann equilibrium. One such method is dynamic nuclear polarization (DNP), which consists of transferring the high polarization of unpaired electron spins to surrounding nuclear spins via microwave irradiation. In the case of dissolution DNP (dDNP), the sample is hyperpolarized in the solid state at low temperature (1-2 K) and moderate magnetic field (3-7 T), where the Boltzmann polarization of electron spins approaches unity, translating into equally high nuclear polarization under DNP. In addition to yielding high nuclear polarization, the high electron polarization has other interesting consequences for NMR. Indeed, as the electron polarization tends towards unity, the electron flip-flop probability vanishes, an effect sometimes referred to as “bath quenching”. By switching on and off microwave irradiation (microwave gating), one switches on and off electron flip-flops and hence paramagnetic relaxation. This has been shown to have a dramatic effect on transverse nuclear relaxation and on nuclear spin diffusion. In this talk, I will review the basic concepts of paramagnetic relaxation and its dependence on electron polarization. I will then present experiments where we used microwave gating to perform efficient CP, to detect EPR properties indirectly via NMR properties, and finally to study nuclear spin diffusion in the vicinity of electron spins.
Speaker's biography:
2014- Undergraduate and Masters, EPFL (Switzerland). Thesis with Prof. Bodenhausen
2022- PhD, CRMN Lyon (France), with Prof. Sami Jannin
Follow Dr. Stern's work here:
Twitter: https://twitter.com/quentinchapp
Google scholar: https://scholar.google.fr/citations?u...
EPR-NMR for Protein Modeling
During the 57th session of the Global NMR Discussion Meetings held on November 29th, 2022 via Zoom, Prof. Gunnar Jeschke from ETH Zurich, gave a talk on the topic "Integrating EPR distance distribution restraints with NMR data in protein models". The recording serves as a tutorial.
Abstract:
This zoominar will start with a short explanation of in silico spin labelling, which is useful for planning paramagnetic relaxation enhancement (PRE) NMR experiments as well as DEER EPR experiments for measuring distance distributions. I will continue with a primer on converting DEER data into distance distributions. The zoominar concludes with an example of using distance distributions in modelling a weakly structured low-complexity domain of an RNA-binding protein.
Speaker's biography:
1993-1996 PhD at ETH Zurich, Switzerland, with A. Schweiger
1998-2006 Group Leader, Max Planck Institute for Polymer Science in Mainz, Germany, with H. W. Spiess
2006-2008 Professor at the University of Konstanz, Germany
2008- Professor at ETH Zurich
Follow Prof. Jeschke's work here:
Website: https://epr.ethz.ch/
Paramagnetic effects in NMR: From PRE to metal ions DNP
During the 52nd session of the Global NMR Discussion Meetings held on October 4th, 2022 via Zoom, Dr. Daniel Jardon Alvarez from Weizmann Institute of Science gave a talk on the topic "Paramagnetic effects in NMR: From PRE to metal ions based DNP ". The recording serves as a tutorial.
Abstract:
DNP enhancements are distance independent as long as the nuclear relaxation is governed by paramagnetic relaxation enhancement (PRE) from the polarizing agents. This enables large and homogeneous enhancements in the bulk of inorganic materials upon doping with paramagnetic metal ions. In this talk I will present the basics of PRE and solid effect DNP and, from there, justify the initial statement.
Speaker's biography:
2006-2012: BSc, MSc - Ludwig-Maximilians University, Germany
2012-2016: PhD - University of São Paulo, Brazil
2016-2019: Postdoc - Ohio State University, USA
2019-2021: Postdoc - Weizmann Institute, Israel
2021-present: Senior Intern - Weizmann Institute, Israel
Follow Dr. Jardon Alvarez's work here:
Google scholar: https://scholar.google.com/citations?...
Twitter: @dani_jardon
Review on DNP from metal ion dopants: https://www.sciencedirect.com/science...
Paramagnetic NMR: Motion, Migration, Charge Compensation in a Na+ Battery
During the 44th session of the Global NMR Discussion Meetings held on March 8th, 2022 via Zoom, Euan Bassey from Prof. Clare Grey's research group at the University of Cambridge gave a talk on the topic below. The recording serves as a tutorial.
Topic: Motion, Migration and Charge Compensation in a Na+ Ion Battery Cathode: Tales from the Paramagnetic NMR Storybook
Abstract: Sodium-ion batteries (NIBs) are a more sustainable and significantly cheaper energy storage alternative to lithium-ion batteries (LIBs) and as such are poised to play a vital role in future grid-based energy storage. To date, the capacities and rate capabilities of NIBs—limited by the cathode—are too low for many real-world applications, and the sources of NIB degradation during charge and discharge have not received the attention that LIBs have. If we are to address the energy storage problem and improve the electrochemical performance of NIB cathodes, we must understand the sources of energy losses of this poor rate behaviour in terms of the changes to the chemical structure of the cathode during charge and discharge.
Solid-state NMR (ss-NMR) is ideally suited to studying such structural changes; variable-temperature 23Na ss-NMR is invaluable in assessing the extent of Na+ ion mobility (and hence the charge-discharge rates possible in NIB cathodes), whilst 17O NMR provides a local handle on the charge compensation scheme. Amongst the families of NIB cathode materials, layered NIB cathodes are particularly attractive, owing to their high Na+ mobility and good gravimetric capacities.
In this presentation, we provide an overview of paramagnetic NMR, the effect of motion on NMR spectra and the assignment of highly paramagnetic NMR spectra. We introduce Na0.67[Mg0.28Mn0.72]O2, a high-capacity, high-rate Na+-ion cathode and go on to report the changes in Na+ ion dynamics during its first charge-discharge cycle. Using a combination of variable temperature 23Na NMR and ab initio calculations of the NMR shifts and energy barriers, we assess the mobility of Na+ ions in the structure and hopping routes of these ions. For the first time, we elucidate the superstructure of P2-Na0.67[Mg0.28Mn0.72]O2 through powder synchrotron X-ray diffraction, powder neutron diffraction and pair distribution function analysis. We examine the structural changes in this material using 25Mg and 17O NMR and use these to develop a mechanism for charge compensation.
Speaker's biography: Euan completed his BA(Cantab) and MSci in Natural Sciences at the University of Cambridge. Having fallen in love with magnetic resonance techniques and solid-state chemistry, he is currently pursuing a PhD in Chemistry, supervised by Prof. Clare Grey. Now in his fourth year, he wishes to enthuse and inspire others to use magnetic resonance techniques to understand novel systems.
Twitter: @EuanBassey
Characterization of Metal Halide Perovskites using Solid-State NMR
During the 36th session of the Global NMR Discussion Meetings on Zoom, Dr. Dominik Kubicki, University of Warwick, gave a talk on the characterization of metal halide perovskites using solid-state nuclear magnetic resonance (NMR).
Abstract: Determining the structure-property relationships at multiple length scales is one of the key tenets of rational design of new materials. I will use the example of metal halide perovskites to discuss how we can determine the atomic-level structure of solids in an element-specific manner using solid-state NMR. The range of problems includes quantifying dopant incorporation, phase segregation, halide mixing, decomposition pathways, passivation mechanisms, short-range and long-range dynamics. I will focus on the experimental challenges and discuss practical aspects of recording solid-state NMR data on this class of materials.
Bio: Dominik J. Kubicki is an assistant professor in the Department of Physics at the University of Warwick. He graduated from the Warsaw University of Technology and completed his PhD in solid-state NMR with Lyndon Emsley at EPFL (Switzerland) in 2018. He then worked in the group of Michael Grätzel and subsequently held a Marie Curie-Skłodowska Fellowship at the University of Cambridge working with Sam Stranks and Clare Grey. His research focuses on new materials for sustainable optoelectronic technologies.
Website: https://kubickilab.wordpress.com/
Google scholar: https://scholar.google.ch/citations?u...
Twitter: @DominikJKubicki
Protein Structure Determination Using Paramagnetic NMR
The 17th session of the Global NMR Discussion Meeting was held on 27th October 2020 via Zoom. Dr. Alireza Bahramzadeh gave a talk on the use of paramagnetic nuclear magnetic resonance (NMR) spectroscopy for protein structure determination. The video was recorded live during the presentation and serves as an educative lecture.
Abstract: The long-range nature of the paramagnetic effects arising from unpaired electrons of metal ions renders them a powerful NMR spectroscopic tool for the study of the structure and dynamics of biological macromolecules. In this tutorial, we will discuss protein structure determination using paramagnetic NMR. The first part will cover different types of paramagnetic metal ions and their paramagnetic effects in NMR, mainly focusing on using techniques which better immobilize metal ions onto the proteins and do not impact the protein structure; the second part will consider Pseudocontact Shifts (PCSs) for determining the 3D structure of proteins.
Biography: Alireza received a bachelor of Chemical Engineering and a master of Polymer engineering from the University of Tehran, Iran. During his master’s project, he worked on developing new nanomembranes for heavy metal ions removal in water. In 2015, he moved to Australia and joined the research group of Professor Gottfried Otting to undertake a Ph.D. During his Ph.D., he worked on developing new ways of studying protein structure using paramagnetic NMR spectroscopy.
Follow Alireza on Twitter: @alireza_bahramz
Google scholar page: https://scholar.google.com/citations?...
Research Gate: https://www.researchgate.net/profile/...
Paramagnetic Metal Ion Polarizing Agents for DNP
The 15th session of the Global NMR Discussion Meeting was held on 29th September 2020 via Zoom. Prof. Björn Corzilius gave a talk on paramagnetic metal ion polarizing agents for dynamic nuclear polarization (DNP) nuclear magnetic resonance spectroscopy (NMR). The video was recorded live during the presentation and serves as an educative lecture.
Prof. Corzilius is the leader of the Solid-State DNP research group at the Institute of Chemistry and the Department of Life, Light & Matter, at the University of Rostock, Germany.
Website: http://www.solidstatednp.com/