DOCSLIB.ORG

Quantitative Structure-Based Prediction of Electron Spin Decoherence in Organic Radicals Elizabeth R

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Quantitative Structure-Based Prediction of Electron Spin Decoherence in Organic Radicals Elizabeth R Subscriber access provided by University of Washington | Libraries Physical Insights into Quantum Phenomena and Function Quantitative Structure-Based Prediction of Electron Spin Decoherence in Organic Radicals Elizabeth R. Canarie, Samuel M. Jahn, and Stefan Stoll J. Phys. Chem. Lett., Just Accepted Manuscript • DOI: 10.1021/acs.jpclett.0c00768 • Publication Date (Web): 13 Apr 2020 Downloaded from pubs.acs.org on April 16, 2020 Just Accepted “Just Accepted” manuscripts have been peer-reviewed and accepted for publication. They are posted online prior to technical editing, formatting for publication and author proofing. The American Chemical Society provides “Just Accepted” as a service to the research community to expedite the dissemination of scientific material as soon as possible after acceptance. “Just Accepted” manuscripts appear in full in PDF format accompanied by an HTML abstract. “Just Accepted” manuscripts have been fully peer reviewed, but should not be considered the official version of record. They are citable by the Digital Object Identifier (DOI®). “Just Accepted” is an optional service offered to authors. Therefore, the “Just Accepted” Web site may not include all articles that will be published in the journal. After a manuscript is technically edited and formatted, it will be removed from the “Just Accepted” Web site and published as an ASAP article. Note that technical editing may introduce minor changes to the manuscript text and/or graphics which could affect content, and all legal disclaimers and ethical guidelines that apply to the journal pertain. ACS cannot be held responsible for errors or consequences arising from the use of information contained in these “Just Accepted” manuscripts. is published by the American Chemical Society. 1155 Sixteenth Street N.W., Washington, DC 20036 Published by American Chemical Society. Copyright © American Chemical Society. However, no copyright claim is made to original U.S. Government works, or works produced by employees of any Commonwealth realm Crown government in the course of their duties. Page 1 of 15 The Journal of Physical Chemistry Letters 1 2 3 4 5 6 7 Quantitative Structure-Based Prediction of Electron 8 9 10 11 12 Spin Decoherence in Organic Radicals 13 14 15 16 Elizabeth R. Canarie‡, Samuel M. Jahn‡, Stefan Stoll* 17 18 19 20 Department of Chemistry, University of Washington, Seattle, Washington, United States, 98195 21 22 23 Corresponding Author 24 25 *E-mail: [email protected] 26 27 28 29 ABSTRACT The decoherence, or dephasing, of electron spins in paramagnetic molecules limits 30 31 32 sensitivity and resolution in electron paramagnetic resonance (EPR) spectroscopy, and it repre- 33 34 sents a challenge for utilizing paramagnetic molecules as qubit units in quantum information de- 35 36 vices. For organic radicals in dilute frozen aqueous solution at cryogenic temperatures, electron 37 38 spin decoherence is driven by neighboring nuclear spins. Here, we show that this nuclear-spin- 39 40 41 driven decoherence can be quantitatively predicted from molecular structure and solvation geom- 42 43 etry of the radicals. We use a fully deterministic quantum model of the electron spin and up to 44 45 2000 neighboring protons with a static spin Hamiltonian that includes nucleus-nucleus couplings. 46 47 48 We present experiments and simulations on two nitroxide radicals and one trityl radical, which 49 50 have decoherence time scales of 4-5 μs below 60 K. We show that nuclei within 12 Å of the 51 52 electron spin contribute to decoherence, with the strongest impact from protons 4-8 Å away. 53 54 55 56 57 58 59 60 ACS Paragon Plus Environment 1 The Journal of Physical Chemistry Letters Page 2 of 15 1 2 3 TOC GRAPHICS 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 KEYWORDS 23 24 25 26 nuclear spin diffusion, cluster correlation expansion, phase memory time, coherence, EPR, DNP 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 ACS Paragon Plus Environment 2 Page 3 of 15 The Journal of Physical Chemistry Letters 1 2 3 The spins of unpaired electrons in organic radicals and metal ions are extensively used in 4 5 6 pulse electron paramagnetic resonance (EPR) spectroscopy to probe the structure and dynamics of 7 8 the nano-environment around the electrons.1–3 Molecule-based unpaired electrons are also inves- 9 10 tigated as potential building blocks for devices useful to quantum information science (QIS).4–6 In 11 12 13 this context, they are often referred to as “molecular spin qubits”. In both cases, a key limitation 14 15 is the fact that excited electron spins lose coherence over time. This process, called decoherence, 16 17 dephasing, or transverse relaxation, results in the loss of signal. In EPR, decoherence limits sen- 18 19 sitivity and spectral resolution. In QIS applications, it impacts the efficient transfer of information 20 21 22 between coupled qubits, and it limits the complexity of algorithms that can be executed. Extending 23 24 coherence times is therefore an important development goal in both fields. For this, a detailed 25 26 understanding of the physical origins of decoherence is crucial. 27 28 29 There are many processes that drive electron spin decoherence, including molecular mo- 30 31 tions and magnetic interactions7. It is possible to eliminate the effect of motions (librations, thermal 32 33 methyl rotations, etc.) on decoherence by operating at low temperatures. Magnetic interactions 34 35 36 among electron spins, and between electron spins and nearby nuclear spins, also contribute to 37 38 decoherence. Processes due to couplings between electron spins can be eliminated by dilution. At 39 40 sufficiently low temperatures and low electron spin concentrations, decoherence is driven by 41 42 nearby nuclear spins.8,9 This mechanism, often called nuclear spin diffusion, has been described 43 44 45 semi-classically as arising from stochastic energy-conserving flip-flops of pairs of nuclei, leading 46 47 to spectral diffusion of the electron spin resonance frequency and consequently to decoherence.10– 48 49 12 The problem with this stochastic model is that it is not predictive and does not provide insight 50 51 52 into the physical origin of the assumed flip-flop rate. 53 54 55 56 57 58 59 60 ACS Paragon Plus Environment 3 The Journal of Physical Chemistry Letters Page 4 of 15 1 2 3 Here, we experimentally deter- 4 5 6 mine the decoherence behavior of three 7 8 prototypical organic radicals in frozen 9 10 aqueous solutions, at temperatures and Figure 1. Two-pulse echo pulse sequence. For a decoherence experi- 11 ment, the spin echo amplitude is recorded as a function of increasing τ. 12 13 concentrations low enough to eliminate 14 15 contributions of any motional or electron-electron processes to decoherence. We show that the 16 17 nuclear-spin-driven decoherence of the radicals can be quantitatively predicted directly from their 18 19 molecular geometry and solvation structure, using a combination of molecular dynamics (MD) 20 21 22 and quantum spin dynamics, without the need for any adjustable free parameters. 23 24 Electron spin decoherence can be measured using various pulse EPR techniques. The most 25 26 straightforward is the two-pulse echo decay (Figure 1). This technique uses the pulse sequence 27 28 29 2 echo and records the decay of the echo amplitude resulting from increasing 30 31 πthe⁄ inter− -pulse delay − π − . 32 33 We investigated the decoherence characteristics of three different radicals: 2,2,6,6-tetra- 34 35 36 methylpiperidine-1-oxyl (TEMPO), its perdeuterated isotopologue (d18-TEMPO), and a perdeu- 37 13 38 terated trityl radical (p1TAM) (Figure 2). TEMPO and d18-TEMPO both are N/O-centered radi- 39 40 cals with four neighboring methyl groups and differ only in that all 1H atoms in TEMPO are re- 41 42 2 43 placed with H atoms in d18-TEMPO. The trityl 44 45 radical, p1TAM, is a C-centered radical and has 46 47 12 deuterated methyl groups. The concentra- 48 49 tions of the radicals were kept low enough to 50 51 52 minimize additional decoherence effects aris- 53 Figure 2. Radicals used in this study. From left to right, TEMPO, 54 ing from instantaneous diffusion mediated by d18-TEMPO, and p1TAM. 55 56 57 58 59 60 ACS Paragon Plus Environment 4 Page 5 of 15 The Journal of Physical Chemistry Letters 1 2 3 14,15 electron-electron couplings. Electron T1 val- 4 5 6 ues are on the order of 0.1–1 s and do also not 7 8 contribute to decoherence. All samples were pre- 9 10 pared in a solution of 1:1 (w:w) H2O:glycerol 11 12 13 and were snap frozen in liquid nitrogen. The ex- 14 15 periments were performed from 20-60 K at Q- 16 17 band frequencies (ca. 33 GHz). 18 19 Figure 3 shows the experimental two- 20 21 Figure 3. Experimental decoherence behavior of the molecules pulse echo decays at 20 K, presented in black. used in this study (black), stretched exponential (SE) fits (gray), 22 and the structure-based simulations (red). From top to bottom, ap- 23 proximately 10 μM p1TAM, 100 μM d18-TEMPO, and 200 μM 24 For all samples, the coherence decays on a simi- TEMPO. The experiments were performed in 1:1 (w:w) H2O 25 :glycerol at 20 K and ca. 33 GHz. The SE fits gave x values of 3.37, 2.81, and 2.77 and TM values of 5.37, 4.23, and 4.33 μs for 26 lar timescale and is completely lost within 10 μs.
Load more

Recommended publications
  • Advances in Photosynthesis and Respiration
    Biophysical Techniques in Photosynthesis Volume II Advances in Photosynthesis and Respiration VOLUME 26 Series Editor: GOVINDJEE University of Illinois, Urbana, Illinois, U.S.A. Consulting Editors: Julian EATON-RYE, Dunedin, New Zealand Christine H. FOYER, Newcastle upon Tyne, U.K. David B. KNAFF, Lubbock, Texas, U.S.A. Anthony L. MOORE, Brighton, U.K. Sabeeha MERCHANT, Los Angeles, California, U.S.A. Krishna NIYOGI, Berkeley, California, U.S.A. William PARSON, Seatle, Washington, U.S.A. Agepati RAGHAVENDRA, Hyderabad, India Gernot RENGER, Berlin, Germany The scope of our series, beginning with volume 11, reflects the concept that photosynthesis and respiration are intertwined with respect to both the protein complexes involved and to the entire bioenergetic machinery of all life. Advances in Photosynthesis and Respiration is a book series that provides a comprehensive and state-of-the-art account of research in photo- synthesis and respiration. Photosynthesis is the process by which higher plants, algae, and certain species of bacteria transform and store solar energy in the form of energy-rich organic molecules. These compounds are in turn used as the energy source for all growth and reproduction in these and almost all other organisms. As such, virtually all life on the planet ultimately depends on photosynthetic energy conversion. Respiration, which occurs in mitochondrial and bacterial membranes, utilizes energy present in organic molecules to fuel a wide range of metabolic reactions critical for cell growth and development. In addition, many photosynthetic organisms engage in energetically wasteful photorespiration that begins in the chloroplast with an oxygenation reaction catalyzed by the same enzyme responsible for capturing carbon dioxide in photosynthesis.
    [Show full text]
  • Simulation and Theory of Classical Spin Hopping on a Lattice
    magnetochemistry Article Simulation and Theory of Classical Spin Hopping on a Lattice Richard Gerst , Rodrigo Becerra Silva and Nicholas J. Harmon * Department of Physics, University of Evansville, Evansville, IN 47722, USA; [email protected] (R.G.); [email protected] (R.B.S.) * Correspondence: [email protected] Abstract: The behavior of spin for incoherently hopping carriers is critical to understand in a variety of systems such as organic semiconductors, amorphous semiconductors, and muon-implanted materials. This work specifically examined the spin relaxation of hopping spin/charge carriers through a cubic lattice in the presence of varying degrees of energy disorder when the carrier spin is treated classically and random spin rotations are suffered during the hopping process (to mimic spin–orbit coupling effects) instead of during the wait time period (which would be more appropriate for hyperfine coupling). The problem was studied under a variety of different assumptions regarding the hopping rates and the random local fields. In some cases, analytic solutions for the spin relaxation rate were obtained. In all the models, we found that exponentially distributed energy disorder led to a drastic reduction in spin polarization losses that fell nonexponentially. Keywords: spintronics; organic semiconductors; hopping transport; spin transport 1. Introduction Citation: Gerst, R.; Becerra Silva, R.; Spin relaxation of carriers has garnered much interest in the past few decades due to Harmon, N.J. Simulation and Theory the prospect of spin electronic or spintronic devices that use spin functionality in addition to of Classical Spin Hopping on a charge functionality. However, most work has been concentrated on band transport [1–5].
    [Show full text]
  • Dirac Material Graphene
    Dirac Material Graphene Elena Sheka Russian Peoples’ Friendship University of Russia Moscow, 117198 Russia [email protected] Abstract. The paper presents author’s view on spin-rooted properties of graphene supported by numerous experimental and calculation evidences. Correlation of odd pz electrons of the honeycomb lattice meets a strict demand “different orbitals for different spins”, which leads to spin polarization of electronic states, on the one hand, and generation of an impressive pool of local spins distributed over the lattice, on the other. These features characterize graphene as a peculiar semimetal with Dirac cone spectrum at particular points of Brillouin zone. However, spin-orbit coupling (SOC), though small but available, supplemented by dynamic SOC caused by electron correlation, transforms graphene-semimetal into graphene-topological insulator (TI). The consequent topological non-triviality and local spins are proposed to discuss such peculiar properties of graphene as high temperature ferromagnetism and outstanding chemical behavior. The connection of these new findings with difficulties met at attempting to convert graphene-TI into semiconductor one is discussed. Key words: graphene, Dirac fermions, quasi-relativistic description, hexagonal honeycomb structure, local spins, open-shell molecules, spin-orbital coupling, quantum spin Hall insulator, high temperature ferromagnetism, chemical activity. 1. Introduction Presented in the current paper concerns three main issues laying the foundation of spin features of graphene: (1) a significant correlation of pz odd electrons, exhibited in terms of spin peculiarities of the unrestricted Hartree-Fock (UHF) solutions, (2) spin-orbital coupling (SOC) and (3) the crucial role of the C=C bond length distribution over the body in exhibiting the spin- based features.
    [Show full text]
  • The Effects of Weak Magnetic Fields on Radical Pairs
    Bioelectromagnetics The Effects of Weak Magnetic Fields on Radical Pairs Frank S. Barnes1* and Ben Greenebaum2 1Department of Electricaland Computer Engineering, University of Colorado, Boulder, Colorado 2Department of Physics, University of Wisconsin-Parkside, Kenosha,Wisconsin It is proposed that radical concentrations can be modified by combinations of weak, steady and alternating magnetic fields that modify the population distribution of the nuclear and electronic spin state, the energy levels and the alignment of the magnetic moments of the components of the radical pairs. In low external magnetic fields, the electronic and nuclear angular momentum vectors are coupled by internal forces that outweigh the external fields’ interactions and are characterized in the Hamiltonian by the total quantum number F. Radical pairs form with their unpaired electrons in singlet (S) or triplet (T) states with respect to each other. At frequencies corresponding to the energy separation between the various states in the external magnetic fields, transitions can occur that change the populations of both electron and nuclear states. In addition, the coupling between the nuclei, nuclei and electrons, and Zeeman shifts in the electron and nuclear energy levels can lead to transitions with resonances spanning frequencies from a few Hertz into the megahertz region. For nuclear energy levels with narrow absorption line widths, this can lead to amplitude and frequency windows. Changes in the pair recombination rates can change radical concentrations and modify biological processes. The overall conclusion is that the application of magnetic fields at frequencies ranging from a few Hertz to microwaves at the absorption frequencies observed in electron and nuclear resonance spectroscopy for radicals can lead to changes in free radical concentrations and have the potential to lead to biologically significant changes.
    [Show full text]
  • The Scientific Case 67 5
    5. The Scientific Case 67 5. Chemistry 5.1 Introduction whereas, including cooperative Panel: magnetic interactions, the U.E. Steiner (Konstanz) In chemistry, the application of modern field of molecular (Chairman) magnetic fields has a long magnetism offers new possibilities R. Bittl (Berlin) tradition and has led to well for structural control by magnetic M. Ernst (Nijmegen) established disciplines and fields. In the following sections O. Kahn (Bordeaux) techniques. Two main purposes in these several areas are discussed using high magnetic fields may be from the point of view of the distinguished; the probing of likely impact of intense magnetic structural and dynamical fields. properties and the controlling of chemical processes and structures. 5.2 Molecular magnetism The ability of a magnetic field to function as a probe is usually based Molecular magnetism is a rather on the exploitation of the field new field of research which has dependence of some property of emerged during the last decade or the chemical substance or system, so. It deals with the physics and including its interaction with chemistry of open-shell radiation; i.e. various kinds of molecules and of molecular spectroscopies, of which NMR is assemblies involving open-shell the most vital and powerful one. units. What characterizes this field Thereby detailed qualitative and of research is its deeply quantitative information can be multidisciplinary character. It gained as to chemical composition brings together organic, inorganic, (chemical analysis) as well as and organometallic synthetic structural and dynamical chemists along with theoreticians, properties. Structural aspects solid state physicists, materials pertain to the characterization of and life scientists.
    [Show full text]
  • Coherent Spin Dynamics of Radical Pairs in Weak Magnetic Fields
    Coherent Spin Dynamics of Radical Pairs in Weak Magnetic Fields by Hannah J. Hogben A thesis submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy Trinity Term 2011 University of Oxford Department of Chemistry Physical and Theoretical Chemistry Laboratory Oriel College Abstract Coherent Spin Dynamics of Radical Pairs in Weak Magnetic Fields Hannah J. Hogben Department of Chemistry Physical and Theoretical Chemistry Laboratory and Oriel College Abstract of a thesis submitted for the degree of Doctor of Philosophy Trinity Term 2011 The outcome of chemical reactions proceeding via radical pair (RP) intermediates can be in- fluenced by the magnitude and direction of applied magnetic fields, even for interaction strengths far smaller than the thermal energy. Sensitivity to Earth-strength magnetic fields has been sug- gested as a biophysical mechanism of animal magnetoreception and this thesis is concerned with simulations of the effects of such weak magnetic fields on RP reaction yields. State-space restriction techniques previously used in the simulation of NMR spectra are here applied to RPs. Methods for improving the efficiency of Liouville-space spin dynamics calculations are presented along with a procedure to form operators directly into a reduced state-space. These are implemented in the spin dynamics software Spinach. Entanglement is shown to be a crucial ingredient for the observation of a low field effect on RP reaction yields in some cases. It is also observed that many chemically plausible initial states possess an inherent directionality which may be a useful source of anisotropy in RP reactions. The nature of the radical species involved in magnetoreception is investigated theoretically.
    [Show full text]
  • The Resolution of the Diamond Problem After 200 Years
    Treatise on the Resolution of the Diamond Problem After 200 Years Reginald B. Little* and Joseph Roache Florida A&M University Florida State University National High Magnetic Field Laboratory Tallahassee, Florida 32308 Abstract: The problem of the physicochemical synthesis of diamond spans more than 200 years, involving many giants of science. Many technologies have been discovered, realized and used to resolve this diamond problem. Here the origin, definition and cause of the diamond problem are presented. The Resolution of the diamond problem is then discussed on the basis of the Little Effect, involving novel roton-phonon driven (antisymmetrical) multi-spin induced orbital orientation, subshell rehybridization and valence shell rotation of radical complexes in quantum fluids under magnetization across thermal, pressure, compositional, and spinor gradients in both space and time. Some experimental evidence of this magnetic quantum Resolution is briefly reviewed and integrated with this recent fruitful discovery. Furthermore, the implications of the Little Effect in comparison to the Woodward-Hoffman Rule are considered. The distinction of the Little Effect from the prior radical pair effect is clarified. The better compatibility of radicals, dangling bonds and magnetism with the diamond lattice relative to the graphitic lattice is discussed. Finally, these novel physicochemical phenomena for the Little Effect are compared with the natural diamond genesis. * corresponding author; email : [email protected] Keywords: diamond, high pressure, plasma deposition, catalytic properties, magnetic properties. 1. Introduction – The Diamond Problem: A long history of giants of science has defined and contributed to the solution of the diamond problem. Section 2 considers the cause of the diamond problem.
    [Show full text]
  • CHIRAL INDUCED SPIN SELECTIVITY EFFECT: FUNDAMENTAL STUDIES and APPLICATIONS by Supriya Ghosh B.Sc., University of Calcutta
    TITLE PAGE CHIRAL INDUCED SPIN SELECTIVITY EFFECT: FUNDAMENTAL STUDIES AND APPLICATIONS by Supriya Ghosh B.Sc., University of Calcutta, 2010 M.Sc., IIT Bombay, 2012 M.Sc., University of Alberta, 2015 Submitted to the Graduate Faculty of the Dietrich School of Arts and Sciences in partial fulfillment of the requirements for the degree of Doctor of Philosophy University of Pittsburgh 2021 COMMITTE E PAGE UNIVERSITY OF PITTSBURGH DIETRICH SCHOOL OF ARTS AND SCIENCES This dissertation was presented by Supriya Ghosh It was defended on April 5, 2021 and approved by Dr. Haitao Liu, Professor, Department of Chemistry Dr. Sean Garrett-Roe, Associate Professor, Department of Chemistry Dr. Andrew Gellman, Professor, Chemical Engineering, Carnegie Mellon University Dissertation Advisor: Dr. David Waldeck, Professor, Department of Chemistry ii Copyright © by Supriya Ghosh 2021 iii ABST RACT CHIRAL INDUCED SPIN SELECTIVITY EFFECT: FUNDAMENTAL STUDIES AND APPLICATIONS Supriya Ghosh, PhD University of Pittsburgh, 2021 Since the discovery, chiral induced spin selectivity effect or CISS effect, which refers to the preferential transmission of electron of one spin over another through a chiral molecule/material, has generated significant interest due to its versatile application in different branches of science. Over the years, a large number of theoretical and experimental studies have been performed to understand the mechanism for the CISS effect and also to utilize the effect in different fields of science; such as memory devices, electrocatalytic experiments, chiral separations etc. In this dissertation, fundamental studies of chiral molecules at ferromagnetic interfaces are investigated through surface potential and magnetic measurements. Experiments are also done to study the spin filtering properties of chiral thin films and explore their electrocatalytic activity.
    [Show full text]
  • CURRICULUM VITAE Iannis K. Kominis
    CURRICULUM VITAE Iannis K. Kominis Department of Physics, University of Crete, Heraklion 71103 Greece Email: [email protected] Research Group Website: http://www.quantumbiology.gr 1. BIOGRAPHIC DATA Place - Date of Birth Athens, 1972 High-school German School of Athens, Dörpfeldgymnasium, Abitur Military Service Greek Air Force, 2001 – 2002 Languages Greek (native), English (fluent), German (fluent) 2. ACADEMIC APPOINTMENTS 2018 – present Associate Professor 2013 – 2018 Tenured Assistant Professor 2009 – 2013 Assistant Professor 2004 – 2009 Lecturer Department of Physics, University of Crete, Greece 2002 – 2003 Postdoctoral Research Fellow, Lawrence Berkeley National Laboratory 2002 – 2002 Postdoctoral Researcher, Department of Physics, Princeton University 1996 – 2000 Research Assistant, Department of Physics, Princeton University 3. ACADEMIC VISITS 2015 Kastler Brossel Laboratory, Ecole Normale Superieure 2015 Laboratory of Laser Physics, University of Paris 13, 2015 Department of Chemistry, University of Konstanz 2015 Institute of Analytical Chemistry, Leipzig University 2014 Kastler Brossel Laboratory, Ecole Normale Superieure 2012 Department of Physics, Princeton University 2008 Department of Physics, University of Fribourg 4. ACADEMIC EDUCATION 1996 – 2000 PhD, Physics, Princeton University, USA Thesis Title: Measurement of the Neutron (3He) Spin Structure at Low Q2 and the Extended Gerasimov-Drell-Hearn Sum Rule Supervisor: Prof. G. D. Cates 1990 – 1996 BS, MS, Electrical Engineering, National Technical University of Athens, Greece (GPA=8.6/10). 1993 Advanced Physics School, N.C.S.R. Demokritos, Athens, Greece 1994 Advanced Physics School, University of Crete, Greece 1995 Solid State NMR Group, University of Leipzig, Germany 1997 US Particle Accelerator School, University of California at Berkeley, USA 1997 L3 Collaboration, CERN, Geneva, Switzerland 1999 US Particle Accelerator School, Vanderbilt University, Nashville, USA 5.
    [Show full text]
  • SCM2019, Saint-Petersburg
    SPIN CHEMISTRY MEETING 2019 Book of Abstracts 18-22 August 2019 Saint Petersburg, Russia Sponsors Welcome to the 16th Spin Chemistry Meeting 2019, in St. Petersburg, Russia! Spin Chemistry meeting is a well-established forum gathering scientists from all over the world to discuss progress in magnetic field effects on chemical processes, chemically induced spin hyperpo- larization and related phenomena. Previous Spin Chemistry Meetings have taken place in Tomako- mai, Japan (1991); Konstanz, Germany (1992); Chicago, USA (1994); Novosibirsk, Russia (1996); Jerusalem, Israel (1997); Emmetten, Switzerland (1999); Tokyo, Japan (2001); Chapel Hill, USA (2003); Oxford, UK (2005); San Servolo, Italy (2007); St Catharines, Canada (2009); Noordwijk, The Netherlands (2011); Bad Hofgastein, Austria (2013); Kolkata, India (2015); Schluchsee, Ger- many (2017). This conference will cover the main areas of spin chemistry, including: Magnetic field effects in chemistry and biology Hyperpolarized nuclear magnetic resonance Hyperpolarized electron paramagnetic resonance Novel material and spintronics Theory and spin dynamics New experimental methods SCM-2019 intends to promote interactions and synergies between different areas of spin chemistry. To facilitate participation of young scientists in this activity, tutorials on spin chemistry will be or- ganized prior to main SCM-2019 event. We wish you fruitful conference and enjoyable stay in St. Petersburg! Konstantin Ivanov (Co-chairman) Leonid Kulik (Co-chairman) Committees Local Organizing Committee Jörg Matysik (Leipzig, Germany) Prof. Konstantin Ivanov, co-chairman Kiminori Maeda (Saitama, Japan) Prof. Leonid Kulik, co-chairman Marilena di Valentin (Padua, Italy) Dr. Dmitri Stass, secretary Michael Wasielewski (Evanston, USA) Lionella Sukhinina, accountant Stefan Weber (Freiburg, Germany) Prof. Renad Sagdeev Markus Wohlgenannt (Iowa, USA) Prof.
    [Show full text]
  • EPR in the USSR: the Thorny Path from Birth to Biological and Chemical Applications
    Photosynth Res DOI 10.1007/s11120-017-0432-5 HISTORY AND BIOGRAPHY EPR in the USSR: the thorny path from birth to biological and chemical applications Vasily Vitalievich Ptushenko1,2 · Nataliya Evgenievna Zavoiskaya3 Received: 1 April 2017 / Accepted: 27 July 2017 © Springer Science+Business Media B.V. 2017 Abstract In 1944, electron paramagnetic resonance (EPR) Keywords Electron paramagnetic resonance · Barry was discovered by Evgenii Konstantinovich Zavoisky in the Commoner · Jakov K. Syrkin · Nikolai N. Semenov · USSR (Union of the Soviet Socialist Republics). Since then, Evgenii K. Zavoisky · Vladislav V. Voevodsky · Lev A. magnetic resonance methods have contributed invaluably to Blumenfeld our knowledge in many areas of Life Sciences and Chemis- try, and particularly in the area of photosynthesis research. Abbreviations However, the road of the magnetic resonance methods, as AICP Archive of N.N. Semenov Institute of Chemical well as its acceptance in Life Sciences and Chemistry, was Physics not smooth and prompt in the (former) USSR. We discuss ARAS Archive of the Russian Academy of Sciences the role played by many including Jakov K. Syrkin, Nikolai CIAMT Central Institute for Advanced Medical Training N. Semenov, Vladislav V. Voevodsky, Lev A. Blumenfeld, EPR Electron paramagnetic resonance Peter L. Kapitza, and Alexander I. Shalnikov during the ICP Institute of Chemical Physics (now N.N. early stages of biological and chemical EPR spectroscopy Semenov Institute of Chemical Physics of the in the USSR. Russian Academy of Sciences) IPP Institute for Physical Problems (now P.L. Kapitza Institute for Physical Problems of the Russian Academy of Sciences) KIPC Karpov Institute of Physical Chemistry LPI P.N.
    [Show full text]
  • Sp2 Carbon Stable Radicals
    Journal of C Carbon Research Review sp2 Carbon Stable Radicals Elena F. Sheka Institute of Physical Research and Technology, Peoples’ Friendship University of Russia (RUDN University), 117198 Moscow, Russia; [email protected] Abstract: sp2 Nanocarbons such as fullerenes, carbon nanotubes, and graphene molecules are not only open-shell species, but spatially extended, due to which their chemistry is quite specific. Cogently revealed dependence of the final products composition on size and shape of the carbons in use as well as on the chemical prehistory is accumulated in a particular property—the stabilization of the species’ radical efficiency, thus providing the matter of stable radicals. If the feature is highly restricted and rarely available in ordinary chemistry, in the case of sp2 nanocarbons it is just an ordinary event providing, say, tons-in-mass stable radicals when either producing such widely used technological products as carbon black or dealing with deposits of natural sp2 carbons such as anthracite, shungite carbon, and other. Suggested in the paper is the consideration of stable radicals of sp2 nanocarbons from the standpoint of spin-delocalized topochemistry. Characterized in terms of the total and atomically partitioned number of effectively unpaired electrons as well as of the distribution of the latter over carbon atoms and described by selectively determined barriers of different reactions exhibiting topological essence of intermolecular interaction, sp2 nanocarbons reveal a peculiar topokinetics that lays the foundation of the stability of their radical properties. Keywords: stable radicals; fullerenes; carbon nanotubes; graphene molecules; spin chemistry; topoki- netics 1. Introduction Generally, radicals are objects of the spin chemistry of open-shell molecules.
    [Show full text]