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Kveder M, Rakvin B, You J. A quantum many body model for the embedded electron spin decoherence in organic solids. J Chem Phys 2019; 151:164124. [DOI: 10.1063/1.5124561] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Affiliation(s)
- Marina Kveder
- Division of Physical Chemistry, Ruder Bošković Institute, Bijenička 54, 10000 Zagreb, Croatia
| | - Boris Rakvin
- Division of Physical Chemistry, Ruder Bošković Institute, Bijenička 54, 10000 Zagreb, Croatia
| | - Jiangyang You
- Division of Physical Chemistry, Ruder Bošković Institute, Bijenička 54, 10000 Zagreb, Croatia
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Ylinen EE, Punkkinen M, Birczyński A, Lalowicz ZT. Acetone mobility in zeolite cages with new features in the deuteron NMR spectra and relaxation. SOLID STATE NUCLEAR MAGNETIC RESONANCE 2018; 93:7-15. [PMID: 29803916 DOI: 10.1016/j.ssnmr.2018.05.001] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/13/2018] [Revised: 05/16/2018] [Accepted: 05/16/2018] [Indexed: 06/08/2023]
Abstract
We studied deuteron NMR spectra and spin-lattice relaxation of deuterated acetone-d6, adsorbed into zeolites NaX (1.3) and NaY(2.4) at 100% coverage of sodium cations. At temperatures roughly below 160 K the deuterons are localized and their NMR characteristics are determined by CD3 rotation and rotational oscillations of acetone molecules. In NaX the CD3 rotation and rotational oscillations about the twofold axis of acetone dominate the spectra below 100 K, while above it oscillations also about other axes become important. In NaY dominant features are related to methyl tunnelling and to a smaller extent to rigid acetones, before the rotational oscillations about twofold axis start to prevail above 40 K. The analysis of the strongly non-exponential magnetization recovery was done by applying the recently introduced method (Ylinen et al., 2015 [12]), improved here to take into account the limited fast recovery at the level crossings, 10% at ωt=ω0 and 28% at ωt=2ω0. At first the experimental recovery is fitted by three exponentials with adjustable weights and decay rates. Then these quantities are calculated from activation energy distributions and known expressions for the deuteron relaxation rate. In NaY two distinctly separate activation energy distributions were needed, the dominant one being very broad. The use of three distributions, two of them covering practically the same energies as the broad one, lead to a somewhat better agreement with experiment. In general the theoretical results agree with experiment within experimental scatter. As the final result the mean activation energies and widths are obtained for activation energy distributions.
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Affiliation(s)
- E E Ylinen
- Wihuri Physical Laboratory, Department of Physics and Astronomy, University of Turku, FI-20014, Turku, Finland.
| | - M Punkkinen
- Wihuri Physical Laboratory, Department of Physics and Astronomy, University of Turku, FI-20014, Turku, Finland
| | - A Birczyński
- H. Niewodniczański Institute of Nuclear Physics of PAS, ul. Radzikowskiego 152, 31-342, Kraków, Poland
| | - Z T Lalowicz
- H. Niewodniczański Institute of Nuclear Physics of PAS, ul. Radzikowskiego 152, 31-342, Kraków, Poland
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Soetbeer J, Hülsmann M, Godt A, Polyhach Y, Jeschke G. Dynamical decoupling of nitroxides in o-terphenyl: a study of temperature, deuteration and concentration effects. Phys Chem Chem Phys 2018; 20:1615-1628. [DOI: 10.1039/c7cp07074h] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Distinct matrix- and molecule dependencies govern nitroxide decoherence in o-terphenyl at low temperatures, disclosing an optimal range for dynamical decoupling.
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Affiliation(s)
- Janne Soetbeer
- Laboratory of Physical Chemistry
- ETH Zürich
- CH-8093 Zürich
- Switzerland
| | - Miriam Hülsmann
- Bielefeld University
- Department of Chemistry
- D-33615 Bielefeld
- Germany
| | - Adelheid Godt
- Bielefeld University
- Department of Chemistry
- D-33615 Bielefeld
- Germany
| | - Yevhen Polyhach
- Laboratory of Physical Chemistry
- ETH Zürich
- CH-8093 Zürich
- Switzerland
| | - Gunnar Jeschke
- Laboratory of Physical Chemistry
- ETH Zürich
- CH-8093 Zürich
- Switzerland
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Niedbalski P, Parish C, Kiswandhi A, Kovacs Z, Lumata L. Influence of 13C Isotopic Labeling Location on Dynamic Nuclear Polarization of Acetate. J Phys Chem A 2017; 121:3227-3233. [PMID: 28422500 DOI: 10.1021/acs.jpca.7b01844] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Dynamic nuclear polarization (DNP) via the dissolution method has alleviated the insensitivity problem in liquid-state nuclear magnetic resonance (NMR) spectroscopy by amplifying the signals by several thousand-fold. This NMR signal amplification process emanates from the microwave-mediated transfer of high electron spin alignment to the nuclear spins at high magnetic field and cryogenic temperature. Since the interplay between the electrons and nuclei is crucial, the chemical composition of a DNP sample such as the type of free radical used, glassing solvents, or the nature of the target nuclei can significantly affect the NMR signal enhancement levels that can be attained with DNP. Herein, we have investigated the influence of 13C isotopic labeling location on the DNP of a model 13C compound, sodium acetate, at 3.35 T and 1.4 K using the narrow electron spin resonance (ESR) line width free radical trityl OX063. Our results show that the carboxyl 13C spins yielded about twice the polarization produced in methyl 13C spins. Deuteration of the methyl 13C group, while proven beneficial in the liquid-state, did not produce an improvement in the 13C polarization level at cryogenic conditions. In fact, a slight reduction of the solid-state 13C polarization was observed when 2H spins are present in the methyl group. Furthermore, our data reveal that there is a close correlation between the solid-state 13C T1 relaxation times of these samples and the relative 13C polarization levels. The overall results suggest the achievable solid-state polarization of 13C acetate is directly affected by the location of the 13C isotopic labeling via the possible interplay of nuclear relaxation leakage factor and cross-talks between nuclear Zeeman reservoirs in DNP.
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Affiliation(s)
- Peter Niedbalski
- Department of Physics, University of Texas at Dallas , 800 West Campbell Road, Richardson, Texas 75080 United States
| | - Christopher Parish
- Department of Physics, University of Texas at Dallas , 800 West Campbell Road, Richardson, Texas 75080 United States
| | - Andhika Kiswandhi
- Department of Physics, University of Texas at Dallas , 800 West Campbell Road, Richardson, Texas 75080 United States
| | - Zoltan Kovacs
- Advanced Imaging Research Center, University of Texas Southwestern Medical Center , 5323 Harry Hines Boulevard, Dallas, Texas 75390 United States
| | - Lloyd Lumata
- Department of Physics, University of Texas at Dallas , 800 West Campbell Road, Richardson, Texas 75080 United States
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5
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Pejov L, Petreska I, Kocarev L. Designing field-controllable graphene-dot-graphene single molecule switches: A quantum-theoretical proof-of-concept under realistic operating conditions. J Chem Phys 2015; 143:244704. [PMID: 26723699 DOI: 10.1063/1.4937411] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
A theoretical proof of the concept that a particularly designed graphene-based moletronics device, constituted by two semi-infinite graphene subunits, acting as source and drain electrodes, and a central benzenoid ring rotator (a "quantum dot"), could act as a field-controllable molecular switch is outlined and analyzed with the density functional theory approach. Besides the ideal (0 K) case, we also consider the operation of such a device under realistic operating (i.e., finite-temperature) conditions. An in-depth insight into the physics behind device controllability by an external field was gained by thorough analyses of the torsional potential of the dot under various conditions (absence or presence of an external gating field with varying strength), computing the torsional correlation time and transition probabilities within the Bloembergen-Purcell-Pound formalism. Both classical and quantum mechanical tunneling contributions to the intramolecular rotation were considered in the model. The main idea that we put forward in the present study is that intramolecular rotors can be controlled by the gating field even in cases when these groups do not possess a permanent dipole moment (as in cases considered previously by us [I. Petreska et al., J. Chem. Phys. 134, 014708-1-014708-12 (2011)] and also by other groups [P. E. Kornilovitch et al., Phys. Rev. B 66, 245413-1-245413-7 (2002)]). Consequently, one can control the molecular switching properties by an external electrostatic field utilizing even nonpolar intramolecular rotors (i.e., in a more general case than those considered so far). Molecular admittance of the currently considered graphene-based molecular switch under various conditions is analyzed employing non-equilibrium Green's function formalism, as well as by analysis of frontier molecular orbitals' behavior.
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Affiliation(s)
- Ljupčo Pejov
- Department of Physical Chemistry, Institute of Chemistry, SS. Cyril and Methodius University, Arhimedova 5, P.O. Box 162, 1001 Skopje, Republic of Macedonia
| | - Irina Petreska
- Institute of Physics, Faculty of Natural Sciences and Mathematics, SS. Cyril and Methodius University, P.O. Box 162, 1001 Skopje, Republic of Macedonia
| | - Ljupčo Kocarev
- Macedonian Academy of Sciences and Arts, Krste Misirkov 2, P.O. Box 428, 1000 Skopje, Republic of Macedonia
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Ylinen EE, Punkkinen M, Birczyński A, Lalowicz ZT. The effect of a broad activation energy distribution on deuteron spin-lattice relaxation. SOLID STATE NUCLEAR MAGNETIC RESONANCE 2015; 71:19-29. [PMID: 26482130 DOI: 10.1016/j.ssnmr.2015.10.006] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/24/2015] [Revised: 10/01/2015] [Accepted: 10/07/2015] [Indexed: 06/05/2023]
Abstract
Deuteron NMR spectra and spin-lattice relaxation were studied experimentally in zeolite NaY(2.4) samples containing 100% or 200% of CD3OH or CD3OD molecules of the total coverage of Na atoms in the temperature range 20-150K. The activation energies describing the methyl and hydroxyl motions show broad distributions. The relaxation data were interpreted by improving a recent model (Stoch et al., 2013 [16]) in which the nonexponential relaxation curves are at first described by a sum of three exponentials with adjustable relaxation rates and weights. Then a broad distribution of activation energies (the mean activation energy A0 and the width σ) was assumed for each essentially different methyl and hydroxyl position. The correlation times were calculated from the Arrhenius equation (containing the pre-exponential factor τ0), individual relaxation rates computed and classified into three classes, and finally initial relaxation rates and weights for each class formed. These were compared with experimental data, motional parameters changed slightly and new improved rates and weights for each class calculated, etc. This method was improved by deriving for the deuterons of the A and E species methyl groups relaxation rates, which depend explicitly on the tunnel frequency ωt. The temperature dependence of ωt and of the low-temperature correlation time were obtained by using the solutions of the Mathieu equation for a threefold potential. These dependencies were included in the simulations and as the result sets of A0, σ and τ0 obtained, which describe the methyl and hydroxyl motions in different positions in zeolite.
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Affiliation(s)
- E E Ylinen
- Wihuri Physical Laboratory, Department of Physics and Astronomy, University of Turku, FI-20014 Turku, Finland.
| | - M Punkkinen
- Wihuri Physical Laboratory, Department of Physics and Astronomy, University of Turku, FI-20014 Turku, Finland
| | - A Birczyński
- H. Niewodniczański Institute of Nuclear Physics of PAS, ul. Radzikowskiego 152, 31-342 Kraków, Poland
| | - Z T Lalowicz
- H. Niewodniczański Institute of Nuclear Physics of PAS, ul. Radzikowskiego 152, 31-342 Kraków, Poland
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7
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Beckmann PA. Nonexponential (1)H spin-lattice relaxation and methyl group rotation in molecular solids. SOLID STATE NUCLEAR MAGNETIC RESONANCE 2015; 71:91-95. [PMID: 26256302 DOI: 10.1016/j.ssnmr.2015.07.001] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/02/2015] [Accepted: 07/14/2015] [Indexed: 06/04/2023]
Abstract
We report a quantitative measure of the nonexponential (1)H spin-lattice relaxation resulting from methyl group (CH3) rotation in six polycrystalline van der Waals solids. We briefly review the subject in general to put the report in context. We then summarize several significant issues to consider when reporting (1)H or (19)F spin-lattice relaxation measurements when the relaxation is resulting from the rotation of a CH3 or CF3 group in a molecular solid.
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Affiliation(s)
- Peter A Beckmann
- Department of Physics, Bryn Mawr College, Bryn Mawr, PA 19010, USA.
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8
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Latosińska JN, Latosińska M, Tomczak MA, Medycki W. Complex mechanism of relaxation in solid chloroxylenol (antibacterial/antifungal agent) studied by ¹H NMR spectroscopy and density functional theory calculations. J Phys Chem A 2014; 118:2209-19. [PMID: 24628024 DOI: 10.1021/jp411981s] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Molecular relaxation in antibacterial/antifungal agent: chloroxylenol (4-chloro-3,5-dimethylphenol, PCMX) in the solid state was studied by the (1)H NMR and quantum chemistry calculations. The temperature dependencies of the proton spin-lattice relaxation time (T1) in the ranges 15-273 K (at 24.667 MHz), 77-295 K (at 15 MHz), and 112-291 K at 90 MHz and the second moment (M2) of (1)H NMR resonant line in the range 106-380 K were measured. The two minima in the temperature dependence of T1 revealed two activation processes, whereas the M2 dependence in the studied range was quite flat and revealed the only significant reduction at 380 K. The low temperature part of T1(T) dependence indicated the occurrence of two processes characteristic of methyl bearing solids; the quantum mechanics governed incoherent tunneling (responsible for the low temperature flattening of T1) and the classical Arrhenius dependence governed hindered rotation (related to the wide low temperature minimum of 0.066 s at 57 K, 24.667 MHz). The 2D potential energy surface obtained using DFT/B3LYP/6-311++G(2d,p) calculations revealed the inequivalence of methyl groups and the lack of their interplay/coupling. The activation energies of classical hindered rotation are 3.35 and 2.5 kJ/mol, whereas temperatures at which the proton tunneling T(tun) finally ceases are 52 and 63 K, for inequivalent methyl groups. C(p)(T) required for the estimation of T(tun) was calculated purely theoretically on the basis of the Einstein and Debye models of specific heat and 51 modes of atomic vibrations, 4 internal rotations, and 3 torsions calculated by DFT. The -CH3 motion (tunneling and classical) results in the reduction in the (1)H NMR line second moment from 17.3 G(2) (rigid) to approximately 11.05 G(2). The pointed high temperature minimum T1(T) of 0.109 s at 89 K, 24.667 MHz, which shifts with frequency, was assigned to small-angle libration jumps, by the Θ2 = ±15° between two positions of equilibrium. The activation energy of this motion estimated on the basis of the fit of the theoretical model to the experimental points is 10.5 kJ/mol. The reduction in the (1)H NMR line second moment assigned to this motion is much lower (due to order parameter s = 0.64) and equal to 1.6 G(2). The high temperature reduction from 9.6 G(2) to 0.9 G(2) at 380 K is a result of the phase transition connected with melting (385-389 K).
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Zhang B, Sun C, Alsanoosi AM, Aibout A, Horsewill AJ. Spin-symmetry conversion in methyl rotors induced by tunnel resonance at low temperature. J Chem Phys 2014; 140:084302. [PMID: 24588164 DOI: 10.1063/1.4865835] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Field-cycling NMR in the solid state at low temperature (4.2 K) has been employed to measure the tunneling spectra of methyl (CH3) rotors in phenylacetone and toluene. The phenomenon of tunnel resonance reveals anomalies in (1)H magnetization from which the following tunnel frequencies have been determined: phenylacetone, νt = 6.58 ± 0.08 MHz; toluene, νt(1) = 6.45 ± 0.06 GHz and νt(2) = 7.07 ± 0.06 GHz. The tunnel frequencies in the two samples differ by three orders of magnitude, meaning different experimental approaches are required. In phenylacetone the magnetization anomalies are observed when the tunnel frequency matches one or two times the (1)H Larmor frequency. In toluene, doping with free radicals enables magnetization anomalies to be observed when the tunnel frequency is equal to the electron spin Larmor frequency. Cross-polarization processes between the tunneling and Zeeman systems are proposed and form the basis of a thermodynamic model to simulate the tunnel resonance spectra. These invoke space-spin interactions to drive the changes in nuclear spin-symmetry. The tunnel resonance lineshapes are explained, showing good quantitative agreement between experiment and simulations.
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Affiliation(s)
- B Zhang
- School of Physics and Astronomy, University of Nottingham, Nottingham NG7 2RD, United Kingdom
| | - C Sun
- School of Physics and Astronomy, University of Nottingham, Nottingham NG7 2RD, United Kingdom
| | - A M Alsanoosi
- Physics Department, King Abdulaziz University, P.O. Box 80203, Jeddah 21589, Saudi Arabia
| | - A Aibout
- Laboratoire de Spectroscopie des Materiaux, Université de Mostaganem, B.P. 227, Mostaganem 2700, Algeria
| | - A J Horsewill
- School of Physics and Astronomy, University of Nottingham, Nottingham NG7 2RD, United Kingdom
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10
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Molecular flexibility and structural instabilities in crystalline l-methionine. Biophys Chem 2013; 180-181:76-85. [PMID: 23886538 DOI: 10.1016/j.bpc.2013.06.011] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2013] [Revised: 06/14/2013] [Accepted: 06/14/2013] [Indexed: 11/22/2022]
Abstract
We have investigated the dynamics in polycrystalline samples of l-methionine related to the structural transition at about 307K by incoherent inelastic and quasielastic neutron scattering, X-ray powder diffraction as well as ab-initio calculations. l-Methionine is a sulfur amino acid which can be considered a derivative of alanine with the alanine R-group CH3 exchanged by CH3S(CH2)2. Using X-ray powder diffraction we have observed at ~190K an anomalous drop of the c-lattice parameter and an abrupt change of the β-monoclinic angle that could be correlated to the anomalies observed in previous specific heat measurements. Distinct changes in the quasielastic region of the neutron spectra are interpreted as being due to the onset and slowing-down of reorientational motions of the CH3-S group, are clearly distinguished above 130K in crystalline l-methionine. Large-amplitude motions observed at low frequencies are also activated above 275K, while other well-defined vibrations are damped. The ensemble of our results suggests that the crystalline structure of l-methionine is dynamically highly disordered above 275K, and such disorder can be linked to the flexibility of the molecular thiol-ether group.
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Beckmann PA, Schneider E. Methyl group rotation,1H spin-lattice relaxation in an organic solid, and the analysis of nonexponential relaxation. J Chem Phys 2012; 136:054508. [DOI: 10.1063/1.3677183] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
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12
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Petreska I, Pejov L, Kocarev L. Exploring the possibilities to control the molecular switching properties and dynamics: A field-switchable rotor-stator molecular system. J Chem Phys 2011; 134:014708. [PMID: 21219021 DOI: 10.1063/1.3519638] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
A bistable, dipolar stator-rotor molecular system-candidate for molecular electronics is investigated. We demonstrate that it is possible to control the intramolecular torsional states and dynamics in this system by applying an appropriate additional electric field (instead of biasing one), achieving fine tuning and modulation of the relevant properties. The electric field effects on the quantities responsible for torsional dynamics (potential energy surface, potential barrier height, quantum and classical transition probabilities, correlation time, HOMO-LUMO gap) are studied from first principles. Our results indicate that it is possible to artificially stabilize the metastable conformational state of the studied molecule. The importance of this is evident, as the current-voltage characteristics of the metastable state are clearly distinguishable from the current-voltage characteristics of the two stable states. We report for the first time exact calculations related to the possibilities to control the thermally induced stochastic switching, and reduce the noise in a practical application. Thus, we believe that the molecule studied in this paper could operate as a field-switchable molecular device under real conditions.
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Affiliation(s)
- Irina Petreska
- Institute of Physics, Faculty of Natural Sciences and Mathematics, Ss. Cyril and Methodius University, P.O. Box 162, 1000 Skopje, Republic of Macedonia.
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14
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Sun C, Horsewill AJ. A field-cycling NMR investigation of resonant spin-lattice relaxation features arising from tunnelling methyl groups. SOLID STATE NUCLEAR MAGNETIC RESONANCE 2009; 35:139-146. [PMID: 18951766 DOI: 10.1016/j.ssnmr.2008.08.005] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/10/2008] [Revised: 08/27/2008] [Accepted: 08/28/2008] [Indexed: 05/27/2023]
Abstract
(1)H nuclear spin-lattice relaxation has been investigated in sodium acetate trihydrate and sorbic acid using field-cycling NMR in the solid state. The relaxation is dominated by the reorientation of the methyl groups. Resonant features arising from coherent tunnelling are observed in both the magnetic field dependence of the spin lattice relaxation rate, T(1)(-1)(B(z)) and in the inverse temperature dependence, T(1)(-1)(1/T). The two systems have different barrier heights and tunnelling frequencies, providing different perspectives on the tunnel resonance phenomena. The magnetic field dependence enables different spectral density components to be separately investigated and in the carboxylic acid, sorbic acid, concerted proton transfer in the hydrogen bonds is also identified at low field and low temperature. The methyl hindering barriers and the correlation times characterising the reorientational dynamics has been accurately determined in both materials.
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Affiliation(s)
- C Sun
- School of Physics & Astronomy, University of Nottingham, Nottingham, UK
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15
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Ramanuja M, Ramesh K, Ramakrishna J. NMR relaxation study of disorder in the mixed system BPxGPI(1–x)and the low temperature transition from classical to quantum rotation. Mol Phys 2009. [DOI: 10.1080/00268970902845297] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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16
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Ramanuja M, Ramesh K, Ramakrishna J. NMR relaxation study of disorder in condensed matter – low temperature studies in the mixed system − BPI(1−x)BPx – transition from classical to quantum rotation. Mol Phys 2008. [DOI: 10.1080/00268970801948119] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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17
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Pejov L, Rosa ML, Kocarev L. Dynamics of the central phenylene ring torsional motion in halogenated phenylene ethynylene oligomers. Chem Phys 2007. [DOI: 10.1016/j.chemphys.2007.05.034] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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18
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McDonald P, Vijayaraghavan D, Debenham P, Horsewill A. Pressure dependence of methyl tunnelling in solid diacetyl. Mol Phys 2006. [DOI: 10.1080/00268979300100181] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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19
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Colmenero J, Moreno AJ, Alegría A. Neutron scattering investigations on methyl group dynamics in polymers. Prog Polym Sci 2005. [DOI: 10.1016/j.progpolymsci.2005.08.001] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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20
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Holderna-Natkaniec K, Jurga K, Natkaniec I, Nowak D, Szyczewski A. Molecular dynamics of ethisterone studied by 1H NMR, IINS and quantum mechanical calculations. Chem Phys 2005. [DOI: 10.1016/j.chemphys.2005.06.043] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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21
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Latanowicz L. Proton Spin−Lattice Relaxation of Tunneling Methyl Groups: Calculation of the Time Dependent Correlation Functions. J Phys Chem A 2004. [DOI: 10.1021/jp047668a] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- L. Latanowicz
- Institute of Biotechnology and Environmental Sciences, University of Zielona Góra, Monte Cassino 21 B, 65-651 Zielona Góra, Poland
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22
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Nair S, Dimeo RM, Neumann DA, Horsewill AJ, Tsapatsis M. Methyl rotational tunneling dynamics of p-xylene confined in a crystalline zeolite host. J Chem Phys 2004; 121:4810-9. [PMID: 15332915 DOI: 10.1063/1.1781119] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The methyl rotational tunneling spectrum of p-xylene confined in nanoporous zeolite crystals has been measured by inelastic neutron scattering (INS) and proton nuclear magnetic resonance (NMR), and analyzed to extract the rotational potential energy surfaces characteristic of the methyl groups in the host-guest complex. The number and relative intensities of the tunneling peaks observed by INS indicate the presence of methyl-methyl coupling interactions in addition to the methyl-zeolite interactions. The INS tunneling spectra from the crystals (space group P2(1)2(1)2(1) with four crystallographically inequivalent methyl rotors) are quantitatively interpreted as a combination of transitions involving two coupled methyl rotors as well as a transition involving single-particle tunneling of a third inequivalent rotor, in a manner consistent with the observed tunneling energies and relative intensities. Together, the crystal structure and the absence of additional peaks in the INS spectra suggest that the tunneling of the fourth inequivalent rotor is strongly hindered and inaccessible to INS measurements. This is verified by proton NMR measurements of the spin-lattice relaxation time which reveal the tunneling characteristics of the fourth inequivalent rotor.
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Affiliation(s)
- Sankar Nair
- School of Chemical & Biomolecular Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332-0100, USA.
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23
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Prager M, Grimm H, Desmedt A, Lechner R. Methyl rotational potentials of trimethyl metal compounds studied by inelastic and quasielastic neutron scattering. Chem Phys 2003. [DOI: 10.1016/s0301-0104(03)00207-6] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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Harbridge JR, Eaton SS, Eaton GR. Electron Spin-Lattice Relaxation Processes of Radicals in Irradiated Crystalline Organic Compounds. J Phys Chem A 2003. [DOI: 10.1021/jp021504h] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- James R. Harbridge
- Department of Chemistry and Biochemistry, University of Denver, Denver, Colorado 80208-2436
| | - Sandra S. Eaton
- Department of Chemistry and Biochemistry, University of Denver, Denver, Colorado 80208-2436
| | - Gareth R. Eaton
- Department of Chemistry and Biochemistry, University of Denver, Denver, Colorado 80208-2436
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Molecular deformations of halogeno-mesitylenes in the crystal: structure, methyl group rotational tunneling, and numerical modeling. Chem Phys 2002. [DOI: 10.1016/s0301-0104(02)00817-0] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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Johnson MR, Jones NH, Geis A, Horsewill AJ, Trommsdorff HP. Structure and dynamics of the keto and enol forms of acetylacetone in the solid state. J Chem Phys 2002. [DOI: 10.1063/1.1456032] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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Moreno AJ, Alegría A, Colmenero J, Frick B. Methyl Group Dynamics in Poly(methyl methacrylate): From Quantum Tunneling to Classical Hopping. Macromolecules 2001. [DOI: 10.1021/ma0100854] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- A. J. Moreno
- Departamento de Física de Materiales y Centro Mixto CSIC-UPV/EHU, Universidad del País Vasco (UPV/EHU), Apartado 1072, 20080 San Sebastián, Spain
| | - A. Alegría
- Departamento de Física de Materiales y Centro Mixto CSIC-UPV/EHU, Universidad del País Vasco (UPV/EHU), Apartado 1072, 20080 San Sebastián, Spain
| | - J. Colmenero
- Departamento de Física de Materiales y Centro Mixto CSIC-UPV/EHU, Universidad del País Vasco (UPV/EHU), Apartado 1072, 20080 San Sebastián, Spain
| | - B. Frick
- Institute Laue Langevin, BP 156X, F-38042 Grenoble, France
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Clough S, Horsewill AJ, McDonald PJ. Methyl tunnelling spectroscopy and level crossing phenomena in solid acetone. ACTA ACUST UNITED AC 2000. [DOI: 10.1088/0022-3719/17/6/019] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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29
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Clough S, McDonald PJ. The correlation of methyl tunnelling and thermally activated reorientation: II. ACTA ACUST UNITED AC 2000. [DOI: 10.1088/0022-3719/15/29/003] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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30
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Clough S, McDonald PJ, Zelaya FO. The transition from free quantum tunnelling to thermally driven motion of methyl groups. ACTA ACUST UNITED AC 2000. [DOI: 10.1088/0022-3719/17/25/005] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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31
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Mahgoub AS, Clough S. Quantum tunnelling and hopping motion of methyl groups in cadmium acetate dihydrate. ACTA ACUST UNITED AC 2000. [DOI: 10.1088/0022-3719/18/3/014] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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Gillan MJ. Quantum-classical crossover of the transition rate in the damped double well. ACTA ACUST UNITED AC 2000. [DOI: 10.1088/0022-3719/20/24/005] [Citation(s) in RCA: 296] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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37
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38
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Neumann M, Johnson M, Aibout A, Horsewill A. Measured and calculated rotational tunnelling dynamics in methyl acetate. Chem Phys 1998. [DOI: 10.1016/s0301-0104(98)00039-1] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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39
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Brougham D, Horsewill A, Jenkinson R. Proton transfer dynamics in the hydrogen bond: a direct measurement of the incoherent tunnelling rate by NMR and the quantum-to-classical transition. Chem Phys Lett 1997. [DOI: 10.1016/s0009-2614(97)00493-4] [Citation(s) in RCA: 57] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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40
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Scheurer C, Wiedenbruch R, Meyer R, Ernst RR, Heinekey DM. Quantum mechanical exchange in a transition metal hydride complex: NMR data for [cp(PPh3)IrH3]+ fitted by a two-dimensional model. J Chem Phys 1997. [DOI: 10.1063/1.474112] [Citation(s) in RCA: 46] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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41
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Cleemput MV, Buekenhoudt A, Gerven LV, Horsewill AJ. Quantum and classical dynamics of a methyl group with tunneling frequency 3.4 MHz studied by low field NMR. J Chem Phys 1995. [DOI: 10.1063/1.470515] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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Buekenhoudt A. Temperature dependence of methyl reorientation at intermediate hindering potentials. PHYSICAL REVIEW. B, CONDENSED MATTER 1992; 46:5377-5386. [PMID: 10004318 DOI: 10.1103/physrevb.46.5377] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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43
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van der Putten D, Diezemann G, Fujara F, Hartmann K, Sillescu H. Methyl group dynamics in α‐crystallized toluene as studied by deuteron spin–lattice relaxation. J Chem Phys 1992. [DOI: 10.1063/1.462130] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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Diezemann G, Sillescu H, van der Putten D. Spin lattice relaxation rates of tunnelling CD3 groups. ACTA ACUST UNITED AC 1991. [DOI: 10.1007/bf01309425] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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Jin B, Silbey R. Nuclear spin–lattice relaxation of methyl groups via multiphonon processes. J Chem Phys 1991. [DOI: 10.1063/1.459931] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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Murphy M, White D. Matrix isolation nuclear magnetic resonance studies of methyl group spin–rotation coupling. J Chem Phys 1989. [DOI: 10.1063/1.456789] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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