Muon radical states in some electron donor and acceptor molecules

Pratt, F. L.; Blundell, Stephen J.; Jestädt, T; Lovett, Brendon W.; Macrae, R.; Hayes, W.

doi:10.1002/1097-458x(200006)38:13<::aid-mrc695>3.0.co;2-w

Cited by 15 publications

(18 citation statements)

References 11 publications

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“…Similar low hyperfine interaction states have been found in other organic compounds, 13 attributed to muonium addition to products from molecule cleavage following the highly energetic process of muon implantation. This may be the case of component IV, but we do not rule out the hypothesis that it might be a part of state III's frequency distribution, implying that the anisotropic contribution would be the dominant feature of state III's hyperfine interaction.…”

Section: Cupcsupporting

confidence: 72%

“…The hyperfine interactions of the three states are typical of muoniated Fig. 4; for state III, the line indicates the fitted hyperfine interaction at 100 K. radicals in organic compounds, 13 and a shift to lower values with increasing temperature is observed for states I and II. The same is seen in the temperature dependence of the hyperfine interaction values extracted from the fits to the time spectra ͑Fig.…”

Section: Resultsmentioning

confidence: 93%

“…The Fourier spectrum may be converted to a frequency pair correlation spectrum 13 showing directly the spectral power of each hyperfine interaction in the signal. This is a useful tool to visualize data with several components in the high-field regime, assisting the fits to the time spectra.…”

Section: Resultsmentioning

confidence: 99%

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Muoniated radical states in the organic semiconductor phthalocyanine

et al. 2006

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Phthalocyanine samples of ZnPc, H 2 Pc, and CuPc were investigated with the muon spin rotation technique. In ZnPc and H 2 Pc, three muoniated radical states of paramagnetic origin were identified, two of which have hyperfine interactions in the range 110-150 MHz and correspond to muonium addition at the outer benzene rings. The third state has a smaller hyperfine interaction ͑about 25 MHz͒ and is tentatively assigned to addition at bridging nitrogen atoms. CuPc has an unpaired electron from the Cu atom, which originates a diamagneticlike signal upon muonium addition. The signal has two components with very different relaxation rates, corresponding to two different spatial couplings of the Cu electron with the muonium's electron.

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Section: Cupcsupporting

confidence: 72%

Section: Resultsmentioning

confidence: 93%

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Muoniated radical states in the organic semiconductor phthalocyanine

et al. 2006

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“…Neutral TCNQ has been studied using muon spectroscopy where a radical with an 80 MHz coupling constant was observed which corresponds to coupling of the muon to the nitrogens at the end of the molecule. In reduced TCNQ it may be possible to observe bonding of the muon to the aromatic ring which would have a higher hyperfine coupling [55]. Thus, although deuterium has a nuclear magnetic moment, because it is smaller than that of 14 N and given the suspected stopping site of the muon, it can be effectively ignored.…”

Section: Muon Spin Relaxation Studymentioning

confidence: 99%

Separating the ferromagnetic and glassy behavior within the metal-organic magnetNi(TCNQ)2

et al. 2015

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Publisher's copyright statement:Reprinted with permission from the American Physical Society: Physical Review B 92, 184431 c 2015 by the American Physical Society. Readers may view, browse, and/or download material for temporary copying purposes only, provided these uses are for noncommercial personal purposes. Except as provided by law, this material may not be further reproduced, distributed, transmitted, modied, adapted, performed, displayed, published, or sold in whole or part, without prior written permission from the American Physical Society.Additional information: Use policyThe full-text may be used and/or reproduced, and given to third parties in any format or medium, without prior permission or charge, for personal research or study, educational, or not-for-prot purposes provided that:• a full bibliographic reference is made to the original source • a link is made to the metadata record in DRO • the full-text is not changed in any way The full-text must not be sold in any format or medium without the formal permission of the copyright holders.Please consult the full DRO policy for further details. An in-depth study of the metal-organic magnet Ni(TCNQ) 2 was conducted where the deuterated form was synthesised both to attempt to alter the magnetic properties of the material and to be advantageous in techniques such as neutron scattering and muon spectroscopy. Deuteration saw a 3 K increase in T C with magnetization and heat capacity measurements demonstrating a spin wave contribution at low temperatures confirming the 3D nature of the ferromagnetic state shown by Ni(TCNQ − D 4 ) 2 . AC susceptibility results suggest there is a glassy component associated with the magnetically ordered state, though muon spectroscopy measurements did not support the presence of a spin glass state. Instead muon spectroscopy at zero magnetic field indicated the presence of two magnetic transitions, one at 20 K and another below 6 K; the latter is likely due to the system entering a quasistatic regime, similar to what one might expect of a superspin or cluster glass. Neutron diffraction measurements further supported this by revealing very weak magnetic Bragg peaks suggesting that the magnetism may have a short coherence length and be confined to small grains or clusters. The separation of the ferromagnetic and glassy magnetic components of the material's properties suggest that this system may show promise as a metal-organic magnet which is easily modified to change its magnetic properties, providing larger grain sizes can be synthesized.

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“…This may also be the same situation between TCNQ radicals located within the defect or structurally inhomogeneous regions, where π-orbital overlap is such that a molecular orbital is formed and a singlet ground state is also preferable. Avoided level crossing measurements on neutral TCNQ [36] have shown that the radical state has a strong anisotropy of the spin density at low temperatures that could alter the interactions between TCNQ radical in SP systems as well as within the defect. red Since the sample forms crystallites that are made of small needles, there may be a large amount of structural inhomogenities that could lead to various defects between stacks.…”

Section: Sitesmentioning

confidence: 99%

Magnetic ordering of defects in a molecular spin-Peierls system

Berlie¹,

Terry²,

Cottrell³

et al. 2016

J. Phys.: Condens. Matter

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With interest in charge transfer compounds growing steadily, it is important to understand all aspects of the underlying physics of these systems, including the properties of the defects and interfaces that are universally present in actual experimental systems. For the study of these defects and their interactions a spin-Peierls (SP) system provides a useful testing ground. This work presents an investigation within the SP phase of potassium TCNQF 4 where anomalous features are observed in both the magnetic susceptibility and ESR spectra for temperatures between 60 K and 100 K. Muon spin spectroscopy measurements confirm the presence of these anomalous magnetic features, with low temperature zero-field data exhibiting the damped oscillatory form that is a characteristic signature of static magnetic order. This ordering is most likely due to the interaction between structurally correlated magnetic defects in the system. The critical behaviour of the temperature dependent muon spin rotation frequency indicates that a 2D Ising model is applicable to the magnetic ordering of these defects. We show that these observations can be explained by a simple model in which the magnetic defects are located at stacking faults, which provide them with a 2D structural framework to constrain their interactions.

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Muon radical states in some electron donor and acceptor molecules

Cited by 15 publications

References 11 publications

Muoniated radical states in the organic semiconductor phthalocyanine

Muoniated radical states in the organic semiconductor phthalocyanine

Separating the ferromagnetic and glassy behavior within the metal-organic magnetNi(TCNQ)2

Magnetic ordering of defects in a molecular spin-Peierls system

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