The return of the trapped electron in x-irradiated clathrate hydrates. An ESR investigation

Bednarek, Janusz; Erickson, Roland; Lund, Anders; Schlick, Shulamith

doi:10.1021/ja00023a082

Cited by 19 publications

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“…The additional, smaller splittings detected at 130 K indicate a hyperfine coupling of ≈4 G. The spectrum at 190 K suggests the reappearance of the electron, as deduced from the blue color of the sample and the central sharp line in the ESR spectra. 20 Identification of the quartet indicated by circles in Figure 4 with the methyl radical CH 3 • is demonstrated in Figure 5. Subtraction of the ESR spectrum annealed at 130 K and recorded at 40 K ( Figure 5B) from the unannealed spectrum recorded at 40 K ( Figure 5A) results in the quartet shown in Figure 5C, where the splittings and the number of lines are typical of the methyl radical.…”

Section: Resultsmentioning

confidence: 99%

Unstable Intermediates in X-Irradiated Clathrate Hydrates: ESR and ENDOR of Tetramethylammonium Hydroxide Pentahydrate (TMNOH)

1996

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X-irradiation of tetramethylammonium hydroxide pentahydrate (TMNOH) at 77 K produces trapped electrons, and CH 3 • and (CH 3 ) 3 N + CH 2 • radicals. The trapped electrons were detected by bleaching with visible light and by subtraction of spectra from bleached and unbleached samples. The decay of the methyl radicals starts at ≈100 K and that of the (CH 3 ) 3 N + CH 2 • radicals at ≈150 K. The ESR spectrum measured at 130 K has the best resolution and is a superposition of contributions from the methyl radicals (13%) and from the (CH 3 ) 3 N + CH 2 • radical (87%). The reversibility of the line shapes with temperature variations suggested that the increased resolution observed at 130 K is due to dynamical effects involving the (CH 3 ) 3 N + CH 2 • radicals. ESR spectra from these radicals can be simulated by assuming that the hyperfine tensor components for the two R protons are averaged by two types of motions: rotation of the CH 2 group about the C 2V symmetry axis and precession or wobbling of this axis. The parameters used in the simulation are g iso ) 2.0022, two equivalent R protons with axial hyperfine components A | av ) 25.0 G and A ⊥ av ) 23.0 G, one 14 N nucleus with A N ) 3.9 G, and one remote proton with A H,remote ) 4.2 G. The remote proton is identified with a lattice proton. If the precession model is adopted, the precession angle calculated from the principal values of the hyperfine tensor for the R protons used in the simulations is 47°. For the wobbling model, the wobbling angle deduced is 72°. These results suggest that the hydrogen-bonded cage around the guest allows large-scale dynamical effects even at 130 K.

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Section: Resultsmentioning

confidence: 99%

Unstable Intermediates in X-Irradiated Clathrate Hydrates: ESR and ENDOR of Tetramethylammonium Hydroxide Pentahydrate (TMNOH)

1996

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“…The solvated dielectron can be understood as a stable species formed by the equilibrium between two interacting electrons and surrounding solvent molecules. At present, the existence of solvated dielectrons or captured EE pairs has been confirmed experimentally and theoretically, and such solvated dielectrons exhibit different structures: single cavity‐shaped F ′ central structure; double cavity structure with a certain spatial distance between two weakly‐bound EEs as a bipolaron; and bipolaron non‐cavity structure . Given that the complicated interaction among two related EEs and solvent cavities, the solvated dielectrons dominate much more important electronic, structural properties, and even unique dynamic behaviors, as observed in magnetism, spintronics, nonlinear optical properties, spin coupling dynamics, and other aspects .…”

Section: Introductionmentioning

confidence: 97%

“…In such clathrate hydrates, water molecules as host molecules form a water cage through intermolecular hydrogen bonding to wrap various guest molecules, and the distance between two adjacent cages is generally 6 to 10 Å, such a distance is likely to lead to interactions between the guest species of the clathrate hydrate cavities. Clathrate hydrates encapsulating free radicals, high‐spin substances, charged ions, or even excess electrons (EEs) are likely to exhibit rich magnetic properties and other properties . As a particular example, a recent study reveals that the spin coupling interactions exist between high‐spin O 2 molecules in clathrate hydrates, exhibiting very interesting magnetic properties, and also providing a novel idea for the applications of clathrate hydrates.…”

Section: Introductionmentioning

confidence: 99%

“…Given that the complicated interaction among two related EEs and solvent cavities, the solvated dielectrons dominate much more important electronic, structural properties, and even unique dynamic behaviors, as observed in magnetism, spintronics, nonlinear optical properties, spin coupling dynamics, and other aspects . Therefore, solvated dielectrons are expected to exhibit more intriguing features and promising applications, which has attracted extensive attention and strong interest in research . Moreover, solvated dielectrons are a bit similar to organic diradicals, and may show different novel coupling modes and properties in different media .…”

Section: Introductionmentioning

confidence: 99%

“…Actually, dielectron clathrate hydrates belong to a special class of solvated dielectrons. As early as in 1991, there was an experimental observation of dielectron clathrate by X‐ray irradiation (CH 3 ) 4 N + OH − clathrate hydrates . However, up to now, the related structures and properties of dielectron clathrate hydrates, especially those related to spin couplings, have hardly been studied.…”

Section: Introductionmentioning

confidence: 99%

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Intriguing electric field effect on magnetic spin couplings in dielectron clathrate hydrates

Luo

2019

Int J of Quantum Chemistry

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Clathrate hydrates have appeared as promising icy materials as the radical, high-spin molecule, and even electron clathrate hydrates are found. In particular, dielectron clathrate hydrates are expected to develop as structural units for a novel class of icy magnetic materials because of not only possible spin coupling interaction, but also very sensitive response to electric field of the loosely bound electrons. However, electric field responses concerning the magnetic properties of such hydrates have not been reported so far. In this work, three representative dielectron clathrate hydrate model clusters (e 2 @4 6 6 8 BB, e 2 @5 12 6 2 BB, and e 2 @4 6 6 8 AB) were considered for the exploration of their magnetic spin coupling properties, electron distributions, and energy responses to applied electric field. The results calculated at the density functional theory level show that the energies and electron spin coupling properties of these dielectron clathrate hydrate clusters are quite sensitive to applied electric field, presenting intriguing variations. Most importantly, applied electric field can regulate the strength of spin coupling between two trapped electrons, and even could realize the magnetic interconversion of such dielectron cluster structures between antiferromagnetic and paramagnetic or diamagnetic characteristics. Clearly, the intriguing variations should be attributed to the diffuse character, special mobility and polarizable properties of such trapped electrons, and especially the susceptible redistributions of two electrons (including the electron cloud shape and distance between two electron centers) to the electric field. This work opens up the possibility of designing novel icy magnetic materials with sensitive electric field responses of the magnetic properties. K E Y W O R D S density functional theory calculation, dielectron clathrate hydrate cluster, electric field effect, magnetic spin coupling, through electron-permeating H-bond coupling channel 1 | INTRODUCTIONRecently, clathrate hydrates have been highly valued by both theoretical and experimental researchers [1][2][3][4][5][6][7][8][9][10][11] because of the gas storage capacity and potential applications in icy materials. [9] In such clathrate hydrates, water molecules as host molecules form a water cage through intermolecular hydrogen bonding to wrap various guest molecules, and the distance between two adjacent cages is generally 6 to 10 Å, such a distance is likely to lead to interactions between the guest species of the clathrate hydrate cavities. Clathrate hydrates encapsulating free radicals, high-spin substances, charged ions, or even excess electrons (EEs) are likely to exhibit rich magnetic properties [12][13][14] and other properties. [15,16] As a

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Neutron Scattering of Clathrate and Semiclathrate Hydrates

Desmedt¹,

Bedouret²,

Ollivier³

et al. 2017

Gas Hydrates 1

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The return of the trapped electron in x-irradiated clathrate hydrates. An ESR investigation

Cited by 19 publications

References 0 publications

Unstable Intermediates in X-Irradiated Clathrate Hydrates: ESR and ENDOR of Tetramethylammonium Hydroxide Pentahydrate (TMNOH)

Unstable Intermediates in X-Irradiated Clathrate Hydrates: ESR and ENDOR of Tetramethylammonium Hydroxide Pentahydrate (TMNOH)

Intriguing electric field effect on magnetic spin couplings in dielectron clathrate hydrates

Neutron Scattering of Clathrate and Semiclathrate Hydrates

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