ENDOR studies at 4.2 K of the radicals in malonic acid single crystals

McCalley, Roderick C.; Kwiram, Alvin L.

doi:10.1021/j100114a011

Cited by 25 publications

(44 citation statements)

References 12 publications

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“…The crystals cleaved readily parallel to the intermolecular hydrogen bonding axis [7]. The carboxylic acid protons in malonic acid were exchanged with deuterium by slow evaporation of a D20 solution.…”

Section: Experimental Methods and Data Analysismentioning

confidence: 99%

“…Other minor radicals have been observed by ENDOR [7]. Figure 4 shows the temperature dependence of the rate constants calculated from fits of single exponentials to the recovery curves obtained by inversion recovery, ED-SR, Xband CW-SR, and S-band CW-SR for the high-field line of a polycrystalline malonic acid radical sample.…”

Section: Malonic Acidmentioning

confidence: 99%

“…One crystat was oriented with the H-bonding axis [7] parallel to the axis of the EPR tube and was rotated about the axis of the EPR tube. ELDOR was measured at approximately 15 ~ intervals.…”

Section: Malonic Acidmentioning

confidence: 99%

“…la and b). Irradiated malonic acid has been studied previously by continuous-wave (CW) EPR [5,6], electronnuclear double resonance (ENDOR) [7][8][9] and electron-electron double resonance (ELDOR) [10,11], but the electron spin relaxation processes have not been charo~~ .... acterized. Two persistent radicals are formed by 1,-irradiation of methyl malonic acid (MMA) (Fig.…”

Section: Introductionmentioning

confidence: 99%

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Electron spin relaxation of radicals in γ-irradiated malonic acid and methyl malonic acid

Harbridge

2003

Appl. Magn. Reson.

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Radicals genemted by y-irradiation of malonic acid and methyl malonic acid were studied asa function of temperature by inversion recovery, echo-detected saturation recovery and electronelectron double resonance (ELDOR) at X-band, and by continuous-wave saturation recovery at Xband and S-band. ELDOR reductions for malonic acid radical in polycrystalline and single-crystal samples indicate that nuclear spin relaxation is faster than both electron spin relaxation and cross relaxation between 93 and 233 K. Deuteration of the carboxylate protons caused the maximum ELDOR reduction to shift from about 110 to 150 K, consistent with the assignment of the rapid nuclear spin relaxation to hydrogen-bonded proton dynamies. ELDOR enhancements for both radicals formed in methyl malonic acid indicate that cross relaxation is faster than both electron spin relaxation and nuclear spin relaxation between 77 and 220 K. Enhanced cross relaxation and electron spin relaxation ate attributed to the rotation of methyl groups at a rate comparable to the electron Larmor frequency. The temperature dependence of the enhancement of 1/T~, was analyzed to determine the activation energies for methyl rotation. The same radical is formed in irradiated methyl malonic acid and L-alanine, but the barrier to rotation of the ct-methyl is 500 K in the methyl malonic acid host and 1500 K in the L-alanine host, which indicates a large impact of the lattice on the barrier to rotation.

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Section: Experimental Methods and Data Analysismentioning

confidence: 99%

Section: Malonic Acidmentioning

confidence: 99%

Section: Malonic Acidmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Electron spin relaxation of radicals in γ-irradiated malonic acid and methyl malonic acid

Harbridge

2003

Appl. Magn. Reson.

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“…We demonstrate the utility of this control scheme by exploring Ramsey fringes [24] and Hahn echoes [25] in a 1e-1n system -a single crystal of x-ray irradiated malonic acid [26,27,28]. The parametrized Hamiltonian is H 0 /2π = ν sŜz − ν nÎz + A zxŜzÎx + A zzŜzÎz where ν s = 11.885 GHz, ν n = 18.1 MHz, A zx ≈ 14.2 MHz, and A zz ≈ −42.7 MHz.…”

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confidence: 99%

Universal control of nuclear spins via anisotropic hyperfine interactions

et al. 2008

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We show that nuclear spin subsystems can be completely controlled via microwave irradiation of resolved anisotropic hyperfine interactions with a nearby electron spin. Such indirect addressing of the nuclear spins via coupling to an electron allows us to create nuclear spin gates whose operational time is significantly faster than conventional direct addressing methods. We experimentally demonstrate the feasibility of this method on a solid-state ensemble system consisting of one electron and one nuclear spin.Coherent control of quantum systems promises optimal computation [1], secure communication [2], and new insight into the fundamental physics of many-body problems [3]. Solid-state proposals [4,5,6,7,8] for such quantum information processors employ isolated spin degrees of freedom which provide Hilbert spaces with long coherence times. Here we show how to exploit a local, isolated electron spin to coherently control nuclear spins. Moreover, we suggest that this approach provides a fast and reliable means of controlling nuclear spins and enables the electron spins of such solid-state systems to be used for state preparation and readout [9] of nuclear spin states, and additionally as a spin actuator for mediating nuclear-nuclear spin gates.Model System. The spin Hamiltonian of a single local electron spin with angular momentum, S = 1 2 and N nuclear spins, each with angular momentum I k = 1 2 , in the presence of a magnetic field B is [10]:Here β e is the Bohr magneton, γ k n is the gyromagnetic ratio;Ŝ andÎ k are the spin-1 2 operators. The secondrank tensors g, A k , δ, and D kl represent the electron gfactor, the hyperfine interaction, the chemical shift, and the nuclear dipole-dipole interaction respectively.In the regime where the static magnetic field B = B 0ẑ provides a good quantization axis for the electron spin, the Hamiltonian can be simplified by dropping the nonsecular terms which corresponds to keeping only electron interactions involving S z . The quantization axis of any nuclear spin depends on the magnitudes of the hyperfine interaction and the main magnetic field, as well as their relative orientations. When these two fields are comparable in magnitude [37] H 0 can be approximated by: (2) with N=1. The electron spin state is in an eigenstate of purely the Zeeman interaction, while the nuclear spin state is not an eigenfunction of the Zeeman interaction alone due to the anisotropic hyperfine interaction. Because α0|β1 = 0 and α0|β0 = 0 the electron spin operator (Ŝx) has finite probabilities between all levels (dashed arrows). This allows for universal control of the entire spin system. The filled and unfilled circles represent the relative spin state populations of the ensemble at thermal equilibrium. In our experimental setup the energy differences are ω12/2π = 7.8 MHz, ω34/2π = 40 MHz, ω14/2π = 12.005 GHz, ω23/2π = 11.954GHzThe nuclear dipole-dipole interaction is neglected as it is typically 10 2 times weaker than the hyperfine terms.As described in Figure 1 (N=1), the nuclear spin is qu...

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Electron-Nuclear Multiple Resonance Spectroscopy

Thomann

Bernardo

2007

Encyclopedia of Magnetic Resonance

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ENDOR studies at 4.2 K of the radicals in malonic acid single crystals

Cited by 25 publications

References 12 publications

Electron spin relaxation of radicals in γ-irradiated malonic acid and methyl malonic acid

Electron spin relaxation of radicals in γ-irradiated malonic acid and methyl malonic acid

Universal control of nuclear spins via anisotropic hyperfine interactions

Electron-Nuclear Multiple Resonance Spectroscopy

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