Symmetrization Postulate and Nuclear Magnetic Resonance of Reacting Systems

Bowers, Clifford R.; Jones, D. H.; Kurur, Narayanan D.; Labinger, Jay A.; Pravica, Michael; Weitekamp, D. P.

doi:10.1016/b978-0-12-025514-6.50018-6

Cited by 84 publications

(70 citation statements)

References 25 publications

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“…It is clear that an enormous increase in signal intensity can be achieved if the selective spin state population of a pure sample of the para form can be used in an NMR experiment. As detailed above, the basic PHIP phenomenon [15,16] accomplishes this through chemical reactions that break the symmetry of the spin pair without changing the relative orientations of the spins. In other words, the NMR-silent I = 0 state of two protons is converted into the corresponding NMRactive states of two non-equivalent I = 1/2 particles with the potential for enormous increase in the intensity of the observed transitions [20].…”

Section: Applications Of Isolated Spin Isomersmentioning

confidence: 99%

“…There has been a resurgence of interest in para-H 2 in recent years following the prediction [15] and accidental discovery [16] of strongly enhanced NMR signals in the products of hydrogenation reactions carried out using H 2 enriched in that allotrope. The phenomenon is commonly referred to as para-hydrogen-induced polarization (PHIP).…”

Section: (B) Para-hydrogen Enrichmentmentioning

confidence: 99%

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Nuclear spin isomers of guest molecules in H ₂ @C ₆₀ , H ₂ O@C ₆₀ and other endofullerenes

Chen

Frunzi

et al. 2013

Phil. Trans. R. Soc. A.

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Spectroscopic studies of recently synthesized endofullerenes, in which H 2 , H 2 O and other atoms and small molecules are trapped in cages of carbon atoms, have shown that although the trapped molecules interact relatively weakly with the internal environment they are nevertheless susceptible to appropriately applied external perturbations. These properties have been exploited to isolate and study samples of H 2 in C 60 and other fullerenes that are highly enriched in the para spin isomer. Several strategies for spin-isomer enrichment, potential extensions to other endofullerenes and possible applications of these materials are discussed.

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Section: Applications Of Isolated Spin Isomersmentioning

confidence: 99%

Section: (B) Para-hydrogen Enrichmentmentioning

confidence: 99%

Nuclear spin isomers of guest molecules in H ₂ @C ₆₀ , H ₂ O@C ₆₀ and other endofullerenes

Chen

Frunzi

et al. 2013

Phil. Trans. R. Soc. A.

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“…This causes the off-diagonal terms in the density matrix to dephase, resulting in an equal mixture of singlet and T 0 triplet states in the spin ensemble [18], which is separable [8,9,10]. One possible method that has been suggested to overcome this problem is to perform the slow addition while applying an isotropic mixing sequence [19] to remove the dephasing effect [20].…”

mentioning

confidence: 99%

Preparing High Purity Initial States for Nuclear Magnetic Resonance Quantum Computing

et al. 2004

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Here we demonstrate how para-hydrogen can be used to prepare a two-spin system in an almost pure state which is suitable for implementing nuclear magnetic resonance (NMR) quantum computation. A 12 ns laser pulse is used to initiate a chemical reaction involving pure para-hydrogen (the nuclear spin singlet of H2). The product, formed on the µs timescale, contains a hydrogen-derived two-spin system with an effective spin-state purity of 0.916. To achieve a comparable result by direct cooling would require an unmanageable (in the liquid state) temperature of 6.4 mK or an impractical magnetic field of 0.45 MT at room temperature. The resulting spin state has an entanglement of formation of 0.822 and cannot be described by local hidden variable models.PACS numbers: 03.67. Lx, 03.67.Mn, Introduction. While quantum computing [1] offers the potential of using new quantum algorithms to tackle problems that are intractable for classical processors, its implementation requires the development of quantum devices, which are as yet unavailable. The most complex implementations of quantum algorithms to date have used techniques adapted from nuclear magnetic resonance (NMR) spectroscopy [2,3,4,5], but current liquid state NMR approaches cannot be extended to systems with many quantum bits, as it is not possible to prepare pure initial states by directly cooling the spin system into its ground state [6]. Furthermore, it has been shown that current NMR experiments involve only separable states [7], and thus could in principle be described by local hidden variable models.The conventional approach in NMR quantum computing [4] is to use an ensemble of spins, and to prepare a pseudo-pure ground state [2,4] of the form

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“…Similar to the PASADENA experiments, a reaction solution was prepared by dissolving 3 mmol of [Rh(DPPB)(COD)]BF 4 and, subsequently, 150 mmol of ethyl propiolate in 500 mL of acetone-d 6 . A 5-mm NMR tube with a septum screw cap was used as the sample container and pressurized with H 2 gas up to 3 bar through a needle that was forced through the septum.…”

Section: Altadena Hydrogenation Of Ethyl Propiolate With [Rh(dppb)(comentioning

confidence: 99%

“…In a standard 5-mm NMR sample tube, 2.17 mg (3 mmol) of [Rh(DPPB)(COD)]BF 4 were dissolved in 500 ml of acetone-d 6 . Thereafter, 15.2 mL of ethyl propiolate (14.7 mg, 150 mmol, SCR ¼ 50) were added to the solution, the sample tube temporarily sealed, and the solution thoroughly mixed by shaking.…”

Section: Pasadena Hydrogenation Of Ethyl Propiolate With [Rh(dppb)(comentioning

confidence: 99%

Hydrogen Induced Polarization–Nuclear‐Spin Hyperpolarization in Catalytic Hydrogenations without the Enrichment of Para‐ or Orthohydrogen

Jonischkeit

Woelk

2004

Adv Synth Catal

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Dedicated to Professor Dr. Joachim Bargon (University of Bonn) on the occasion of his 65 th birthday and in recognition of his numerous contributions to chemically induced hyperpolarized NMR.Abstract: During the last 40 years, Prof. Dr. Joachim Bargon, to whom several articles in this issue are dedicated, has contributed more than 90 scientific publications to the understanding of NMR hyperpolarization phenomena such as chemically induced dynamic nuclear polarization (CIDNP) or parahydrogen induced polarization (PHIP). Both techniques are extremely useful for elucidating the mechanisms and kinetics of chemical reactions involving radicals or catalytic hydrogenations, respectively. To honor Joachim Bargon×s scientific achievements, we dedicate to him an additional, newly discovered and somewhat unexpected twist to the PHIP methodology. Accordingly, NMR spectra exhibit the unique, enhanced absorption and emission patterns of PHIP not only if the hydrogen for the catalytic reactions is enriched in one of its nuclear spin states (parahydrogen or orthohydrogen) but also if it is at its thermodynamic equilibrium. Thermally equilibrated gaseous hydrogen is obtained from commercially available hydrogen gas bombs or from electrolytic hydrogen generators. The new finding is explained with the quantum mechanical properties of the small, highly symmetric hydrogen molecule.

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Symmetrization Postulate and Nuclear Magnetic Resonance of Reacting Systems

Cited by 84 publications

References 25 publications

Nuclear spin isomers of guest molecules in H ₂ @C ₆₀ , H ₂ O@C ₆₀ and other endofullerenes

Nuclear spin isomers of guest molecules in H ₂ @C ₆₀ , H ₂ O@C ₆₀ and other endofullerenes

Preparing High Purity Initial States for Nuclear Magnetic Resonance Quantum Computing

Hydrogen Induced Polarization–Nuclear‐Spin Hyperpolarization in Catalytic Hydrogenations without the Enrichment of Para‐ or Orthohydrogen

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Symmetrization Postulate and Nuclear Magnetic Resonance of Reacting Systems

Cited by 84 publications

References 25 publications

Nuclear spin isomers of guest molecules in H 2 @C 60 , H 2 O@C 60 and other endofullerenes

Nuclear spin isomers of guest molecules in H 2 @C 60 , H 2 O@C 60 and other endofullerenes

Preparing High Purity Initial States for Nuclear Magnetic Resonance Quantum Computing

Hydrogen Induced Polarization–Nuclear‐Spin Hyperpolarization in Catalytic Hydrogenations without the Enrichment of Para‐ or Orthohydrogen

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Nuclear spin isomers of guest molecules in H ₂ @C ₆₀ , H ₂ O@C ₆₀ and other endofullerenes

Nuclear spin isomers of guest molecules in H ₂ @C ₆₀ , H ₂ O@C ₆₀ and other endofullerenes