61 research outputs found
Dynamic nuclear polarization and spin-diffusion in non-conducting solids
There has been much renewed interest in dynamic nuclear polarization (DNP),
particularly in the context of solid state biomolecular NMR and more recently
dissolution DNP techniques for liquids. This paper reviews the role of spin
diffusion in polarizing nuclear spins and discusses the role of the spin
diffusion barrier, before going on to discuss some recent results.Comment: submitted to Applied Magnetic Resonance. The article should appear in
a special issue that is being published in connection with the DNP Symposium
help in Nottingham in August 200
Scalable Architecture for a Room Temperature Solid-State Quantum Information Processor
The realization of a scalable quantum information processor has emerged over
the past decade as one of the central challenges at the interface of
fundamental science and engineering. Much progress has been made towards this
goal. Indeed, quantum operations have been demonstrated on several trapped ion
qubits, and other solid-state systems are approaching similar levels of
control. Extending these techniques to achieve fault-tolerant operations in
larger systems with more qubits remains an extremely challenging goal, in part,
due to the substantial technical complexity of current implementations. Here,
we propose and analyze an architecture for a scalable, solid-state quantum
information processor capable of operating at or near room temperature. The
architecture is applicable to realistic conditions, which include disorder and
relevant decoherence mechanisms, and includes a hierarchy of control at
successive length scales. Our approach is based upon recent experimental
advances involving Nitrogen-Vacancy color centers in diamond and will provide
fundamental insights into the physics of non-equilibrium many-body quantum
systems. Additionally, the proposed architecture may greatly alleviate the
stringent constraints, currently limiting the realization of scalable quantum
processors.Comment: 15 pages, 6 figure
Solid-State Dynamics in the closo-Carboranes:A (11)B MAS NMR and Molecular Dynamics Study
This work explores the dynamic behaviour of the three closo-carborane isomers (formula C2B10H12) using modern solid-state magic angle spinning (MAS) NMR techniques and relates the experimental measurements to theoretical results obtained using molecular dynamics simulations. At high temperatures and at B0 = 9.4 T, the 11B MAS linewidths are narrow (40-90 Hz) for the three isomers. The rotational correlation times (tauc) calculated by molecular dynamics are on the picosecond timescale, showing a quasi-isotropic rotation at these temperatures, typical for liquid systems. For all three isomers, the values of the 11B spin-lattice relaxation times (T1) show discontinuities as the temperature is decreased, confirming the phase changes reported in the literature. At low temperatures, the 11B MAS spectra of all three isomers exhibit much broader lines. The simulations showed that the molecular reorientation was anisotropic around different symmetry axes for each isomer, and this was supported by the values of the reduced quadrupolar parameter PQeff derived from “dynamic shift” measurements using 11B MQMAS NMR spectroscopy. The behaviour of PQeff as a function of temperature for para-carborane suggests that molecular reorientation is about the C5 symmetry axis of the molecule at low temperatures and this was supported by the molecular dynamics simulations
Intermediate-Range Order of Alkali Disilicate Glasses and Its Relation to the Devitrification Mechanism
Structural Similarity on Multiple Length Scales and Its Relation to Devitrification Mechanism: A Solid-State NMR Study of Alkali Diborate Glasses and Crystals
Mesoporous Organosilicates from Multiple Precursors: Co-Condensation or Phase Segregation/Separation?
Persistence of Two Neem Formulations on Peach Leaves and Fruit: Effect of the Distribution
Nuclear overhauser effect (NOE) enhancement of 11B NMR spectra of borane adducts in the solid state
A strong 11B {1H} nuclear Overhauser effect (NOE) enhancement can be observed in solid-state 11B NMR spectra of borane adducts, yielding fractional enhancements, fI{S} = (I − I0)/I0, of the magic angle spinning (MAS) NMR signal of up to 155%. This is an interesting and unusual observation as 11B (spin I = 3/2) is a quadrupolar nucleus and the corresponding NOE is completely absent in solution. More generally, it shows that the NOE may have a wider role to play in solid-state NMR studies of dynamics than has been envisaged hitherto
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