Nuclear magnetic resonance , solids computation

Structural information at the molecular level can be extracted using a number of experimental techniques which include, but are not restricted to, optical rotation, infra-red and ultra-violet spectroscopy, nuclear magnetic resonance in the solid state and in solution, diffraction using electrons, neutrons or x-rays. Not all of them, however, are capable of yielding structural details to the same desirable extent. By far, experience shows that x-ray fiber diffraction (2), in conjunction with computer model building, is the most powerful tool which enables to establish the spatial arrangement of atoms in polymer molecules. 

Left and center Two gramicidin A molecules associate to span a cell membrane. Right Axial view showing ion channel. [Structure from B. Roux, "Computational Studies of the Gramicidin Channel." Acc. Chem. Res. 2002,35,366. based on solid-state nuclear magnetic resonance. Schematic at left from L. Stryer. Biochemistry,... 

The ultimate molecular level characterization of a pharmaceutical material is performed on the level of individual chemical environments of each atom in the compound, and this information is best obtained using nuclear magnetic resonance (NMR) spectroscopy. Advances in instrumentation and computer pulse sequences currently allow these studies to be carried out routinely in the solid state.2 Although any nucleus that can be studied in the solution phase also can be studied in the solid state, most work has focused on studies. H-NMR remains an extremely difficult measurement in the solid state, and the data obtained from such work can be obtained only at medium resolution. The main problem is that H-NMR has one of the smallest isotropic chemical shift ranges (12 ppm), but has peak broadening effects that can span several parts per million in magnitude. 

R79 G. Wu and J. Zhu, Nuclear Magnetic Resonance Studies of Alkali Metal Ions in Organic and Biological Solids , Prog. Nucl. Magn. Reson. Spectrosc., [online computer file], 2012, 61, 1. 

R530 A. Zheng, S.-J. Huang, S.-B. Liu and F. Deng, Acid Properties of Solid Acid Catalysts Characterized by Solid-State P Nuclear Magnetic Resonance of Adsorbed Phosphorus Probe Molecules , Phys. Chem. Chem. Phys., [online computer file], 2011,13, 14889. 

Schaefer et al. (19) studied the interphase microstructure of ternary polymer composites consisting of polypropylene, ethylene-propylene-diene-terpolymer (EPDM), and different types of inorganic fillers (e.g., kaolin clay and barium sulfate). They used extraction and dynamic mechanical methods to relate the thickness of absorbed polymer coatings on filler particles to mechanical properties. The extraction of composite samples with xylene solvent for prolonged periods of time indicated that the bound polymer around filler particles increased from 3 to 12 nm thick between kaolin to barium sulfate filler types. Solid-state Nuclear Magnetic Resonance (NMR) analyses of the bound polymer layers indicated that EPDM was the main constituent adsorbed to the filler particles. Without doubt, the existence of an interphase microstructure was shown to exist and have a rather sizable thickness. They proceeded to use this interphase model to fit a modified van der Poel equation to compute the storage modulus G (T) and loss modulus G"(T) properties. 

Carnevale, D. Nuclear Magnetic Resonance Spectroscopy and Computational Methods for the Characterization of Materials in Solution and the Solid State. Ph.D. Thesis, University of St Andrews, Scotland, 2010. 

R 510 L. Spiccia, Homopolynuclear and Heteropolynuclear Rh (III) Aqua Ions - A Review , Inorg.Chim.Acta, 2004,357,2799 R 511 H.W. Spiess, Advanced Solid-State Nuclear Magnetic Resonance for Polymer Science , J.Polym.Sci.,A, Pol.Chem., 2004,42,5031 R 512 H.W. Spiess, Supramolecular Structure and Function from Solid State NMR , Polym.Mater.Sci.Eng., [computer optical disk], 2004, 91,123... 

The above considerations deal with information in a disembodied form. If one actually wants to make a quantum computer, there are all sorts of fabrication, interaction, decoherence, and interference considerations. This is a very rich area of experimental science, and many different avenues have been attempted. Nuclear magnetic resonance, ion traps, molecular vibrational states, and solid-state implementations have all been used in attempts to produce actual quantum computers. 

Nuclear magnetic resonance (NMR) is one of the major experimental tools in structural chemistry and biochemistry. The prediction of NMR shifts from ab initio calculations has been demonstrated for isolated molecules (see NMR Chemical Shift Computation Ab Initio), but the development of a practical ab initio approach for the calculation on NMR shifts in solids has been accomplished only quite recently. Based on DFT-LDA and a pseudopotential plane wave approach, these authors have presented an approach which promises to be useful in the investigation of NMR shifts in crystalline solids as well as in amorphous materials and liquids. As a demonstration of this approach, Mauri et al. have calculated the H NMR shifts of LiH and HF in the state of isolated molecules and in a crystal. In the case of LiH the results show very little change between the free molecule (a = 26.6 ppm) and the crystal (cr = 26.3 ppm). However, a significant change is found for the crystal at high pressures (65 GPa), where the chemical shift increases to 31.2 ppm. A quite different picture is obtained for the HF molecule, where the theory predicts a shift of 28.4 ppm in remarkable agreement with the experimental value of 28.4 ppm. For the HF crystal, a shift of... 

G. P Berman, G.D. Doolen, PC. Hammel, V.Y. Tsifrinovich, Solid-state nuclear spin quantum computer based on magnetic resonance force microscopy, Phys. Rev. B 61 (2000) 14694. 

We propose a nuclear spin quantum computer based on magnetic resonance force microscopy (MRFM). It is shown that a MRFM single-electron spin measurement provides three essential requirements for quantum computation in solids (a) preparation of the ground-state, (b) one- and two-qubit quantum logic gates, and (c) a measurement of the final state. — G.P. Berman, G.D. Doolen, RC. Hammel, V.L Tsifrinovich [Rhys. Rev. B 61 (2000) 14694]... 

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