The Experts below are selected from a list of 170121 Experts worldwide ranked by ideXlab platform
Alexej Jerschow - One of the best experts on this subject based on the ideXlab platform.
-
Solid-State NMR Spectroscopic Methods in Chemistry
Angewandte Chemie International Edition, 2002Co-Authors: David D. Laws, Hans-marcus L. Bitter, A. Laws, David D., Bitter, H.l., Jerschow, Alexej JerschowAbstract:Over the last decades, NMR spectroscopy has grown into an indispensable tool for chemical analysis, structure determination, and the study of dynamics in organic, inorganic, and biological systems. It is commonly used for a wide range of applications from the characterization of synthetic products to the study of molecular structures of systems such as catalysts, polymers, and proteins. Although most NMR experiments are performed on liquid-state samples, solid-state NMR is rapidly emerging as a powerful method for the study of solid samples and materials. This Review outlines some of the developments of solid-state NMR spectroscopy, including techniques such as cross-polarization, magic-angle spinning, multiple-pulse sequences, homo- and heteronuclear Decoupling and recoupling techniques, multiple-quantum spectroscopy, and dynamic angle spinning, as well as their applications to structure determination. Modern solid-state NMR spectroscopic techniques not only produce spectra with a resolution close to that of liquid-state spectra, but also capitalize on anisotropic interactions, which are often unavailable for liquid samples. With this background, the future of solid-state NMR spectroscopy in chemistry appears to be promising, indeed.
-
Solid State NMR Spectroscopy
Angewandte Chemie (International ed. in English), 2002Co-Authors: David D. Laws, Hans-marcus L. Bitter, Alexej JerschowAbstract:Over the last decades, NMR spectroscopy has grown into an indispensable tool for chemical analysis, structure determination, and the study of dynamics in organic, inorganic, and biological systems. It is commonly used for a wide range of applications from the characterization of synthetic products to the study of molecular structures of systems such as catalysts, polymers, and proteins. Although most NMR experiments are performed on liquid-state samples, solid-state NMR is rapidly emerging as a powerful method for the study of solid samples and materials. This Review outlines some of the developments of solid-state NMR spectroscopy, including techniques such as cross-polarization, magic-angle spinning, multiple-pulse sequences, homo- and heteronuclear Decoupling and recoupling techniques, multiple-quantum spectroscopy, and dynamic angle spinning, as well as their applications to structure determination. Modern solid-state NMR spectroscopic techniques not only produce spectra with a resolution close to that of liquid-state spectra, but also capitalize on anisotropic interactions, which are often unavailable for liquid samples. With this background, the future of solid-state NMR spectroscopy in chemistry appears to be promising, indeed.
David D. Laws - One of the best experts on this subject based on the ideXlab platform.
-
Solid-State NMR Spectroscopic Methods in Chemistry
Angewandte Chemie International Edition, 2002Co-Authors: David D. Laws, Hans-marcus L. Bitter, A. Laws, David D., Bitter, H.l., Jerschow, Alexej JerschowAbstract:Over the last decades, NMR spectroscopy has grown into an indispensable tool for chemical analysis, structure determination, and the study of dynamics in organic, inorganic, and biological systems. It is commonly used for a wide range of applications from the characterization of synthetic products to the study of molecular structures of systems such as catalysts, polymers, and proteins. Although most NMR experiments are performed on liquid-state samples, solid-state NMR is rapidly emerging as a powerful method for the study of solid samples and materials. This Review outlines some of the developments of solid-state NMR spectroscopy, including techniques such as cross-polarization, magic-angle spinning, multiple-pulse sequences, homo- and heteronuclear Decoupling and recoupling techniques, multiple-quantum spectroscopy, and dynamic angle spinning, as well as their applications to structure determination. Modern solid-state NMR spectroscopic techniques not only produce spectra with a resolution close to that of liquid-state spectra, but also capitalize on anisotropic interactions, which are often unavailable for liquid samples. With this background, the future of solid-state NMR spectroscopy in chemistry appears to be promising, indeed.
-
Solid State NMR Spectroscopy
Angewandte Chemie (International ed. in English), 2002Co-Authors: David D. Laws, Hans-marcus L. Bitter, Alexej JerschowAbstract:Over the last decades, NMR spectroscopy has grown into an indispensable tool for chemical analysis, structure determination, and the study of dynamics in organic, inorganic, and biological systems. It is commonly used for a wide range of applications from the characterization of synthetic products to the study of molecular structures of systems such as catalysts, polymers, and proteins. Although most NMR experiments are performed on liquid-state samples, solid-state NMR is rapidly emerging as a powerful method for the study of solid samples and materials. This Review outlines some of the developments of solid-state NMR spectroscopy, including techniques such as cross-polarization, magic-angle spinning, multiple-pulse sequences, homo- and heteronuclear Decoupling and recoupling techniques, multiple-quantum spectroscopy, and dynamic angle spinning, as well as their applications to structure determination. Modern solid-state NMR spectroscopic techniques not only produce spectra with a resolution close to that of liquid-state spectra, but also capitalize on anisotropic interactions, which are often unavailable for liquid samples. With this background, the future of solid-state NMR spectroscopy in chemistry appears to be promising, indeed.
Malcolm H. Levitt - One of the best experts on this subject based on the ideXlab platform.
-
Recoupling of heteronuclear dipolar interactions in solid-state NMR using symmetry-based pulse sequences
Chemical Physics Letters, 2001Co-Authors: Xin Zhao, Mattias Edén, Malcolm H. LevittAbstract:We apply symmetry theorems to the problem of heteronuclear dipolar recoupling in the presence of magic-angle spinning in solid-state NMR. Examples are shown in which the13C NMR signal is acquired while rotor-synchronized pulse sequences with the symmetry R1817or R1825are applied to the1H spins. This allows recoupling of heteronuclear dipolar interactions combined with homonuclear Decoupling of the irradiated1H spins. The structure of the13C NMR spectrum is sensitive to bond lengths and bond angles. A two-dimensional procedure is described for applications to multiply isotopically labelled systems. © 2001 Elsevier Science B.V.
-
Symmetry principles for the design of radiofrequency pulse sequences in the nuclear magnetic resonance of rotating solids
Chemical Physics Letters, 2000Co-Authors: Marina Carravetta, Andreas Brinkmann, Mattias Edén, Xin Zhao, Malcolm H. LevittAbstract:Some new symmetry theorems are presented which simplify the task of designing multiple-pulse radio-frequency pulse sequences in magic-angle-spinning solid-state NMR. The symmetry theorems apply to sequences denoted RNnν, which consists of N repetitions of a pulse sequence element R, alternating in phase between the values ±πν/N. Each R element ideally rotates the spins by an angle π about the rotating frame x-axis. The entire RNnν sequence is timed to span n rotational periods. Applications are presented for homonuclear double-quantum and zero-quantum recoupling, heteronuclear Decoupling and heteronuclear recoupling.
-
Pulse sequence symmetries in the nuclear magnetic resonance of spinning solids: Application to heteronuclear Decoupling
Journal of Chemical Physics, 1999Co-Authors: Mattias Edén, Malcolm H. LevittAbstract:We develop the average Hamiltonian theory of a class of symmetrical radio-frequency pulse sequences in the NMR of rotating solids. Theorems are presented which allow one to predict the elimination of many average Hamiltonian terms, without detailed calculation. These results are applied to the problem of heteronuclear Decoupling in the presence of rapid magic angle spinning. We present sequences which minimize the number of heteronuclear terms at the same time as recoupling the homonuclear interactions of the irradiated spins. The performance of the new sequences is tested on 13C labeled calcium formate. Experimental measurements of double-quantum 1H excitation indicate a relationship between good heteronuclear Decoupling of the observed spin species and efficient recoupling of the irradiated spin species. The heteronuclear Decoupling performance of the new sequences is significantly better than that obtained with an unmodulated radio-frequency field. The Decoupling performance is improved further by brea...
Yusuke Nishiyama - One of the best experts on this subject based on the ideXlab platform.
-
determination of nh proton chemical shift anisotropy with 14 n 1 h heteronuclear Decoupling using ultrafast magic angle spinning solid state nmr
Journal of Magnetic Resonance, 2015Co-Authors: Manoj Kumar Pandey, Yusuke NishiyamaAbstract:Abstract The extraction of chemical shift anisotropy (CSA) tensors of protons either directly bonded to 14 N nuclei ( I = 1) or lying in their vicinity using rotor-synchronous recoupling pulse sequence is always fraught with difficulty due to simultaneous recoupling of 14 N– 1 H heteronuclear dipolar couplings and the lack of methods to efficiently decouple these interactions. This difficulty mainly arises from the presence of large 14 N quadrupolar interactions in comparison to the rf field that can practically be achieved. In the present work it is demonstrated that the application of on-resonance 14 N– 1 H Decoupling with rf field strength ∼30 times weaker than the 14 N quadrupolar coupling during 1 H CSA recoupling under ultrafast MAS (90 kHz) results in CSA lineshapes that are free from any distortions from recoupled 14 N– 1 H interactions. With the use of extensive numerical simulations we have shown the applicability of our proposed method on a naturally abundant l -Histidine HCl·H 2 O sample.
-
composite 180 pulse based symmetry sequences to recouple proton chemical shift anisotropy tensors under ultrafast mas solid state nmr spectroscopy
Journal of Magnetic Resonance, 2015Co-Authors: Manoj Kumar Pandey, Michal Malon, Ayyalusamy Ramamoorthy, Yusuke NishiyamaAbstract:Abstract There is considerable interest in the measurement of proton ( 1 H) chemical shift anisotropy (CSA) tensors to obtain deeper insights into H-bonding interactions which find numerous applications in chemical and biological systems. However, the presence of strong 1 H/ 1 H dipolar interaction makes it difficult to determine small size 1 H CSAs from the homogeneously broadened NMR spectra. Previously reported pulse sequences for 1 H CSA recoupling are prone to the effects of radio frequency field ( B 1 ) inhomogeneity. In the present work we have carried out a systematic study using both numerical and experimental approaches to evaluate γ-encoded radio frequency (RF) pulse sequences based on R -symmetries that recouple 1 H CSA in the indirect dimension of a 2D 1 H/ 1 H anisotropic/isotropic chemical shift correlation experiment under ultrafast magic angle spinning (MAS) frequencies. The spectral resolution and sensitivity can be significantly improved in both frequency dimensions of the 2D 1 H/ 1 H correlation spectrum without Decoupling 1 H/ 1 H dipolar couplings but by using ultrafast MAS rates up to 70 kHz. We successfully demonstrate that with a reasonable RF field requirement ( 0 –90° 180 composite-180° pulses, are more robust in combating B 1 inhomogeneity effects. In addition, our results show that the new pulse sequences render remarkable 1 H CSA recoupling efficiency and undistorted CSA lineshapes. Experimental results on citric acid and malonic acid comparing the efficiencies of these newly developed pulse sequences with that of previously reported CSA recoupling pulse sequences are also reported under ultrafast MAS conditions.
Hans-marcus L. Bitter - One of the best experts on this subject based on the ideXlab platform.
-
Solid-State NMR Spectroscopic Methods in Chemistry
Angewandte Chemie International Edition, 2002Co-Authors: David D. Laws, Hans-marcus L. Bitter, A. Laws, David D., Bitter, H.l., Jerschow, Alexej JerschowAbstract:Over the last decades, NMR spectroscopy has grown into an indispensable tool for chemical analysis, structure determination, and the study of dynamics in organic, inorganic, and biological systems. It is commonly used for a wide range of applications from the characterization of synthetic products to the study of molecular structures of systems such as catalysts, polymers, and proteins. Although most NMR experiments are performed on liquid-state samples, solid-state NMR is rapidly emerging as a powerful method for the study of solid samples and materials. This Review outlines some of the developments of solid-state NMR spectroscopy, including techniques such as cross-polarization, magic-angle spinning, multiple-pulse sequences, homo- and heteronuclear Decoupling and recoupling techniques, multiple-quantum spectroscopy, and dynamic angle spinning, as well as their applications to structure determination. Modern solid-state NMR spectroscopic techniques not only produce spectra with a resolution close to that of liquid-state spectra, but also capitalize on anisotropic interactions, which are often unavailable for liquid samples. With this background, the future of solid-state NMR spectroscopy in chemistry appears to be promising, indeed.
-
Solid State NMR Spectroscopy
Angewandte Chemie (International ed. in English), 2002Co-Authors: David D. Laws, Hans-marcus L. Bitter, Alexej JerschowAbstract:Over the last decades, NMR spectroscopy has grown into an indispensable tool for chemical analysis, structure determination, and the study of dynamics in organic, inorganic, and biological systems. It is commonly used for a wide range of applications from the characterization of synthetic products to the study of molecular structures of systems such as catalysts, polymers, and proteins. Although most NMR experiments are performed on liquid-state samples, solid-state NMR is rapidly emerging as a powerful method for the study of solid samples and materials. This Review outlines some of the developments of solid-state NMR spectroscopy, including techniques such as cross-polarization, magic-angle spinning, multiple-pulse sequences, homo- and heteronuclear Decoupling and recoupling techniques, multiple-quantum spectroscopy, and dynamic angle spinning, as well as their applications to structure determination. Modern solid-state NMR spectroscopic techniques not only produce spectra with a resolution close to that of liquid-state spectra, but also capitalize on anisotropic interactions, which are often unavailable for liquid samples. With this background, the future of solid-state NMR spectroscopy in chemistry appears to be promising, indeed.
