The Experts below are selected from a list of 174 Experts worldwide ranked by ideXlab platform
Geoffrey Bodenhausen - One of the best experts on this subject based on the ideXlab platform.
-
Double cross polarization for the indirect detection of nitrogen-14 nuclei in magic angle spinning NMR spectroscopy
Journal of Chemical Physics, 2017Co-Authors: Diego Carnevale, Geoffrey BodenhausenAbstract:Nitrogen-14 NMR spectra at fast magic-angle spinning rates can be acquired indirectly by means of two-dimensional techniques based on double cross polarization transfer 1H → 14N →1H. Experimental evidence is given for polycrystalline samples of glycine, l-histidine, and the dipeptide Ala-Gly. Either one-bond or long-range correlations can be favored by choosing the length of the cross polarization contact pulses. Longer contact pulses allow the detection of unprotonated nitrogen sites. In contrast to earlier methods that exploited second-order quadrupolar/dipolar cross-terms, cross polarization operates in the manner of the method of Hartmann and Hahn, even for 14N quadrupolar couplings up to 4 MHz. Simulations explain why amorphous samples tend to give rise to featureless spectra because the 14N quadrupolar interactions may vary dramatically with the lattice environment. The experiments are straightforward to set up and are shown to be effective for different nitrogen environments and robust with respect to the rf-field strengths and to the 14N carrier frequency during cross polarization. The efficiency of indirect detection of 14N nuclei by double cross polarization is shown to be similar to that of isotopically enriched 13C nuclei.
-
double cross polarization for the indirect detection of nitrogen 14 nuclei in magic angle spinning nmr spectroscopy
Journal of Chemical Physics, 2017Co-Authors: Diego Carnevale, Xiao Ji, Geoffrey BodenhausenAbstract:Nitrogen-14 NMR spectra at fast magic-angle spinning rates can be acquired indirectly by means of two-dimensional techniques based on double cross polarization transfer 1H → 14N →1H. Experimental evidence is given for polycrystalline samples of glycine, l-histidine, and the dipeptide Ala-Gly. Either one-bond or long-range correlations can be favored by choosing the length of the cross polarization contact pulses. Longer contact pulses allow the detection of unprotonated nitrogen sites. In contrast to earlier methods that exploited second-order quadrupolar/dipolar cross-terms, cross polarization operates in the manner of the method of Hartmann and Hahn, even for 14N quadrupolar couplings up to 4 MHz. Simulations explain why amorphous samples tend to give rise to featureless spectra because the 14N quadrupolar interactions may vary dramatically with the lattice environment. The experiments are straightforward to set up and are shown to be effective for different nitrogen environments and robust with respect...
-
Boosting Dissolution Dynamic Nuclear Polarization by Cross Polarization
Journal of Physical Chemistry Letters, 2013Co-Authors: Aurélien Bornet, Sami Jannin, Roberto Melzi, Angel J. Perez Linde, Patrick Hautle, Ben Brandt, Geoffrey BodenhausenAbstract:The efficiency of dissolution dynamic nuclear polarization can be boosted by Hartmann-Hahn cross polarization at temperatures near 1.2 K. This enables high throughput of hyperpolarized solutions with substantial gains in buildup times and polarization levels. During dissolution and transport, the C-13 nuclear spin polarization P(C-13) merely decreases from 45 to 40%.
-
nmr cross polarization by adiabatic passage through the hartmann hahn condition aphh
Chemical Physics Letters, 1994Co-Authors: S Hediger, Geoffrey Bodenhausen, Beat H Meier, Narayanan D Kurur, R R ErnstAbstract:Abstract It is shown that the heteronuclear cross-polarization efficiency in the rotating frame can be improved by sweeping the radio-frequency amplitude adiabatically through the Hartmann—Hahn condition. The enhancement is particularly significant for strongly coupled IS spin systems with weak dipolar coupling to extraneous spins. A good approximation to an adiabatic transfer is obtained with a tangential time dependence of the radiofrequency field amplitude whereby transient oscillations are efficiently suppressed.
-
coherence transfer in nuclear magnetic resonance by selective homonuclear hartmann hahn correlation spectroscopy
Journal of the American Chemical Society, 1991Co-Authors: Robert Konrat, Irene Burghardt, Geoffrey BodenhausenAbstract:New NMR techniques are described for transferring transverse magnetization between scalar-coupled nuclei in the rotating frame. The methods involve simultaneous spin-locking of two selected spins A and X, using cosinusoidal modulation of the radio frequency (rf) carrier. If transverse magnetization of spin A is excited selectively before spin-locking, for example with a self-refocusing 270 Deg Gaussian pulse, in-phase magnetization will be transferred from spin A to spin X, and in-phase multiplets are obtained in both one- and two-dimensional spectra. The method allows one to verify whether two particular spins are connected by a scalar coupling. Examples are shown for peptides and basic pancreatic trypsin inhibitor (BPTI). The fine structure of the multiplets yields information on couplings to further spins. In contrast to nonselective spin-lock expts., the magnetization cannot diffuse to a manifold of coupling partners. If relayed coherence transfer is to be achieved deliberately, several spins may be locked simultaneously by imposing an addnl. modulation on the rf carrier. [on SciFinder (R)]
Nathaniel J Traaseth - One of the best experts on this subject based on the ideXlab platform.
-
utilizing afterglow magnetization from cross polarization magic angle spinning solid state nmr spectroscopy to obtain simultaneous heteronuclear multidimensional spectra
Journal of Physical Chemistry B, 2012Co-Authors: James R Banigan, Nathaniel J TraasethAbstract:The time required for data acquisition and subsequent spectral assignment are limiting factors for determining biomolecular structure and dynamics using solid state NMR spectroscopy. While strong magnetic dipolar couplings give rise to relatively broad spectra lines, the couplings also mediate the coherent magnetization transfer via the Hartmann Hahn cross polarization (HH-CP) experiment. This mechanism is used in nearly all backbone assignment experiments for carrying out polarization transfer between 1 H, 15 N, and 13 C. In this Article, we describe a general spectroscopic approach to use the residual or afterglow magnetization from the 15 N to 13 C selective HH-CP experiment to collect a second multidimensional heteronuclear dataset. This approach allowed for the collection of two multidimensional (2D NCA and NCO or 3D NCACX and NCOCX) datasets at the same time. These experiments were performed using instrumentation available on all standard solid state NMR spectrometers configured for magic angle spinning and were demonstrated on uniformly [ 13 C, 15 N] and [1,3- 13 C] glycerol labeled ubiquitin. This method is compatible with several other sensitivity enhancement experiments and can be used as an isotopic filtering tool to reduce the spectral complexity and decrease the time needed for assigning spectra.
-
utilizing afterglow magnetization from cross polarization magic angle spinning solid state nmr spectroscopy to obtain simultaneous heteronuclear multidimensional spectra
The Journal of Physical Chemistry, 2012Co-Authors: James R Banigan, Nathaniel J TraasethAbstract:The time required for data acquisition and subsequent spectral assignment are limiting factors for determining biomolecular structure and dynamics using solid-state NMR spectroscopy. While strong magnetic dipolar couplings give rise to relatively broad spectra lines, the couplings also mediate the coherent magnetization transfer via the Hartmann–Hahn cross-polarization (HH–CP) experiment. This mechanism is used in nearly all backbone assignment experiments for carrying out polarization transfer between ¹H, ¹⁵N, and ¹³C. In this Article, we describe a general spectroscopic approach to use the residual or “afterglow” magnetization from the ¹⁵N to ¹³C selective HH–CP experiment to collect a second multidimensional heteronuclear data set. This approach allowed for the collection of two commonly used sequential assignment experiments (2D NCA and NCO or 3D NCACX and NCOCX) at the same time. Our “afterglow” technique was demonstrated with uniformly [¹³C,¹⁵N] and [1,3-¹³C] glycerol-labeled ubiquitin using instrumentation available on all standard solid-state NMR spectrometers configured for magic-angle-spinning. This method is compatible with several other sensitivity enhancement experiments and can be used as an isotopic filtering tool to reduce the spectral complexity and decrease the time needed for assignment.
Martin B. Plenio - One of the best experts on this subject based on the ideXlab platform.
-
resolving single molecule structures with nitrogen vacancy centers in diamond
Scientific Reports, 2015Co-Authors: Matthias Kost, Jianming Cai, Martin B. PlenioAbstract:We present theoretical proposals for two-dimensional nuclear magnetic resonance spectroscopy protocols based on Nitrogen-vacancy (NV) centers in diamond that are strongly coupled to the target nuclei. Continuous microwave and radio-frequency driving fields together with magnetic field gradients achieve Hartmann-Hahn resonances between NV spin sensor and selected nuclei for control of nuclear spins and subsequent measurement of their polarization dynamics. The strong coupling between the NV sensor and the nuclei facilitates coherence control of nuclear spins and relaxes the requirement of nuclear spin polarization to achieve strong signals and therefore reduced measurement times. Additionally, we employ a singular value thresholding matrix completion algorithm to further reduce the amount of data required to permit the identification of key features in the spectra of strongly sub-sampled data. We illustrate the potential of this combined approach by applying the protocol to a shallowly implanted NV center addressing a small amino acid, alanine, to target specific hydrogen nuclei and to identify the corresponding peaks in their spectra.
-
Resolving single molecule structures with Nitrogen-vacancy centers in diamond
Scientific Reports, 2015Co-Authors: Matthias Kost, Jianming Cai, Martin B. PlenioAbstract:We present two-dimensional nuclear magnetic resonance spectroscopy protocols based on nitrogen-vacancy (NV) centers in diamond as efficient quantum sensors of protein structure. Continuous microwave driving fields are used to achieve Hartmann-Hahn resonances between NV spin sensor and proximate nuclei for selective control of nuclear spins and measurement of their polarization. Our protocols take advantage of the strong coupling between the NV sensor and the nuclei, thus facilitating coherence control of nuclear spins and relax the requirement of nuclear spin polarization. We dramatically reduce the experimental effort by employing a singular value thresholding matrix completion algorithm from signal processing to regain the resolution of protein structure based on sub-sampled data from NV based single molecule nuclear magnetic resonance spectroscopy. As an illustration, we demonstrate the power of this approach by identifying the nitrogen-Hydrogen interaction peak in an Alanine spectrum based on merely 5% of the sample data.
-
detecting and polarizing nuclear spins with double resonance on a single electron spin
Physical Review Letters, 2013Co-Authors: Paz London, Martin B. Plenio, Jianming Cai, Jochen Scheuer, Ilai Schwarz, Alex Retzker, Masayuki Katagiri, Tokuyuki Teraji, S KoizumiAbstract:We report the detection and polarization of nuclear spins in diamond at room temperature by using a single nitrogen-vacancy (NV) center. We use Hartmann-Hahn double resonance to coherently enhance the signal from a single nuclear spin while decoupling from the noisy spin bath, which otherwise limits the detection sensitivity. As a proof of principle, we (i) observe coherent oscillations between the NV center and a weakly coupled nuclear spin and (ii) demonstrate nuclear-bath cooling, which prolongs the coherence time of the NV sensor by more than a factor of 5. Our results provide a route to nanometer scale magnetic resonance imaging and novel quantum information processing protocols.
James R Banigan - One of the best experts on this subject based on the ideXlab platform.
-
utilizing afterglow magnetization from cross polarization magic angle spinning solid state nmr spectroscopy to obtain simultaneous heteronuclear multidimensional spectra
Journal of Physical Chemistry B, 2012Co-Authors: James R Banigan, Nathaniel J TraasethAbstract:The time required for data acquisition and subsequent spectral assignment are limiting factors for determining biomolecular structure and dynamics using solid state NMR spectroscopy. While strong magnetic dipolar couplings give rise to relatively broad spectra lines, the couplings also mediate the coherent magnetization transfer via the Hartmann Hahn cross polarization (HH-CP) experiment. This mechanism is used in nearly all backbone assignment experiments for carrying out polarization transfer between 1 H, 15 N, and 13 C. In this Article, we describe a general spectroscopic approach to use the residual or afterglow magnetization from the 15 N to 13 C selective HH-CP experiment to collect a second multidimensional heteronuclear dataset. This approach allowed for the collection of two multidimensional (2D NCA and NCO or 3D NCACX and NCOCX) datasets at the same time. These experiments were performed using instrumentation available on all standard solid state NMR spectrometers configured for magic angle spinning and were demonstrated on uniformly [ 13 C, 15 N] and [1,3- 13 C] glycerol labeled ubiquitin. This method is compatible with several other sensitivity enhancement experiments and can be used as an isotopic filtering tool to reduce the spectral complexity and decrease the time needed for assigning spectra.
-
utilizing afterglow magnetization from cross polarization magic angle spinning solid state nmr spectroscopy to obtain simultaneous heteronuclear multidimensional spectra
The Journal of Physical Chemistry, 2012Co-Authors: James R Banigan, Nathaniel J TraasethAbstract:The time required for data acquisition and subsequent spectral assignment are limiting factors for determining biomolecular structure and dynamics using solid-state NMR spectroscopy. While strong magnetic dipolar couplings give rise to relatively broad spectra lines, the couplings also mediate the coherent magnetization transfer via the Hartmann–Hahn cross-polarization (HH–CP) experiment. This mechanism is used in nearly all backbone assignment experiments for carrying out polarization transfer between ¹H, ¹⁵N, and ¹³C. In this Article, we describe a general spectroscopic approach to use the residual or “afterglow” magnetization from the ¹⁵N to ¹³C selective HH–CP experiment to collect a second multidimensional heteronuclear data set. This approach allowed for the collection of two commonly used sequential assignment experiments (2D NCA and NCO or 3D NCACX and NCOCX) at the same time. Our “afterglow” technique was demonstrated with uniformly [¹³C,¹⁵N] and [1,3-¹³C] glycerol-labeled ubiquitin using instrumentation available on all standard solid-state NMR spectrometers configured for magic-angle-spinning. This method is compatible with several other sensitivity enhancement experiments and can be used as an isotopic filtering tool to reduce the spectral complexity and decrease the time needed for assignment.
Diego Carnevale - One of the best experts on this subject based on the ideXlab platform.
-
Double cross polarization for the indirect detection of nitrogen-14 nuclei in magic angle spinning NMR spectroscopy
Journal of Chemical Physics, 2017Co-Authors: Diego Carnevale, Geoffrey BodenhausenAbstract:Nitrogen-14 NMR spectra at fast magic-angle spinning rates can be acquired indirectly by means of two-dimensional techniques based on double cross polarization transfer 1H → 14N →1H. Experimental evidence is given for polycrystalline samples of glycine, l-histidine, and the dipeptide Ala-Gly. Either one-bond or long-range correlations can be favored by choosing the length of the cross polarization contact pulses. Longer contact pulses allow the detection of unprotonated nitrogen sites. In contrast to earlier methods that exploited second-order quadrupolar/dipolar cross-terms, cross polarization operates in the manner of the method of Hartmann and Hahn, even for 14N quadrupolar couplings up to 4 MHz. Simulations explain why amorphous samples tend to give rise to featureless spectra because the 14N quadrupolar interactions may vary dramatically with the lattice environment. The experiments are straightforward to set up and are shown to be effective for different nitrogen environments and robust with respect to the rf-field strengths and to the 14N carrier frequency during cross polarization. The efficiency of indirect detection of 14N nuclei by double cross polarization is shown to be similar to that of isotopically enriched 13C nuclei.
-
double cross polarization for the indirect detection of nitrogen 14 nuclei in magic angle spinning nmr spectroscopy
Journal of Chemical Physics, 2017Co-Authors: Diego Carnevale, Xiao Ji, Geoffrey BodenhausenAbstract:Nitrogen-14 NMR spectra at fast magic-angle spinning rates can be acquired indirectly by means of two-dimensional techniques based on double cross polarization transfer 1H → 14N →1H. Experimental evidence is given for polycrystalline samples of glycine, l-histidine, and the dipeptide Ala-Gly. Either one-bond or long-range correlations can be favored by choosing the length of the cross polarization contact pulses. Longer contact pulses allow the detection of unprotonated nitrogen sites. In contrast to earlier methods that exploited second-order quadrupolar/dipolar cross-terms, cross polarization operates in the manner of the method of Hartmann and Hahn, even for 14N quadrupolar couplings up to 4 MHz. Simulations explain why amorphous samples tend to give rise to featureless spectra because the 14N quadrupolar interactions may vary dramatically with the lattice environment. The experiments are straightforward to set up and are shown to be effective for different nitrogen environments and robust with respect...
