Geoffrey Bodenhausen

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A method for nuclear magnetic resonance (NMR) or magnetic resonance imaging (MRI) measurements, includes creation of enhanced polarization of nuclei of a first kind within a sample in a magnetic field at cryogenic temperatures and transfer of the polarized ...

We systematically studied the enhancement factor (per scan) and the sensitivity enhancement (per unit time) in C-13 and Si-29 cross-polarization magic angle spinning (CP-MAS) NMR boosted by dynamic nuclear polarization (DNP) of functionalized mesoporous si ...

A new sequence is described to measure the cross-correlation rates between the chem. shift anisotropy of the carbonyl carbon-13 nucleus and the dipole-dipole interaction between this carbonyl and the alpha-proton in proteins. The sequence is based on the sym. reconversion principle and is insensitive to exptl. errors and to violations of the secular approxn. The cross-correlation rate depends on the backbone angle y. The advantages and limitations of the sequence are discussed. [on SciFinder (R)]

By combining indirect detection of N-14 with dynamic nuclear polarization (DNP) using a gyrotron, the signal-to-noise ratio can be dramatically improved and the recovery delay between subsequent experiments can be shortened. Spectra of glassy samples of the amino acid proline doped with the stable bi-radical TOTAPOL rotating at 15.625 kHz at 110K were obtained in a 400 MHz solid-state NMR spectrometer equipped with a gyrotron for microwave irradiation at 263 GHz. DNP enhancement factors on the order of epsi

A new scheme is proposed for solid-state NMR which uses simultaneous frequency and amplitude modulation (SFAM) to restore heteronuclear dipolar interactions between two unlike spin-1/2 nuclei such as 13C and 15N under fast magic angle spinning (MAS). The carrier frequency of one of the spins is modulated cosinusoidally while its RF amplitude is modulated as a sine wave. It is shown by expts. and simulations that the scheme allows one to reintroduce the heteronuclear dipolar interactions even at very high sp

The experimental determination of slice profiles excited by applying radiofrequency pulses in the presence of a gradient generally results in magnitude profiles. The conditions necessary to obtain a phase-sensitive picture of the profile of a slice are discussed. A distinction is made between the "excitation profile" (distribution of the transverse magnetization immediately after the RF pulse) and the "slice profile" (distribution after refocusing by gradient reversal and/or imperfect gradient switching). M

New 2-dimensional NMR correlation methods are presented which allow one to obtain selected high-resoln. multiplets where all signals have pos. pure absorption peak shapes. The multiplets do not suffer from any cancellation effects, and their fine structure consists of a simple superposition of square patterns in 2-dimensional frequency domain that can be readily interpreted. The intensities of doublets, triplets, and quartets obey the same simple binomial rules as those for conventional 1-dimensional NMR sp

It is shown by theory and expt. how coherent superpositions of quantum states in 3-level systems can be manipulated by irradiating 2 connected transitions with 2 resonant fields with suitably shaped time-dependent amplitudes and phases. Three variants are discussed; (i) adiabatic coherence transfer (ACT) between 2 transitions, which may be either allowed or forbidden; (ii) nonadiabatic transfer of coherence to a nonirradiated transition by controlled violation of adiabaticity (CVA); (iii) coherence transfer

Dissolution dynamic nuclear polarization (D-DNP) experiments enabled us to study the kinetics of the enzymatic phosphorylation reaction of glucose to form glucose-6-phosphate (G6P) by hexokinase (HK), with or without the presence of an excess of G6P, which ...

The ruthenium-containing sensitizing dye N719 grafted on TiO2 nanoparticles was investigated by solidstate NMR. The carbon resonances are assigned by means of 13C cross-polarized dipolar dephasing experiments. DFT calculations of the carbon magnetic shield ...

A method for performing magnetic resonance spectroscopy on solid sample containing nuclei of interest with spin quantum number I, comprising: subjecting the sample to a static magnetic field, spinning the sample at the magic angle and broad-band excitation ...

The internuclear distance between two homonuclear dipolar-coupled dil. spins-1/2, SA and SX, can be measured by rotational resonance expts. in solid state NMR. These involve rotating the sample at the magic angle while fulfilling the condition for rotational resonance, WA-WX= nwr, where WA and WX are the isotropic shifts. Interpretation of the results is simplest if the spin system is prepd. in a state of pure difference polarization, described by an initial d. operator V(t = 0) = D = SAz-SXz, regardless of

To understand the behavior of many NMR expts., it is important to det. the spatial distribution of the B1 field. In this paper, we show how this distribution can be mapped independently of spin d., coil responsiveness, and nonlinearities of the B0 field gradients. As a byproduct we obtain a map of the (possibly nonlinear) spatial variation of the B0 field gradients used in the imaging procedure. (c) 1999 Academic Press. [on SciFinder (R)]

In a method for exciting transverse magnetization by irradiating a nuclear spin system subjected to a const. magnetic field with a frequency-modulated RF-pulse (chirp-pulse) and with a further frequency-modulated RF-pulse (further chirp-pulse) for refocusing the magnetization, the RF-pulse and the further RF-pulse overlap each other in time at least partially. Thus, the duration of the pulses can be reduced. [on SciFinder (R)]

A soln. is presented to the problem of phase dispersion in the resultant magnetization for pulses used for high-resoln. NMR work by demonstrating how a Gaussian pulse having an on-resonance flip angle of 270 Deg has much improved phase properties over the conventional 90 Deg Gaussian pulse. Since the whole pulse is soft, the coupling partners of a multiplet are not affected, and the evolution of the magnetization due to couplings will be refocused in exactly the same way as if it were due to chem. shifts. A

Measurements of spin-lattice relaxation, combined with 2-dimensional measurements of single-and double-quantum spin-echo decay rates, were used to detn. the complete set of spectral d. parameters which characterize D relaxation of CD2Cl2 partially oriented in a nematic liq. crystal (Merck Licristal Phase V). At 31.5 Deg and 9.2 MHz, terms describing cross-correlation between 2 D quadrupole coupling tensors are comparable to the autocorrelation terms. A partial interpretation of these results in terms of ani

In gas phase, collisions that affect the rotational angular momentum lead to the return of the magnetization to its equilibrium (relaxation) in Nuclear Magnetic Resonance (NMR). To the best of our knowledge, the longitudinal relaxation rates R-1 = 1/T-1 of ...

A discussion with 8 refs. is given on the assignment of NMR spectra of complex systems, such as 1H or 13C spectra of macromols., which can be greatly facilitated by exploiting the phenomenon of coherence transfer. The topol. of the spin systems, i.e. the no. of spins and their connectivities through scalar or dipolar couplings, can be probed by suitably tailored sequences of radio-frequency pulses, and mapped by 2-dimensional Fourier transform methods. The interpretation of the resulting spectra can be faci

The theory of single-transition cross-polarization in NMR is presented and verified by exptl. evidence. In comparison to conventional cross-polarization a qual. change in the mechanism is obsd. Under the influence of matched radiofrequency fields with amplitudes that are smaller than the scalar coupling const. JIS for a two-spin system with I=(1)/(2) and S=(1)/(2) in isotropic soln., two simultaneous coherence transfer processes are obsd. between single-transition coherences which have phases that are paral

Two-dimensional Fourier transform (2D FT) spectroscopy was applied to ion-cyclotron resonance (ICR) to obtain direct evidence for mass transfer due to ion-mol. collisions. The 2D FT ICR expt., which is closely analogous to 2D exchange NMR spectroscopy (NOESY), yields similar information to tandem mass spectroscopy (MS/MS), but could in principle be extended to study a manifold of mass-transfer processes simultaneously. [on SciFinder (R)]

Geoffrey Bodenhausen

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Methods for nuclear magnetic resonance (NMR) or magnetic resonance imaging (MRI) measurements using long-lived states

Analysis of sensitivity enhancement by dynamic nuclear polarization in solid-state NMR: a case study of functionalized mesoporous materials

Cross-correlation between a carbonyl C' chemical shift anisotropy and a long-range dipolar C'HA coupling in proteins using symmetrical reconversion

Solid-state nitrogen-14 nuclear magnetic resonance enhanced by dynamic nuclear polarization using a gyrotron

Recoupling of heteronuclear dipolar interactions in solid state magic-angle spinning NMR by simultaneous frequency and amplitude modulation

Methods for reconstructing phase sensitive slice profiles in magnetic resonance imaging

Selective magnetic resonance correlation spectroscopy with in-phase multiplets

Coherence transfer in three-level systems: controlled violation of adiabaticity and antiparallel double resonant irradiation

Toward Quantitative Measurements of Enzyme Kinetics by Dissolution Dynamic Nuclear Polarization

Solid-state carbon-13 NMR and computational characterization of the N719 ruthenium sensitizer adsorbed on TiO2 nanoparticles

Procédé pour spectroscopie RMN d'échantillons solides

Preparing initial conditions for rotational resonance in solid state NMR spectroscopy

Mapping the B1 Field Distribution with Nonideal Gradients in a High-Resolution NMR Spectrometer

A method for exciting transverse magnetization in magnetic resonance

Self-refocusing effect of 270 Deg Gaussian pulses: applications to selective two-dimensional exchange spectroscopy

The determination of all six spectral densities of motion for partially oriented dichloromethane-d2

Collisional cross-section of water molecules in vapour studied by means of H-1 relaxation in NMR

The characterization of networks of coupled spins by coherence transfer in nuclear magnetic resonance

Quasi-isotropic single-transition cross-polarization in nuclear magnetic resonance

Two-dimensional Fourier transform ion cyclotron resonance mass spectrometry