Recent  

We present a tutorial on the cross-polarization experiment, which has been the main method of magnetization transfer in solid-state NMR for decades. We explain the principles of its volume-selective performance in the presence of magic angle spinning and radiofrequency field inhomogeneity and the decrease of efficiency with increasing sample rotation frequency.

Detailed balance is a principle that underlies some fundamental laws in physics. Motivated to analyze asymmetry in three-site NMR relaxation-exchange maps, 2D Monte-Carlo simulations of vacancy and gas diffusion were executed. They show that detailed balance is violated for a small fraction of molecules diffusing in confinement. This fraction exchanges coherently in circles between three relaxation pools. It is understood to be a manifestation of diffusion eigenmodes or diffusive resonance.

This paper describes the design and implementation of new technology for nuclear magnetic resonance which is a technique used to understand molecular structure and dynamics of many systems. The spherical sample container and its apparatus introduced in this paper is used to perform initial proof of principle experiments at cryogenic temperatures. Further development of this technology will facilitate more flexibility in magnetic resonance experiments.

Hyperpolarization methods offer the possibility to overcome the inherent sensitivity limits of nuclear magnetic resonance (NMR) given by the thermal Boltzmann spin distribution. The radio-frequency (RF) pulses to monitor the hyperpolarization process alter it by depleting the created magnetization. Possible corrections are simulated with a rate-equation model containing a single source and relaxation rate. The accuracy is demonstrated experimentally, enabling the use of larger flip angles.

A novel cell-free protein synthesis system called eCells produces amino acids based on specific isotopes using low-cost precursors. The system selectively labels methyl groups; i.e valine and leucine with high efficiency. eCells achieve high levels of ¹³C incorporation and deuteration in protein preparations, making them suitable for NMR experiments of large protein complexes. It is easy to prepare and can be scaled up in volume, making it a promising tool for protein production and NMR studies.

Since its discovery 65 years ago, the solid-state DNP effect has been rationalized in terms of mixing of the Zeeman energy levels. Before becoming aware of this explanation, Erb, Motchane and Uebersfeld proposed a dynamical equation to make sense of their experiments. Here we provide a formal justification of their phenomenological equation. The result is a different way of thinking about the solid-state effect with novel implications about the effect in liquids.

We show that the field profile of the solid effect in liquids is rich in dynamical information, including about time scales of molecular diffusion. We develop a general theoretical framework for extracting this information through quantitative fits to the experimental data. Unusual peaks in the enhancement field profile, which resemble thermal mixing but are not related to it, are demonstrated to arise in liquids under some conditions. These additionally restrict the dynamical parameters.