Session TOD. There are 5 abstracts in this session.

Session: INSTRUMENTATION 1, time: 10:45 - 11:10 am

Terahertz Sources for DNP NMR

Richard Temkin
MIT, Cambridge, MA

As Dynamic Nuclear Polarization (DNP) NMR research moves to higher magnetic field, the development of appropriate instrumentation for DNP becomes much more challenging. For NMR spectrometers operating between 800 MHz and 1.2 GHz, the required sources for DNP range in frequency from 527 GHz to 790 GHz. At present, the only sources capable of producing the required tens of watts of power at these frequencies are gyrotrons. In addition to the THz source development, technology challenges include the transmission lines from the source to the sample and the efficient coupling of the source power into the sample. This talk will describe efforts at our Center to develop the needed THz instrumentation for DNP NMR at these high magnetic fields.

Session: INSTRUMENTATION 1, time: 11:10 - 11:25 am

Magic Angle Spinning Spheres and Improved Microwave Coupling for Magnetic Resonance

Pin-Hui Chen; Chukun Gao; Nicholas Alaniva; Lauren Price; Edward Saliba; Thomas Osborn Popp; Sarah Overall; Alexander Däpp; Alexander Barnes
ETH Zürich, Zürich, Switzerland

Advanced magic angle spinning (MAS) dynamic nuclear polarization (DNP) NMR instrumentation, such as spherical rotors for stable and fast spinning and dielectric lenses to effectively couple the microwaves into the sample, are developed to improve NMR resolution and sensitivity in different aspects. Spherical rotors conserve space in the probe head and simplify sample exchange and microwave coupling for DNP. Cross polarization experiments on [U-13C, 15N] alanine are demonstrated with a 4 mm spherical rotor spinning at 11.4 kHz with N2(g). Spinning with He(g) enables spinning frequencies >28 kHz. Moreover, dielectric lenses for cylindrical and spherical rotors are analyzed to increase electron Rabi frequencies. The calculated γeB1/(2πP1/2) is 1.7 MHz/W1/2, comparable to Bruker’s optimized 1.3 mm MAS DNP probe.

Session: INSTRUMENTATION 1, time: 11:25 - 11:40 am

Realtime optimization of multidimensional NMR spectroscopy on embedded sensing devices

Yiqiao Tang
Schlumberger-Doll Research, Cambridge, MA

The increasingly ubiquitous use of embedded devices calls for autonomous optimizations of sensor performance with meager computing resources. Aiming at improving the measurement efficiency, we show an OED (Optimal Experimental Design) routine where NMR quantities of interest of probable samples are partitioned into distinctive classes, with the corresponding sensor signals learned by supervised learning models. The trained models, digesting the compressed live data, are subsequently executed at a miniautrized NMR spectrometer for continuous classification and optimization of measurements. We demonstrate the closed-loop method with multidimensional NMR relaxometry on a wide range of complex fluids. The realtime portion of the procedure demands minimal computing load, and is ideally suited for instruments that are widely used in remote sensing and IoT networks.

Session: INSTRUMENTATION 1, time: 11:40 - 11:55 am

Optimized Quadrature Head Coil Improves SNR at ultra-low field

Neha Koonjoo1, 2; Shen Sheng1, 3; Charlotte Sappo4; Matthew Rosen1, 2
1MGH/A.A. Martinos Center, Boston, MA; 2Department of Physics, Harvard University, Cambridge, MA; 3Chongqing University, Chongqing, China; 4Institute of Imaging Science Vanderbilt University, Nashville, TN

High performance RF coil design is challenging at ultra-low field as rules of thumb learned from high-field may not apply. Previously, we built a 2-channel quadrature head coil with orthogonal B1 fields using an air-core transformer to null the mutual coupling between the coil, however this was unsuccessful in boosting the SNR beyond that of our single-channel spiral volume coil for brain imaging at 276 kHz. Here, a new optimized quadrature coil with a capacitive decoupling element and a new outer layer coil was designed. Images acquired show an expected 2-factor or more enhancement in combined maximum SNR.

Session: INSTRUMENTATION 1, time: 11:55 - 12:20

Ferroelectric ceramic detectors for ultra-high field magnetic resonance

Marine Moussu1, 2; Stanislav Glybovski3; Julia Krug4; Andrew Webb5; Redha Abdeddaim1; Luisa Ciobanu6
1Aix Marseille University, Marseille, France; 2Multiwave Innovation, Marseille, France; 3ITMO University, Saint-Petersburg, Russia; 4Wageningen University, Wageningen , The Netherlands; 5Leiden University Medical Center, Leiden, The Netherlands; 6CEA/DRF/Joliot/Neurospin, Gif-sur-Yvette, France

In Magnetic Resonance Microscopy (MRM), losses inherent to the probe and its interactions with the sample fundamentally limit the achievable Signal-to-Noise Ratio (SNR). The reference volumetric probe for MRM is the solenoid, for which the performance is intrinsically limited by the electric field induced in the sample. Here, we show that high permittivity ceramic ring resonators can overcome this limitation. For imaging at 17.2T (730MHz), we demonstrate, experimentally and theoretically using the first transverse electric mode (TE), that the ceramic resonator provides a two-fold SNR gain when compared to the optimal solenoid. Moreover, results obtained when exploring the first hybrid mode (HEM) of the same resonator type show the potential of its use at a higher operating frequency (950MHz).