Session PG. There are 26 abstracts in this session.

Session: Hyperpolarization, poster number: 217
Electron Decoupling with Dynamic Nuclear Polarization and Magic Angle Spinning Using a Frequency Tunable Gyrotron
Edward Saliba; Erika Sesti; Nicholas Alaniva; Eric Choi; Brice Albert; Faith Scott; Alexander Barnes
Washington University in St. Louis, St. Louis, MO
Presented is experimental data showing the narrowing of the [13C, 15N]-urea peak under microwave irradiation swept about the electron resonant frequency using a frequency tunable gyrotron. Electron decoupling has been demonstrated using both direct polarization of the carbons and with cross polarization. In addition to a narrowing of the peaks, an increase in the area of the peak is also observed. When electron decoupling is performed near the boiling point of liquid helium, a shift in the peak is additionally observed.

Session: Hyperpolarization, poster number: 218
Carbon-carbon J-coupling measurements at natural abundance enabled by dDNP 
Martins Otikovs1; Gregory L. Olsen1; Eriks Kupce2; Lucio Frydman1
1Weizmann Institute of Science, Rehovot, Israel; 2Bruker UK Ltd, Coventry, UK
1D version of INADEQUATE or of its analogues that enable determination of carbon-carbon J couplings, in principle, yield the same information as their 2D counterparts, if no ambiguities remain, i.e., if JCC couplings between potentially adjacent carbon pairs are sufficiently different to enable univocal pairing. We demonstrate here the feasibility using 13C-based dissolution DNP to extract JCC couplings in one scan at natural abundance with a sub-Hertz precision. This is shown for a range of compounds, including natural products as α-pinene, menthol and limonene.

Session: Hyperpolarization, poster number: 219
Over 1000-Times More Sensitive MAS NMR –DNP at 16.4 T and 30 K–
Yoh Matsuki1; Yuki Endo2; Shinji Nakamura2; Shigeo Fukui3; Toshitaka Idehara4; Jagadishwar Sirigiri5; Takahiro Nemoto2; Hiroto Suematsu2; Toshimichi Fujiwara1
1Osaka University, Suita, Japan; 2JEOL RESONANCE Inc., Tokyo, Japan; 3CryoVac Corp., Osaka, Japan; 4University of Fukui, Fukui, Japan; 5Bridge12 Technologies Inc., Framingham, MA
Ultra-low temperature (ULT) MAS DNP is a promising approach to regain the efficiency of the cross effect-based DNP lost at high field conditions. The closed-cycle helium MAS DNP probe system we have reported in 2015 was a major technical breakthrough for a routine application of ULT DNP, enabling to sustain stable MAS (4 kHz) at 40 K virtually indefinitely without consuming any helium. Here we report a significant extension of the system that enables the MAS rate of 8 kHz at 40 K. The effective sensitivity gain taking account of the quenching effect exceeded 1000 with AMUPol at 30 K. Two intriguing DNP data will be discussed that are observable only at this high nuclear polarization or at low temperature.

Session: Hyperpolarization, poster number: 220
Microwave field characterization in heterogeneous MAS DNP samples
Armin Purea1; Benjamin Ell2; Christian Reiter1; Fabien Aussenac3; Frank Engelke1
1Bruker BioSpin, Rheinstetten, Germany; 2Karlsruhe Institute of Technology, Karlsruhe, Germany; 3Bruker France, Wissembourg, France
In MAS DNP, the addition of dielectric particles to samples leads to substantially increased NMR signals, as shown by Kubicki et al.
We have further investigated this effect by analyzing its dependence on particle size, beam polarization and variability of particle distributions. Results were obtained at 263 GHz from EM simulations and DNP experiments.
Variation of size showed a maximum increase for particles of a few hundred microns. It was also found that multiple simulated particle distributions of nominally same filling factor shift the polarization dependence by different amounts, which was confirmed experimentally. Time-domain analysis revealed a longer decay time of the B1 field in samples with particles, indicating that the particle distribution forms a resonating structure.

Session: Hyperpolarization, poster number: 221
DNP-Enhanced solid-state NMR at Cryogenic Temperatures: a Tool to Snapshot Conformational Ensembles of α-Synuclein in Different States
Boran Uluca1, 2; Thibault Viennet1, 2; Dušan Petrović1; Hamed Shaykhalishahi1, 2; Franziska Weirich1, 2; Aysenur Gönülalan1; Birgit Strodel1, 3; Manuel Etzkorn1; Wolfgang Hoyer1; Henrike Heise1
1Research Center, Juelich, Juelich, Germany; 2Institute of Physical Biology, Heinrich-Heine-Univ, Duesseldorf, Germany; 3Institute of Theoretical and Computational Chemist, Duesseldorf, Germany
Low-temperature NMR spectra usually suffer from severe line broadenings due to freezing out different conformations. While this is usually accounted for as an unwanted side-effect of DNP-NMR, these inhomogeneously broadened lines also contain valuable information about conformational ensembles of (disordered) proteins. α-synuclein is chosen as a model protein for the study of conformational ensembles of intrinsically unfolded proteins, and its enormous structural variability is investigated in frozen solution. We exploited the inhomogeneously broadened line shapes in selectively labeled α-synuclein under different conditions: in the fully disordered form, in the fibrillated form, and in contact with lipid bilayers in the form of nanodiscs. Our approach provides quantitative information on the propensity to sample transient secondary structures in different functional states.

Session: Hyperpolarization, poster number: 222

Peptide-Based Biradicals for Dynamic Nuclear Polarization Solid-State NMR

Daniel Conroy1; John Herbert1; Melanie Rosay2; Christopher P. Jaroniec1
1The Ohio State University, Columbus, OH; 2Bruker BioSpin, Bedford, MA

We describe the modular generation of nitroxide-based biradical polarizing agents for dynamic nuclear polarization solid-state NMR, via solid-phase peptide synthesis. Four representative peptides, each having two nitroxide-containing unnatural amino acids, were used as exogenous polarizing agents to enhance solid-state NMR spectra of 13C,15N-proline at 14.1 T and 100 K. At their optimal concentrations, absolute NMR signal enhancements-per-unit time range from 5 to 10 s1/2. These results compare favorably with TOTAPOL and AMUPol, with enhancements of 3 and 18 s1/2, respectively. Biradical peptides are a promising tool for DNP solid-state NMR because they display an array of physiochemical properties and may be tailored toward different applications, including the ability to target specific sites in biomolecules by covalent attachment or non-covalent binding.

Session: Hyperpolarization, poster number: 223
Electron Decoupling with Magic Angle Spinning Below 6 Kelvin and DNP within Human Cells Using Fluorescent Polarizing Agents 
Erika Sesti; Brice Albert; Edward Saliba; Faith Scott; Chukun Gao; Nicholas Alaniva; Natalie Golota; Pinhui Chen; Patrick Judge; Edward Fisher; Alexander Barnes
Washington University in St. Louis, St. Louis, MO
We present the first DNP results employing a tri-modal polarizing agent including; a biradical for efficient DNP transfer, a targeting peptide for internalization within human cells, and a fluorophore to enable confocal microscopy and sub-cellular localization. We therefore introduce a magnetic resonance strategy that can provide atomic level structural details of biomolecules and also sub-cellular localization. We describe the first MAS DNP experiments performed <6 K on model systems and intact human cells. Furthermore, we show that microwave driven electron decoupling effectively attenuates detrimental interactions between electron and nuclear spins to increase the resolution and signal intensity in two-dimensional NMR spectra of biomolecules. Recently developed frequency agile gyrotrons are employed for electron decoupling yielding time domain manipulation of hyperfine interactions.

Session: Hyperpolarization, poster number: 224
Toward Clinical-Scale Production and MRI of Hyperpolarized Propane Gas
Oleg Salnikov2; Kirill Kovtunov2; Igor Koptyug2; Panayiotis (Peter) Nikolaou1; Eduard Y Chekmenev1
1Vanderbilt University, Nashville, TN; 2ITC, SB RAS, Novosibirsk, Russian Federation

Heterogeneous Parahydrogen Induced Polarization (PHIP) of propane has been demonstrated about a decade ago. It has been demonstrated that the lifetime of hyperpolarized propane gas can be enhanced by a factor of >3 via the use of long-lived spin states at low magnetic fields—allowing in principle for its biomedical use as an inhalable contrast agent. Here, we present our recent work on preparation of hyperpolarized propane on a clinical scale (~0.5 L of HP propane in 2.0 seconds) with nuclear spin polarization approaching 1%, which we confirm through MRI. Furthermore, we explore a possibility of preparation of HP propane gas from anesthetic cyclopropane, which may be more biologically compatible and more hyperpolarized compared to propylene substrate for PHIP hydrogenation.

Session: Hyperpolarization, poster number: 225
In-situ rotational Raman spectroscopy mapping internal gas temperatures and atomic absorption spectroscopy measuring Rubidium density, during stopped-flow 129Xe SEOP
James Harkin1; Robert Irwin1; Jonathan Birchall1; Boyd M. Goodson2; Michael J. Barlow1
1University Of Nottingham, Nottingham, United Kingdom; 2Southern Illinois University, Carbondale, IL
Efforts to further improve the quantity and rate at which near unity polarised 129Xe gas can be produced in a clinical setting has led to investigations into better understanding the underlying SEOP dynamics. With this in mind, the internal gas temperature and 129Xe polarisation were measured during SEOP at various points in the cell using Raman spectroscopy and low field NMR respectively. In addition, atomic absorption spectroscopy was used to measure how the Rb vapour density varies during SEOP. It was observed that gas mixes with a higher mole fraction of 129Xe to N2 resulted in an increased temperature variation across the cell throughout the run; with internal gas temperatures rising to 100C-200C above the oven temperature.

Session: Hyperpolarization, poster number: 226
AsymPol: a family of simple asymmetric bis-nitroxides for efficient dynamic nuclear polarization
Frederic Mentink-Vigier1, 2; Ildefonso Marin-Montesinos2; Anil P. Jagtap3; Thomas Halbritter3; Johan van Tol4; Sabine Hediger2; Daniel F Lee2; Snorri Th. Sigurdsson3; Gael De Paepe2
1NHMFL, CIMAR, Tallahassee, FL; 2INAC/MEM CEA Grenoble Alpes, Grenoble, France; 3Department of Chemistry, University of Iceland, Reykjavik, Iceland; 4NHMFL, EMR, Tallahassee, FL
A new family of polarizing agents for Dynamic Nuclear Polarization is introduced. Guided by advanced MAS-DNP simulations and practical considerations the AsymPol family is built on asymmetric bis-nitroxides, in which a piperidine-based radical and a pyrrolinoxyl or a proxyl radical are tethered. The relatively short linker produces a sizable intramolecular electron dipolar coupling and J exchange interaction for faster polarization times, while providing favorable relative nitroxide orientations for the Cross-Effect mechanism. The result of this approach is illustrated through an in-depth study of two members of the family, AsymPol and AsymPolPOK, both of which provide a very high sensitivity gain.

Session: Hyperpolarization, poster number: 227
Optically Detected ESR of 85Rb & 133Cs during Clinical-Scale Stopped-Flow Spin-Exchange Optical Pumping of Xe
Bryce Kidd1; Justin M. Porter1; Dustin Basler1; Robert K. Irwin2; Tania LaGambina2; Eduard Y. Chekmenev3; Michael J. Barlow2; Boyd M. Goodson1
1Southern Illinois University, Carbondale, IL; 2University of Nottingham, Nottingham, UK; 3Vanderbilt University, Nashville, TN
Optically detected electron spin resonance (ODESR) can directly probe the alkali metal spin polarization during spin-exchange optical pumping (SEOP); however, it can be challenging at high Xe densities and resonant laser fluxes. We have constructed an ODESR setup for measuring the alkali metal electron spin polarization under such conditions (i.e. clinical-scale stopped-flow SEOP). At lower Xe densities, the Rb lines could be partially resolved, allowing PRb to be calculated for different conditions. The approach has been extended from 85Rb to (more challenging) 133Cs, enabling comparison of ESR linewidths for Rb and Cs as functions of experimental variables. Such ODESR should allow comparison with (and validation of) bulk PRb estimates made using an indirect Beer’s law / magnetic-field-cycling approach.

Session: Hyperpolarization, poster number: 228
Parahydrogen Induced Polarization of Water and other Neat Liquids by Heterogeneous Catalysis
Evan Zhao1; Raghu Maligal-Ganesh2; Yong Du1; Tommy Zhao1; James Collins3; Wenyu Huang2, 4; Clifford R Bowers1
1Department of Chemistry, University of Florida, Gainesville, Fl; 2Department of Chemistry, Iowa State University, Ames, IA; 3McKnight Brain Institute, University of Florida, Gainesville, FL; 4Ames Laboratory, U.S. Department of Energy, Ames, IA
Lehmkuhl et al. recently reported that hyperpolarized water can be produced by parahydrogen induced polarization (PHIP) using a dissolved iridium complex containing an L-histidine additive. PHIP of water by heterogeneous catalysis, which offers the possibility for quick and complete separation of the catalyst from a hyperpolarized neat liquid, has not been previously reported. We present the discovery of a catalyst for the alignment of the proton magnetic moments in water molecules (as well as methanol and ethanol molecules) from parahydrogen. After simply bubbling para-enriched H2 gas through a suspension of the insoluble nanoparticles, the protons of the liquid yield intense stimulated emission NMR signals. Details about the catalyst, experimental conditions, and a hypothesis for the molecular mechanism will be presented.

Session: Hyperpolarization, poster number: 229
Magic-Angle Spinning NMR Instrumentation and Experiments Below 6 K
Erika Sesti; Nicholas Alaniva; Peter Rand; Eric Choi; Brice Albert; Edward Saliba; Faith Scott; Alexander Barnes
Washington University in St. Louis, St. Louis, MO
Magic-angle spinning (MAS) NMR experiments performed below 6 K result in an increase in signal intensity due to the enhanced Boltzmann polarization. Combining this scheme with dynamic nuclear polarization (DNP) can further increase this sensitivity. Finite element analysis, computer-aided design (CAD), and computational fluid dynamics (CFD) were employed to develop and characterize our cryogenic instrumentation. Liquid helium used as a variable temperature fluid, centered on the spinning MAS rotor, allowed for sample temperatures below 6 K. At temperatures below 6 K, we achieve MAS spinning frequencies up to 8.5 kHz. 13C CPMAS spectra show high sensitivity with only a single transient. Under MAS, longitudinal nuclear relaxation times are remarkably shorter than what has been recorded in static systems.

Session: Hyperpolarization, poster number: 230
Evidence For Emphysematous Changes in Cystic Fibrosis Lung Disease Using Diffusion-Weighted HP 129Xe MRI
Abdullah Bdaiwi1, 2; Robert Thomen1; Laura Walkup1; Kai Ruppert1; Hui Wang3; John Clancy1; Jason Woods1; Zackary Cleveland1, 2
1Cincinnati Children’s Hospital Medical Center, Cincinnati, OH; 2University of Cincinnati, Cincinnati, OH; 3Philips Healthcare, Cincinnati, OH
Because gas diffusion within porous materials is restricted by pore dimensions, diffusion-weighted hyperpolarized 129Xe MRI has emerged as a powerful probe of pulmonary microstructure. By mapping the 129Xe apparent diffusion coefficient (ADC), it is possible to assess increases in alveolar size due to normal growth or alveolar destruction. Diseases characterized by alveolar destruction (e.g., emphysema) accelerate age-dependent ADC increases. We demonstrate age-dependent increases in 129Xe ADC are accelerated in Cystic Fibrosis (CF) patients, relative to healthy subjects and further demonstrate that ADC correlates negatively with lung function. These results suggest emphysematous tissue destruction plays a role in CF progression and argue 129Xe MRI can non-invasively quantify disease progression and therapy response in this fatal disorder.

Session: Hyperpolarization, poster number: 231

Third-Generation Automated Clinical-Scale Batch-Mode Xe-129 Hyperpolarizer

Panayiotis (Peter) Nikolaou1; Aaron Coffey1; Bryce Kidd2; Megan Murphy2; Boyd M. Goodson2; Michael J. Barlow3; Eduard Y Chekmenev1
1Vanderbilt University, Nashville, TN; 2SIUC, Carbondale, IL; 3University of Nottingham, Nottingham, United Kingdom

The advances in the field of hyperpolarized (HP) noble gas production and imaging have been largely enabled by the development of low-cost, high-power frequency-narrowed laser diode arrays (LDAs) and the improvement of Xe-129 polarizer technology in general. Here we present the development and features of the next-generation Batch-Mode Xe-129 Spin Exchange Optical Pumping Automated hyperpolarizer. The key innovations of this device include aluminum jacket for optical pumping cell thermal management, next-generation LDA and advanced process and NMR/IR sensing integration. These innovations result in faster polarization cycle time (<30 mins), high Xe-129 polarization (>50%) in Xenon-rich mixture (~50% by volume), while retaining small footprint (0.55-m width x 1.25-m length x 1.35-m height) and cryogen-free operation.

Session: Hyperpolarization, poster number: 232
Multifunctional mesoporous silica nanoparticles for hyperpolarized xenon magnetic resonance imaging
Xiaoxiao Zhang; Qianni Guo; Yaping Yuan; Weiping Jiang; Xin Zhou
Wuhan Inst. of Physics and Mathematics, CAS, Wuhan, China
129Xe magnetic resonance imaging (129Xe MRI) is useful to detection biological molecular with high sensitivity. By coating the surface with silica, FLAMEs overcome the following two major limitations: (1) the rapid chemical exchange of Xe between PFC nanoemulsions and solution; (2) impractical modifiability of the surface of nanoemulsions. By taking advantage of these properties, we demonstrated its use for targeted detection of αvβ3 integrin overpressed A549 cells.

Session: Hyperpolarization, poster number: 233
Next-generation Hyperpolarized Molecular Agents: Diazirines, Tetrazines and para-Nitrogen
Guannan Zhang; Johannes Colell; Thomas Theis; Qiu Wang; Junu Bae; Warren Warren
Duke University, Durham, NC
Recently it has been shown to be possible to directly hyperpolarize 15N2 magnetization and long-lived 15N2 singlet spin order in diazirines, using the SABRE-SHEATH method. Here, we discuss extensions to hyperpolarize 15N2-diazirine, its ability to sustain long-lived hyperpolarized spin state, and approaches using tetrazines to directly create para-15N2. Hyperpolarized z-magnetization and singlet order were created on the 3-(2-(methylsulfinyl)ethyl)-3H-diazirine-1,2-15N2 by bubbling para-H2 at adequate field. For z-magnetization and singlet order, enhancements of 2700 and 500 were observed at 8.5 T. T1 lifetimes are 33 s and 138.7 s at 8.5 T and 3 G, respectively. We will also discuss the strategy which uses tetrazines to create long-lived polarization or singlets, and present evidence for creation of para 15N2.

Session: Hyperpolarization, poster number: 234
Room-Temperature DNP Using Milliwatt Solid-State Microwave Sources And Integrated MW/RF Probeheads
Alexander A. Nevzorov; Sergey Milikisiyants; Antonin Marek; Alex I. Smirnov
North Carolina State University, Raleigh, NC
Room-temperature DNP apparatus operating at 200 GHz electron/300 MHz proton frequencies is described. The main innovation is in integrating a tunable MW/RF probehead acting simultaneously as a resonator for the electronic spin excitation and NMR excitation and detection. Another notable feature is in employing all solid-state devices for frequency-agile mm-wave operation and integration with quasioptics to minimize non-resonant losses. 13C DNP enhancement of 1,500 was obtained for synthetic diamond at the maximum power of just 200 mW. Significant DNP enhancement of ca. 90 was observed even at extremely low mm-wave powers < 100 μW. A gated regime for DNP was also demonstrated, which yields a minimal decrease in the DNP efficiency due to spin diffusion being dominant magnetization transfer mechanism.

Session: Hyperpolarization, poster number: 235
Liquid-State Polarization of 30% through Photo-Induced Non-Persistent Radicals on 13C Pyruvic Acid
Andrea Capozzi; Magnus Karlsson; Jan Raagaard Petersen; Mathilde Lerche; Jan Henrik Ardenkjaer-Larsen
DTU, Lyngby, Denmark
The dissolution DNP range of applications is limited by the relatively fast decay of the nuclear spin polarization. The employment of UV-induced non-persistent radicals, represents an elegant solution to tackle these drawbacks proving to pave the way to hyperpolarized samples’ storage and transport far away from their production site.
Nevertheless, since its introduction, the spread of the technique has been prevented by the relatively low achievable polarization, slow buildup time and time-consuming sample preparation. In the present work, thanks to a thorough investigation of the radical generation process and distribution of the photo-induced paramagnetic centers inside the DNP samples, we provide a robust protocol to enhance the efficiency and performances of the UV-radical technique.

Session: Hyperpolarization, poster number: 236
A narrow line UV-induced non-persistent radical to generate highly polarized transportable glucose solid samples
Andrea Capozzi1; Saket Patel2; Olivier Ouari2; Magnus Karlsson1; Mathilde Lerche1; Arnaud Comment3; Jan Henrik Ardenkjaer-Larsen1
1DTU, Lyngby, Denmark; 2Aix-Marseille Université, Marseille, France; 3GE Healthcare, Chalfont Saint Giles, UK
Photo-induced radicals, generated via UV-light irradiation of frozen solutions containing a fraction of pyruvic acid, are suitable to perform DNP on several substrates. The unique property of this polarizing agents is their non-persistency: they suffer from thermal stress and they can be scavenged inside the polarizer when the DNP sample is still solid, paving the way to hyperpolarization storage and transport.
In the present work, we tackled the main drawback associated to DNP photo-induced non-persistent radicals: the low achievable polarization. This is due to the fairly large ESR linewidth of the radical when PA is the precursor. A precursor with a narrower ESR line and not involved in any metabolic process is the object of the present study.

Session: Hyperpolarization, poster number: 237
Dynamic Nuclear Polarization with Magic-Angle Spinning Below 6 K
Nicholas Alaniva; Erika Sesti; Eddie Saliba; Eric Choi; Brice Albert; Faith Scott; Chukun Gao; Patrick Judge; Natalie Golota; Alexander Barnes
WUSTL, St. Louis, MO
Experiments in magic-angle spinning Nuclear Magnetic Resonance (MAS NMR) are used to determine distances and orientations within biomolecular structures to a high degree of certainty. These results, although accurate, can take great amounts of time to obtain. Dynamic Nuclear Polarization (DNP) allows for enhancement of the signal through polarization transfer from radical electron spins to nuclear spins of interest. Conducting experiments at temperatures below 6 K further increases signal sensitivity. The combination of these two strategies removes the need for extensive signal averaging and drastically reduces the length of experiments, allowing for meaningful data to be collected at unprecedented rates.

Session: Hyperpolarization, poster number: 238
Increasing the Sensitivity and Information Content of 2D Protein NMR using Hyperpolarized Water

Or Szekely1; Greg L. Olsen1; Isabella C. Felli2; Rina Rosenzweig1; Lucio Frydman1
1Weizmann Institute of Science, Rehovot, Israel; 2CERM University of Florence, Sesto Fiorentino (Florence), Italy
Hyperpolarized NMR studies on proteins under physiological conditions become feasible if exploiting the exchanges that transfer magnetization from hyperpolarized water to the backbone amides. 2D “HyperW” 1H-15N correlations can be aided by the relatively long lifetimes T1 that under suitable conditions will characterize the water. We describe improvements in optimizing the ensuing experiment, including provisions for obtaining well-resolved post-dissolution spectra with residue-specific enhancements in the tens- and hundreds-fold. This approach is useful for studies of intrinsically disordered proteins (IDPs) or domains which are liable to fast hydrogen exchanges –but also for well-folded proteins. The biophysics underlying this residue-specific behavior is examined, the information that it carries is compared with results arising from alternative methods, and its overall potential is discussed.

Session: Hyperpolarization, poster number: 239
NEPTUN: Nuclear Exchange Polarization by Transposing Unattached Nuclei
Meike Emondts1; Daniel Schikowski1; Jürgen Klankermayer1; Philipp P. M. Schleker2, 3
1RWTH Aachen, Aachen, Germany; 2Max-Planck-Institut für Chem. Energiekonversion, Mülheim an der Ruhr, Germany; 3Forschungszentrum Jülich GmbH, Jülich, Germany
The OneH-PHIP effect describes the hydrogenation of a substrate with only one proton deriving from parahydrogen. In this study, we theoretically investigate the conditions under which the two hydrogen atoms stemming from parahydrogen can be separated while maintaining the spin order. Furthermore, based on experimental and theoretical results, we describe the parahydrogen hyperpolarization mechanism of bulk water based on polarization transfer through chemical exchange of the protons. The quantum mechanics are in agreement with the OneH-PHIP theory, but the substrate stays chemically unaltered. We therefore introduce NEPTUN (Nuclear Exchange Polarization by Transposing Unattached Nuclei) as non-hydrogenative pendant to OneH-PHIP, comparable of SABRE being the non-hydrogenative counterpart to the ALTADENA/PASADENA mechanism.

Session: Hyperpolarization, poster number: 240
9.5 mm MAS Transmission Line Probe for Time Domain DNP
Natalie Golota; Pinhui Chen; Chukun Gao; Brice Albert; Faith Scott; Erika Sesti; Edward Saliba; Nicholas Alaniva; Alexander Barnes
Washington University in St. Louis, St. Louis, MO
We present a new double resonance 1H and 13C 9.5 mm transmission line probe for MAS NMR DNP at 198 GHz/300 MHz. We present an assembly in which the rotor contains a Teflon lens for focusing of microwave power into a sample volume 1.7 μL. An additional Teflon lens is used to focus microwaves out of the waveguide and onto a quasi-optic mirror for maximum microwave power incident to the sample. HFSS calculations indicate an electron Rabi frequency of 4.7 MHz using the newly operational frequency agile gyrotron supplying 13 W at the sample. This will allow for time domain DNP experiments using the frequency swept integrated solid effect and improved electron decoupling.

Session: Hyperpolarization, poster number: 241
Understanding 1H-1H polarization transfer at solvent-particle interfaces under low-temperature DNP conditions
Nathan Prisco1; Rahul Sangodkar1; Thomas Farmer1; Arthur Pinon2; Brennan Walder2; Jayasubba Reddy Yarava2; Lyndon Emsley2; Brad Chmelka1
1UC Santa Barbara, Santa Barbara, CA; 2Ecole Polytechnique Fédérale de Lausanne, Lausanne, Switzerland
Dynamic nuclear polarization (DNP)-enhanced solid-state NMR spectroscopy produces spin-polarization gradients within a frozen organic solvent or an organic solid from which polarization is relayed, typically by 1H-1H spin diffusion, to the surface and/or within the interior of a solid sample. By application of 1H-1H spin diffusion models, experimental polarization build-up times (TB), stretched-exponential factors (β), and DNP enhancements (𝓔) may be used to estimate characteristic dimensions (e.g., surface-layer thicknesses or particle sizes) over length scales ranging from 1 nm – 10s µm. Here, we report DNP-surface-enhanced 13C{1H} and 29Si{1H} CP-MAS NMR to measure 1H polarization build-up kinetics in tricalcium silicate (Ca3SiO5) hydrated under ambient conditions without and with 13C-enriched sucrose, a well-known hydration inhibitor.

Session: Hyperpolarization, poster number: 242
Enhancing SEOP Hyperpolarization of 129Xe: Alkali Metal Choice, Laser Technology, and Cell Design
Michael Molway1; Bryce Kidd1; Liana Bales1; Megan Murphy1; Dustin Basler1; Justin Porter1; Panayiotis (Peter) Nikolaou2; Aaron Coffey2; Matthew Rosen3; Michael J. Barlow4; Eduard Chekmenev5; Boyd M. Goodson1
1SIUC, Carbondale, IL; 2Vanderbilt University, Nashville, TN; 3MGH/A.A. Martinos Center, Boston, MA; 4University of Nottingham, Nottingham, United Kingdom; 5Wayne State University, Detroit, MI
The present work concerns optimization of clinical-scale hyperpolarize 129Xe production by stopped-flow spin-exchange optical pumping (SEOP), with respect to alkali metal choice, laser technology, and SEOP cell design. Although Rb has been the preferred AM for SEOP, there are potential advantages to using Cs for 129Xe hyperpolarization. In our study, In situ low-field (~5.7mT) measurements showed that the Cs/129Xe nuclear spin polarization was ~2 fold larger than that of Rb/129Xe, even though the laser power used for Cs was ~2.5-fold lower than that for Rb. Other work includes the use of Al-walled cells, where we are currently investigating the use of an internal coating to protect the chemical integrity of the Al walls while improving the 129Xe T1 and polarization.