Ultra-low temperature MAS-DNP

Daniel Lee 1 Eric Bouleau 2 Pierre Saint-Bonnet 3 Sabine Hediger 1 Gael de Paepe 1
1 RM - Magnetic Resonance
MEM - Modélisation et Exploration des Matériaux : DRF/INAC/MEM
2 L3C - Laboratoire de Calculs et Conception Cryogénique
SBT - Service des Basses Températures : DRF/INAC/SBT
3 LCF - Laboratoire de Cryogénie pour la Fusion
SBT - Service des Basses Températures : DRF/INAC/SBT
Abstract : Since the infancy of NMR spectroscopy, sensitivity and resolution have been the limiting factors of the technique. Regular essential developments on this front have led to the widely applicable, versatile, and powerful spectroscopy that we know today. However, the Holy Grail of ultimate sensitivity and resolution is not yet reached, and technical improvements are still ongoing. Hence, high-field dynamic nuclear polarization (DNP) making use of high-frequency, high-power microwave irradiation of electron spins has become very promising in combination with magic angle sample spinning (MAS) solid-state NMR experiments. This is because it leads to a transfer of the much larger polarization of these electron spins under suitable irradiation to surrounding nuclei, greatly increasing NMR sensitivity. Currently, this boom in MAS-DNP is mainly performed at minimum sample temperatures of about 100 K, using cold nitrogen gas to pneumatically spin and cool the sample. This Perspective deals with the desire to improve further the sensitivity and resolution by providing "ultra"-low temperatures for MAS-DNP, using cryogenic helium gas. Different designs on how this technological challenge has been overcome are described. It is shown that stable and fast spinning can be attained for sample temperatures down to 30 K using a large cryostat developed in our laboratory. Using this cryostat to cool a closed-loop of helium gas brings the additional advantage of sample spinning frequencies that can greatly surpass those achievable with nitrogen gas, due to the differing fluidic properties of these two gases. It is shown that using ultra-low temperatures for MAS-DNP results in substantial experimental sensitivity enhancements and according time-savings. Access to this temperature range is demonstrated to be both viable and highly pertinent. (C) 2015 Elsevier Inc. All rights reserved.
Document type :
Journal articles
Complete list of metadatas

https://hal-cea.archives-ouvertes.fr/cea-01849839
Contributor : Jérôme Planès <>
Submitted on : Thursday, July 26, 2018 - 3:15:12 PM
Last modification on : Thursday, April 4, 2019 - 5:10:42 PM

Identifiers

Collections

Citation

Daniel Lee, Eric Bouleau, Pierre Saint-Bonnet, Sabine Hediger, Gael de Paepe. Ultra-low temperature MAS-DNP. Journal of Magnetic Resonance, Elsevier, 2016, 264, pp.116-124. ⟨10.1016/j.jmr.2015.12.010⟩. ⟨cea-01849839⟩

Share

Metrics

Record views

54