25-30 August 2019
Henry Ford Building
Europe/Berlin timezone

Confining and Quantifying Hyperpolarization: 460 GHz-700 MHz DNP NMR using Closed-Cycle Helium MAS and Dual Gyrotron Setup

27 Aug 2019, 10:30
35m
Lecture Hall D (Henry Ford Building)

Lecture Hall D

Henry Ford Building

Invited talk Hyperpolarization techniques Hyperpolarization

Speaker

Dr Yoh Matsuki (Osaka University)

Description

Sensitivity of magic-angle spinning (MAS) solid-state NMR has been dramatically improved by the advent of high-field dynamic nuclear polarization (DNP) techniques through numerous discussions and breakthroughs made for improving the signal enhancement factor. Beyond the discussions on the sensitivity gain, we here propose two new methods to pursuit hitherto under-explored curiosity: a method to confine the hyperpolarization for spatially selective observation of mesoscale molecular domains, and a method that enables quantitation of absolute 1H polarization amplitude and its spatial distribution around a radical molecule (polarizing agent). The former method utilizes our unique double-gyrotron setup and its ability to switch the microwave frequency back and forth over the range of 0.7 GHz in synchrony to the RF pulses. Each microwave frequency is set to excite the positive or negative DNP effect in turn, producing a sort of “polarization wave” in space around the radical molecule. The second method is based on the use of a closed-cycle helium MAS system for ultra-low temperature DNP, enabling the total sensitivity gain exceeding a factor of 1000 at T = 30 K and B0 = 16.4 T. In such a case, the high-order spin-correlated term (2 IzSz) in the quasi-equilibrium spin density operator grows in a significant amplitude and, as we show, is observable separately from the lowest-order Zeeman term (Sz) for the polarization quantitation. The method does not require evaluation of “microwave-off” signal as well as un-doped reference sample, and is also unaffected by the quenching and depolarization effects, providing an accurate and efficient way for the polarization quantitation. Potential applications will also be discussed.

Primary authors

Dr Yoh Matsuki (Osaka University) Mr Tomoaki Sugishita (Osaka University) Prof. Toshimichi Fujiwara (Osaka University)

Presentation Materials

There are no materials yet.