DNP enhanced NMR using a high-power 94 GHz microwave source:a study of the TEMPOL radical in toluene

Kryukov, Eugeny V. and Newton, Mark E. and Pike, Kevin J. and Bolton, David R. and Kowalczyk, Radoslaw M. and Howes, Andrew P. and Smith, Mark E. and Dupree, Ray (2010) DNP enhanced NMR using a high-power 94 GHz microwave source:a study of the TEMPOL radical in toluene. Physical Chemistry Chemical Physics, 12 (22). pp. 5757-5765. ISSN 1463-9076

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Abstract

DNP enhanced 1H NMR at 143 MHz in toluene is investigated using an NMR spectrometer coupled with a modified EPR spectrometer operating at 94 GHz and TEMPOL as the polarisation agent. A 100 W microwave amplifier was incorporated into the output stage of the EPR instrument so that high microwave powers could be delivered to the probe in either CW or pulsed mode. The maximum enhancement for the ring protons increases from −16 for a 5 mM TEMPOL solution to −50 for a 20 mM solution at a microwave power of 480 mW. The temperature dependence of the enhancement, the NMR relaxation rates and the ESR spectrum of TEMPOL were also studied in an effort to obtain information on the dynamics of the system.

Item Type:
Journal Article
Journal or Publication Title:
Physical Chemistry Chemical Physics
Uncontrolled Keywords:
/dk/atira/pure/subjectarea/asjc/1600/1606
Subjects:
Departments:
ID Code:
65095
Deposited By:
Deposited On:
07 Jun 2013 09:23
Refereed?:
Yes
Published?:
Published
Last Modified:
07 Apr 2020 02:31