Title: Design and implementation of a J -coupled spectrometer for multidimensional structure and relaxation detection at low magnetic fields

Abstract

In recent years, it has been realized that low and ultra-low field (mT-nT magnetic field range) nuclear magnetic resonance (NMR) spectroscopy can be used for molecular structural analysis. However, spectra are often hindered by lengthy acquisition times or require large sample volumes and high concentrations. Here, we report a low field (50 µT) instrument that employs a linear actuator to shuttle samples between a 1 T prepolarization field and a solenoid detector in a laboratory setting. The current experimental setup is benchmarked using water and ¹³C-methanol with a single scan detection limit of 2x10²⁰ spins (3 μL, 55 M H₂O) and detection of 2.9x10¹⁹ (200 μL, 617 mM ¹³C-methanol) spins with signal averaging. The system has a dynamic range of >3 orders of magnitude. Investigations of room-temperature relaxation dynamics of 13Cmethanol show that sample dilution can be used in lieu of sample heating to acquire spectra with linewidths comparable to high-temperature spectra. These results indicate that the T₁ and T₂ mechanisms are governed by both the proton exchange rate and the dissolved oxygen in the sample. Finally, a 2D correlation spectroscopy (COSY) experiment is reported, performed in the strong coupling regime that resolves the multiple resonances associated with the heteronuclearmore » Jcoupling. The spectrum was collected using 10 times less sample and in less than half the time from previous reports in the strong coupling limit.« less

Authors:

Kaseman, Derrick  ^[1];

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• Search DOE PAGES for ORCID "0000-0003-2076-1264"

Magnelind, Per Erik  ^[1];

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Widgeon Paisner, Scarlett  ^[1];

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Yoder, Jacob Luther  ^[1];

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Alvarez, Marc Anthony  ^[1];

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Urbaitis, Algis V.  ^[1];

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Janicke, Michael Timothy  ^[1];

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• Search DOE PAGES for ORCID "0000-0002-3139-2882"

Nath, Pulak  ^[1];

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• Search DOE PAGES for ORCID "0000-0003-1135-4130"

Espy, Michelle A.  ^[1];

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• Search DOE PAGES for ORCID "0000-0001-8427-3513"

Williams, Robert F.  ^[1]

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• Search DOE PAGES for ORCID "0000-0002-4310-6249"

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+ Show Author Affiliations

1. Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

Publication Date:

Mon May 04 00:00:00 EDT 2020

Research Org.:

Los Alamos National Laboratory (LANL), Los Alamos, NM (United States)

Sponsoring Org.:

USDOE Laboratory Directed Research and Development (LDRD) Program

OSTI Identifier:

1630861

Alternate Identifier(s):

OSTI ID: 1617094

Report Number(s):

LA-UR-19-29923
Journal ID: ISSN 0034-6748; TRN: US2200949

Grant/Contract Number:  

89233218CNA000001; 20170048DR

Resource Type:

Accepted Manuscript

Journal Name:

Review of Scientific Instruments

Additional Journal Information:

Journal Volume: 91; Journal Issue: 5; Journal ID: ISSN 0034-6748

Publisher:

American Institute of Physics (AIP)

Country of Publication:

United States

Language:

English

Subject:

47 OTHER INSTRUMENTATION