Field-cycling method with central transition readout for pure quadrupole resonance detection in dilute systems

Dmitri Ivanov, Alfred G. Redfield

Research output: Contribution to journalArticle

11 Scopus citations

Abstract

We present a modification of a field-cycling method which uses the NMR signal of the central transition at high field to indirectly detect zero-field quadrupole transitions. The quadrupole transitions at zero-field are detected as changes in the overall intensity of the central transition signal after the field cycle, and the method is relatively immune to lineshape distortions of the central transition caused by receiver dead time, frequency response of the probe, longer pulse lengths, etc. Cross-polarization with protons is used to enhance the central-transition signal and to increase the recycling rate of the experiment. The technique is especially useful when mixtures of several species are present. In a frozen solution of phenylboronic acid, 11B quadrupole signals of the tetrahedral species at 600kHz and planar-trigonal species at 1450kHz are clearly resolved. The field-cycling approach allows high-sensitivity detection of low-frequency quadrupole transitions; the experiment is sensitive enough to study boronic-acid protease inhibitors bound to proteins and may possibly be extended to lower sensitivity nuclei. The experiments are performed using a low-temperature field-cycling apparatus, operated at 10-30K, capable of pneumatically moving the sample from the high field of a commercial 500MHz magnet to the area above the top of the magnet where the low field is controlled by a pair of Helmholz coils.

Original languageEnglish (US)
Pages (from-to)19-27
Number of pages9
JournalJournal of Magnetic Resonance
Volume166
Issue number1
DOIs
StatePublished - Jan 1 2004
Externally publishedYes

Keywords

  • Cross-polarization
  • Field-cycling
  • Line separation
  • Low-temperature probe
  • Quadrupole resonance

ASJC Scopus subject areas

  • Biophysics
  • Biochemistry
  • Nuclear and High Energy Physics
  • Condensed Matter Physics

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