Cascaded z-filters for efficient single-scan suppression of zero-quantum coherence

Kristin E. Cano, Michael J. Thrippleton, James Keeler, A. J. Shaka

Research output: Contribution to journalArticlepeer-review

40 Scopus citations


A simple and robust method to suppress zero-quantum coherence (ZQC) in NMR experiments, in a single scan and with very high suppression ratio, is described. It is an appreciable improvement on a previous technique by Thrippleton and Keeler [Angew. Chem. Int. Ed. 42 (2003) 3938]. The method, called a z-filter cascade, preserves longitudinal, or z-magnetization, with high efficiency. Losses depend mostly on T1 relaxation but not T 2 relaxation mechanisms. At the same time, suppression of ZQC can be essentially complete in a single scan. The time duration of the z-filter cascade scales inversely to representative chemical shift differences between the coupled spins, and is typically a few tens of milliseconds. The high efficiency of the zero-quantum suppression and excellent retention of the desired z-magnetization, in a single scan without resort to phase cycling or difference spectroscopy, makes the z-filter cascade a useful new pulse sequence building block for a whole range of NMR experiments. In cases where unwanted residual ZQC may have previously contributed to baseline "t 1-noise" in two-dimensional NMR spectra, the z-filter cascade can deliver a noteworthy improvement in spectral quality.

Original languageEnglish (US)
Pages (from-to)291-297
Number of pages7
JournalJournal of Magnetic Resonance
Issue number2
StatePublished - Apr 2004
Externally publishedYes


  • Artifact suppression
  • Broadband inversion pulse
  • Pulsed field gradient
  • z-filter
  • Zero-quantum coherence

ASJC Scopus subject areas

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

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