Asymmetric Adiabatic Pulses for NH Selection

Tsang Lin Hwang, Peter C.M. Van Zijl, Michael Garwood

Research output: Contribution to journalEditorial

29 Scopus citations

Abstract

Many types of NMR experiments demand the use of frequency-selective pulses to invert magnetization within discrete frequency limits. For certain experiments, only one side of the inversion band must be sharply demarcated, in which case this transition bandwidth can be narrowed when using an asymmetric adiabatic full passage. In the present study, a highly efficient asymmetric adiabatic full passage was created from a combination of two adiabatic half passages which used different modulation functions (HS1/2 and tanh/tan). Each adiabatic half passage occupied a different amount of time in the total pulse and performed one-half of the inversion. On one side, HS1/2 produced a sharp transition between inverted and noninverted states which was approximately 2.5 times narrower than the transition bandwidth afforded by a symmetric hyperbolic secant pulse of equal length. On the other side of the narrow transition band, the tanh/tan pulse achieved broadband inversion. These asymmetric pulses were applied to select NH groups immediately adjacent to the water signal in water-flip-back HSQC experiments using a double spin echo for the reverse INEPT step.

Original languageEnglish (US)
Pages (from-to)173-177
Number of pages5
JournalJournal of Magnetic Resonance
Volume138
Issue number1
DOIs
StatePublished - May 1999

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Keywords

  • Adiabatic full passage
  • Asymmetric pulses
  • Selective spin inversion

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