Coherence-transfer table: A convenient method for deriving coherence-transfer pathways of an NMR pulse sequence. II. Coherence-transfer table inI+,I?, andIz system

Coherence selection as an integral element of most multipulse NMR methods also represents a bottleneck to the efficiency of multidimensional NMR methods. In particular, phase cycling often requires total scan numbers in excess of signal-tonoise demands. M. H. Levitt and coworkers have recently introduced cogwheel phase cycling in solid-state NMR, which improves on this problem. In this article we recapitulate the principles of coherence selection in multipulse and multidimensional NMR. The fundamental differences between various coherence selection strategies are discussed, and examples of implementing cogwheel phase cycling in liquid-state NMR experiments commonly used for biopolymers are given. Design guidelines are suggested for incorporating cogwheel phase cycles into other pulsed NMR techniques. For experiments with multiple coherence transfer steps, cogwheel phase cycling is more efficient in spectrometer time usage than traditional nested phase cycling, as the scan numbers can be adjusted in smaller steps. Even compared with pulsed field gradient selection methods advantages exist, especially for fast relaxing resonances.

Section: Tracing Coherence Orders With Coherence Transfer Pathwaysmentioning

confidence: 99%

Coherence pathway selection by cogwheel phase cycling in liquid‐state NMR

Zuckerstätter

Müller

2007

About the CRAZED sequence

Branca

Capuani

Maraviglia

2004

ABSTRACT:In this article we report a detailed and understandable analysis of the evolution of various coherence orders in a Correlated 2D spectroscopy Revamped by Asymmetric Z-gradient Echo Detection (CRAZED) like pulse sequence, used to select a signal from intermolecular Multi Quantum Coherences (iMQCs). Because the signal tonoise-ratio of iMQC is much lower than the signal from conventional single quantum coherence (SQC), an optimization of experimental parameters is a necessity when measurements are made with iMQC. For this purpose a phase cycle is shown that not only allows a simpler selection of a particular quantum coherence order, but also removes receiver artifacts.

Multiple‐modulation‐multiple‐echo magnetic resonance

Sigmund

Cho

Song

2007

ABSTRACT:We describe several applications of a versatile pulse sequence family employing multiple spin echoes within one acquisition to accelerate multidimensional experiments. The core sequence, called multiple modulation multiple echo, measures the maximal set of spin echoes generated from a set of RF pulses with unequal time spacings. These echoes can be modulated individually to exhibit different encoding. As a result, one scan of the sequence determines a series of data points as a function of the specific encoding mechanism. The variety of realizations of this sequence includes single shot measurements of diffusion or flow in 1D, 2D, and single-scan 2D slice-selective imaging. The essential spin dynamics of such sequences is introduced and their applications are reviewed.