CPMG pulse sequence

The CPMG pulse sequence is composed of the initial 90° radiofrequency (rf) excitation pulse followed by a series of 180° rf pulses spaced to allow a train of... 

Figure 4.1.1 CPMG pulse sequence designed for three-dimensional imaging. TE is echo time, and Gi, G2 and G3 represent the gradient magnetic fields along the directions of zlt z2 and z3, respectively.

CPMG pulse sequence Carr-Purcell-Meiboom-Gill pulse sequence. A pulse sequence used for removing broad signals from a spectrum by multiple defocusing and refocusing pulses. 

T2 measurements usually employ either Carr-Purcell-Meiboom-Gill (CPMG) [7, 8] spin-echo pulse sequences or experiments that measure spin relaxation (Tlp) in the rotating frame. The time delay between successive 180° pulses in the CPMG pulse sequence is typically set to 1 ms or shorter to minimize the effects of evolution under the heteronuc-lear scalar coupling between 1H and 15N spins [3]. 

Fig. 4. The CPMG pulse sequence. An echo is formed halfway between two consecutive K pulses. The echo amplitude (or the Fourier transform of the half-echo) provides an evaluation of T2 less affected by translational diffusion than in the simple Hahn sequence. The phase change of k pulses with respect to the initial Jt/2 pulse cancels the effect of (re) pulse imperfections.

The CPMG pulse sequence is shown in Fig. 1. The initial 90° radio-frequency (RF) excitation pulse is followed by series of 180° RF pulses spaced to allow a train of echoes to be observed between the pulses. The echo amplitudes are attenuated due to relaxation effects, which are described in Section 2.2. Both the first 90° and subsequent 180° pulses are non-selective broadband pulses. 

The T2 of the mobile phase is determined by a Carr-Purcell-Meiboom-Gill (CPMG) pulse sequence in that work. Based on an easily accessible NMR parameter, i.e., T2, the above empirical correlation, which is claimed by the... 

When NMR was performed the media hydrated with 1 1 H20 D20 were packed in 10 mm NMR tubes to reach a sample height of 8 to 10 mm. A 90° pulse WALTZ sequence was used with acquisition parameters 7.45 to 780 /AS pulse width, 1500 to 20,000 Hz pulse width, 0.012 to 0.166 sec acquisition time and recycle delay > 5Ti. Spin-spin relaxation time (T2) was determined with a Carr-Purcell-Meiboom-Gill (CPMG) pulse sequence with interpulsed spacing (t) ranging from 5 to 500 ms. At least eight different T values were used for each T2 determination. 

Ross A, Czisch M, King GC (1997) Systematic errors associated with the CPMG pulse sequence and their effect on motional analysis of biomolecules. J Magn Reson 124 355-365... 

Cortical astrocytes, cerebellar neurons and 0-2A progenitor cells have been investigated with MASS H NMR. All cells contained creatine and significant amounts of lipid resonances even when a T2-edited CPMG pulse sequence was used to selectively attenuated resonances from macromolecules. Principle component analysis readily differentiated the spectra, however the lipid content of the cells contributed most to the separation of cell types. The nature of the NMR-visible mobile lipid signal that is observed under certain conditions in... 

Fig. 11. Onset of nonexponential decay in liquid HP xenon due to dipolar fields. Open circles show envelope of the transverse magnetization signal obtained with CPMG pulse sequence for r = 100ms and an applied longitudinal field gradient di/Ez/dz = 1.4mGcm Solid line is a model of the initial magnetization gradient growth with no free parameters. (Courtesy of Michael Romalis. Reprinted from Ref. 224 with permission. Copyright 2001, The American Physical Society.)...

Studies on dynamic processes by CPMG, based on transverse relaxation rates, are limited to relatively small (<20 kDa) proteins. TROSY [85] (transverse relaxation optimized spectroscopy) CPMG, however, extends the size limitation (up to a 54 kDa) imposed on relaxation measurements due to the fast decay of transverse magnetization in larger macromole-cules [86]. Further, CT TROSY-based CPMG pulse sequences were utilized for measuring double (DQ), zero (ZQ), and single... 

Multinuclear solid-state NMR experiments have been performed on cis-platin and four related square-planar compounds by Lucier et WURST-CPMG pulse sequence was utilized in NMR experiments to acquire i95pt, 35 1 uitra-wideline NMR spectra of high quality. From these... 

Fig. 39. Quality control of a conveyor-belt section with steel cords, (a) Position of measurement points, (b) T2 values for upper and lower sides determined with the CPMG pulse sequence (N) upper side and ( ) lower side. Reproduced from Ref. 193, with permission from Rapra Technology.

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