Coherence transfer echoes

Figure 7.24 (a) Coherence transfer echos formed after a dephasing period of... 

Fig. 2. Pulse sequence for selective reverse INEPT using pulsed field gradients to select the coherence transfer echo. The 180° pulse pair in the middle of the 2r delay is not normally needed for t < 50 ms, and the second proton 180° pulse and first t2 delay maybe omitted if a linear phase gradient in the resultant spectrum can be tolerated. The second field gradient pulse has an area (7c/th) times that of the first.

Figure 5 Diagram showing contours that arise from broad hyperfine lines detected hy nuclear coherence transfer echoes under conditions of (a) weak and (h) strong hyperfine coupling...

Fig. 10. Pulse sequence for selective detection of coherence of order TV by capturing coherence transfer echoes.

The phase properties of MQC transfer echoes have also been employed to selectively detect desired orders of MQ spectra. Using the basic sequence (Fig. 2), an additional (fixed) period d is inserted in the MQ pulse sequence, prior to the mixing pulse of the MQ pulse sequence (Fig. 10). MQC evolves beyond the normal tx period and coherence transfer echoes of the TV-quantum coherences maximise in the detection period at a time TVJ.35,41,42 The echoes of different coherence orders maximise at different times in the detection period and the spectra of different orders of coherence can be obtained by sampling the FID in the appropriate window in the detection period. 

Figure 5.20. The coherence transfer echo is apparent in an FID taken from an N-type COSY data set.

Three different ID ESEEM schemes using the pulse sequence in Figure 5c and die nuclear CTE have been proposed deadtime-free ESEEM by nuclear coherence transfer echoes (DEFENCE) [24], the combination peak (CP) experiment, and the... 

Ponti A, Schweiger A. 1995. Nuclear coherence-transfer echoes in pidsed EPR. J Chem Phys 102 5207-5219. 

P.H. Bolton and G. Bodenhausen, Resolution enhancement, coherence transfer echoes. J. Magn. Resonance 46, 306 (1982). 

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