Behavior of Two Almost Identical Spins during the CPMG Pulse Sequence |
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| Authors: | Zdeněk To?ner Dr Antonín ?koch Dr Jozef Kowalewski Prof |
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| Institution: | 1. Department of Chemistry, Faculty of Science, Charles University in Prague, Hlavova 2030/8, 128 43 Prague 1 (Czech Republic), Fax: (+420)?221951326;2. MR Unit, Department of Diagnostic and Interventional Radiology, Institute for Clinical and Experimental Medicine, Vìdeňská 1958/9, 140 21 Prague (Czech Republic);3. Department of Physical, Inorganic and Structural Chemistry, Arrhenius Laboratory, Stockholm University, 106 91 Stockholm (Sweden) |
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| Abstract: | Multiple‐spin‐echo experiments have found wide use in nuclear magnetic resonance spectroscopy. In particular, the Carr–Purcell–Meiboom–Gill (CPMG) pulse sequence is used to determine transverse relaxation times T2. Herein it is demonstrated, both theoretically and experimentally, that for a pair of almost identical spins‐1/2 the experimental setup can have a profound effect on the observed spin dynamics. It is shown that, in the case of dipolar relaxation, the measured T2 values can roughly vary between the limits of identical and unlike spins, just depending on the repetition rate of π pulses with respect to chemical shift separation. Such an effect can, in the extreme narrowing regime, amount to a 50 % difference. |
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| Keywords: | CPMG J‐coupling NMR spectroscopy relaxation spin echoes |
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