Non‐Linear Signal Detection Improvement by Radiation Damping in Single‐Pulse NMR Spectra |
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| Authors: | Dr Judith Schlagnitweit Dr Steven W Morgan Dr Martin Nausner Prof Norbert Müller Prof Hervé Desvaux |
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| Institution: | 1. Institute of Organic Chemistry, Johannes Kepler University, Altenbergerstra?e 69, 4040 Linz (Austria), Fax: : (+43)?732?2468?8747;2. CEA, IRAMIS, SIS2M, Laboratoire de Structure et Dynamique par Résonance Magnétique, UMR CEA/CNRS 3299, CEA/Saclay, 91191 Gif‐sur‐Yvette (France), Fax: (+33)?16908?2199;3. Ecole Normale Supérieure;4. CNRS, UPMC 24 rue Lhomond, F‐75005 Paris (France);5. Current address: Department of Physics, Brooklyn College, 2900 Bedford Avenue, Brooklyn, NY 11210 (USA);6. Current address Department of Chemical Physics, Weizmann Institute of Science, P.O. Box 26, Rehovot 76100 (Israel) |
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| Abstract: | When NMR lines overlap and at least one of them is affected by radiation damping, the resonance line shapes of all lines are no longer Lorentzian. We report the appearance of narrow signal distortions, which resemble hole‐burnt spectra. This new experimental phenomenon facilitates the detection of tiny signals hidden below the main resonance. Theoretical analysis based on modified Maxwell–Bloch equations shows that the presence of strong transverse magnetization creates a feedback through the coil, which influences the magnetization of all spins with overlapping resonance lines. In the time domain this leads to cross‐precession terms between magnetization densities, which ultimately cause non‐linear behavior. Numerical simulations corroborate this interpretation. |
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| Keywords: | analytical methods cross‐precession magnetic properties NMR spectroscopy radiation damping |
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