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Non‐Linear Signal Detection Improvement by Radiation Damping in Single‐Pulse NMR Spectra
Author(s) -
Schlagnitweit Judith,
Morgan Steven W.,
Nausner Martin,
Müller Norbert,
Desvaux Hervé
Publication year - 2012
Publication title -
chemphyschem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.016
H-Index - 140
eISSN - 1439-7641
pISSN - 1439-4235
DOI - 10.1002/cphc.201100724
Subject(s) - magnetization , spins , radiation damping , spectral line , bloch equations , precession , physics , resonance (particle physics) , nuclear magnetic resonance , computational physics , signal (programming language) , time domain , pulse (music) , line (geometry) , larmor precession , chemistry , condensed matter physics , atomic physics , optics , magnetic field , quantum mechanics , detector , computer science , programming language , geometry , mathematics , computer vision
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.