Rapid-Pulsing Artifact-Free Double-Quantum-Filtered Homonuclear Spectroscopy: The 2D-INADEQUATE Experiment Revisited |
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| Authors: | Maryse Bourdonneau Bernard Ancian |
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| Institution: | aUnité Mixte de Recherche Bruker, CNRS, Université Louis Pasteur, UMR 50, 34, rue de l'Industrie, F-67166, Wissembourg Cedex, France;bDepartment of Chemistry, Université Paris 7-Denis Diderot, 2, Place Jussieu, F-75251, Paris Cedex 05, France;cBruker (UMR 50), Buroparc n° 1, 3, Avenue du Général de Gaulle, F-91090, Lisses, France |
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| Abstract: | Rapid pulsing artifacts are observed in the conventional phase-cycled carbon-13 2D INADEQUATE experiment. By using the product operator formalism, it is shown that they result from the effects of imperfect 90° and 180° excitation pulses on the most abundant molecules containing only one isolated carbon-13 nucleus. The labeled longitudinal magnetization remaining at the end of one scan is recycled by the subsequent acquisition, giving rise to multiple-quantum (p= 0, ±1, ±2, …) artifacts in theF1dimension. By considering pairs of scans instead of single scans, a new phase cycle is proposed. It is based on a scheme for compensating for imperfections in the excitation cluster by a proper combination of the pulse phases in two consecutive scans. Because the artifacts are 90° out of phase compared to the desired signal, a concomitant rearrangement of the receiver phase achieves suppression of all unwanted signals. Experiments are presented on menthol dissolved in CDCl3as a test compound. Improvements in spectrum quality as well as increased sensitivity are discussed. |
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