Highly resolved double absorption 2D NMR spectra from complex severely truncated 2D phase-modulated signals by filter-diagonalization-averaging method.

Vladimir A. Mandelshtam, Nathan D. Taylor, Haitao Hu, Mari Smith and A. J. Shaka.

Department of Chemistry, University of California at Irvine, Irvine, CA 92697, USA.

Application of the filter diagonalization method (FDM) to the spectral estimation of purely phase-modulated 2D-J NMR data is described. It is shown that obtaining an entire 2D line list of spectral parameters is not a prerequisite for constructing a spectral estimate of the data. Common problems with 2D FT analysis, such as phase-twist lineshapes, spectral broadening from the time-frequency uncertainty principle, and vanishing phase-sensitive 45° projections, can be ameliorated using 2D FDM. Averaging over several different FDM calculations improves the spectral presentation. Examples are shown with complex spectra obtained using only a handful of time increments.