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

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.