TOP-PASS: a processing algorithm to reduce 2D PASS acquisition time.

Area of Science:

• Solid-state Nuclear Magnetic Resonance (NMR) Spectroscopy
• Advanced Spectroscopic Techniques
• Materials Characterization

Background:

• Slow-speed Magic Angle Spinning (MAS) NMR spectra exhibit spinning sideband resonances around an isotropic frequency.
• Two-dimensional Phase Adjusted Spinning Sideband (2D PASS) experiments correlate these sidebands with a zero-frequency spectrum.
• Affine transformations are typically used to process 2D PASS data, converting it to a spectrum of isotropic frequencies versus sidebands.

Purpose of the Study:

• To investigate an alternative affine transformation for 2D PASS experiments.
• To demonstrate the potential of the Two-dimensional One Pulse (TOP) experiment's affine transform for 2D PASS.
• To improve spectral width and reduce experiment time in 2D PASS NMR.

Main Methods:

• Applied an alternative affine transformation (from TOP experiment) to 2D PASS data.
• The alternative transform involves active shears in direct and indirect dimensions, followed by passive scaling.
• The method was theoretically described and validated with (29)Si and (13)C NMR spectra.

Main Results:

• The alternative affine transform creates a 2D signal correlating pure isotropic frequencies to spinning sidebands.
• This processing enhances the spectral width in the anisotropic (spinning sideband) dimension.
• A significant reduction in minimum experiment time for 2D PASS is achievable, especially for dispersed sideband patterns.

Conclusions:

• The TOP experiment's affine transform offers an effective alternative for 2D PASS processing.
• Enhanced anisotropic spectral width leads to more efficient 2D PASS NMR experiments.
• This advancement is particularly beneficial for analyzing complex solid-state NMR spectra.