Controlling coherence using the internal structure of hard pi pulses

Area of Science:

• Solid-state Nuclear Magnetic Resonance (NMR) spectroscopy
• Quantum control of spin coherence

Background:

• Hard pulses in NMR are often approximated as delta functions.
• Controlling coherence in the presence of significant resonance offset variations is challenging.
• Existing methods may not be robust to large spread in resonance offsets.

Purpose of the Study:

• To exploit the difference between hard pulses and their approximations for coherence control.
• To demonstrate variants of the magic echo technique effective despite large resonance offset spreads.
• To reduce the NMR linewidth of solids, specifically silicon-29.

Main Methods:

• Utilizing zeroth- and first-order average Hamiltonian theory.
• Applying modified magic echo sequences.
• Experimental validation using 13C NMR at 60°C and 29Si NMR.

Main Results:

• Demonstrated coherence control by exploiting pulse imperfections.
• Successfully implemented magic echo variants robust to large resonance offsets.
• Achieved a ~70,000-fold reduction in 29Si NMR linewidth for silicon.

Conclusions:

• The precise control of hard pulses offers a powerful method for managing spin coherence.
• The developed techniques significantly enhance spectral resolution in solid-state NMR.
• This approach holds promise for advanced magnetic resonance microscopy and imaging of solids.