Controlling coherence using the internal structure of hard pi pulses

TL;DR

This paper introduces a method to control quantum coherence in NMR by exploiting the internal structure of hard pi pulses, significantly improving linewidths and demonstrating potential for advanced imaging applications.

Contribution

It presents novel pulse sequence variants that utilize average Hamiltonian theory to enhance coherence control despite resonance offset spreads.

Findings

Achieved a 70,000-fold reduction in 29-Si NMR linewidth.

Demonstrated robustness of magic echo variants with large resonance spreads.

Potential applications in magnetic resonance microscopy and solid-state imaging.

Abstract

The tiny difference between hard pi pulses and their delta-function approximation can be exploited to control coherence. Variants on the magic echo that work despite a large spread in resonance offsets are demonstrated using the zeroth- and first-order average Hamiltonian terms, for 13-C NMR in C60. The 29-Si NMR linewidth of Silicon has been reduced by a factor of about 70,000 using this approach, which also has potential applications in magnetic resonance microscopy and imaging of solids.