# Effective Hamiltonian-Based DNP Sequence Optimization

## TL;DR

This paper introduces optimized DNP sequences using effective Hamiltonians, improving NMR signal enhancement through better control of spin dynamics.

## Contribution

The novelty lies in using continuous Floquet theory to optimize on-resonance and off-resonance DNP sequences.

## Key findings

- The on-resonance sequence achieved a 100 MHz electron offset bandwidth with 25 MHz microwave power.
- The off-resonance sequence covered 20 MHz at a 50 MHz center with 20 MHz microwave power.
- Continuous Floquet theory proved effective for optimizing pulsed DNP sequences.

## Abstract

Dynamic nuclear polarization (DNP) enhances the intensity
of NMR
signals by transferring polarization from electron spins to nuclei
via microwave irradiation. Pulsed DNP methods offer more control on
the spin dynamics than conventional continuous-wave approaches. Here,
we report on-resonance and off-resonance DNP sequences optimized using
effective Hamiltonians derived from continuous Floquet theory. Experiments
at 80 K and 0.35 T using a sample of 5 mM Trityl OX063 in a glycerol-d8/D2O/H2O matrix (60:30:10, v/v/v) demonstrate
that the optimized on-resonance sequence achieves 100 MHz electron
offset bandwidth, while the off-resonance sequence centered at an
electron offset of 50 MHz can cover 20 MHz, with 25 and 20 MHz of
microwave power, respectively. These results demonstrate that continuous
Floquet theory is a useful framework for the optimization of pulsed
DNP sequences.