High-field solution state DNP using cross-correlations

At the magnetic fields of common NMR instruments, electron Zeeman frequencies are too high for efficient electron-nuclear dipolar cross-relaxation to occur in solution. The rate that process fades with frequency as omega^{-2} - absence isotropic hyperfine couplings, liquid state dynamic nuclear polarisation (DNP) high-field magnets is therefore impractical. However, contact coupling and not only mechanisms can move magnetisation nuclei liquids: multiple cross-correlated (CC) relaxation processes also exist, involving various combinations interaction tensor anisotropies. rates some those have more favourable behaviour than cross-relaxation, but due difficulty their numerical particularly analytical treatment, they remain largely uncharted. In this communication, we report evaluation every rotationally driven 1e1n 2e1n spin systems, well optimisations steady-state DNP respect Hamiltonian parameters. A previously unreported cross-correlation (CCDNP) mechanism was identified system, interference effects inter-electron exchange coupling. Using simulations, found realistic parameters yield stronger at cross-relaxation.