Radical-free dynamic nuclear polarization using electronic defects in silicon

TL;DR

This paper demonstrates a radical-free dynamic nuclear polarization technique using silicon nanoparticles, enabling high nuclear-spin polarization without radicals, with potential applications in nanostructure fabrication and surface molecule studies.

Contribution

It introduces a novel radical-free polarization method utilizing silicon surface defects, avoiding contaminating radicals and expanding applications in nanostructures and surface chemistry.

Findings

Successful polarization of 1H nuclei in water and water-ethanol mixtures.

Identification of silicon surface dangling bonds as the polarization source.

Potential for creating high nuclear-spin polarized solutions without radicals.

Abstract

Direct dynamic nuclear polarization of 1H nuclei in frozen water and water-ethanol mixtures is demonstrated using silicon nanoparticles as the polarizing agent. Electron spins at dangling-bond sites near the silicon surface are identified as the source of the nuclear hyperpolarization. This novel polarization method open new avenues for the fabrication of surface engineered nanostructures to create high nuclear-spin polarized solutions without introducing contaminating radicals, and for the study of molecules adsorbed onto surfaces.