Adiabatic cross-polarization

TL;DR

This paper introduces an adiabatic cross-polarization scheme that efficiently enhances the polarization of rare nuclei in various samples by adiabatically converting Zeeman order into dipolar order and back, outperforming traditional methods.

Contribution

It presents a novel adiabatic cross-polarization method using low-power frequency-sweeping pulses for static samples, improving polarization transfer efficiency.

Findings

Significant increase in rare nuclei polarization in solids and liquids.

Effective in static samples with low-power pulses.

Applicable to solids, liquid crystals, and molecules in solvents.

Abstract

A scheme of adiabatic cross-polarization is described. It is based on demagnetization - remagnetization, when the Zeeman order of abundant nuclei in the laboratory frame is first adiabatically converted into the dipolar order, and then, into the Zeeman order of rare nuclei. The scheme, implemented with two low-power frequency-sweeping pulses, is very efficient for static samples and can significantly increase polarization of rare nuclei, compared to the conventional Hartmann-Hahn cross-polarization. The experimental examples are presented for solids, liquid crystal, and molecules in a liquid-crystalline solvent.