Adiabatic Fast Passage Spin Manipulation Measurements in Solid Polarized Targets

TL;DR

This paper reports advances in adiabatic fast passage (AFP) techniques for rapid spin manipulation in polarized solid targets, including efficiency measurements, a novel spectral analysis method, and polarization-dependent efficiency studies.

Contribution

It introduces new AFP efficiency data for various materials, a joint lineshape analysis method for extracting polarization components, and studies the dependence of AFP efficiency on initial polarization.

Findings

AFP efficiency varies across different target materials.

The joint lineshape analysis can extract vector and tensor polarizations from AFP spectra.

AFP efficiency in irradiated $^{15}$NH$_3$ depends strongly on initial polarization.

Abstract

Adiabatic fast passage (AFP) is an attractive technique for rapidly reversing polarization and manipulating spin populations in polarized solid targets. It enables frequent spin flips without requiring dynamic nuclear polarization (DNP) repolarization between reversals, which can take tens of minutes to several hours. We report AFP measurements for several target materials in a 5~T, 1~K DNP target system. The main advances are threefold: (i) new measurements of AFP efficiency in irradiated $^{15}$NH$_3$, irradiated $^{14}$ND$_3$, and butanol systems prepared either with TEMPO doping or by irradiation, summarized in a dedicated table; (ii) a joint manipulated-lineshape analysis, demonstrated here on irradiated deuterated butanol AFP spectra, that extracts the vector and tensor polarization components of a spin-1 system from AFP-manipulated NMR spectra, including non-Boltzmann ``half-flip'' states for which standard intensity-ratio methods fail; and (iii) an efficiency study of an irradiated $^{15}$NH$_3$ sample showing a strong dependence of AFP efficiency on the initial polarization.