Logo
ScienceStack
Table of Contents
Fetching ...
Sign In

Adiabatic Fast Passage Spin Manipulation Measurements in Solid Polarized Targets

M. F. Hossain, K. Nakano, N. G. Vismith, D. Keller

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.

Adiabatic Fast Passage Spin Manipulation Measurements in Solid Polarized Targets

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 NH, irradiated ND, 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 NH sample showing a strong dependence of AFP efficiency on the initial polarization.

Paper Structure

This paper contains 26 sections, 25 equations, 4 figures, 3 tables.

Table of Contents

  1. Introduction
  2. Experimental apparatus and target materials
  3. 5 T/1 K polarized target system
  4. Target cups and sample masses
  5. Irradiated ammonia and deuterated ammonia
  6. Butanol-based target materials
  7. AFP theory: from rotating-frame adiabaticity to solid-state limits
  8. Rotating-frame description and Landau--Zener adiabaticity
  9. Spin-temperature (Provotorov) viewpoint in solids
  10. Radiation damping, auto-oscillation, and superradiance
  11. Spin-1 (deuteron) AFP with quadrupolar splitting
  12. Vector and tensor polarimetry in non-equilibrium AFP states
  13. Definitions
  14. New analysis method
  15. Lineshape model for the deuteron spin system
  16. ...and 11 more sections

Figures (4)

  • Figure 1: Example NMR lineshape of a spin-1 target with non-cubic symmetry, showing the two overlapping absorption lines $I_{+}$ (red) and $I_{-}$ (green).
  • Figure 2: Evolution of the deuteron NMR signal in irradiated deuterated butanol during an AFP sweep: (a) initial equilibrium configuration, (b) intermediate AFP state exhibiting hole burning, and (c) fully inverted state. The lower panel in each subfigure shows the fit residuals.
  • Figure 3: AFP-induced hole burning in irradiated deuterated butanol. The dip near $R \lesssim 0$ is an unintended burn produced by continued irradiation after the sweep terminated.
  • Figure 4: Pedestal AFP manipulation in irradiated deuterated butanol, with additional hole burning on the left pedestal. The burn reduces $I_+$ in the shoulder region while enhancing $I_-$ in the right pedestal at half the depletion rate, demonstrating the rates-response mechanism.