| Summary: | <p>Dissolution dynamic nuclear polarization is used to prepare nuclear spin
polarizations approaching unity. At present, <span class="inline-formula"><sup>1</sup></span>H polarization
quantification in the solid state remains fastidious due to the requirement of measuring
thermal equilibrium signals. Line shape polarimetry of solid-state nuclear
magnetic resonance spectra is used to determine several useful properties
regarding the spin system under investigation. In the case of highly
polarized nuclear spins, such as those prepared under the conditions of
dissolution dynamic nuclear polarization experiments, the absolute
polarization of a particular isotopic species within the sample may be
directly inferred from the characteristics of the corresponding resonance
line shape. In situations where direct measurements of polarization are
complicated by deleterious phenomena, indirect estimates of polarization
using coupled heteronuclear spins prove informative. We present a simple
analysis of the <span class="inline-formula"><sup>13</sup></span>C spectral line shape of [2-<span class="inline-formula"><sup>13</sup></span>C]sodium acetate
based on the normalized deviation of the centre of gravity of the <span class="inline-formula"><sup>13</sup></span>C
peaks, which can be used to indirectly evaluate the proton polarization of
the methyl group moiety and very likely the entire sample in the case of
rapid and homogeneous <span class="inline-formula"><sup>1</sup></span>H–<span class="inline-formula"><sup>1</sup></span>H spin diffusion. For the case of
positive microwave irradiation, <span class="inline-formula"><sup>1</sup></span>H polarization was found to increase
with an increasing normalized centre of gravity deviation. These results
suggest that, as a dopant, [2-<span class="inline-formula"><sup>13</sup></span>C]sodium acetate could be used to
indirectly gauge <span class="inline-formula"><sup>1</sup></span>H polarizations in standard sample formulations,
which is potentially advantageous for (i) samples polarized in commercial
dissolution dynamic nuclear polarization devices that lack <span class="inline-formula"><sup>1</sup></span>H
radiofrequency hardware, (ii) measurements that are deleteriously influenced by radiation damping or complicated by the presence of large background signals and (iii) situations where the acquisition of a thermal equilibrium
spectrum is not feasible.</p>
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