Dynamic nuclear polarization enhancement of protons and vanadium-51 in the presence of pH-Dependent vanadyl radicals

© 2014 John Wiley & Sons, Ltd. We report applications of dynamic nuclear polarization to enhance proton and vanadium-51 polarization of vanadyl sulfate samples dopedwith TOTAPOL undermagic angle spinning conditions. The electron paramagnetic resonance response stemming from the paramagnetic 51V species was monitored as a function of pH, which can be adjusted to improve the enhancement of the proton polarization. By means of cross-polarization from the proton bath, 51V spins could be hyperpolarized. Enhancement factors, build-up times, and longitudinal relaxation times T1(1H) and T1(51V) were investigated as a function of pH.