title: Dynamic nuclear polarization enhancement of protons and vanadium-51 in the presence of pH-dependent vanadyl radicals.
abstract: We report applications of dynamic nuclear polarization to enhance proton and vanadium-51 polarization of vanadyl sulfate samples doped with TOTAPOL under magic angle spinning conditions. The electron paramagnetic resonance response stemming from the paramagnetic (51)V 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, (51)V spins could be hyperpolarized. Enhancement factors, build-up times, and longitudinal relaxation times T1((1)H) and T1((51)V) were investigated as a function of pH.
authors.affiliation: Institut des Sciences et Ingénierie Chimiques (ISIC), Ecole Polytechnique Fédérale de Lausanne (EPFL), 1015 Lausanne, Switzerland.
authors.forename: Angel J
authors.initials: AJ
authors.lastname: Perez Linde
authors.forename: Diego
authors.initials: D
authors.lastname: Carnevale
authors.forename: Pascal
authors.initials: P
authors.lastname: Miéville
authors.forename: Andrzej
authors.initials: A
authors.lastname: Sienkiewicz
authors.forename: Geoffrey
authors.initials: G
authors.lastname: Bodenhausen
keywords: DNP; EPR; MAS; NMR; vanadium-51