Long-lived states originating from Para-Hydrogen stored for minutes in high magnetic fields

MARÍA BELÉN FRANZONI; LISANDRO BULJUBASICH; HANS W. SPIESS; KERSTIN MÜNNEMANN

Conferencia; EUROMAR 2012; 2012

The problem of low sensitivity in NMR can be overcome by hyperpolarization techniques. Yet, this approach is restricted to relatively short time scales depending on the nuclear T 1 relaxation times, in the range of seconds. This makes long-lived singlet states very useful in hyperpolarization studies, where Para Hydrogen Induced Polarization (PHIP) is particularly attractive because of the p-H 2  singlet symmetry. Most PHIP experiments, however, are performed on asymmetric molecules in order  to directly convert the initial singlet state to an NMR observable triplet state. We showed that in Cs-symmetric molecules a long-lived singlet state created by PHIP can be stored for several minutes on protons in high magnetic fields. Subsequently, it is converted into high non-thermal magnetization by controlled singlet-triplet conversion via level anti-crossing and observed.