title: Robust conversion of singlet spin order in coupled spin-1/2 pairs by adiabatically ramped RF-fields.
abstract: We propose a robust and highly efficient NMR technique to create singlet spin order from longitudinal spin magnetization in coupled spin-½ pairs and to perform backward conversion (singlet order)→magnetization. In this method we exploit adiabatic ramping of an RF-field in order to drive transitions between the singlet state and the T±triplet states of a spin pair under study. We demonstrate that the method works perfectly for both strongly and weakly coupled spin pairs, providing a conversion efficiency between the singlet spin order and magnetization, which is equal to the theoretical maximum. We anticipate that the proposed technique is useful for generating long-lived singlet order, for preserving spin hyperpolarization and for analyzing singlet spin order in nearly equivalent spin pairs in specially designed molecules and in low-field NMR studies.
authors.affiliation: International Tomography Center, Siberian Branch of the Russian Academy of Science, Institutskaya 3A, Novosibirsk 630090, Russia; Novosibirsk State University, Pirogova 2, Novosibirsk 630090, Russia.
authors.forename: Andrey N
authors.initials: AN
authors.lastname: Pravdivtsev
authors.affiliation: International Tomography Center, Siberian Branch of the Russian Academy of Science, Institutskaya 3A, Novosibirsk 630090, Russia; Novosibirsk State University, Pirogova 2, Novosibirsk 630090, Russia.
authors.forename: Alexey S
authors.initials: AS
authors.lastname: Kiryutin
authors.affiliation: International Tomography Center, Siberian Branch of the Russian Academy of Science, Institutskaya 3A, Novosibirsk 630090, Russia; Novosibirsk State University, Pirogova 2, Novosibirsk 630090, Russia.
authors.forename: Alexandra V
authors.initials: AV
authors.lastname: Yurkovskaya
authors.affiliation: International Tomography Center, Siberian Branch of the Russian Academy of Science, Institutskaya 3A, Novosibirsk 630090, Russia; Institut für Experimentalphysik, Freie Universität Berlin, Arnimallee 14, Berlin 14195, Germany.
authors.forename: Hans-Martin
authors.initials: HM
authors.lastname: Vieth
authors.affiliation: International Tomography Center, Siberian Branch of the Russian Academy of Science, Institutskaya 3A, Novosibirsk 630090, Russia; Novosibirsk State University, Pirogova 2, Novosibirsk 630090, Russia. Electronic address: Ivanov@tomo.nsc.ru.
authors.forename: Konstantin L
authors.initials: KL
authors.lastname: Ivanov
keywords: Adiabatic transitions; Long-lived states; Spin pairs; Spin relaxation