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Highly Efficient Polarization of Spin-1/2 Insensitive NMR Nuclei by Adiabatic Passage through Level Anticrossings
journal contribution
posted on 2015-12-17, 04:54 authored by Andrey
N. Pravdivtsev, Alexandra V. Yurkovskaya, Nikita
N. Lukzen, Konstantin L. Ivanov, Hans-Martin ViethA method is proposed to transfer spin order from para-hydrogen, that is, the H2 molecule in its singlet state,
to spin-1/2 heteronuclei of a substrate molecule. The method is based
on adiabatic passage through nuclear spin level anticrossings (LACs)
in the doubly rotating frame of reference; the LAC conditions are
fulfilled by applying resonant RF excitation at the NMR frequencies
of protons and the heteronuclei. Efficient conversion of the para-hydrogen-induced polarization into net polarization
of the heteronuclei is demonstrated; the achieved signal enhancements
are about 6400 for 13C nuclei at natural abundance. The
theory behind the technique is described; advantages of the method
are discussed in detail.