Transfer of para-hydrogen spin order into polarization by diabatic field cycling

In a para-hydrogen induced polarization (PHIP) experiment, it is possible to obtain a substantial net polarization of a hetero nucleus using a diabatic field cycling scheme. This is experimentally demonstrated for hydroxyethyl propionate. The screening of the ambient magnetic field was accomplished by using several concentric mu-metal cylinders. The field cycling is modeled as a sudden decrease from intermediate field to low field, followed by an adiabatic remagnetization. An analytical expression for the polarization as a function of the constituent scalar couplings, using an idealized field cycling profile, is derived for an AA'X spin system. It is also demonstrated that the hyperpolarized compound can be used for magnetic resonance imaging (MRI). (C) 2004 Academie des sciences. Published by Elsevier SAS. All rights reserved.