Spin relaxation for laser-pumped hyperpolarized spins

摘要

In this work it has been found that the conventional spin relaxation equations are not valid for the hyperpolarized spins. New longitudinal relaxation equations for the dipole- dipole coupled hyperpolarized spins have been derived. These new equations predict that the longitudinal magnetization relaxation for hyperpolarized spins is, in general, bi- exponential instead single exponential. They also predict that for dipole-dipole coupled hyperpolarized spins the steady state longitudinal magnetization is larger than the thermal equilibrium magnetization. These findings are useful as the base-line information for accurate analysis of the effects of the paramagnetic sources on relaxation of hyperpolarized spins in living body.