Nuclear Polarization of Hydrogen Molecules from Recombination of Polarized Atoms

The nuclear polarization of H2 molecules formed by recombination of polarized H atoms on a Cu surface was measured as a function of external magnetic field and of temperature of the surface. The proton polarization of the molecules was determined by scattering of a longitudinally polarized 203-MeV proton beam in the Indiana University Cyclotron Facility storage ring. The nuclear polarization of the molecules, relative to the polarization of the atoms before recombination, increased from near zero in a weak magnetic field to 0.42 6 0.02 in a 0.66 T field. A simple model of the relaxation accounts quantitatively for the observations.