Ym. Xiao et al., NUCLEAR-RELAXATION DURING THE FORMATION OF H-2 FROM SPIN-POLARIZED HYDROGEN, Physical review. B, Condensed matter, 48(21), 1993, pp. 15744-15754
We report an NMR study of solid H-2 formed by the recombination of dou
bly polarized atomic hydrogen at a temperature of approximately 0.3 K.
The molecules are formed in a highly excited ortho state with M(I) =
-1, thermalize through collisions with the He-4-coated walls of the co
ntainment chamber, and form a solid. The solid is essentially pure ort
ho H-2 in the fcc phase, as expected. However, the nuclear polarizatio
n is close to zero, in contrast to the value of -1 if there was no rel
axation, and +0.034 if the spin temperature was in equilibrium with th
e surface of the cell. Possible mechanisms for depolarization are disc
ussed, though no plausible explanation for the loss has yet been found
.