抄録
The rate of para-ortho conversion in solid deuterium (D2) is calculated taking two types of interactions, i.e., the magnetic dipole-dipole interaction between D2 molecules and the coupling between the nuclear quadrupole moments of one D2 molecule and the total quadrupole moment of the other molecule. It is found that both interactions make about the same contributions to the para-ortho conversion if only the interactions among para molecules are taken into account. However, the ortho molecules with I=2 also interact magnetically with para molecules and convert them into ortho molecules. The calculated conversion rate due to the para-para interactions is found to be 0.01 % per hour times c2, where c is the para concentration, while that due to the para-ortho interactions to be 0.01 % per hour times c(1−c), so that the c2 termes eventually cancel each other, leaving a total conversion rate which is proportional to c.
