Studies of the positive muon behavior in solid H-2 and D-2

Using a pulsed muon beam, we have investigated the microscopic mu(+) behavior in solid H-2 and D-2 down to 0.6 K by the mu(+)SR method. From the studies of mu(+) spin relaxation phenomena in solid para-H-2 and ortho-D-2, we have found that mu(+) forms three distinct microscopic states; H-2 mu(+) (D-2 mu(+)) (20 similar to 25%), muonium (15 similar to 20%) and mu(+) (similar to 60%). In H-2 mu(+), the mu(+) spin is depolarized in solid para-H-2 and a local magnetic field B-loc = 1 similar to 2 G is deduced from LF-mu(+)SR measurements. The magnitude of B-loc is inconsistent with the magnetic dipolar field (similar to 25 G) expected from the magnetic moments of two protons in the H-2 mu(+) molecule and suggests that the H-2 mu(+) molecule might be in the rotationally excited state. From LF-mu(+)SR measurements, muonium and mu(+) have been found to diffuse in solid o-D-2. The diffusion rate of muonium is two order of magnitude larger than that of mu(+).