A Raman scattering study was made of H2 trapped at the interstitial T site in Si. Both ortho and para nuclear-spin states of H2 and D2 were observed. It was shown that the Raman signals of H2 and D2 in the J = 0 state, where J was the rotational quantum number, disappeared preferentially from the spectra during laser excitation or prolonged storage at room temperature in the dark. This surprising behavior was tentatively explained by positing different diffusion rates of H2 in the J = 0 and J = 1 states.

Ortho and Para Interstitial H2 in Silicon. E.V.Lavrov, J.Weber: Physical Review Letters, 2002, 89[21], 215501 (4pp)