Insight into the rotational motion of H2 in Si from the IR spectrum of HD

The rotational-vibrational transitions of HD in Si are subject to less restrictive selection rules than for the homonuclear H2 and D2 molecules and give rise to a richer IR spectrum. IR lines for transitions between rotational-vibrational states of the interstitial HD molecule with rotational quantum numbers J=0, 1, and 2 have been observed. The assignment of the rotational-vibrational spectrum of interstitial HD, with additional transitions that occur for HD but not for H2 or D2, is confirmed by uniaxial stress results.