A new infra-red absorption line at 3191.1/cm was discovered for the interstitial HD molecule in Si. This new line appeared for sample temperatures above approximately 20K and lies 73.9/cm below the 3265.0/cm line previously observed for HD. The 73.9/cm energy difference was attributed to the rotation of the interstitial HD molecule. The selection rules associated with these two lines were consistent with the puzzling absence of an ortho-para splitting in the infra-red absorption spectra of H2 and D2 in Si.

Key to Understanding Interstitial H2 in Si. E.E.Chen, M.Stavola, W.B.Fowler, P.Walters: Physical Review Letters, 2002, 88[10], 105507 (4pp)