Symmetry of MolecularH2in Si from a Uniaxial Stress Study of the3618.4cm−1Vibrational Line

Abstract

Uniaxial stress has been used in conjunction with vibrational spectroscopy to probe the structure and microscopic properties of interstitial ${\mathrm{H}}_2$ in Si. The stress splitting pattern observed for the $3618.4\mathrm{cm}{}^{-1\mathrm{}}$ line assigned to ${\mathrm{H}}_2$ is consistent with triclinic ( ${\mathrm{C}}_1$) symmetry of a static center. The piezospectroscopic tensor determined in these experiments suggests a near $〈100〉$ orientation for the ${\mathrm{H}}_2$ molecular axis. The low symmetry that has been found in these experiments on the $3618.4\mathrm{cm}{}^{-1\mathrm{}}$ line is unexpected.