FOURIER-TRANSFORM VIBRATIONAL SPECTROSCOPY OF SI2C IN SOLID AR

A Fourier transform infrared study of the vibrational spectrum of Si2C produced by vaporizing mixtures of silicon and carbon-12 or carbon-13 and quenching the products in Ar at 13 K has confirmed a previously observed vibration at 1188.4 cm-1 as the nu-3"(b2), antisymmetric Si-C stretching mode, and resulted in the identification of a new vibration at 839.5 cm-1 as the nu-1"(a1), symmetric Si-Si stretching fundamental. No bending mode has been observed; however, the identification of an absorption at 1354.8 cm-1 as the nu-2"(a1) + nu-3"(b2) combination band is proposed. The results are confirmed by C-13, Si-29, and Si-30 isotopic data and are in excellent agreement with the predictions of ab initio calculations carried out by Rittby in collaboration with this work. Force constant adjustment calculations confirm the ground state geometry as a floppy, bent symmetrical structure.