VIBRATIONAL-SPECTRUM OF LINEAR C3H IN SOLID ARGON

A Fourier transform infrared isotopic study has been made of the deuterium and carbon-13 substituted C3H radical produced by trapping in solid Ar the products of the vacuum ultraviolet photolysis of CH2CHCH3 (propylene) or a mixture of methane and acetylene. The 1824.7 and 1159.8 cm-1 absorptions, which in earlier work using only deuterium isotosopic data could be assigned to either the cyclic or linear isomer, can now be definitely identified on the basis of extensive C-13 isotopic measurements as the nu2(sigma+) and nu3(sigma+) fundamentals of linear C3H. The frequencies of the fundamentals and D and C-13 isotopic shifts are in good agreement with the predictions of preliminary ab initio calculations for the linear isomer.