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 13C isotopic measurements as the ν2(σ+) and ν3(σ+) fundamentals of linear C3H. The frequencies of the fundamentals and D and 13C isotopic shifts are in good agreement with the predictions of preliminary ab initio calculations for the linear isomer.