A CC STRETCHING VIBRATION OF THE C6H (HEXATRIYNYL) RADICAL IN AR AT 10-K

A study of the Fourier transform infrared (FTIR) spectrum of the products of the vacuum ultraviolet (VUV) photolysis of acetylene and 1,3-butadiene trapped in solid Ar has resulted in the identification of a vibration of the C6H (hexatriynyl) radical at 1953.4 cm-1. The spectra of various D and C-13 isotopomers of C6H produced from isotopically substituted precursors have been observed. The complex, overlapping spectra resulting from partial C-13 substitution have been fitted using a force constant adjustment calculation and support the assignment of the 1953.4 cm-1 absorption to a C = C stretching fundamental of linear C6H. The results of an ROHF/6-31G* ab initio calculation of the vibrational frequencies for the fundamentals of linear C6H are also reported.