Acetylene vacuum absorption

A number of hydrocarbon radicals having multiple bonds at the radical centre have also been trapped in inert matrices and studied by IR spectroscopy. Thus, ethynyl radical was obtained by vacuum UV photolysis (9) of matrix-isolated acetylene (Shepherd and Graham, 1987) as well as when acetylene and argon atoms excited in a microwave discharge were codeposited at 12 K (Jacox and Olson, 1987). An appearance of diacetylene bands was observed when the matrices were warmed up, while the absorptions of the radical C2H disappeared. Detailed isotopic studies of D-and C-labelled ethynyl radicals showed a surprisingly low frequency of the C=C bond stretching vibration at 1846 cm instead of c.2100cm for a true C=C triple bond (the band at 2104 cm was attributed to the... 

The absorption of acetylene in the vacuum-UV spectral region has also received extensive study, both experimentally [363-370] and theoretically [371-374]. The spectral region 155-200 nm displays an abundance of complex, diffuse vibronic structure [365]. Much of this absorption, which is substantially stronger than that associated with the A—X system at longer... 

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