Excitation spectroscopy of the acetylene ÖX transition in the 220 nm wavelength region

The fluorescence excitation spectrum of the à 1Au–X 1Σg+ transition of acetylene has been examined in the 220 nm wavelength region. Sharp lines were observed at frequencies that agree with earlier studies using absorption spectroscopy, and most lines previously reported as blended were well resolved. Time-resolved fluorescent decays following excitation in four of the peaks revealed suprisingly long lifetimes (2–5 μs in the low-pressure limit). Two of the levels exhibited modulation in their fluorescent decays.