Pulsed molecular beam infrared absorption spectroscopy of HCCHCO

The rotationally resolved absorption spectrum of the HCCHCO dimer was observed in the region of the CO monomer vibration by a rapid-scan infrared diode laser and a pulsed molecular beam. The observed spectrum of HCCHCO supported a linear molecule. The vibrational wavenumber is determined to be 2149.3444(13) cm−1 and the shift is 6.073 cm−1 from the fundamental of the CO monomer.