Pulse Pyrolysis Infrared Laser Jet Spectroscopy of Chloroketene

The short-lived molecule chloroketene (ClHCCO) was generated by the pyrolysis of chloroacetyl chloride in a high-temperature nozzle and the infrared laser-absorption spectrum of its nu(2) fundamental band was measured between 2153 and 2161 cm(-1). The spectrum was greatly simplified by comparison with a room-temperature spectrum enabling 230 lines of the (35)ClHCCO isotopomer to be assigned and measured. A least-squares fit of these transitions yielded accurate molecular parameters for the v(2) = 1 state using ground state constants from microwave spectroscopy. The nu(2) band origin of (35)ClHCCO is 2157.19238(16) cm(-1). A comparison of simulated and experimental spectra showed that the rotational temperature of the jet spectrum was around 35 K. Copyright 2000 Academic Press.