Pulse pyrolysis infrared laser jet spectroscopy of chloroketene

The short-lived molecule chloroketene (ClHCCO) was generated by the pyrolys is of chloroacetyl chloride in a high-temperature nozzle and the infrared l aser-absorption spectrum of its v(2) fundamental band was measured between 2153 and 2161 cm(-1). The spectrum was greatly simplified by comparison wit h a room-temperature spectrum enabling 230 lines of the (ClHCCO)-Cl-35 isot opomer to be assigned and measured. A least-squares fit of these transition s yielded accurate molecular parameters for the v(2) = 1 stare using ground state constants from microwave spectroscopy. The v(2) band origin of (ClHC CO)-Cl-35 is 2157.19238(16) cm(-1). A comparison of simulated and experimen tal spectra showed that the rotational temperature of the jet spectrum was around 35 K. (C) 2000 Academic Press.