Supersonic free-jet quantum cascade laser measurements of ν4 for CF335Cl and CF337Cl and FTS measurements from 400 to 1260 cm−1

A supersonic free-jet spectrum of the ν4 band of CF3Cl has been measured using a quantum cascade laser system. Those measurements were combined with a low temperature (−67 °C) FTS spectrum of the region 1060-1260 cm−1 and with room temperature FTS measurements down to 400 cm−1 to give improved values for the rovibrational constants for the ν1, ν2, ν3, 2ν3, 2ν5, ν4, and ν5 states of CF335Cl and CF337Cl. The principal perturbation found by earlier investigators in the ν1 band is treated as a very weak Coriolis interaction at several avoided crossings of the rotational levels of the ν1 state and the 2ν5 state with kl < 0. None of the other vibrational states showed any signs of perturbations. With these new measurements we now have high resolution data on all of the fundamental vibrational states except ν6.