Mid-Infrared Diode Laser Spectroscopy of X ; 1 A ' HC35 Cl.

The observation of the C-Cl stretching fundamental of HC35 Cl in its ground X ; 1 A ' state is reported. HCCl was formed in a continuous flow system by the excimer laser photolysis of CHBr2 Cl at 193 nm and the transient absorption recorded by infrared diode laser spectroscopy. The band has a -type character and the fundamental vibrational frequency is found to be 811.5963 cm-1 . No evidence was found for perturbations in either the ground or vibrationally excited states, implying that the excited triplet a 3 A " states lies above the C-Cl stretching level in HCCl. The observed rotation-vibration transitions were well fit by a standard asymmetric rotor Hamiltonian. There is a decrease in the A rotational constant on vibrational excitation, suggesting that some bend-C-Cl stretch coupling is present.