The 5-0 overtone absorption spectrum of HCl

The 5-0 overtone absorption spectrum of HCl was recorded using intracavity laser absorption spectroscopy. The Ti-sapphire-based intracavity laser absorption spectrometer was used in the measurements. Spectra were recorded as a series of overlapping 6.9-7.2 cm-1 wide spectral segments. The generation time used was 100 μs which resulted in an effective pathlength of 23.6 km for the 1.81 m long intracavity compartment that contained the HCl gas. Most lines were recorded at 12-22 torr pressure, measured with a 100 torr full scale Baratron capacitance manometer. A few lines of higher J were recorded at 52-55 Torr. Calibration was accomplished by alternatively measuring the spectrum of the intracavity HCl species and an I2 absorption spectrum was recorded from an extra-cavity iodine cell heated to approximately 500 °C. Very good agreement was observed among the values for the molecular constants.