Infrared Stark spectroscopy of the hydrogen–HF binary complex

A sub-Doppler resolution infrared spectrum has been measured for the HF stretch of the H2–HF complex using the optothermal detection method. Infrared Stark spectra have also been obtained from which both the ground and first vibrationally excited state dipole moments have been obtained. It is clear from these measurements that the HF subunit undergoes wide amplitude bending motion even in the zero-point bending state. Broadening of the transitions due to the finite lifetime (27 ns) of the excited vibrational state is just discernible under the highest resolution conditions.