High resolution optothermal spectra have been obtained for the Ar-HCl and Ar-DF complexes which conclusively show that they do not dissociate on H/D-X vibrational excitation. The observed linewidths place a lower Limit on the lifetimes of 500 ns, while time-of-flight considerations indicate that the lifetimes are in excess of 0.4 ms. Stark spectra are also reported, which result in the determination of the (upsilon = 1) excited state dipole moments of these complexes.