Dipole moment of nonrigid molecular systems: The dipole moment of hydrochloric dimers

摘要

In recent experiments on HCl dimers, three surprising observations were found. A "dipole moment" was measured in Stark-shift-related experiments despite the spectroscopic indication of fast tunneling motion. The measured dipole moment varied with the state probed, and the apparent first-order Stark effect was observed only in the case of the heterodimer H~(35)Cl-H~(37)Cl but not for the homodimers (H~(35)Cl)_2 or (H~(37)Cl)_2. We present physical arguments which explain all the observations and indicate that the spectroscopy has to be reinterpreted and that the isotope effect in the tunneling motion can not be inferred simply from the spectroscopy.