Molecular control using dc electric fields: Quenching of the tunneling in HF dimer

High resolution, optothermal infrared spectra have been obtained for the HF dimer in a uniform de electric field, varying in strength from 0-150 kV/cm. These fields not only serve to orient the molecules in the space fixed frame, but also to quench the tunneling motion that is normally characteristic of the HF dimer. This is attributed to the fact that the electric field makes the double well tunneling problem asymmetric in the limit that the molecules are well oriented. A simple 1-D model is used to qualitatively explain the results.