Stark spectroscopy of polar molecules solvated in liquid helium droplets

Presented here are the first rotationally resolved Stark spectra of a polar molecule in a liquid. This high-resolution spectroscopy is made possible by the fact that superfluid liquid helium is extremely homogeneous. The results presented here show that the interactions between the molecule and the helium solvent result ins splitting very similar to that induced by the applied electric field, providing new insights into the nature of these interactions. [S0031-9007(99)09227-3].