ABSOLUTE CALIBRATION OF ELECTRIC-FIELDS USING STARK SPECTROSCOPY

We have established a direct link between laboratory electric fields a nd the atomic constants using Stark spectroscopy on n = 15 sublevels o f Li-7, coupled with an R-matrix theory of the Stark effect. Measureme nts are made with frequency-stabilized laser excitation by scanning th e field from zero to above the saddle point. To estimate the zero-fiel d energies we use quantum defect parameters from the polarization mode l for l greater than or equal to 4, and a fit to all available spectra l data for l less than or equal to 3. We claim that the electric field is known to about +/-2 ppm +/-5 mV/cm. Improvements and extensions ar e discussed.