Measured third-order susceptibility and excited-state oscillator strengths for atomic mercury

We have measured the null positions in the third-order susceptibility for two-photon resonant (6 ${}_{}{}^1{}_{}{}^{}7$ ${}_{}{}^1{}_{}{}^{}$,3S) sum-frequency mixing in atomic mercury. In addition, we have made measurements of some 7S-nP oscillator strengths using a fluorescence-dip technique. Combined with earlier results we are able to obtain a set of 7S-nP (n=7–13) oscillator strengths which gives a good description of the third-order susceptibility. The uncertainty in the 7S-nP oscillator strengths is typically 35–50%. The absolute third-order susceptibility has been determined for energies less than 83 000 ${\mathrm{cm}}^{\mathrm{-}1}$ with an uncertainty of typically 20–30%.