Collisional perturbation of states in atomic ytterbium by helium and neon

Results of an investigation of collisional deexcitation of the metastable $6s6p{}^{3}{P}_{0}$ state in atomic ytterbium by helium and neon buffer gases are reported. We find upper limits for the quenching cross sections to be ${\ensuremath{\sigma}}_{\mathrm{He}}l13\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}22}{\mathrm{cm}}^{2}$ and ${\ensuremath{\sigma}}_{\mathrm{Ne}}l8\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}22}{\mathrm{cm}}^{2}.$ The small cross sections may allow an ytterbium parity nonconservation experiment to be performed in a vapor cell. We have also measured the pressure broadening and shift of the $6s6p{}^{3}{P}_{0}\ensuremath{\rightarrow}6s7s{}^{3}{\mathrm{S}}_{1}$ and ${6s}^{2}{}^{1}{S}_{0}\ensuremath{\rightarrow}6s6p{}^{3}{P}_{1}$ transitions by helium and neon.