We investigate heteronuclear collisions in isotope mixtures of laser-cooled metastable (
3P2) neon. Experiments are performed with spin-polarized atoms in a magnetic trap for all two-isotope combinations of the stable neon isotopes
20Ne,
21Ne, and
22Ne. We determine the rate coefficients for heteronuclear ionizing collisions to ${\ensuremath{\beta}}_{21,20}=(3.9\ifmmode\pm\else\textpm\fi{}2.7)\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}11}$ cm
3/s, ${\ensuremath{\beta}}_{22,20}=(2.6\ifmmode\pm\else\textpm\fi{}0.7)\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}11}$ cm
3/s, and ${\ensuremath{\beta}}_{21,22}=(3.9\ifmmode\pm\else\textpm\fi{}1.9)\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}11}$ cm
3/s. We also study heteronuclear elastic collision processes and give upper bounds for heteronuclear thermal relaxation cross sections. This work significantly extends the limited available experimental data on heteronuclear ionizing collisions for laser-cooled atoms involving one or more rare gas atoms in a metastable state.
Using crossed atomic beams and mass spectrometric ion detection we have studied the formation of negative Ca ions in slow collisions between laser-excited state-selected Ne** ( ns , J = 2) and Ne** ( nd , J = 4) Rydberg atoms and ground state Ca atoms. The rate coefficients exhibit resonant behaviour with maxima at an effective principal quantum number n * of about 11.5 and an estimated peak value of about 10 −8 cm 3 s −1 . Two different theoretical calculations, based on a curve-crossing model and on a modified adiabatic theory, respectively, yield n *-dependences of the rate coefficients in good agreement with the experimental results.