Associative ionization of laser-excited Rydberg states in strontium vapor.

Using mass spectrometry we have confirmed that Sr(2)(+) ions are produced from laser-populated Rydberg states by the associative ionization process Sr(5snl) + Sr(5s(2)) ? Sr(2)(+) + e(-). Dimer ion signal was detected for the 5s6d(3)D(2) level, indicating that the binding energy of Sr(2)(+) exceeds 0.77 eV. We have observed that under certain conditions the Rydberg states are destroyed by electron-impact ionization before an associative ionization collision can occur.