Associative ionization in collisions between excited Na atoms in the 3(2)P(3/2) and the 3(2)P(1/2) states

For the first time, associative ionization has been observed in an atomic beam of excited sodium atoms in both the 3(2)P(3/2) and the 3(2)P(1/2) state. Relative values for the partial cross sections were obtained specified according to the different magnetic substate combinations of the two fine-structure states. These were found to be comparable to those for associative ionization between two Na*(3p;2P(3/2)) atoms. However, the effect of the 3(2)P(1/2) excitation on the Na-2(+) ion production rate was found to be considerable and to depend strongly on the relative polarizations of the laser beams producing the two populations due to the redistribution of the involved magnetic sublevels. The results indicate that the initial orientation of the electron spin S does not significantly influence the associative ionization reaction at the mean collision energy of 25 meV.