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 ato mic 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 obtain ed specified according to the different magnetic substate combinations of the two fine-structure states. These were found to be comparable t o 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 pr oduction rate was found to be considerable and to depend strongly on t he relative polarizations of the laser beams producing the two populat ions 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 a t the mean collision energy of 25 meV.