VIBRATIONAL-STATE DISTRIBUTIONS RESULTING FROM ASSOCIATIVE IONIZATIONIN NA(3P)-NA(3P) COLLISIONS

We report on the vibrational energy distribution in Na-2(+)(X(2) Sigma (g)(+)) ions resulting from the associative ionization reaction betwee n two Na(3p) atoms as determined via their wavelength-dependent photod issociation. Results at 10, 25, 85 and 140 meV mean collision energy w ere obtained for excitation of the sodium atoms with circularly polari zed light. For 10 and 25 meV mean collision energy the results show a dominant population of the v = 3 state (55% and 33%, respectively). Fo r 85 meV collision energy two maxima are found, located near v = 3 and 7, whereas for 140 meV the results show a roughly linear increase of the vibrational population with v within the wavelength range measured . These results are in agreement with previously published results for conditions where a comparison was possible. Measurements at 25 meV ex citing with linearly polarized instead of circularly polarized light d o not differ significantly from the results mentioned above. The measu red vibrational state distributions give information on the shape, at small internuclear distances, of the diabatic molecular potential curv e(s) involved in the associative ionization process.