EXCITATION-FUNCTION OF THE AL-2-]ALO+O REACTION - A COMPARISON WITH KINETICS(O)

The reaction Al(P-2(J)) + O-2(X(3) Sigma(g)(-)) --> AlO(X(2) Sigma(+)) + O(P-3(J)), Delta epsilon(0) = -0.145 eV, is reinvestigated using co mbined pulsed lasers and pulsed, crossed, supersonic molecular beams. The relative reactive cross section is found to decrease within the sa mpled relative translational energy domain epsilon(tr) = 0.041-0.42 eV . The observed complex dependence reveals a shift from covalent to ion ic in the character of the interaction potential experienced by the re actants with increasing collision energy. The variation of the thermal rate constant calculated from the excitation function is in excellent agreement with recent kinetic measurements of Garland performed in th e temperature range 298-1083 K. Decrease of the rate constant at highe r temperatures is predicted by the analytical expression k(T) = 0.66 X 10(-10) T-0.2/{1 + T/2100}(1.7) cm(3) molecule(-1) s(-1).