A NEW THEORETICAL APPROACH TO COLLISION-INDUCED AUTOIONIZATION IN ATOM DIATOM SYSTEMS WITH REPULSIVE INTERACTIONS

A two-dimensional classical trajectory model of the dynamics of the io nization event in low-energy collisions in repulsive autoionizing A+B C systems is introduced. The approach makes full use of the fact that before the ionization event A+ BC(v(n)) --> [A...BC+ (v') ] + e - tak ing place in repulsive systems, the BC coordinate is weakly coupled to the remaining ones. A separate quantum mechanical treatment of the pe rturbed BC(nu'') [BC+ (nu') ] vibrational motion is adopted and includ ed into the calculation of static characteristics of the system which thus depend on the A-BC distance R, the A*-BC angle gamma and the per taining vibrational quantum numbers of the perturbed BC and BC+. The B C collision partner is treated as a rigid rotor. Test calculations on He(2 3S)-H-2(nu'' = 0) with collision energy ranging from 10 to 150 me V (the average almost-equal-to 51 meV) are presented. The approach is found to yield a picture of the He (2 3S) + H-2 (nu'' = 0) - [ He...H- 2+ (nu') ] + e - ionization event, which is close to that provided by precise Penning electron spectra measurements.