DYNAMICS OF MOLECULAR PENNING IONIZATION - ANGLE-ENERGY DISTRIBUTIONSOF N-2(-ASTERISK(2(1)S)+N-2() FROM HE)

Angle-energy distributions resulting from the Penning ionization of N- 2 by metastable singlet helium He(2(1)S) at collision energies of 2.5 and 4.4 kcal/mol have been measured using crossed supersonic molecula r beams and a rotatable mass-spectrometric detector. Predominantly for ward scattering of N-2(+) is observed, and although substantial backsc attering is also present at both energies, the collision intermediates are mainly short-lived. Both the sharpness of the forward-scattering peak and the mean recoil energy increase at the higher energy. The res ults are compared to quantum scattering calculations based on a recent ly proposed set of potential surfaces. (C) 1998 Elsevier Science B.V.