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eV.deg) 1/2, FIG. 3. The quantity NE^'^ is plotted as a function of T-E6. N is the index number for the extrema of n(T) (A^ = 0,1, 2, • • • for maxima; i, i, •' • for minima). Open symbols are maxima, closed are minima: circles, 200 eV; triangles, 300 eV; squares, 350 eV.where J LL is the reduced mass and b^ and ^a ^^^ the values of the impact parameter b corresponding to the two scattering potentials for a given scattering angle 0, The linear dependence of NE^^^ on T shows that Ab is approximately independent of r: Afe^0.62a.u. At 350 eV, the behavior of the differential cross section is more complicated: Oscillations appear also in this case, but they seem to be distorted by another phenomenon. In this case the quantity NE^^^ is still a linear function of T-TQ (see Fig. 3), but the slope d(NE^^^)/dT and the values of Ab are slightly larger than for the previous energies. With regard to the diabatic correlation diagram of the Heg"*" system,^ the mechanisms causing the two curve crossings can be considered as possible mechanisms for the He {ls3p, ^P) excitation, corresponding to two electrons being elevated from the (lsag)(2/)au)^^Sg antibonding input channel to {ls(y^)^{4da^)^Z^ and (Isag)-(4^7rg)2 2ng.In an attempt to clarify the parts played by short-range and long-range crossings, we are currently investigating the "companion" level R. L.