ON THE UNEXPECTED OSCILLATION OF THE TOTAL CROSS-SECTION FOR EXCITATION IN HE2++H COLLISIONS

Recent calculations and measurements have revealed unexpected oscillat ions of the total cross section for excitation in low-to intermediate- energy He2+ + H collisions. A physical explanation of this behavior is given here stemming from analysis of classical trajectory Monte Carlo simulations, molecular orbital close coupling calculations, and solut ion of the time-dependent Schrodinger equation on a numerical lattice. These results indicate that the observed behavior should be character istic of a wide range of reactions in ion-atom collisions.