DIRECT IONIZATION IN THE QUASI-MOLECULE H-HE

Doubly differential cross sections for electron ejection in H-He colli sions have been measured in the incident atom energy range 2.3-10 keV. Analysis of the experimental data on the basis of the adiabatic theor y of direct ionization has been made and parameters of the quasimolecu le, namely, the energy of the initial 2p sigma state coupled with the continuum, the effective charge, and the real and imaginary parts of t he internuclear distance at which the ''superpromoted'' diabatic term crosses boundary of continuum, have been determined. The values of the initial-state energy and the effective charge agree well with the cor responding parameters of the Li united atom, whereas the dynamical cha racteristics ReR(E) and ImR(E) reveal considerable influence of electr on correlations. The possibility for the development of an alternative method of quantitative spectroscopy of quasimolecules based on the an alysis of experimental data on differential cross sections for direct ionization is discussed.