Absolute doubly differential cross-sections for electron emission in 25 MeVIuMO" + He collisions were measured as a function of the electron energy and emission angle.The data show enhancement at forward angles and reduction at backward angles with respect to results derived using the Born approximation. Comparison with a continuum distorted-wave approximation suggests that this observation can be explained by the combined influence of the projectile and t,arget Coulomb fields on the ejected electron. This two-centre effect is found to be particularly important for electron emission at backward angles.

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