Many Electron Continua in Strongly Perturbing Collisions of Heavy Ions with He, Ne and Ar

S. Hagmann, I. Ali
James R. Macdonald Laboratory, Kansas State University

The quantitative description of many-electron continua which are produced in multiple ionization of atoms in strongly perturbing collisions beyond total cross sections has eluded an a priori theoretical description since a longtime due to the many-body Coulomb continua involved. In order to provide detailed experimental multiple ionization continuum electron momentum spectra we have measured doubly differential cross sections for electron emission in collisions of F⁹⁺ and I²³⁺ with He, Ne and Ar targets for strong perturbations with emphasis on those ionization channels where the target is left highly ionized. Electrons with energies between 0 and 1000 eV and emission angles between 0° and 180° were measured using an electrostatic toroidal electron analyzer equipped with a 2D-position sensitive electron detector in coincidence with the recoiling target ion. We find the cross section for forward electron emission to increase with recoil charge state, i.e. ionization multiplicity, before decreasing again for higher recoil charge states whereas the transverse and backward electron emission is decreasing monotonously with increasing multiplicity. Similarly, inner shell ionization cross sections, seen via Auger emission, exhibit a dependence on the ionization multiplicity comparable to the forward continua.

Supported by Div. of Chem. Sciences, Office of Basic Energy Sciences, Office of Energy Research, U.S. Dept of Energy.

 

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