The differential cross sections of the process Na + I Na+ + I- on
the energy range from 13 to 85 eV have been measured using hybrid crossed beam/gas target atomic beam setup
. They have also been calculated using a semi-classical LZ model with the lowest-order stationary-phase approximation, uniform rainbow approximation and JWKB phase shifts
. We conclude that for these cross sections:
- the Landau-Zener theory can be applied by the simple use of the
in order to calculate the energy-dependent and impact-parameter dependent differential cross section contributions
A value of the parameter H12 can be estimated from the measurements.
- the rotational coupling makes clear the large contribution to the differential cross section for collisions with large impact parameters
, leading to an experimental estimation of Hrot.
- impact-parameter method and classical deflection function
give the correct angular positions of special features of the differential
cross section due to scattering from the known ionic potential curve
and from the known part of the covalent potential.
- lowest-order stationary-phase approximation, uniform rainbow
approximation and JWKB phase shifts
give a perfect description of the
primary rainbow and some low-number supernumeraries, but a rather
serious discrepancy arises with the interference structure when
collisions with large impact parameters contribute to the
differential cross section. The discrepancy is dependent on the
- interference structure of the contributions due to scattering with
small impact parameters leads to an estimation of the covalent
repulsive potential relative to the known ionic repulsive potential.
It is expected that the objection of conclusion 4 to the
interference structure does not hold because of the very good
agreement of calculated and measured energy dependence of the
repulsive interference structure.