An inversion procedure to recover the intermolecular potentials from low-energy (4-14 eV) differential scattering data for the systems HeH', NeH', ArH, and KrH' is presented. The first step in this procedure is to construct the phase shifts (t)(f)) from the experimental differential cross section 0(8) and, for reasons of intuition, the corresponding classical deflection function. This is accomplished by employing a new technique developed recently by Remler which involves singularities in the S matrix. The Remler method is as accurate as, but less cumbersome than, the frequently employed standard partial-wave sum and in addition leads to an intuitive connection between t)(l) and o(8). Having found (n(f)), the inter molecular potential may be determined by means of the transformation method of Vollmer.To test the entire inversion procedure, the intermolecular potential obtained from the H +He scattering data is compared to the ab initio calculation by Wolniewicz of the ground-state potential for HeH'. This method should be applicable to any spherically symmetric scattering system.

95'7electron's energy are not accounted for in the model. These would be expected to be larger for the smaller nuclei. A more detailed examination of the formulation is required to see if one can retain the basic simplicity of the impulse model and obtain corrections for these effects. publication with the understanding that no limitation shall exist on the reproduction and distribution of its published or unpublished form in whole or in part for any purpose of the U. S. Government.The result of a differential scattering experiment of H by Ne at 5. 71-eV collision energy is compared to the differential cross section predicted by (a) a JWKB partial-wave calculation based on a potential model, (b) a similar calculation based on the ab initio Peyerimhoff calculated intermolecular potential for the NeH' system, and (c) a new and more efficient calculational scheme developed by Remler involving Regge poles. The agreement of the Peyerimhoff prediction, (b), with the experimental data is very good. Differences between the Peyerimhoff potential and the final values of the parameters retrieved from the iterative calculation in (a), as well as implicit ambiguities of (a) in reproducing the features of a low-resolution experiment, are discussed in terms of semiclassical theory and the Remler-Regge method.

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