We report experimental measurements of the differential cross sections for scattering of electrons in the range 8-20 eV from helium and argon through scattering angles of 10 degrees -140 degrees in the presence of a high intensity ( approximately 108 W cm-2) carbon dioxide laser. The majority of the results reported are scattering from argon under conditions for which the Kroll-Watson approximation, usually applied to these types of measurements, predicts zero cross sections. The cross sections reported range up to approximately 12% of the appropriate field-free elastic scattering cross sections in strong disagreement with the theoretical predictions.

The authors report experimental measurements of electron spectra resulting from the scattering of low energy (6.2-32 eV) electrons by helium atoms through an angle of 9 degrees in the presence of a high intensity ( approximately 108 W cm-2)CO2 laser. The intensities of the additional peaks caused by the presence of the laser which occur separated from the elastic scattering peak by multiples of the photon energy are much greater than expected on the basis of calculations, using the Kroll-Watson approximation (1973). The intensity of these free-free transitions also increases with decreasing electron energy, again in disagreement with the calculations. The authors propose that the disagreement between the experimental results and those calculated is due to the electrons scattering from a helium target polarized by the laser field.

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We report measurements of the differential cross section for scattering of electrons, from helium, with energies in the range 1–20 eV through scattering angles of 14°–140° in the presence of a high-intensity carbon dioxide laser. These results were obtained with beam geometries for which the Kroll–Watson approximation, normally applied to these types of measurements, predicts zero cross sections. The cross sections reported are not zero but confirm similar experiments with argon as the scattering centre. PACS No.: 34.80Qb