Total Electron Scattering Cross Sections inO2and Ne

A modified Ramsauer technique has been used to measure the total low-energy scattering cross sections of electrons in ${\mathrm{O}}_2$ over an energy range from 2.35 to 21 eV, and in Ne over a range from 0.37 to 20 eV. A broad clearly defined "bump" is observed in the $e-{\mathrm{O}}_2$ cross section with the maximum occurring between 11 and 12 eV. Both the ${\mathrm{O}}_2$ and Ne cross-section data are in good agreement with Brüche's measurements at energies above 2 eV. Extrapolation of the low-energy Ne data to zero energy, using modified effective-range theory, yields a zero-energy scattering length of $(0.\mathrm{}30\pm 0.03)a_0$, where $a_0$ is the Bohr radius.